To Valve or not to Valve that is the Question

[oldie]

Hi All,
I did say in my Introduction that I would ask stupid questions, so here's the first.
System is a open vented pumped system with a gas boiler running 12 rads 10 of which have tcv's fitted
My central heating room stat is placed in the usual position ie , in the hall but unfortunatly it's placing is very near both the Kitchen and living room doors, so the thermostat "see's" the radiated heat both from the kitchen and our open log fire in the living room, and of course closes down the central heating leaving the rest of the house cold. So stage one was to move the thermostate to a slighly better position ( easiest location without too much cable on veiw ) which is at the top of the stairs on the first floor. Stage two was then to fit a thermostatic valve on the Rad in the hall to controle the heat in this area. I did intend fitting a thermostatic valve on the other last Rad in my system at the same time so that all of the systems rads are controled by tsv. Now this is where I have become so totally confused I don't even now know wether I should post in the Centrel heating forum or the Valve and Tap forum I have tried Googling for advice and asking a couple of Plumbers and Heating engineers that I know but I keep getting conflicting information. Some tell me that I must leave at least one rad free of a tcv, but others say as long as I have a open vented system I can fit tcv on all rads. Now, they can't all be correct. So your advice on this major dilemma would be greatly appreciated. I did say I would be asking stupid questions
oldie

 

[dontknowitall]

Generally you'll fit the room thermostat in the coldest draught free part of the house and if this room has a radiator then you do not fit a trv to it as the room thermostat and trv will send conflicting messages to the boiler/heating system.

Hope this answers the question (and also that I've answered correctly!)

 

[doitmyself]

Moving the thermostat upstairs will get it away from the direct heat from the kitchen and log fire, but it may not make that much difference as heat rises.

The radiator where the thermostat is located should not have a TRV fitted. If the TRV shuts off at a lower temperature than the stat, the stat will never shut the boiler off. If the TRV is set to a higher temp than the stat, the TRV will never shut off. If you don't want to go to the expense of removing the TRV, you can either remove the head or just set it to max.

If you installed a wireless stat, you can locate it almost anywhere, e.g a better location in the hall.

 

[oldie]

I have already moved the stat to the first floor landing as this area does not have a rad and thus is the coldest part of the house, so now it only reads the ambient temperature of the house.So far this seems to have been successful as now the heating upstairs remains on ,and even my loft music room now gets more heat and is a lot more comfertable that it used to be. The idea of fitting a trv to the hall rad is to control the heating in this area is so that when the log fire is on, this area already gets enough radiated heat. so when the room stat on the first floor level is calling for heat
it gets a bit to warm. So the queston was, is it permisible or advisable to have all the house rads controled by TRV'S
Thanks for your further Advice.
oldie

 

[doitmyself]

The radiator in the area covered by the room stat should not have a TRV. I explained why in my last reply. There is no rad upstairs on the landing, any heat the thermostat gets is indirect from the hall or possibly the bedrooms, so in some ways the rule cannot apply. The problem still is that the landing may never reach the temperature set on the stat if the TRVs are set to a lower temperature; and if they are set to a higher temperature, the room stat will shut the boiler off too early.

You may get away with having TRVs on all rads as the stat is not directly in an area covered by a rad with a TRV, but I think you will just have to experiment with the stat setting. The important thing is that all rooms can reach their set temperature and the TRVs operate before the thermostat shuts the boiler off. Also that the room stat will always operate and close the boiler down.

 

[Puddle]

How about putting thermostatic valve on hall radiator and stick room thermostat in music room as this seems to be the end of the circuit, removing the thermostatic valve in music room if fitted (this you could use in for hall) use wireless room thermostat to save on visible cabling

 

[oldie]

Thanks very much for the information, it's very much appreciated and confirms what I originally thought. I had looked at the wireless stat option, but being an old bu--er I'm always suspicious of "these new fangled thing's" and prefer to actully see what's going on ,I suppose It's due to my engineering back ground, I all ways work on the assumption that I can see what water is doing, but make a mistake with gas or electricity and it can creep up behind you and give you a belt at the back of the headwhen you don't expect it, so to speak
oldie

 

[johnsco]

I've done away with my room stat and have TRVs on all rads.
I depend on the boiler setting and the TRVs to regulate the temperature in each room.
Wherever you put a room stat, it's going to be a compromise.

 

[doitmyself]

I've done away with my room stat and have TRVs on all rads. I depend on the boiler setting and the TRVs to regulate the temperature in each room. Wherever you put a room stat, it's going to be a compromise.

So the boiler will keep going, even if all TRVs have operated, until the boiler stat says the water is up to temperature? What a waste of fuel.

Though I suppose you could always be running round the house with a thermometer to measure the room temperature and when all rooms are warm enough go to the boiler and turn it off. Then, when the rooms' temperature drop, go the boiler and turn it up again.

Come to think of it, with all that exercise you wouldn't need central heating.

I agree that room thermostats can be a problem, but it can normally be overcome with a little thought.

 

[oldie]

Ahhhhhhhhhhhh !!!!
So it is ok to have TRV's on all of the rad's and that really, was what my orignal question was all about. When I asked several Plumbers that I know, and also even Googled this question I kept getting contradictory answers, some stating that you couldn't put TRV's on all rad's, as at least one rad had to left without, and others telling me that as long as it was a "open vented" system I could put TRV's on all of the rad's , so I ended up as "confused of Brighton" to misquote a well known "Priviate Eye " saying.
So Thanks again for all of your help
oldie

 

[dontknowitall]

Shurely some mistake? hehe

If you put TRVs on all the radiators and not install a room thermostat the boiler cannot receive an electrical signal to stop when the radiators are warm enough (see doitmyself's post). It will continue to heat water until the boiler's own thermostat kicks in to make it stop.

If the radiators are warm enough already (before the boiler's thermostat closes) there will be a waste of fuel, more CO2, etc. If you simply turn the boiler's thermostat down it might not be enough to heat some of the radiators or the hot water.

The idea of putting the room thermostat in the coldest part of the house is that if that area is warm enough, the rest of the house will be warm too.

 

[oldie]

I seem to have inadvertantly poked a stick in a hornets nest ,so to speak .In my own particulr situation I have kept the room stat but moved it to a cooler part of the house,as where it was originally placed it was influanced by the radated heat from both Kitchen and livingroom log fire thus switching off the heat to the rest of the house.
Soooooo is it correct or at least ok to fit TRV's to the last two remaining rad's in the house or do I have to leave one rad without.
"Still confused of Brighton" : )
oldie

 

[dontknowitall]

If it's working fine, I'd leave it alone.

Part L (I think) of the building regs says that each radiator has to have a TRV except where there is a room thermostat.

The whole idea is not to waste energy and add CO2 to the atmosphere so common sense has to apply sometimes, even if the rules aren't being followed to the letter.

Re the hornet's nest, as long as we don't argue or fight, I'm all for hearing different opinions. For myself I don't mind being told that something is wrong. It's part of the learning process.

Also, if someone at a future date finds this thread and has a similar issue, then hopefully what's been discussed above will help.

Hope you're less confused now!

 

[doitmyself]

is it correct or at least ok to fit TRV's to the last two remaining rad's in the house or do I have to leave one rad without.

Ideally you should not have a TRV on the rad in the room where the stat is located, for the reasons I gave earlier. I suppose you could argue that the hall, stairs and landing are a room, therefore it should not have a TRV on the hall rad. You said earlier that you have already fitted a TRV to that rad, but you can overcome this by either removing the TRV head or setting the TRV to max.

Personally, I would fit TRVs to the remaining rads and set the hall rad TRV to max. You will have to experiment to find the best setting for the stat to make sure all rooms have reached temperature before the stat switches the boiler off. You may also have to reduce the hall rad TRV setting if the hall gets to hot. The stat on the landing will be getting "indirect heat" from all over the house.

 

[oldie]

Thanks all, I'm now much clearer on what to do, as the Room Stat is on the first landing and the only rad's on the stairs are either on the floor above or the ground floor. So I will use TRV'S on both of the remaining rad's(including the hall) that at the moment do not have them fitted.
Sooooooooooo a huge thank you to all concerned your advice has been really appreciated and very helpful.
As a non Plumber ( only a thick engineer )I probably will not have a lot to offer this forum so my contribrutions may not fall thick and fast in the future, but I shall still continue to visit you all, seeking advice and trying to improve my knowledge, and if possible, occasionly giving my half an olive's worth ( that's about 2p in todays market place surly )
Soooooooo thanks again all, and may you all prosper in this very dificult time, as due to "all of the" Goverments policys unfortunately we are very short of real Real Skilled People in "all" of the Trades with no real apprenticeships offered anywere. My own is now dead of course due to the short term policys of proffit before people vertually all Major Engineering is now being sourced abroad.
oldie