Green Building Forum - UFH Actuator on Mixing Valve? Wed, 09 Sep 2026 00:10:26 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276220#Comment_276220 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276220#Comment_276220 Thu, 17 Oct 2019 10:12:34 +0100 Yalch
I've got an underfloor Heating system in my dining room that I've put into the Limecrete screed and am putting wood on top.

The water currently starts at the boiler (Manual, not smart), runs to the mixing valve through the pump round the system with auto actuators on and so on, with a return to the boiler etc...
(this is the pump and Mixing valve I have: https://www.theunderfloorheatingstore.com/manifold-pump-mixing-valve-unit)

anyways I've read that its best to keep it on low constantly and then turn up the temp when you want to warm the room and best on a smart thermostat to do this with so it's warm when you're up. (I currently have it attached to a Nest)

My question is: Is this the most efficent way to run the system?
And if so whats the best way to automatically change the temperature? (would I need to figure out a way to get an actuator to fit on my mixing valve?)

Thanks in advance,
Jon]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276232#Comment_276232 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276232#Comment_276232 Thu, 17 Oct 2019 21:40:23 +0100 tony
Problem is that may not necessarily be the most comfortable.

Cheapest and least energy is to switch it off

most comfortable might be to run house at min temp of 16C when out, sleeping , when away set to min of 8C

When in use a controller that will learn lead times and then set 18 C for breakfast, 16 when out, 21 in the evenings and week ends

21C at breakfast time is 30% more expensive than 18 C and in my opinion unnecessary. you might find 20C is warm enough with UFH

I dont have a heating system and my home has a very stable temperature (comfortable)

Automatic , best use something like Loxone, mat be hive or nest or a programmable room stat that learns to get to the set temp on time.

Heat pumps can be 350% or 400% efficient but cost more to run than a gas or oil boiler which is only 90 something % efficient ,

Heat loss is proportional to de;lta T (the difference in temperature between inside and outside, reducing inside temperature reduces heat loss reduces energy use and cost

For me it is all about reducing energy demand not energy efficiency, some use vast amounts of energy very efficiently .....]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276233#Comment_276233 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276233#Comment_276233 Thu, 17 Oct 2019 23:30:29 +0100 Yalch
This is super useful information.

So if I was to run like you say: "use a controller that will learn lead times and then set 18 C for breakfast, 16 when out, 21 in the evenings and week ends"

What would be the best way to change the temperatures automatically? Would I need to get an Actuator for my mixing valve or is there a better way to change the temp?

Thanks again,
Jon]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276235#Comment_276235 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276235#Comment_276235 Fri, 18 Oct 2019 07:18:52 +0100 tony
Things like hive and nest have apps on your phone making needing unexpected changes easier]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276236#Comment_276236 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276236#Comment_276236 Fri, 18 Oct 2019 08:12:03 +0100 GreenPaddy
I might be misunderstanding your question, but sounds like you think you should be adjusting the set value at the mixing valve at the manifold. That is not how you control UFH.

That TMV should be set at commissioning, may have some slight adjustment over the first few months, say into the first winter, but then left alone. Every system is different with lots of varying parameters, but something around 40oC for that TMV might be about right. That does NOT mean the house will get to 40oC, just that it blends the feed water to the UFH pipes to be up to a max of 40oC.

House temperature should be controlled by "zone" room stats. These should ideally be programmable, so that, as Tony suggests, you set various temperatures over the 24 hour period. The old way was to guess what the room temp would be at a certain time, run the boiler for another guessed time period, switching the boiler off and on. Guessing at room temp based on time wasn't a sensible way to meet required temps.

Programmable stats let you choose the temp target for each zone/room, and the UFH valves will open to allow water to raise the room temp, and close when it has been met. I don't know how you've got the NEST set up, but you ought to have various stats around the house, controlling to set temps for those areas, at different times of the day.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276237#Comment_276237 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276237#Comment_276237 Fri, 18 Oct 2019 09:32:20 +0100 Yalch
Yes I was under the impression that the water temp needed to be adjusted via the mixing valve so that it could be run at a lower temp in the "down time" but I guess the system would just have to reheat the slab after it goes under the 16 degrees? Wouldn't this use more energy as the slab has to be reheated as opposed to running a low temp of water through it the whole time?

Thanks very much for this.
Jon]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276245#Comment_276245 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276245#Comment_276245 Fri, 18 Oct 2019 13:17:22 +0100 GreenPaddy
I never set clients "away from home" temp less than 15oC, and backup frost stat at anything below 12oC. I tend to build very well insulated houses, so that is very little energy consumption in reality. Heating up a cold slab will of course take energy, but less than keeping it unnecessarily warm continuously. Personally, I would tend to vary between 18oC at night, and 20oC or maybe 20.5oC daytime. A 0.5oC can actually make a lot of difference. Focus your energy on getting those programmed correctly.

As with most of these things, take a happy medium of not living like a hermit, nor heating with windows and doors open to keep cool. Don't worry about the slab, it will do it's thing. Just focus on what you can sensibly control, which is room temperatures. Install a sensible number of room stats, to get the room temperatures right for you, and programme them so that the UFH works to only heat it to the temp you require, during the programmed time periods.

By not setting the UFH TMV too high, you won't get so much over shoot in temp, but will take a little longer to respond. Don't over think it.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276247#Comment_276247 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276247#Comment_276247 Fri, 18 Oct 2019 13:52:11 +0100 bhommels Most boiler brands offer this as an option, and with a modulating boiler it is more efficient than most other solutions.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276258#Comment_276258 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276258#Comment_276258 Fri, 18 Oct 2019 23:06:56 +0100 borpin Posted By: bhommelsIf you are serious about it I would consider a weather compensation controller.The flaw with these is they usually only take into account temperature and not solar gain. I've certainly not found one that does anyway.

The other thing I have found with UFH is that adjusting by 0.1°C makes a big difference. Most commercial thermostats I have come across work on 0.5°C and that is just too wide a range for UFH. I have a DHT sensor and control the UFH via HomeAssistant.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276259#Comment_276259 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276259#Comment_276259 Sat, 19 Oct 2019 00:14:02 +0100 WillInAberdeen
We had weather compensation as an option on an ashp. It responded to outside air temperature, but not to sunshine or clear night skies or strong cold winds, or to factors like us arriving home and needing to whack the heating up.

However it did also have a better option: load compensation. It looked at the difference between the temperature of the heating flow and the return, and the pump flowrate, and worked out how much heat was being consumed by the house, instead of projecting that from the outside temperature. Then it adjusted the pump speed and flow temperature to give the lowest (most efficient) flow temperature that could deliver the required heat.

I don't know why this isn't more common, as it was quite effective, and saves an outside measurement.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276261#Comment_276261 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276261#Comment_276261 Sat, 19 Oct 2019 10:36:46 +0100 Yalch Happy to know not to have to worry about the Slab temp to much and concentrate on the overall room temp via air stats.

Also the load comp sounds great, I'll have a look into that too.

Thanks again all of you, hopefully should have a comfotable effecient system one day :D]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276291#Comment_276291 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276291#Comment_276291 Mon, 21 Oct 2019 14:33:20 +0100 Mike1
In both the above cases, the BLC1.A controls the boiler output by adjusting the circulation temperature. Whilst both methods of operation will improve the overall system efficiency, the load compensation method will be easier to install in most properties because an outside temperature sensor is not required. The weather compensation method will usually give higher overall system efficiency.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276292#Comment_276292 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276292#Comment_276292 Mon, 21 Oct 2019 15:30:00 +0100 Rex
The boiler control input is from a combination of the w/c, set temp and return flow temp. One is fixed (set temp), the w/c does tell the boiler to run or not, depending upon the return flow temp. But this only works if the pumps are more or less running 24/7. No pump, no return flow temp reading.

If there is no requirment for the UFH to kick in, the pumps have to be running for the boiler to process that information. So one way or another, it is not very engery efficient.

So I ignore it all and have the heating switch on twice a day, early morning and late afternoon; it is sufficient to keep my highly insulated house warm without using excessive energy. More specifically, I am not running the pumps needlessly.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276308#Comment_276308 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276308#Comment_276308 Tue, 22 Oct 2019 01:05:03 +0100 gyrogear
We have no room thermostat. The internal temperature is not taken into account, it works just on external temp.

The system is open loop: the PLC puts the power on on a percent basis (from 0 to 100%), if the conditions are met (essentially, the external temp below which I want heat=ON, and the "maximum floor T°never exceed"). Works basically in the Off Peak tariff only -- 6 hrs overnight, and 2 hrs at mid-day...

The power delivered by the floor supply relays ("driver") is expressed as a percentage of load (0% = no load ; 100% = full load, maximum power input) (7500 W), conditioned by a time base (= duty cycle): the load will be put on to the floor, for x% of the time, and I get to decide on the time base, from 1 to 20 minutes) (depending on how the house is feeling, and - precisely - estimated solar gain !).

Installation is 40 yrs old and works great, the only disadvantage being it needs paying for!
Since we insulated the house & changed the windows etc. we have not used the floors (for over 4 yrs) - we dropped the contract from 60 to 45 A and gained 100 Euros a year on the standing charge...

"The best heating system is the one you don't need to turn on" :devil:

gg]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276310#Comment_276310 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276310#Comment_276310 Tue, 22 Oct 2019 09:08:44 +0100 philedge Posted By: gyrogear

We have no room thermostat. The internal temperature is not taken into account, it works just on external temp.

gg

Surely the first heating control device you should have is at least one room stat?? Outside temp is irrelevant once the room is up to temp.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276313#Comment_276313 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276313#Comment_276313 Tue, 22 Oct 2019 14:09:53 +0100 gyrogear
I ought to have added that the "maximum floor T°never exceed" is user-parameterable...
For example, I can set it from 7°C to 40°C.

A room thermostat is the last thing one wants ! as it would "encourage anyone" (!) to interfere with the logic...
All the setting are done down on the floor control panel, which is tied in to the MLVB.

gg]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276314#Comment_276314 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276314#Comment_276314 Tue, 22 Oct 2019 15:47:24 +0100 philedge
If finger trouble is a problem, chose a stat with a limit on it or use a hidden stat with a remote sensor]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276315#Comment_276315 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276315#Comment_276315 Tue, 22 Oct 2019 15:54:40 +0100 djh Posted By: philedgeA room stat(s)is almost certainly the first control device you need, unless youre running a GG interactive custom system. Pretty sure its a building regs requirement??
My feedback on the future homes consult was partly to the effect that their planned and existing control requirements are a bunch of garbage.

In the right circumstances, controlling slab temperature is equally, probably more, useful.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276318#Comment_276318 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276318#Comment_276318 Tue, 22 Oct 2019 18:23:18 +0100 philedge UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276319#Comment_276319 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276319#Comment_276319 Tue, 22 Oct 2019 19:15:20 +0100 barney
With careful design and a lot of tweaking during the first year, you can operate a system with essentially no controls in the room at all

Regards

Barney]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276323#Comment_276323 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276323#Comment_276323 Tue, 22 Oct 2019 20:43:01 +0100 gyrogear Posted By: djhunless youre running a GG interactive custom system. Pretty sure its a building regs requirement??

If GG means "me", then I can assure you it is not custom !

There is a whold street-load of them up here, all the houses date from the same period (1980 - 1985)

https://www.forumbrico.fr/comment-regler-son-chauffage-au-sol-electrique

sorry it's in French !

gg]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276337#Comment_276337 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276337#Comment_276337 Wed, 23 Oct 2019 13:15:55 +0100 djh Posted By: philedgeI might be missing something, but Im struggling to see any circumstances when youd want to start or continue with heat input if the room is at or above desired temperature. Is there something obscure Im missing?
In a well-insulated house, controlling the heat fed into a slab by the air temperature above is not a stable control system. The air temperature increases a noticeable time after the heat is fed into the slab, so the room overheats. Consequently, it's better to measure the slab temperature, which reacts more quickly.

It's only in less well-insulated houses that the heat loss from the room is fast enough to stabilise an air temperature-controlled system.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276339#Comment_276339 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276339#Comment_276339 Wed, 23 Oct 2019 13:56:18 +0100 CWatters Posted By: Yalchanyways I've read that its best to keep it on low constantly and then turn up the temp when you want to warm the room and best on a smart thermostat to do this with so it's warm when you're up. (I currently have it attached to a Nest)

In general the lower the room temperature the less energy is being lost from your house. So you should always aim to have the room temperature as low as possible.

However...

If you set it to be "on low constantly" (say 16C) that doesn't necessarily mean the _heating system_ is using energy. It will only start using energy when the room temperature actually falls below 16C triggering the stat.

So for example suppose you set it to 21C during the day and 16C at night. When night time arrives the room will still be at 21C which is more than 16C so the heating will go off. It will stay off until the room temperature falls below 16C. If your house is well insulated that might not happen. In which case setting it to 16C at night uses no more energy than switching it off totally at night.

Clearly if your house doesn't need heating for longer periods (eg for the 4 weeks every January when you go to the Maldives :-) then setting it to OFF would use less than setting it 16C because temperatures might fall below 16C. If you really do go away in winter then setting it to 10C (or whatever minimum your insurance policy requires) is the way to go.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276340#Comment_276340 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276340#Comment_276340 Wed, 23 Oct 2019 13:57:11 +0100 gyrogear Posted By: djhAnd I can assure you that it wasn't me that posted that!!!

oops, I do beg your pardon !

gg]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276355#Comment_276355 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276355#Comment_276355 Thu, 24 Oct 2019 12:45:33 +0100 borpin Posted By: djhIn a well-insulated house, controlling the heat fed into a slab by the air temperature above is not a stable control system. The air temperature increases a noticeable time after the heat is fed into the slab, so the room overheats. Consequently, it's better to measure the slab temperature, which reacts more quickly.To some extent. But this does depend on the water supply temperature (so max temperature of the slab), how uniform the slab temperature is, how long the loops are (shorter = more reactive), floor covering and whether the control mechanism understands the hyteresis of the system (plus more I've not thought of).

I pretty much know the temperature of the slab by comparing the flow and return temperatures. I also know (by observation), how long the room takes to warm up from x to y temp (external temp seems to only impact how much it has cooled down, not how quickly the room warms up using the UFH). So I can determine that, if the room's temp = target-x, it will take y hours to warm to target.

On this basis I have created a control structure, based on room temp and time to target, that gets the room to where I want it to be and keeps the room at a pretty stable temperature (flow water runs at about 32DegC).

However, most commercial systems don't do that - they simply take the temperature now and if warm enough switch off and switch on when cooler than target.

The control of the input temperature to my UFH is via a TRV with external temp probe. I'd like to be able to control this such that on startup, the flow would be warmer and dimish as it reaches target temp. Then you can, to some extenbt, control the room temp by the flow temp (if you know the rate of loss - for that you'd need some weather compensation). But I have not found a TRV that I can control wirelessly.

I would be interested to see what a Nest would make of the hysteresis of my system, but I'm not forking out on whim. I do have a Heatmiser controller that is supposed to 'learn' but doesn't so is now the fallback if the computer controlled system fails. In addition it only steps and controls in 0.5 degrees so pretty much useless for me. I'm currently set to 20.3!

Personally, I find the biggest issue is overheating when there are lots of folk in the house for a family meal. Almost impossible to mitigate as it needs to be warm enough for when the first folk arrive. Alternatively I could tell them to keep their coats on for an hour or so!]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276369#Comment_276369 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276369#Comment_276369 Thu, 24 Oct 2019 17:55:04 +0100 djh Posted By: borpinTo some extent.
I think what you've done is show how complicated you have to get to take the instability out of the system. :bigsmile:

If you want a room temperature of say 20°C then controlling the slab temperature to 21-2°C will be enough to pretty much solve the problem in a PH AIUI. Obviously if you've allowed the house to cool below the set point then you'll need to increase the temperature for a while to recover, but then why would you allow the house to cool down in normal usage?

Personally, I find the biggest issue is overheating when there are lots of folk in the house for a family meal. Almost impossible to mitigate as it needs to be warm enough for when the first folk arrive. Alternatively I could tell them to keep their coats on for an hour or so!

Overheating is definitely a bigger problem to solve, but not in winter since you can simply turn up the MVHR (and maybe open the bypass or let it happen automatically) or you can just open windows.]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276380#Comment_276380 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276380#Comment_276380 Thu, 24 Oct 2019 21:52:55 +0100 philedge

It's only in less well-insulated houses that the heat loss from the room is fast enough to stabilise an air temperature-controlled system.

Ok. I can see from the different systems being talked about here, they are all complex, interactive systems that are far from mainstream. Our room stat seems to work ok with our part UFH/part radiator system, but the UFH cant do the full heat demand so the room stat can hold off the rads and the room cant overheat.... until we light the woodburner!]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276397#Comment_276397 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276397#Comment_276397 Fri, 25 Oct 2019 13:00:08 +0100 borpin Posted By: djhIf you want a room temperature of say 20°C then controlling the slab temperature to 21-2°C will be enough to pretty much solve the problem in a PH AIUII think that is really optimistic to only have a couple of degrees difference. You are working off theory I gather not real world experience?

Posted By: djhObviously if you've allowed the house to cool below the set point
I'd not expect to maintain the temperature overnight.

Posted By: djhyou'll need to increase the temperature for a while to recover
And, as I said, that is an issue I have yet to find a solution to. If I could, I would.

Posted By: djhbut not in winter since you can simply turn up the MVHR
Believe me, from experience, if only it was that easy.

Posted By: djhyou can just open windows.
Trouble is, when you only have doors!!!!

I made an error in not specifying the doors in the main living area to be Tilt & Turn and they are just turn :cry:]]> UFH Actuator on Mixing Valve? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276401#Comment_276401 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16288&Focus=276401#Comment_276401 Fri, 25 Oct 2019 18:18:44 +0100 djh Posted By: borpinTrouble is, when you only have doors!!!!
Eh? Fire regs require means of escape from rooms? Oh, I suppose you have one of these new-fangled open-plan layouts? I'm afraid I'm an old fogey with a separate kitchen with window (because when my wife fries belacan/balachan I feel I can't breathe the air though I enjoy the result), dining room with a sliding patio door, and living room (because my wife can't stand it when I play the Who at 11). The living room has one opening window (fire regs) and one picture window. (and common sense says have an opening window in every room, just in case of some unforseen circumstance)

Door stops are available for turn-only openings. :bigsmile:

We have one outward-opening door in the conservatory that I would really like to be able to 'wedge' open but the suppliers say there are no suitable restrictors (aluminium-faced timber) and I haven't yet found any in the shops. A conventional door stop is impractical because there is a step down outside the door. :cry:]]>