TRV doesn't turn off

Discussion in 'Plumbers' Talk' started by Simon M, Jan 25, 2019.

  1. Simon M

    Simon M New Member

    Hi all, please could you help with my problem , I have replaced my living room radiator with a tall designer one that I also moved 4ft to one side of its original place. I chopped out the wall so that I could bury pipes (no plaster/cement in contact with copper) and fit neat looking corner valves. My issue is that the trv doesnt seem to turn off the radiator as it should, I have a log burner and my living room hitting 26 degrees still has the radiator piping hot! I've checked I'm on the flow and not the return, also no draft blowing around the valve making it stay on, the pin is not stuck in and I have to turn it to No1 before it will shut off! I'm confused, any help appreciated
  2. andy48

    andy48 Active Member

    Is the TRV head in a corner so not sensing room air temperature?
    Is the TRV head fully screwed on?

    The Teach likes this.
  3. The Teach

    The Teach Well-Known Member

    Simon M,is the new heat emitter an actual radiator or a gloried import towel warmer ?

    Maybe the trv is not required,the room temperature can be measured with a thermometer :) some trv's are not so good at auto controlling temperature (response times vary from 30 mins +++) but handy for the used to manually adjust them.
  4. Simon M

    Simon M New Member

    Ah yes the TRV is in the corner of my living room , about 10 inches in from the corner, never realised it wouldn't pick up the room temp, head screwed on correctly so must be that it's the corner issue. Thanks to you both for helping.
  5. The Teach

    The Teach Well-Known Member

    Unless you live in the above location you will not get the best performance from the heat emitter although they are handy to adjust but in the recent cold snap they can be on full all the time. The air flow around the trv is important,its winter enjoy the heat :)
  6. Simon M

    Simon M New Member

    Yes, to be honest the radiator is to heat the living room when I don't have the log burner lit hense wasn't too concerned about designer rad giving less btu's. But that apart I need it to turn itself off when the log burner is lit otherwise it gets rediculassly hot. I may take carpet back and re-pipe the flow to other side so taking trv away from corner.
  7. rogerk101

    rogerk101 Well-Known Member

    Many radiators don't care whether the TRV is on the flow or the return side. Before replumbing the piping, just try switching the TRV and the lockshield around. You may save yourself a lot of unnecessary work.
  8. Heat

    Heat Well-Known Member

    It would take a lot to stop the TRV not sensing temperature.
    If it was turned down to a mid setting for example, the sensor should still close off.
    I find TRVs, while not the most accurate of temperature control, will work very well in nearly all locations, unless you locate them behind a curtain or in a draft
    It is possible to have a faulty TRV head or body.
    Simon M likes this.
  9. Simon M

    Simon M New Member

    It's not a bi-directional valve so probably need to swap pipes or buy a new valve to put on return side. It crossed my mind to be a faulty trv but everyone I spoke to seemed to think it unlikely as very rare?
  10. Baxi Boy

    Baxi Boy Member

    I have known faulty tvr valves,old ones by Honeywell,which would either come on but not switch off,or just not open by themselves.They are quite cheap,from £8,and mostly bi directional now,so try a new one is best.
  11. MGW

    MGW Well-Known Member

    I wanted to stop living room over heating when sun hits the bay window, I found an electronic head helped, but it needs to be on the feed, although the valve will work bi-directional, if supply is lock shield end then there is a delay before the TRV head gets heat from radiator, there are two sensors with the electronic heads, one for air and one for the water, the latter compensates for the heat from the radiator.

    I found with the electronic head on return, by careful adjusting the lock shield valve I did get it to work OK.

    I know you have simple wax type, but they will likely act the same, however with the electronic version you can set the to 20 deg C and they should be within 0.5 deg of setting, so I know what the temperature is set at so I just adjust the lock shield valve until it is no more than one degree higher than that temperature, and once set once it seems stay at setting when outside temperature varies as it should.

    I am sure you could do the same with the wax, however you don't really know what equals 20 deg C however it should be around 3.5 so set at 3.5 then turn down lock shield.

    A radiator full of water retains a lot of heat, and both wax and electronic valves are slow to move, so you need the set the lock shield so there is enough time for the TRV to turn off before the radiator gets stinking hot. The best valve I have is the cheap unnamed valve from screwfix, it actually works better than the Honeywell valves, both with electronic heads on them. Hall radiator always spot on.
    Baxi Boy likes this.
  12. Simon M

    Simon M New Member

    Thanks for that, really appreciate all the advice, I'm going to upgrade some older radiators upstairs soon so I'll drain down and do all jobs together .

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