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Unable to regulate individual radiators

Discussion in 'Plumbing and Central Heating' started by Boodog, 20 Feb 2012.

  1. Boodog

    Boodog

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    Hi - We have a Worcester boiler with oil fired central heating and water system. Most of the radiators have trv's fitted, with regulating options 0-5 on them. However, I've noticed that only some radiators seem to be working properly, whereas the others can only be either switched on or off - so even at option 2, for example, we get the same output (very hot) as at option 5.

    I would like to vary the output of individual radiators so that they aren't going at full power in rooms we aren't really using much but would like some heating as dampness can be a problem. We do have a thermostat to regulate the temperature in the hallway but I find this a bit useless given where it is and I don't necessarily need a very warm hallway to heat the rooms.

    I've read about sticking TRV's and tho I haven't had a look yet, am not sure that is our problem as this seems to imply heating is either on or off, whereas you can turn ours on and off but just not down - or up.

    Please can you help with this.
     
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  3. simond

    simond

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    A trv does not regulate the water temp in the radiator.

    It is a very basic device which merely samples room temp and turns the rad water flow on/off to suit the number on the side.
     
  4. Boodog

    Boodog

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    Thanks Simon - understand this now!
     
  5. JohnD

    JohnD

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    you can adjust the heat output of radiators by balancing them. For example if you had a big radiator in a small room, and a small radiator in a big room, you could make the big rad run cooler so that the small room heats up slower.

    but as you have TRVs the small room will not overheat, so propably not worth worrying about.

    it is worth doing though if some of your rads run too cool.

    You use the TRVs to set the room temperature that you want, and when the room reaches this temperature, it will turn the rad off. If the room is very cold, then the rad will be hot even if you turn the TRV down to Frost Protection.
     
  6. D_Hailsham

    D_Hailsham

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  7. Boodog

    Boodog

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    Am a bit confused now - because I have a wall mounted, temperature thermostat in the hall which controls temperature throughout the house (dependant on hall temperature of course), surely this will overide the individual radiator valve setting. So if the temperature is set to 20 degs in the hall, and I set a radiator to number 2 (17 degs according to Danfoss site) - will I end up with 17 or 20 degs in the room that I have set the radiator to 2?

    Just moved into this house and confused as to why you'd install individual thermostatic valves, plus a temperature thermostat in the hall - a room you aren't really bothered about being a comfortable temperature.
     
  8. JohnD

    JohnD

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    the trv and the room stat both turn off heat when they reach the setting.

    so the idea is to put the wall stat in the room which is coldest, and slowest to warm up. It will keep the boiler going until that room is warm enough cause the room stat to turn off the boiler.

    however, prior to that, as and when each of the other rooms reaches the temperature set on its trv, its radiator will be turned off by the trv.

    this enables you to set some rooms to be relatively cool, by turning down the trv settings. As soon as these rooms reach their temperature, they will stop taking heat from the boiler, so saving gas.
     
  9. Boodog

    Boodog

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    Thanks John (and everyone else for replies). Makes sense now!
     
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  11. mysteryman

    mysteryman

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    TRVs don't just turn on and off - they modulate or throttle back the water flow into the radiator as the room temperature approaches set point.
     
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  12. MJN

    MJN

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    To minimise under/overshoot they are however designed to have a very steep response curve around the set point so in the context of the OP's question they can be regarded as being on/off devices.

    Mathew
     
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  13. JohnD

    JohnD

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    they are also more likely to be noisy when they are at the "almost closed" position as the water squirts through a restricted orifice, and especially if they have been fitted the wrong way round.
     
  14. simond

    simond

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    If you have a TRV in the space monitored by the room stat, it should be removed/disabled, btw.
     
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  15. Boodog

    Boodog

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    Cheers Simon - There is a TRV in the hall that has the room thermostat - think this is what has led to my confusion with the whole thing. I haven't been able to see the point of the thermostat because of where it is - the sun tends to heat up some of the rooms, but not the hall, bathroom and one of the bedrooms, so means there's an uneven temperature throughout. Using the trvs, now i know that they do work, will solve this but means am only setting the thermostat to make sure the boiler comes on. If I take the TRV off the hall radiator, this means i'll need to heat up the hall to suit the thermostat, which i don't really want to do. the house is a hodge podge of different things - there are 2 older radiators that have knobs with on and off and 2 arrows pointing directions - am just experimenting with these to see if i can regulate the heat in anyway as well.

    Maybe it's a case of getting used to something new. I do also have a multifuel stove and find that i can regulate the temperature of this far easier!
     
  16. JohnD

    JohnD

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    you do not need to make the hall hotter than you want. If it warms up too fast you can turn down the lockshield a bit so it warms slower than the other rooms.

    the old practice of putting the wall stat in the hall is dying out now. It makes more sense to have it in the room you use most, as long as there is no other source of heat in there to confuse it, like a log fire, sunny window, or big cooker.
     
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  17. Boodog

    Boodog

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    Thank you to everyone who has replied today - finally got this sorted and had a nice even temperature throughout the house this evening. Guess I probably have a girl's logic (illogic) when it comes to plumbing - although, I can highly recommend making thermal interlined curtains for keeping out the cold and saving money on fuel bills....!

    Many Thanks,
    Gill.
     
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