Hi Julian, My system seems to be working ok since I lowered the pressure in the expansion vessel. There was no pressure in the system when I reset the expansion vessel, I then repressurised the system to approx 0.5 bar at an average temperature of 40 degrees top and bottom in the tank. It is clear to me that the expansion vessel pressure is directly linked to my boiler losing pressure. (ie. forcing woater out through the PRV when the tank gets hot). I've only really had 2 fires in the boiler since I lowered the pressure in the expansion vessel.

I'm wondering if there is anyone on here that knows about these expansion vessels as really I'm only hit and miss with my ideas. Wouls it be safe for me to lower the pressure in the expansion vessel to below 1 bar given that the cold pressure in the whole system would be at 0.5 bar when it is relatively cold???

I guess I'm asking the same question as Julian, Should the cold system pressure equal the same pressure as the expansion vessel or is there a minimum pressure that the expansion vessel should be maintained at????


Regards

Dan

My general rule is keep it simple, I have a bit of an aversion for over complicated plumbing. I only have the ACASO automix 20 situated before the pump with the temp sensor after the pump. You could also use the ACASO CT. Essentially the same valve just working from a different set of commands. I haven't found the need for anything else. After the modulating pump, I split the circuits into 3 zones, each with a 2 port control valve, TRVs on all rads and a 3 channel programmer. All very simple I know but it works fine.
Regarding insulation; DIN standards are I believe minimum 100mm, personally I wouldn't consider anything less, and I'd use something better than polystyrene. My accumulator has a flexible 100mm tight fitting jacket and I'm trying to figure out how to increase that. Starting from scratch I'd opt for about 150mm, If space is tight build that figure into your tank calculations. I don't think an 1800l tank is big enough with a 40kW? boiler, with 2 properties I would think in terms of at least 2500l
The loading valve (laddomat 21 or the ACASO version) is essential.
Instead of a stored DHW system also look at a plate heat exchanger
I can't really answer the point about the baffle plate.

Mike

Hi Peter,
Just another thought. If you're having a tank built make sure the construction is good, ( not all welding is not up to standard ), and you will need it pressure testing, again I think DIN standard is 3 bar.

Mike

Thank you for the advice given, Mike, I can agree with keeping things simple, if its not there it can not go wrong! For the insulation for the tank you mention a minimum of 100mm but something better than polystyrene, what type would you suggest? Is glass fibre any better? Is the problem with polystyrene relatively poor insulation value or the lack of polystyrene to withstand constant high temperature?

The accumulator tank will be flat sided and internally braced so either wool type or board type insulation will suit. (For the tank construction I am happy with the welder as someone who has done very good work for me in the past and my son (final year Mech. Eng.) will do the design spec. with a design working pressure of 3 bars.) I take the point about the size of the tank and having reworked a few things I can squeeze in a tank of 2500lts but the tank dimensions at 2M high, 2.5M long and 0.5M deep is not very good for stratification. This sizing will allow for 150mm of insulation.
The decision to keep the system open vented is in part to minimise the stress on the flat sided tank and in part that the system has been unvented for 15 years and I don’t want to disturb this method of running.

The 300ltr. DHW indirect tank is in plan because on the one hand this gives the opportunity to put in an electric element on night rate for back up and on the other hand the fact that I have one already helps the decision. (Currently there is 1 120ltr tank in each house and this so far has been sufficent).
Julian, the houses are reasonably insulated and this is being improved as opportunity/cash allow. The tourist guest house is not occupied too much in the winter, Christmas and New Year and occasional winter weekends, the majority of the heating load for this comes in spring and autumn. There is also a frost protection demand as we get occasional night temperatures as low as -18.

Picking up on the comment
'The upgrade will be to
1, Install an accumulation tank (1800lts) which will be purpose made to fit the space.
2, Replace the existing boiler temperature control valve with a Laddomat 21 to get some gravity circulation in the event of a power cut. (Only 4 boil-ups in 15 years!!!!)'

I am speaking as a supplier Eco Angus i would point out 2 things on the above comment;
1. Akvaterm could make a bespoke tank to 1800 litres with seamless polyurethane insulation jacket for minimum heat dissipation (maximise the use of your wood fuel)
2. Laddomat 21-60 <80kW Laddomat 21-100 80kW and above improved design (self actuating valve when there is a power cut) with insulated jacket on casing to protect from frost in Winter.

My gasification boiler was new in Nov, as was my flue. After burning in the true batch style through to mid Jan it really turned cold and my TS temp had collapsed by morning after one burn, but one burn lasted a minimum of 8 hours and having 2 separate burns just seemed a little silly apart from time consuming so I took to starting my burn at lunchtime and then, with a 'full' TS, add some really big logs - the boiler kept the tank nicely topped up as the radiators took the heat and some time in the small hours the boiler finished its burn.

OK I guess it isn't as efficient but that is my call. However, below is a pic of the inside of the cowl on my flue - I even found some crusty bits in my gutter! The flue itself is not encrusted, just a few mm of deposit that I guess is normal. The big issue was inside the back of my boiler; here there is some sort of tall chamber where the flue gasses go after being pulled through the heat exchanger and they are then pushed up to the top of the boiler and up the flue. A really large amount of crud had accumulated in the bottom (20-30mm) and I had a bottom of the flue/back of the boiler fire - the significant additional insulation I had added to this area was no doubt a contributory factor and the fact that the emergency water cooling valve (with plastic shell) was inside some insulation was just stupid!

So I learnt that if I choose to burn in a slumbering mode I must:

1/Clean the cowl mid-season.
2/Empty the back of the boiler exhaust area as part of my regular weekly (ish) clean of the heat exchanger.
3/Not put any destructible part of the boiler inside any additional insulation I might get the courage to re-apply in the distant future......

Hope this helps someone.

I hope no one minds me reviving for this thread but having read through it 3 or 4 times now over the past year and referred to it whenever I needed to check something, it seems wrong to let it die.

I live in France and am hoping to install a Log Boiler in the very near future. The house is an old stone farm house and from mine and the calculations of the 2 plumbers we have had quotes from, I will need a boiler in the 35KW-40KW range. The system, which will be replacing an old fuel boiler, will power 10 radiators initially but when our renovations are complete this will increase to 15 with UFH also installed and integrated into the system. At a later date I also hope to incorporate solar thermal into the mix to take care of DHW in the summer and also contribute what it can in the colder months.

Although our French is pretty good, it doesn't as yet extend to the finer points of plumbing jargon so having absorbed all the information I could about mixing values and modulating pumps from this thread, I was hoping I could pick your collective brains to see if this quote below seems to cover all requirements and which bits seem reasonably priced


ETA 40KW Boiler €11076
2 x 825l Tanks €3167
"Groupe de relevage de temperature R5/4" (temperature reading ensemble?!) €854.49
Vanne Melangeuse R5/4" (3 way mixer valve) €166
"Securite Thermique 3/4" (thermal security?!) €92
Ambiant thermostat €97
2 x 80l Expansion tank €101
"Soupage de securite a mano, purgeurs auto" (manometre safety valve and automatic purgers?!) €45
"Module hydraulique de chauffage avec vanne de melange" (hydraulics module with mixing valve) €702
Pipes, wiring and various fixtures €390
Chimney flue, joints, purger and fixings €697
Technician to sign it off/start it up €235
Labour €2304

Total at 5.5% VAT €21028

Although Im sure the ETA boiler is a wonderful piece of kit, does it really have that many more bells and whistles to warrant spending €8000 odd more than a similar sized Orlan, Atmos etc?

My main concern though is that 1650l of accumulator tanks is not enough. The cellar that will be housing the equipment does have height and access width limitations so I can only assume he has quoted for these based on their dimensions. If so, is it feasible to link 3 tanks or is that likely to start affecting efficiency?
Ive contacted Akvatherm about their bespoke tanks but if anyone can recommend any other firms that produce tanks that would fit in a confined space it would also be most appreciated?

Thanks

Andy

ditto - I run 40kW into a 2000 ltr tank (adeqate) and I wouldn't have a litre less and would have prefered 500 more (no space). Ref costs: I fitted it myself and only paid for the certificate. For the full system and a sophisticated solar set up the costs (euros) were as follows:

Boiler 4561
Inhibitor 291
Plumber for Solar Installation 360
Thermal Store 2288
Parts parts for boiler and Solar 2283
Radiator TRVs 180
5xFPs 2681
Solar Parts 1463
Solar Panels Pipe 825
Copper Pipe/fixtures/insulation 2780
Plumber's Certificate 554
Main Flue 1380

A lot less than yours - all my parts are top quality except my boiler (but it is hard to believe how it could be 5k better!!!) and I can't believe you are getting good VFM overall. My supplier delivered and commissioned the kit in the price of the parts. I widened my access door and dug out a pit in my floor to get one tank - 2/3 tanks are no problem though just a bit more heat loss so really hit that insulation. My friend compromised in tank size - don't do it - there has to be a better way - we are talking quality of life for LIFE - one outside perhaps?

Thanks for your input. What are the drawbacks of having too little storage? Although I have sized the boiler according to our maximum volume after renovations, we will probably shut off part of the house in winter so is there any harm in just 2/3 loading the boiler for example?

With regards the quote above, I was trying to determine whether it represented reasonable value when you factor in a 40% rebate on materials here in France, but it now transpires that we have used our quota for the next couple of years so I guess I will buy all the equipment myself from Kotly (or somewhere else if someone can recommend anyone) and just pay for our local engineer to install it.

Mike, if you can dig out the manufacturers of the bespoke tanks you mention that would be great.

Andy

I have been burning wood for 4 years using a Baxi Solo Innova 50Kw wood burning boiler with 2500 litre Aquaterm tank with Acaso Termovar loading unit and Acaso CT Automix.

The installation is used to provide CH and DHW to a 4500 sq ft well insulated house over three floors plus underfloor heating in a conservatory. The installation works very well, it is located in a garage alongside the property which also houses a buffer store for 2-6 weeks wood - this provides additional drying when wood is brought in from the external stores. The unit is fired between one and three times per day in the winter depending on how much of the house is in use, and once every 5 days in the summer for DHW.

A couple of things I have found useful:

The radiator TRVs were replaced by three zones of Honeywell CM Zone wireless radiator controllers in the parts of the house we most frequently use - common areas, lounge, selected bedrooms etc. The remaining bedrooms retain their TRVs which are turned on manually when required. The fourth zone controls the Underfloor heating in the Conservatory. Two controllers provide automatic and manual control of the wireless valves and when the valves detect heat requirements in the room in front of the radiator they switch the pump on via a wireless controller. This system combined with the Heat Store provides almost immediate heat to the selected zone and when up to temperature are remarkably accurate in controlling room temperature and minimising un-necessary load on the heat store. These systems are not cheap but given the investment in the rest of the system have been invaluable in getting the most from it.

The other area which does not seem extensively covered in this forum is wood sourcing and storage. We use between 30-40 cubic meters of wood per year and I made all the original mistakes in burning unseasoned timber. In my experience only one thing matters in optimising wood use and that is the level of moisture in the wood - this is more important than type of wood or any other factor. I started by building lean-to woodstores and stacking wood in these after splitting - if you do an analysis of how often you lift wood during this sort of process - felling, collecting, unloading, splitting, stacking and then collecting by trailer for the garage store its frightening.

So turning to storage I now use bays constructed from Heras fencing used for security on building sites - I construct a three sided bay with a pallet floor in a convienient and accessable part of the garden, throw processed wood into it direct from the splitter (no stacking) and then bolt a front on it and throw more logs over the top until the whole thing is full with a mound of process logs on the top - I then cover it with a camoflage tarpaulin and tie it down and forget it for 1-3 years. The sides of the fencing and the pallets ensure good air circulation for drying and the whole thing holds about 20-25 cubic meters of processed logs ready for the garage.

I source wood as a preference from tree surgeon yards (scrap wood) that has to be removed from customers sites and cannot be processed in automatic splitters. Occasionaly I get to know of a large tree that has been felled and will go and clear it. The preferred method is to have a large pile of logs cut for the splitter and then hire a 20 ton grab lorry - they usually charge about £100 - £120 but I dont reckon on paying for the wood. These are superb as the lorries can pick up this quantity in an hour and will tip it right next to my Heras fencing storage bays.

i appreciate I am fortunate in having plenty of space and live in a rural area with plenty of trees - I would be very interested in any other members experiences of wood collection and processing - i reckon that ignoring my time my heating costs between £700 and £900 per year, I do have someone help with the processing on a paid basis.

dieseldogg, hmmm strong winds and you start with "tidy"...must be south Wales!!!!!

Erm, ye tried to source or buy "large pallet boxes" I did, too expensive by far, and I already got the forklift.
I am considering strapping the split 1.0m lengths in nominal 1.0m diameter bundles, can then lift with the forks to stack higher, plus all that other movment from outside to inside to the boiler.
This was why I considered a wood-chip burner initally, to burn my own wood chip, but then I needed a chipper....& none to hire back then and unjustifibly expensive to buy my own.
sigh.

Hi all, I am making a comment to this old thread because I can't seem to make a new thread as it keeps saying site not secure and other microsoft/google b/s. Anyway, I am resurrecting this thread because residual heat is mentioned a few pages back and that is what I want to make use of. My boiler, an Orligno 200, weighs 700kg and takes about 1/3 of a firebox full of wood just to get to temperature before it can put any energy into the tank, then at the end of the burn all that energy dissipates into the boiler shed. I would like to install a diverter system to use the boiler heat to heat the radiators once the burn is over which would also put a more definite end to the burn which can see the fan and laddomat pump going for a good two hours with nothing really left in the firebox using unnecessary electric. Has anyone done this or got any ideas ? "Do"s and "Don't"s ?
Thanks in advance,

Yes I'm at about the same wattage of laddomat and fan. I think if I "tee" in between the boiler and laddomat with a second mixing valve then I could extract energy from the water and the steel of the boiler before I start using the tank. The boiler mass and water totalling over 700kg at 72 degrees, the temperature that the laddomat closes, down to 40 or even 35 degrees would be probably about 25 % of the total burn energy that usually goes to waste. Generally we would need the heat and it would be certainly used. I just want to make it automated and safe.

It's about 50/50 at the moment with regard to buying wood and getting it from my property.
I take your point about the boiler not all being at 72 but there must be a fair bit of useable energy there. Talking of negating the laddomat's purpose, I need to think about that with regard to the changing state of the laddomat and it's pump...
There is a small layer of insulation around the boiler about 30mm thick and the idea of an insulated box would be an improvement but at this time of year I would aim to light the boiler every two days so probably would have lost most of the residual even with a good cover of insulation.