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thermostat on wall with TVR'S

Postby lucadobe » Mon Nov 30, 2009 10:09 am

We have TVR's fitted and a wall stat..i have just read elsewhere you should'nt have wall stat in same room as TVR.Notice we have to keep going in bedroom to turn up wall stat when temp drops ( not ideal place for stat but was already there ) whats best solution because i want the TVR's to regulate the rooms? Do i need to change the bedroom TVR?
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Postby sparx » Mon Nov 30, 2009 9:43 pm

Hi. yes wherever the stat is (normally a hallway) you don't have a trv,
the stat should be set slightly higher than the temp in the rooms with trv's so that when they are all satisfied the stat cuts out the boiler to prevent it 'cycling' ON/OFF on its inbuilt stat.
Not ideal having stat in a bedroom!
Why do you need to keep adjusting stat? when temp. drops stat calls boiler thats it's job, trv's set temp in each room.
You do need to move the stat for proper control.
regards Sparx
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Postby ericmark » Mon Nov 30, 2009 10:41 pm

Because a wall stat can have a built in timer and not just switch off and on I can see why one would have on in bedroom to control to a lower temperature at night but during the day it would need to be set so TRV is lower than wall stat or it will turn off central heating in rest of house.

Yes you should have no TRV where you have a wall stat. If that is in coldest room. But if not in coldest room that does not work.

The wall stat where TRV's are fitted only really turns off system in summer. With modern boiler it senses the temp of return water and adjusts flame hight to suit and in winter the boiler does not turn off it just goes up and down in output as radiators cool the TRV opens and it sends back cool water and boiler flame goes up. As the TRV warms up it causes the bypass valve to open and hot water returns to boiler and turns flame down. When is reaches min setting then it turns off. A timer in the boiler restarts the boiler every so often and if hot water returns the time is increased and if cold water returns the time is decreased this is called anti-cycle.

Putting the wall stat in a morning sunny window will inhibit the start when the sun is out and stop it heating the house when it is likely we will have a nice day and in summer.

The same applies in any room if the wall stat is set higher than the TRV then it will only switch off in the summer and so stop the boiler cycling.

Although this may make sense it is very rarely done. Took ages to get my sons house right then he sold it to live on a boat. My house has old boiler and does not vary flame height so downstairs is on wall stat and upstairs on TRV to stop bed rooms from getting too hot.

In my house designed 1980 open plan if you leave a bedroom door open that room is like an oven.

My daughter has wall stat but only really uses it to turn off system in summer and to time when it runs.

Of course a lot is to do with design of house but I hope I've given you some pointers?
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Postby lucadobe » Tue Dec 01, 2009 7:58 am

The room itself was the living room originally ,so thats why the stat is in there, the previous owners moved the living area to the back of the bungalow hence the bedroom has the stat...moving the stat is not an option for obvious reasons, the hall is quite small anyway and has a rad and the living area is much bigger but with 2 rads all fitted with TVR's. Would changing the TVR in the same room as the stat alter things?
Our boiler is an Ideal ( not a combi ) along with the rads are only 4 yrs old and are working really well...we are clicking the stat back and forth at times because it seems the boiler is coming on too frequent even though the room with the stat is warm enough, which makes sense that the stat and the TVR in that room are working against each other??
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