Green Building Forum - Heating and cooling

Our old mate Damon Hart-Davis

SteamyTea — Sat, 19 Nov 2016 13:21:21 +0000

Some of the older members may remember that Damon was working and a self setting/programmable room stat.

He has asked me to post up a link to the website.

Hopefully it is not too commercial and others find the project useful.

https://myradbot.com/

New Heating System Advice

Herodotus — Sun, 06 Nov 2016 09:11:43 +0000

Hi All,

Looking for some advice on how best to approach a new heating system - primarily for DHW but perhaps later for SH via UFH.

We live in a small single storey house with a flat roof in the mountains in southern Spain. We are currently working on getting it properly insulated (from the outside!) but the bureaucracy involved means it's probably going to take a while. We currently have 3 woodburning stoves - two small freestanding ones and a larger glass-fronted one built into the old chimney in the living room. For DHW we have a decrepit on-demand gas boiler connected to a cylinder outside.

Our DHW demands are fairly limited. Normally we'd have between 2 and 4 people living in the house, but we're all grubby hippies and we probably shower a maximum of 2.5 times a week on average, and we probably don't use more than 30l of water when we do - so that's 300l of shower water a week - of which not all will be from the hot water system. The rest is washing up/domestic cleaning, so I'd guess we're not normally using more than 100l of DHW / day at the absolute maximum - and usually less.

The DHW system needs changing urgently. Our water comes from our own springs, and we don't have a huge head on it - currently only a few metres - might end up being more soon if we can get another tank commissioned a bit higher up - but pressure isn't great. We're having loads of problems with insufficient pressure causing the boiler to cut in and out when having a shower + the boiler is old and not very good anyway. We have a lot of free wood available and an aversion both to on-demand gas boilers - which I've never liked - and using fossil fuels for heating generally.

We'd like to move to heating our water with wood + PV electric (we have a 3.75k solar array whose output we are rarely using to the max) + possibly some sort of simple solar collector. For the time being we're going to try and continue to do space heating using the wood burners but it's possible that at some point in the future we'd like to have the option to do something with UFH if we have the time/money to redo all the floors :-/

The obvious simple solution in a UK property would be a vented DHW cylinder with two coils, one from a wood boiler and one from the solar (with the option to add a buffer for UFH later). The problem with this is that, living in a single storey building with a flat roof, the venting/expansion requirement is tricky to do. I don't want to have to have a pump just to get adequate DHW pressure. Is there a way round this that I'm missing?

From a safety perspective, I'm pretty uncomfortable about a sealed system with a solid fuel boiler. Even with pressure relief valves and maybe a heat-dump towel rail or somesuch, the prospect of having a potential bomb that could flatten my house if I overstoke the boiler makes me twitchy. Also, pressurised cylinders seem like an important potential point of failure even in "normal usage" - I believe in the UK they need to be inspected annually for this reason? Am I being unduly paranoid about this? Is there a way to use a sealed system with a solid fuel stove safely?

That leaves me with some sort of thermal store option - dumping the heat from boiler + solar + electric into a big tank of water and then extracting it into DHW via an internal coil/internal tank/external PHX. In the future we could potentially use the store water to run UFH as well. On paper this looks like the most suitable option for us, but it's also going to be expensive + I'm worried that for the quantity of DHW we need it's pretty wasteful heating a big thermal store. I'm also lost on the whole internal coil vs external PHX thing - I'm obviously keen to maintain as much stratification as possible so that we can get sensible temp DHW with a minimum size store, but I can't work out which system is better for that. PHXs can return cool water to the bottom of the tank, but only if the hot water demand is enough to coil the primary circuit water significantly; coils give you a certain amount of stored hot water + they're simpler + their impact on the cylinder water isn't dependent on speed of DHW demand, but I'm guessing that even the best designed coil is going to destratify the cylinder more than a PHX system operating in ideal conditions...

Other points to note (in no particular order):

* We're at 1200m altitude and it does freeze here occasionally - solar collector probably needs to be indirect with glycol I guess
* We get a pretty decent amount of sun most of the year - our small DHW water needs can probably be delivered from solar almost all of the time if it's done right

Any thoughts/pointers gratefully received!

Cheers,

Noisy Hot Water tank when heating is on

Dominic Cooney — Fri, 04 Nov 2016 19:03:17 +0000

Haven't posted on here for a while...
but have been busy as we've sold up and bought a smallholding 2 years ago. There's so so much that could be discussed regarding the new place but -
the problem that's bugging me at the moment is the noise of running water from the hot water tank when the central heating is on.
We recently had the system drained down in order to have a new immersion element fitted (it was completely shot and was tripping the electric), and a leak fixed on a radiator pipe on the ground floor.
The immersion now works fine and provides hot water when the oil boiler is not in use, so there was no problem for the first few weeks
When I came to put the heating on now that the weather has gotten a bit cooler (just for an hour morning and evening to take the chill off), there is a lot of noise from the hot water tank, gurgling and such but mainly sounds like running water. Only when the pump is running. Pump seems to be working, can get heat to all radiators.

When the heating (timed) goes off the noise stops.

It didn't make this much noise before all this.
I had been using the oil boiler for hot water only for a while until I got the plumber in to do the immersion, and it wasn't making all this noise.

Bog standard Hot Water tank is on the first floor, indirect heating coil (I'm guessing) nothing fancy. woefully under-insulated of course, but that's another story for another day...

Been up in the loft and there doesn't seem to be any sign of boiling or bubbling in the expansion tank.

Any thoughts or suggestions?
I could probably bleed all the radiators again to be certain, but I can't help thinking it is something else, maybe an airlock or something? The system is quite old and has been extended/added to over the years.

Triple Wall Chimney Question

ComeOnPilgrim — Mon, 31 Oct 2016 18:10:26 +0000

We have a new build which we hope to be very airtight. I was quite excited by a triple wall chimney which offered to suck the air needed for the stove through the same chimney as the smoke would go through. However, the company have just quoted me Â£4K for installation, or Â£2K for the materials. This seems a bit pricey, so I am reconsidering it. I have a couple of questions:
1. What's the real benefit of a triple wall chimney? Could I not just get a double wall chimney and have a different pipe bring the air to the stove?
2. I was previously thinking that the chimney would go through the ceilings and the roof, but this is quite problematic as the joists do not line up on the 1st and 2nd floors, and then there are the rafters on the roof. Could I not just go through the external wall and up the outside of the building?

Infrared radiant bathroom heaters

smudger — Fri, 29 Aug 2014 15:04:45 +0100

I was about to order some Rointe Towel rails for our bathrooms (running off economy 10) to combat chill and counter mould on walls (solid block, north facing). If the green deal is ever resurrected we will externally insulate but in meantime we need to do something this winter.

An older post mentioned infrared radiant heaters as an alternative (in ceiling, not what we want to do). I've come across 'mirror' types that go on the wall but struggling to differentiate between them and they are also more expensive than the rointes.

Will they do the job I want and any seen any in the flesh to be able to recommend any?
Ecolec, greenage, ecolec, agadon and stove centre have been thrown up by g**gle.

thx

Hot bedroom with twinwall flue,how to cool...

Julesbarn — Thu, 27 Oct 2016 20:57:57 +0100

Hi again,

After remedial first floor ts insulating,(with great results),one of the bedrooms is still getting too hot..and of course it's the one with the flue passing through. It happens when the stove is running; not when the ts is charged. The small landing remains cooler. The flue is boxed in and vented top and bottom,with 60mm clearance as it should be.

I thought a clever fan arrangement might work to redistribute the unwanted extra heat, and I had a mild eureka moment!

We have a flue thermostat which starts the back boiler circuit pump when the flue reaches a certain temperature. If i wire up a little fan to start when the pump kicks in, (and of course stop when the pump stops; when the flue has cooled enough),then i can have heat extraction from the boxed-in void when appropriate.

Of course,i must maintain my 60mm clearance between flue and combustibles, so the fan cant be within the boxed-in void. Perhaps a length of 50mm diameter stainless flexi pipe (i happen to have some lying around) could take the heat from the void, with the fan located on the cieling below,in the sitting room, above the wood stove, but 60mm+ from the flue. Not only will this put the unwanted extra bedroom heat where i want it, but help move and mix the radiant heat from the stove across the gf sitting room and open plan kitchen/dining area.(a bit like those stove-top heat driven fans).

Please tell me this is a good idea..or why it may not be! (maybe it's been done before). I used to sometimes have the most wonderful inventive ideas whilst drinking too many beers of an evening in my workshop...until the morning,when i saw my sketches and scribblings from the night before,and felt a bit silly! I don't do that any more. So,again,i hope I'm not missing something.

Any thoughts welcome

Thanks,

Jules

Thermal store..too hot upstairs!

Julesbarn — Sun, 23 Oct 2016 15:13:03 +0100

Hello everyone,
I've just joined this brilliant forum,and firstly I'm seeking help with a dilemma in my recently completed barn conversion.

I did all the work myself,and we love the results,but I was probably given some not so good advice along the way.we have a 390 l thermal store located on the small,first floor (rooms I'm the roof,so low volume as well as floor area),which is served by a 14kw wood boiler stove in the sitting room near the stairs. (Solar thermal yet to be fitted; coil waiting at the bottom of the store). The system seems to work really well; with plate heat exchanger for dhw,ground floor ufh,and a small radiator circuit on first floor which we will probably never use : (

Our problem is that it gets too hot upstairs for our two daughters bedrooms, sometimes even when the stove is not lit,but the store is hot.(me and partner,have gf bedroom which is cool if we want). As a result,the girls insist on opening the roof windows to cool their rooms,thus letting a lot of precious heat out and noticeably cooling down the ground floor. It really frustrates me; i meticulously fitted a lot of insulation in the roof, and even used a perlite/lime backing plaster on the thick cob walls for that extra bit of warmth (perhaps?!?).

My thoughts on how i can improve the situation are....

1. Add loads more insulation around the thermal store itself - which I'm in the process of doing,

2. Insulate the ts cupboard doors- done that, with 25mm celotex,

3. Add more insulation to the ts cupboard itself,

4. Tell the girls to shut their bedroom doors if their windows are open - they don't always, so I'm often trotting up the stairs to check.. A real hassle!

5. Fit door closers on their bedroom doors - "dad, you're getting a bit anal about all this heat loss stuff !" ,

6. Somehow fitting a fan somewhere clever to either send heat from the ts cupboard,or ff in general,downstairs to equalise the temperature of the barn.

I can't isolate the two floors,the landing is tiny so a door at the top of the stairs wouldn't work,or comply with regs, and the bottom of the(kinda) spiral stairs are open to the sitting room and a very beautiful feature,and i aint moving the store downstairs...there's nowhere it can sensibly go (and the thought of re-routing all the plumbing..!)

Soo, I'd love to know your thoughts; if any or which of my ideas,would help remedy the situation. Of course,it's not all the thermal store's fault,bless it...the woody puts out 5 kw max to space (officially),and,as i said, it's located near the stairs. Oh,and by the way,all first floor voids are well insulated,with super good underlay n carrpet above!

Many thanks, (as i have gone on a bit)

Jules

Solar collector for MVHR pre-heating

EasyBuilder — Thu, 22 Sep 2016 22:59:55 +0100

Except during a heatwave my MVHR takes its input from the loft at the top of a south facing roof slope. Even with an efficient heat exchanger there is benefit, especially because I've added a thermostat to turn on boost and summer bypass when the incoming air is over 22Â°. With this it can heat the house on sunny days from March onwards. However there's less benefit in winter, not just through less sunshine, but also because the roof loses a lot of heat at night and is slow to warm up. Would it be better to take the fresh air from a solar collector on the south wall mounted below the eaves? I've seen them made from twin wall polycarbonate, or from perforated metal, but don't know which would be best, or what the optimum size would be. I'd appreciate tips from folk with experience of these things.

Insulating wooden panel doors

Julesbarn — Tue, 25 Oct 2016 12:10:17 +0100

Hi. I am already getting a fair amount of condensation on my two external panel doors on chilly mornings (on the panels themselves). Is there any harm in insulating the panels,if the edges are sealed to the door?
The doors are chunky douglas fir,the panels being 22mm thick. They are stable doors,top part 2g argon 16mm gap,and hardly any condensation yet,but the bottom panels have been pretty wet some mornings. Worst affected is east facing, other west facing and not so bad for some reason.

I could make some doug fir panels to fix over existing recessed panels giving a 15mm gap to fill with....
Bubble foil,carpet underlay,celotex cut down to 15(horrible job),something reflective, or just a gap vented/unvented??

Is it worth it? Any ideas welcome

Thanks,

Jules

Heating P&ID. Please can someone check my proposal. Stove, GSHP, UFH.

geoheated — Tue, 25 Oct 2016 13:22:25 +0100

Hi All,

Would appreciate any feedback on my layout. It took some months for me to get this down on paper.
Its part of my renovation of the entire house.

I have no experience with stoves but have spoken to a few people and read alot about the requirements.

I have purchased a good used 6kW GSHP. Heat losses for the house are around 5kW peak.

I hope to extend the house in a few years, so ground loop and DHW tank are sized to allow for an 8kW GSHP and 2 bath's 1 Shower.

Hope it makes sense....

Thanks

Heating solution for straw bale hall - Radiators or IR?

Sandbank — Sat, 22 Oct 2016 15:25:01 +0100

I need advice for affordable options to retrofit permanent heating in a new strawbale hall, 80m2 with a high sloping ceiling. Ceiling, floor and upper walls lined with sheep's wool, covered with plasterboard. Rationel windows and entry door. (We did not have enough money to put the heating in at time of construction, otherwise UFH would have been desirable). The hall is mainly used evenings for dining, also in the day for groups eg for yoga/meditation - so noise is a factor, also ease of use as its hired by outside groups. To date, we use 4 x 3kw oil-filled radiators, to establish the requirements. Left overnight they heat the room sufficiently for a weekend.
One option (cheapest?) is to hardwire in electric radiators - there are limited fixing points on the walls, but it is possible. Maybe in conjunction with a heat curtain at the entrance door.
Another option is Infra-red from the ceiling? Would this be more efficient in the long term? The hall is generally clear of furniture etc.
There is an array of 64 solar panels on the roof, which feed into our general supply for other buildings. See www.kenchhill.co.uk

Infrared heater staring at wall

gyrogear — Sat, 08 Oct 2016 00:49:26 +0100

Since I retired my electric floors, our large lounge can be pretty cool of a winter morning (18.7Â°C on 15 November last year, which was too cold even for me...). This is no doubt due to the fact that my (purposely undersized) 7.5 kW woodstove does not last through the night... One solution is to set the alarm for 5:30, do a quick burn and go back to bed - not very "lifestyle-friendly"...

I am therefore considering adding two low-cost infrared heaters -- dual 600/1200 watt (tubes). Since these are not very aesthetic, I want to mount them on the back side of the tie beam that connects the two roof trusses (we have a cathedral ceiling) -- the tie beam is parallel to the ridge purlin, and about 2.5 meters below it.

The heaters would then be well above floor level, off our general trafficable route, and out of sight. They would be pointed at a partition wall, 4m x 4m and 1.5 meters distant, which is the frontage to our northern rooms (bathrooms, toilets, box-room, loftspace). The partion wall is hollow-brick with plaster over. The backside of the upper half (to loft space) is insulated with 30mm XPS.

The idea is to use the IR to warm the partition wall, turning it into a sort of "storage radiator". This would collaborate with our ceiling fan... For just a couple of hours - once the sun gets going (around 10-ish) we are generally OK...

If the system works, I would get the electrician to install some sort of timer control.

Would be grateful for opinions, to see to what extent I am "off the wall".

gg

Ariston NUOS

smudger — Fri, 30 Sep 2016 21:07:38 +0100

Anyone seen, used or opinions on these?

http://www.aristonthermo.com/en/Brand/water_heating

http://www.bse3d.com/wp-content/uploads/2014/10/Ariston-Heathrow-Perfectionists-Cafe-NUOS.pdf

I'm looking for efficient water heating system with a bit more flexibility than off peak cylinder/immersion (we also have 'excess pv' to benefit from).

Any alternative solutions to look at?

small Backboiler heat sink

Terry Hudson — Sat, 17 Sep 2016 15:25:27 +0100

Im plumbing in a simple primary radiator circuit off a wood burner back boiler that only puts out 3 Kw
I will use a pump as I want a rad in the cellar as well as the ground floor.
I only need a tiny heat sink radiator of a half a KW ? (in case of power failure)
How much heat is lost on a 6 meter 28 ml copper pipe to the loft vent?
does the heat sink radiator have to be the first radiator?
can it be in the cellar on the return run?
It seems like I am asking the impossible.
Any thoughts would be appreciated.
I am likely going to want to use the fire, without heating anywhere upstairs is my problem.
Thanks

Crazy idea - smoke alarm inside MVHR plenum?

Swarm — Mon, 05 Sep 2016 00:04:17 +0100

I'm thinking of adding more smoke alarms, to bedrooms, a cupboard with server in etc. Then I thought, what about adding one inside the extract plenum for my MVHR. Then if by some remote case of a fire starting in a bathroom, the smoke would quite quickly find it's way into the plenum and trigger the alarm.

Which will then alarm the others and shut down power to the MVHR.

Rehau Helix Probe alternative

jonc_uk — Mon, 05 Sep 2016 16:37:51 +0100

Hi All,

I have an extension which has a basement and intended to install about 20 Rehau helix probes underneath it to create an inter-seasonal heat store.

The basement has been dug, and formwork is scheduled for the end of the week. Today I have found out that Rehau have stopped supplying them!

Does anyone know of an alternative? This is the one opportunity I have for the heat store. I did a lot of research about methods of storing the heat and these seemed like the best solution. The floor area is about 220sqm.

Thanks for any help.

Jonathan

Calling Kinetic MVHR users - remote boost control upgrade

Swarm — Sun, 04 Sep 2016 19:28:59 +0100

I've experienced issues with the humidistat in my Kinetic where it will cycle between low mode and boost at night. So I've just turned off the humidistat.

This is not ideal for showers etc. so I'm wondering about using Z-wave home automation (which I already use and am familiar with) and humidity sensors in each room, or possibly little switches in bathrooms for manual control. Or both!

I'm posting in the hope that someone more proficient in electrical setup can assist a little bit. I can do all the home automation side but don't quite get the wiring of how the following will interact:

Fibaro switch manual: http://manuals.fibaro.com/content/manuals/en/FGS-222/FGS-222-EN-A-v1.01.pdf

From the Kinetic manual:

"The unit can be switched to boost by a variety of methods:
ï® Applying 240 V to the LS input .
ï® Switching across 1 of 5 pairs of switch terminals.
ï® Applying between 0 and 10 V as a proportional input to two input terminals. "

Page 23 / 24 of the Kinetic manual is relevant: http://www.vent-axia.com/files/pdf-downloads/439817Q_4.pdf

Any help much appreciated, or I will have to try Vent Axia support and hope they're helpful. :)

Rayburn and smokey chimney

Quercus-Jim — Fri, 02 Sep 2016 11:14:38 +0100

Hello all,
Wondered if anyone could help shed some light on why my newly installed (used) Rayburn Royal mf seems to smoke excessively (from the flue top). It's a cooker only installed with a 6" twin wall flue which rises to about 4m above a flat roof. The thing that's baffling me is that I'm burning kiln dried hardwoods (which burn very cleanly in our Rojek boiler and produce no smoke once heated up) but with the spin wheel open to any degree and the flue damper open it chucks out a dark brown smoke which doesn't ease up even when everything has warmed up. I've tried all combinations of spin wheel open/shut and various damper positions but nothing calms it down. It has a very good draw and doesn't takes minutes to get going like a furnace. The only way I can stop it smoking is to close the spin wheel fully and almost fully shut the damper then it produces barely a whisp of smoke. Thing is, I don't like shutting it down within a few minutes of lighting as it's obviously going to soot up the appliance and flue. This seems almost backwards to me, as ime a woodburner would smoke more if you bank it down soon after lighting. Have checked the inside of firebox and under hot plate and nothing wrong, flue was new, wood around 18% mc. Surely it should be burning very cleanly given the above? Can too much draw make dry wood smoke excessively? I ain't never seen it with 2 woodburners and a boiler but this setup seems special. Any ideas gratefully received! Thanks Jim

MVHR Duct Condensation trap or not?

Phil.Chaddah-Duke — Tue, 09 Aug 2016 09:14:25 +0100

Hi guys, currently extending our MVHR system to new basement incl moving unit. I see references on at least one site if needing a trap at bottom of vertical pipework carrying stale air to outside to stop any condensation running into unit. We are using 160mm round steel ducting which is inside heated envelope along with unit itself. The unit has a drain but I assume that deals with water from the heat exchanger.

I can see the theory that as the warmer air meets colder pipe as it exits the building but don't find any such drain product for steel ducting and also how would such a trap work as it would need to he airtight? Any thoughts/experiences appreciated?

running a DC fan off of a battery charger ?

gyrogear — Fri, 26 Aug 2016 00:11:59 +0100

I have two battery chargers - one is "automatic" (to avoid over-charging): per booklet, the absorbed power = 90W.
Booklet also says : "do not use this device for anything other than charging a battery". fair enough.

My second charger is old and I have lost the booklet, but it works!
It charges at 3.5 A, off 240V AC.
I have used it to run an automobile fan - 90 W, 12 V, it runs at around half-speed, which is OK for my application.
I am (1) curious to calculate the absorbed power and (2) curious to know whether I should not use it in this application ?

(I don't want any fires !).

Thanks for any assistance !

gg

MVHR filters and traffic pollution

Swarm — Thu, 25 Aug 2016 17:54:19 +0100

I've only had my MVHR running for a few months and noticed that one of the filters is very dark grey, rather than the white it was. The MVHR vents are about 10m up on the outside of the house and about 5m horizontally from a road that's not that busy. Although we do have a bus stop outside... :(

Has anyone else experienced traffic pollution on their filters? It makes me wonder what is getting past the filters...

Also, is it normal for a lot of water to be in the heat exchanger, I pulled it out to check it over and got a shock when water started spilling out!

Lastly, as mentioned in another topic, I'm getting quite a lot of fruit flies and the odd fly + month loitering in the unit too. Just concerned something may not be set up correctly as I have no previous experience of MVHR.

How to set up test for UK A2A heat pump performance

GarethC — Wed, 10 Aug 2016 10:57:36 +0100

How could you do this?

Am I right that you'd just need a shed of a reasonable size with an A2A heat pump installed. Would need to work out the heating needs of the shed, and probably insulate a wee bit to make it sensible.

Would you need to heat using an electric heater to confirm the heating needs empirically?

Internal target temp set to 20 degrees for between say 8am and 10pm. Monitor to track electric usage.

Wouldn't even need a whole year of data to be useful. Would even be good just to have a bit of data to see how humid/wet days affect it, and what happens in the external temperature zone of between zero and 7, where funny things MAY happen.

Ventilation MVHR for shop?

Victorianeco — Wed, 03 Aug 2016 11:13:35 +0100

The shop (7m x 8m) has no opening windows apart from in the small WC, I have insulated the loft using 350mm mineral wool and will be using 50mm PIR for IWI. The ceilings are 3m high.

There is also a basement which has no insulation whatsoever....

What form of ventilation should I use? A single heat recovery extractor fan? A MVHR unit located in the basement with exhaust and supply and the inlet located in the basement and the outlet floor level in the shop?

Heating will be by an ASHP/Air Con unit

Ideas please?

UFH - carbon saving with electric?

alexj — Tue, 02 Aug 2016 09:19:29 +0100

I'm considering UFH for our Victorian ecoretrofit, for the first floor bathroom and the open plan kitchen/living room. The bathroom will be first, the downstairs will probably but not definitely happen. My priority is to cut carbon and use non-toxic materials - this means they should be natural, biodegradable or recyclable.

I'd like advice on the type of system and on the Carbon Question (below).

Systems:
I am looking at 3 options:
- wet UFH throughout, run on gas - advantage is that we could in the future swap this to running on an air source heat pump
- electric UFH in the bathroom (easier and cheaper as we're doing this room first) and then wet in the downstairs rooms if/when we get round to it
- a sort of hybrid - a system from Jupiter, which uses a tile instead of screed, so a wet system but dry install. Advantage here is the ability to specify wood fibre insulation instead of EPS (expanded polystyrene) and not totally bury the pipes that run underneath the bathroom floor under a solid screed.

The Carbon Question:
I've installed solar pv which should generate c. 3000kWh pa. We use c. 600kWh. Both figs are based on 6mnths data, Jan-July. (I now realise I overspeccd this and should have gone partly thermal. Bugger.)

So if I install electric UFH in the bathroom, do I make a carbon saving as compared to using gas, as we generate so much 'surplus' electricity? I haven't got any storage for the pv and obviously we'll be mostly using grid electricity when we actually need the UFH on, but is the net effect one of saving carbon? I buy electricity from Good Energy.

Help with choosing thermal store

ltaylor88 — Fri, 03 Jun 2016 09:33:05 +0100

Hi I'm new to the forum but have read a lot of posts already. We have just bought a good sized 3 bed bungalow in need of refurbishment and new heat system as it has storage heaters.

We have just installed a Wood burning back boiler with 7.kw to water 4.5 to room (more on coal) the property already benefits from a Solar thermal panel on the roof which I have been plesently surprised by as I thought Id be ripping it off. and we later plan to fit oil as a backup when funds allow.

The solar is currently as it was installed just to a single coil 120ltr tank with immersion. its in a stupid place so we want to move it.

we are at the point we want to hook the stove up to the new rads but im at point where I need to chose a system. I had been planning using a netralizer (dunsley or systemlink) but there is very little info on them and what info on forums there is always seem to have some saying saying "Why not fit a Thermal Store". So.... I have been looking at thermal stores instead. we have a budget of around a Â£1000 for the store. I have found one thats fits the bill at a good price from a company that sounds like popperpylinders.co.uk they have very good reviews on there normal cylinders. It is a oven vented store with two boiler inputs(direct), Heating direct. Indirect solar and mains indirect hot water via coil rather than heatX(as we have very hard water)

Our stove is in the front room on a central single chimney. and If I go with the TS I would like to put it in the loft directly above the stove. on an open vented system

Do you recommend integral header tank?
Can I take just two feeds from stove to TS ( ie Stove vent from TS)
Is a 10% heat leak ok on the stove
Will a 250 ltr give us decent hot water supply or should we go 300?

any working schematics for my system would be appreciated.

Sorry for babbling on.

Thermal store dhw coil setup

ALwoodburner — Sun, 17 Jul 2016 00:45:08 +0100

Hi everyone,
Been following with great interest and have learnt a great deal so Thanks for that.
The setup: Galu 300l solar TS as yet not plumbed in . Store has a preheat coil and a top coil. In the room below a morso db15 boiler stove.What I have in mind is a coil around the stove pipe to act as a preheat to the preheat. It'll get pretty hot if no hot water is used for even a short time . My first question being ,would this coil need it's own expansion vessel ?
And if I fit a pressure reducing valve in the cold supply where would be a good place to put it . I'm wondering if the first preheat could restrict the flow a little ?
One last thing ,where would a pressure relief valve be best situated in same circuit.
Any help would be greatly appreciated.
Alex.

MVHR & Open Windows on hot nights

richardelliot — Tue, 19 Jul 2016 13:23:47 +0100

We are two weeks into living in our new house. The first few days were very hot internally (I fear we have a bit too much solar gain), but once the MVHR was turned on the internal temperature regulated itself a lot better and we were trying to keep the windows closed (which is what I understand you should do with MVHR). Generally this was working ok, but I did notice that two of us sleeping in the bedroom overnight definitely heated up that one room quite a bit.

Last night in London was very warm (as was the rest of the country I think). The MVHR, even on night time purge, didn't seem to be cutting it so we threw open the windows to get a cooling cross breeze coming through the house.

Interested to know what other people with MVHR did last night / will be doing over the next few days. Do you open your windows? Or should the MVHR be able to cope?

Can i avoid an ASHP and still comply with the SAP requirements?

treeplanter — Tue, 05 Jul 2016 10:31:10 +0100

I am building a new house, 158m2 internal space. I have to meet sustainable regulations as it was on a 'greenfield' site (between two houses, on a road in a village - but it had cows on it), so i am not passive house standard, they call it an 'eco-house' which in reality seems to be only a bit higher than standard building regs.

There is no town gas here so the SAP report says to use an ASHP to UFH with an electric emersion heater for DHW.
â€¦.however my preference would be to drop the ASHP altogether and have Calor gas, a PV array and a small wood burner with a back boiler. I have also downloaded all the Accredited Details forms, which i will document as i go, to improve my SAP rating.

Question is how can i calculate if this is possible? Do i go back to the report writer or can i do it myself? I'm concerned that if i wasn't to pass the SAP rating i wouldn't get my VAT back :sad:

How not to install a mini-split

Ed Davies — Mon, 11 Jul 2016 10:27:51 +0100

https://twitter.com/passivistas/status/751714535074127872

Why am I not surprised at this news, re a quietly abondonded biomass heating scheme

orangemannot — Wed, 29 Jun 2016 11:44:30 +0100

https://www.theguardian.com/environment/2016/mar/03/uea-abandons-ambitious-biomass-scheme
sigh!

MVHR and stove

Davegilsenan — Sat, 25 Jun 2016 22:23:21 +0100

Hi all,
First post on here.

I have searched around and the subject of wood burning stoves and mvhr has been covered but not quite the situation I have.
I am building an extension - the part of the original house that remains is old, leaky etc. The new extension is being built with lots of care and attention to detail but without a particular air tightness target.
I am installing an MVHR mostly to avoid having to install little useless extract fans in the kitchen, utility, downstairs toilet, bathrooms as required by building control. I hate those little fans which do nothing except make noise.
I want to install a small stove in the living/dining area. Can anyone see a reason these won't be compatible or is there anything in particular I should look out for? I know on really airtight houses there can be issues.
Unfortunately, the location for the stove is not on an outside wall so a direct air supply isn't possible.
I guess I'll have to have the requisite free ventilation area although there is plenty of leakage available already in the house.

Thanks,
Dave.

Speccing my air to air heat pump system

GarethC — Thu, 16 Jul 2015 12:08:49 +0100

While I struggle to find a sound consultant that can provide the necessary analysis, I'm beginning to spec the heating system I'd like to install.

Current requirements:

1. Single outdoor unit (better cost/benefit than multiple units + easier to get permission, but louder and slightly lower COPs than two smaller units)

2. SCOP of 4+ (to cut CO2 by 40%, and heating costs by 25%, vs. my high efficiency combi boiler). Ideally, Iâ€™d like an official SCOP of nearer 5, as I apply a 20% haircut to official figures, but Iâ€™d need an R32 system and suitable ones arenâ€™t available yet. Maybe by the time planning comes throughâ€¦

3. Circa Â£2k for equipment (including ducting etc. if necessary)

4. 10kW max output

5. Heat distribution to three zones (had hoped that one central zone would suffice, with heat flowing to other rooms naturally, but donâ€™t think it would work)

Point 4 is taxing me. Which would be better, a single internal unit ducted to three zones or a multi split system with three internal units? I -think- the latter, as:

1. Running the narrow pipework to each zone would be a lot easier than installing outward and return ducting between each zone and a single central unit, plus thermostats for each zone.
2. The wall mounted units will mix the warm air in faster and better than air delivered through a duct.

A single indoor unit is cheaper than three indoor units, but I think the hassle and cost of ducting, plus the less efficient air mixing, offsets the benefits.

Would appreciate any thoughts on this issue, and any others please.

Cutting UK heating + hot water C02 by 56%, subsidy free

GarethC — Wed, 09 Sep 2015 12:44:37 +0100

This is pursuant to another thread. And Iâ€™ve touched on this before. Itâ€™s an interesting thought experiment. Iâ€™m sure itâ€™s full of holes, but if not, thereâ€™s a knighthood in there for someone. Discuss!

â€œHow to reduce UK space heating and hot water carbon emissions by 56% compared to current levels over twenty years, subsidy free, cheaply and with no other government intervention (maybe).â€

An air source heat pump system which provides heating and hot water for Â£3k at an SCOP of 4.0 would reduce space heating and hot water C02 emissions by 42% (see note 1) compared to a high efficiency natural gas boiler at current grid intensity (0.519kg/kWh, 2) and cut running costs by 25% (3).

The average household gas bill is Â£752. A 25% decrease saves Â£188 per year, Â£940 in five (say Â£1k). A replacement boiler costs Â£2k installed. Our system costs Â£1k more, but savings would cover this in 5 years â€“ an excellent payback incentivising homes to adopt just for financial, let alone green, reasons. Note, no subsidies anywhere here, in fact delivering long term reductions in domestic heat bills.

Gas boilers last about 20 years. Almost all must be replaced by then. All boilers might be replaced with our new systems over that period without forced ditching of working boilers. This would deliver a 42% cut in total UK domestic heating and DHW emissions by the end of the period.

If some of the gas displaced (wouldnâ€™t need all of it) instead generated electricity in new gas power stations, they would deliver electricity with marginal emissions of 396kg/kWh (4), 24% lower than current grid intensity. Powering our systems with this electricity would deliver emission cuts of 56%. It should also lower electricity costs, improving system payback and incentives to adopt.

If, over that 20 years, other measures reduce grid intensity, as they will, then emissions cuts would be even larger. These measures might raise electricity costs by a third, and homes would still pay no more than today for heating and hot water due to the lower running costs of the new systems.

We need to cut emissions by 90% vs. 1990 to be sustainable. If domestic heating + DHW emissions have already fallen by 15% (donâ€™t know!), then our systems would help cut emissions by 1-0.85*0.44 = 63% vs 1990 by, say 2035 (if we start replacing soon). With cuts in grid intensity, better heat pumps and fabric improvements (lower demand) by then, we could be done for domestic heating + DHW (businesses too?).

So, we need to design a system fitting the requirements chaps! Really should be doable.

1. Natural gas space heating emissions are 0.184 kg/kWh (http://tinyurl.com/nwc4rlq) divided by 82.5% efficiency = 0.224 kg/kWh. Therefore a system with an SCOP of 4.0 will deliver emission reductions of 1-0.519/4.0/0.224=42%.

2. Not 0.462kg/kWh and 47% as used previously. Previous figure used doesnâ€™t include 7% grid losses, and the emission intensity of imported energy. Although advised by DEFRA, I canâ€™t think why you would exclude these.

3. Average domestic price of gas in Q1 2015 was 5.0p/kWh, and price of electricity was 15.6p/kWh (http://tinyurl.com/o8zybas). So 4 SCOP delivers 1-15.6/5/4=25% saving.

4. Taken gas turbine emissions as 370 kg/kWh from the 2014 IPCC report (http://tinyurl.com/nub25kr)*1.07=396kg/kWh including grid losses. Divided by 4.0 SCOP= 0.099. 1-0.099/0.224 = 56% reduction. This intensity figure doesnâ€™t include â€˜life cycleâ€™ add-ons, but I donâ€™t think other figures Iâ€™ve used do either. Should they?? If so, gas boiler emissions figures should probably have a life cycle figure included too if not already. Check IPCC report for figures.

Connecting PEX (or Pex-Al-Pex) to aluminium

gyrogear — Mon, 30 May 2016 01:13:36 +0100

I want to make a solar absorber comprising a series of aluminium channels, and have got the picture that brass unions are out...

I want to use screw connections into the aluminium wall (1mm thick), but am having a time tracking something down. I thought that nylon might be OK.

Collector will be outside :shamed: and in potentially saline atmosphere...

All help much appreciated.

gg

thermostatic valves for ventilation duct

tychwarel — Sat, 21 May 2016 16:33:46 +0100

We have just completed a 100kW community hydro scheme in which the building is cooled by a passive ventilation system (near floor level vents for incoming cool air and heated air leaving through high level vents).
Today the generator set got a little to warm (running flat out at 100kW). This suggests as we thought during the design phase that we need a little more ventilation, however we donâ€™t want the building getting too cold in the winter so would like to put thermostatic valves on the vents.
Has anyone know a supplier for basic mechanical thermostatic dampers that would fit the 100mm ducting we are using.

"Smart" wall thermostat to maximise use from solar thermal panels

gohuwgo — Wed, 18 May 2016 08:02:08 +0100

Iâ€™m after advice for a wall thermostat to maximise the use we make of the solar heat we generate from our thermal panels. Hereâ€™s the issue:-
In an Alpine climate, on sunny days, our solar system generates lots of lovely hot water. However, production stops when we run out of cold water to heat, and when this happens Iâ€™d like to use the excess to start the UFH, using the wall thermostats connecting to the bottom of the water store tank. We can already achieve the same manually when at the building by looking at the temperature stats on the water store, but weâ€™re often not there so would like to do this automatically, and be able to monitor over wifi.

Currently we have 3 (non wifi) thermostats over the building (one on each of the 3 floors), and they are set to start the heating when the building is used most of the time (post 4pm, and pre 9am). On cloudy / foggy / snowy days I want to keep the heat in the tank, so itâ€™s ready for night time heating / DHW, when itâ€™s needed most. Note the DHW and UFH comes from the same tank â€“ see below.
Iâ€™d like to find a Wifi connected smart wall thermostat that connects to our Akvatherm 1000ltr water store, so we can:-
1) Control Wall Thermostat remotely via Wifi, and be able to set rules such as: if temp > 35 degs at bottom of tank between 10am and 5pm then direct heat to UFH.
2) Control the immersion heaters on the water store remotely (the Akvatherm water store has 2 immersion heaters, 6kw each â€“ one for DHW, and the other for heating backup), and check they are working properly.

I looked at the Nest system, but not sure if this will work for what I want to do (but maybe it doesâ€¦). There seems so many thermostat variants out there, and am very confused which one would work for our situation. HELP!

Description of system & environment
French Alpine chalet for 12 pax (170m2 â€“ 6 bedrooms), situated at 1350 meters. Heating & DHW load required early morning and post skiing (post 4pm). Usually most people are out in the day. Some weeks have zero occupancy, so much reduced DHW load â€“ in these weeks, we have very little cold water to heat for the solar panels to heat.
Power generation: Solar array of 17.5m2; woodburning fire (16 KW); 2x 6KW immersion heater electric backup for DHW & heating
Heat Storage: water storage tank (Akvaterm 1000 ltr) plus thermodynamic store of 250ltr acting as a pre heater. The Akvaterm supplies DHW from the top of the tank, and feeds building UFH from the middle of the tank (as per manufacturerâ€™s spec)
Other: x3 wall thermostats to control UFH. Currently set to times when heating is most required (morning / evening, with lower temps in the day). No direct link from thermostats to water stores, but it would be good to have this.

Recommendations for Gas System Boiler with Heat Store

ComeOnPilgrim — Mon, 09 May 2016 19:20:36 +0100

Hello, I'd like to have a largish heat store that can be used with a wood burner in the winter and solar in the summer. It will also need a gas boiler. I understand that I will need a 'system' boiler, but not sure what boilers to be looking at. Does anybody have any recommendations for a suitable gas boiler that would be robust and good value for money?

Best Insulation for Central Heating Pipes?

brighton_dude — Thu, 21 Apr 2016 21:45:42 +0100

Myself and a friend are insulating the floors in my 1957 bungalow. We have the floors all removed so now the joists are visible. The insulation will be of the hard type and it will go between the joists.

Underneath the joists are the pipes for the central heating. These currently have foam insulation probably put on in the 80s when I guess the central heating went in. It is 9 mm thick. I am planning on replacing it all with 25 mm thick foam pipe insulation mainly because I can. While I have access it seems sensible to improve this insulation.

I'm wondering if there is anything out there that is better than the 25 mm thick foam insulation? While I have the floorboards up it would be nice to get the best possible insulation onto those pipes.

Do I need to use a Thermal Store?

MagsonDave — Wed, 04 May 2016 12:53:44 +0100

We have a large Victorian house heated by a floor standing gas boiler situated in one of the cellar rooms. The CH system has separate ground/cellar floor and 2nd floor zones with a third set of pipes for DHW. The adjoining cellar room has been converted into a study with heating provided by 2 radiators and I am also going to fit a wood burner into the old fireplace for additional heating in the winter.
I have been considering upgrading the wood burner to include a back boiler and use it to feed a Thermal Store along with the gas boiler so that I can also use the plentiful supply of wood that I have to help reduce the considerable gas heating bill throughout the winter months.
I know that a Thermal Store is the most elegant solution but I am questioning why I need it in my particular application and why I cannot simply put the wood burner in series immediately before the gas boiler and use it as a "pre-heater" for the water? The gas boiler will always be my main source of heating and the wood burner will only be used during the cold winter months - I can't see any pitfalls with my plan not to use a TS.
Any input/comments gratefully received....

Best Value Combi?

Victorianeco — Tue, 26 Apr 2016 18:40:31 +0100

Worcester Bosch Greenstar 28i Â£600

Any good?

Oddity in this heating diagram from Vaillant

cjard — Wed, 04 May 2016 07:16:46 +0100

My air source HP comes with a nice diagram of where to put the volts. Some connections are volt free, hence extra relays but the main thrust of my query is the timer and immersion relay. In short, the heat pump is effectively controlled by some on off switches that activate it, toggle ufh or dhw, toggle heat/cool etc on terminals 3 6 7 13 and 15. The command unit just sets parameters of Heat performance and reports on sensors, it doesn't seem to issue and control commands unless it is functioning as sole thermostat (it doesn't have dhw orogramming)

In this diagram, a time clock activates it for dhw.. But unless the stat has a temperature below which it is open eg 40 degrees, and then it is closed up to 65 at which point it opens again, then it looks like a call for dhw means both HP and immersion activate? If the stat has a range then I can see how a tank at 0 would be first heated by the pump, which would then tail off as it peaked at eg 40, and the immersion take over til whatever temp is dialled in..

I just don't seem to find stats that work that way, so im wondering if this diagram is not really a situation one would create in practice. I think instead if it had a 2 channel progger, I could ask for dhw on channel 1, and really just do pasteurising on channel 2 using the immersion.. But if I did want a larger volume of very hot water regularly, configure channel 2 to coincide with channel 1 ending its call for dhw from the pump and use the immersion to top off? (Or fit an inline heater)

Edit: added a couple of other pics from a different manual that help explain the inputs 3,6,7,13,15 etc

Over heating from south facing windows

hebden-passive-house — Mon, 02 May 2016 19:33:28 +0100

Hi all I imagine this will have been discussed before but I can't find it. I am about to move into rented apartment it has a large south facing window. There is electric heating in the flat so I am glad of the window for the solar gains in winter but I am worried about it over heating in summer. I know on passive houses they put louvers to stop this. I was thinking of doing something similar on the balcony on the out side of the window. The other two windows face west so hopefully they should be okay. Any ideas?

Heat loss calculations

cascina — Mon, 25 Apr 2016 20:06:18 +0100

I am trying to put together a plan for a heating system on a new project. We are based in italy and the house is of concrete construction. I installed heating systems commercially in the uk for a number of years and did heat loss calculations on most of my installs to make sure the right boiler was selected for the job. To do this, I used the 'whole house heat loss method' using software from www.idhee.org.uk. Using this I had options to enter the dimensions of the property, current insulation, glazing, aspect, location etc. to come up with a heat loss figure which I would then use to size the boilers central heating load and de-rate the boiler as required.

I am now looking at a concrete house which appears to have no insulation in it. It is over four floors including the basement and the roof has 3 rooms and a bathroom within it under the pitched roof. Looking at the openings for the velux windows, the roof appears to be approximately 10" thick and is described by the builder and agent as 'cemento armature' which I think is reinforced concrete. What we want to do initially is to add EWI to the external structure, but the large roof was recently replaced due to a leak, with new battens and the original coppi tiles. This means within the roof space mostly pitched, we will be using IWI. Given all the surfaces are pitched concrete, I presume that this would be done in the same way as external wall, using an adhesive and then insulation screws/bolts drilled into the roof?

I will be doing the IWI straight away before winter, but the EWI may have to wait until next spring due to the rest of the work required from the builder. The question then is: how do I go about calculating heat loss before and after improvements?

Currently there is a 30 year old oil boiler and dead oil tank, so we are starting fresh. I am looking to install a wood burning boiler and have significant storage available in the adjacent barns for the wood storage. I would then be looking at having a pellet boiler to act as a reserve for when I am not there and my wife is unable due to childcare etc. I also like the redundancy of multiple input systems for when one breaks down in the depths of winter and I am away.

I have installed a few thermal stores before but normally to act as a buffer between wood burning stove with back boilers and gas boilers in SE England, but not to enable batch burning from log boilers. I would like the ability to batch burn as infrequently as possibly, so having calulated the heat loss, would want to size a thermal store appropriately to the log boiler, but oversize the log boiler for the house's heat loss to enable less frequent burning and also utilise the larger logs that appear compatible with larger log boilers.

We would also be looking to add thermal solar (I have a 30 tube ET setup in storage from a previous project) which should be able to provide most of our house DHW during the non-heating season. The main house is approximately 550m2 not including the basement.

Any help in formulating a plan would be most gratefully received as reading this forum has given me a massive appetite for getting this right first time round.

Thanks in advance.

Boiler Size & Thermal Store

clawlor — Thu, 17 Dec 2015 14:17:27 +0000

We're renovating a double upper which comprises the entire first floor and attic of a Georgian house. We've done some heat loss calcs and are in the process of doing a SAP calc. So far with the heat loss calcs we estimate that we will need approx 22kW boiler which the results of the SAP will hopefully clarify. We are hoping to use a thermal store and I was wondering if anyone has experience of how this would effect the boiler size? If the thermal store reduces boiler cycling and heat up time we therefore believe that a smaller boiler will be required although I can't seem to find a definitive answer to this on the manufacturers website.

Also I was wondering how the boiler should be sized for dhw load? -I've been told to allow 3kW for heating water.

We are spec'ing & installing the heating system from scratch so it's an opportunity to get the most efficient system possible for the flat.
Thanks C

Dumping hot water

tony — Wed, 20 Apr 2016 10:21:42 +0100

This is a hotel situiation,

Monster HW system, loads of outlets.

As it took too long for HW to get to taps someone installed solenoid valves in each services rooms associated with the any HW outlets and web linked them.

This is the regime, 5:30 dump hot water to drain through all of them for 20 mins, then every half hour dump hot water to drain for five mins until 11:30, similar in the evening

How widespread is this practice? What are we up against here.

ISO pipe thread designations

Shevek — Tue, 12 Aug 2014 11:27:28 +0100

I've entered the dark world of ISO pipe thread designations. For instance I have a plumbing fitting with an R 1/2 thread and one with a G1B thread.

Am I right in saying that 1/2" and 3/4" brass fittings will fit these respectively?

And what does the R, G and B stand for? And what does the 1 in G1B stand for?

Most secure heating and backup

ChrisEngland — Tue, 05 Apr 2016 11:18:15 +0100

Various problems meant I couldn't get to my second home over the winter - visited recently to find oil heating had failed and there was flooding from burst pipe/tank in loft (even through water was turned off and drained). The question is what to do about the heating to preclude a possible repeat, with lowest carbon footprint. My initial thought would be ASHP with inline immersion heaters in case of ASHP failure. Any thoughts about reliablilty and alternative systems would be appreciated. There is no gas to the cottage and single phase electricity - would flicker be a problem with ASHP?

Ventilation heat loss calculation

jwd — Thu, 07 Apr 2016 16:47:19 +0100

Hi
Im doing a project for a course that needs a simple calculation for the heat loss via ventilation for an office and have got myself in a muddle as the number I have found seems way too large.
The office is 6 m X 10m by 3.5m. It has an occupancy of 10 people and a photocopier. The CIBSE standards tell me I need to allow 10l/s for each person and part F tells me I need another 20 l/s for the copier in order to keep Co2 to an acceptable level. That would make a total of 120 l/s. It is 22 deg c inside and 4 deg c out side. what would be the heat losses due to ventilation? I have assumed it is naturally ventilated. I used a formula where heat extracted is 1.2 x q (the req ventilation rate in l/s) x dt (temp differential - 18 degrees).

Can anyone tell me if I am a)barking up the right tree or b) where I hae gone wrong ?

Cheers
JW

Vent Axis HR100

jemhayward — Thu, 27 May 2010 14:53:44 +0100

This unit is not very efficient (70% claimed) and uses a significant amount of power 18W low, 30W high, but it has two advantages for me:
1. its quite small so may well fit above my bathroom ceiling
2. its cheap (<Â£200), and as I need a decent extractor fan anyway the extra for HR is quite small

It would be used for extracting stale damp air from a small shower room, and would vent fresh into the adjacent (huge) living room.

Would the efficiency and power consumption tip the balance into energy consumption, rather than energy saving?

Disappearing Heat

gyrogear — Fri, 01 Apr 2016 18:48:40 +0100

Desirous to get green, I thought I'd try heating my crawlspace using house air.

I installed a couple of inline fans and started pulling air out of a warm basement room, and my (warmer) lounge.

However, the Crawlspace temperature immediately started *DROPPING* ! and kept dropping until I reduced the fans to half-speed, then it rose slightly.

When I turned the fans OFF, the CS temp returned to its normal level.

Would appreciate an explanation of what is happening, in layman terms if at all possible :sad:

cheers,

gg