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Worth replacing TRVs?

Discussion in 'Plumbing and Central Heating' started by curium, 9 Jan 2014.

  1. curium

    curium

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    Many of the TRVs in our house are not functioning and have been removed.

    Is it worth replacing them? When I googled to look for a supplier of replacements I came across many articles stating they are a waste of time and to get a wireless room thermometer and have a heating engineer ensure the system is properly balanced.

    I've also read that it is mandatory to fit them.

    I'll probably get the system balanced as the boiler needs a service and the flue guard replacing so I'll ask the engineer's opinion.

    Wondered what the forum's thoughts were?
     
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  3. ALEC1

    ALEC1

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    not really...the issue with TRVs is that although they throttle back the heat output of the radiators the boiler is blissfully unaware of this and keeps pumping water at a preset temperature...

    a more logical way to vary heat output of radiator is by varying the flow temperature of the boiler with compensation controls, such as viessmanns vitotronic 200 weather compensation control or vaillants vac 470. Both these originate in Germany where a boiler has to be installed with an out door sensor to maximise fuel savings. on cold days the boiler temperatures are high and on warmer days the flow temperature is cooler...
     
  4. JBPHS

    JBPHS

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    Rubbish! A TRV does not directly control the boiler. When a TRV closes, the heat continues through the system. In simple terms, hotter water reaches the boiler more quickly, end of heat cycle is reached sooner.

    I do agree though that weather compensation is a good idea. Problem being is that a lot of customers don't understand how it works, despite keeping it simple as ALEC1 said that the cooler it is outside, the hotter the heating water will be.

    If your existing boiler has built-in weather compensation and is 'looking' for an outside sensor for this feature to operate, it is worthwhile. If you have a non-condensing boiler, don't bother, chances are that you will need a new controller, a TMV, alteration of pipework etc. near the boiler.

    James.
     
  5. 45yearsagasman

    45yearsagasman

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    That's what Alec said if I read his post correctly.
     
  6. JBPHS

    JBPHS

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    If you continued to read what I said, you may understand me more clearly. Consider the scenario; A property has 20 radiators, 18 of which are fitted with TRV's. All of the system is functioning correctly. The temperature inside the property is 10°C. After 1 hour of the boiler continuously running, 17 TRV's close down as they are now up to temperature. In remaining room with the TRV, the owner realises that a window was left open. The window is now closed and the room is still 10°C. If the boiler is blissfully unaware of the TRV's from closing, does this mean that the boiler continues to run for another hour? ;) ;)

    Que the smartass replies. . .

    TRV's should be fitted in a domestic property (including boiler swaps) as part of the Domestic Heating Compiance Guide.

    James.
     
  7. rjm2k

    rjm2k

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    Err doesn't all that depend where the room stat is?
     
  8. ALEC1

    ALEC1

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    As TRVs close so the return temperature rises an flow velocity increases with fixed speed pumps...

    A rising return temp forces the boiler to cycle at a fixed temperature which is wasteful of gas.

    If you click on the word article in the first post you are taken to an article about why TRVs are a waste of time in small applications such as are generally found in the uk...
     
  9. JBPHS

    JBPHS

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    He's a brickie who has ended up lecturing. I bet he can't demonstrate how to correctly perform a gas soundness test though with his wealth of knowledge. ;)

    Universities are full of academics who publish reports to argue for or against other authors (who then usually right another report to try and prove their original ideas are correct).

    The fact is that the majority of domestic heating systems in the UK are not used as efficiently as they can be. I.e. Heating on for 2 hours in the morning and two hours in the evening, room stats used as on off switches (either max temp or min temp) and as Mr Howell suggests, a lot of heating systems are not balanced properly. It's sad, but a lot of installers just want to do the boiler swap, job done (in their eyes), paid and be in the pub by 2pm. Me on the hand has forgotten what a pub is for! :(
     
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  11. tiptoptrump

    tiptoptrump

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    All my TRV's control my boiler. at least in the rooms I want them too. When the last TRV in the circuit is closed the boiler switches off. If one room falls below the set temperature, that TRV opens and starts the boiler. As soon as it is up to temp it closes and the boiler stops again! The benefits of digital TRV's and a fancy controller!!
     
  12. JBPHS

    JBPHS

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    Evohome?

    James
     
  13. ALEC1

    ALEC1

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    weather compensation is only economically interesting on domestic installs if it works directly on the boiler flow temperature with the sensor wired back to the PCB...anything else would require mixing valves and be very expensive.

    I agree the man from the telegraph doesn't know that much, but he is right about TRVs...
     
  14. curium

    curium

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    This seems to be a contentious topic.

    Given I don't have a fancy boiler - potterton suprima with a boiler mate 2 - I take it that replacing all the TRVs won't make any difference energy wise?

    I'll get it serviced and see if I can have a wireless thermostat fitted.
     
  15. 45yearsagasman

    45yearsagasman

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    JBPHS. That was not intended as you put it, "a smartass reply".
    It was however me trying to join in the post and possibly offer advice. Why so touchy?
     
  16. tiptoptrump

    tiptoptrump

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    I was going to go for Evohome but last years model didn't cover enough rooms.
    I have the Danfoss Link CC with Living Connect Wireless TRV's.
    More than happy with it, Another two weeks to go before its been in 12 months but I am looking at about 35% gas saving on last years results.
    Works perfectly with the other half's demands for comfort over cost. as all the rooms can be individually programmed for different setback times & temperatures, giving me the savings when she is either in bed or out of the house.
     
  17. JBPHS

    JBPHS

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    Touchy about TRV's?

    By the way, I was referring to any smartass posts after my 2nd post on this thread, i.e. The one made by rjm2k.

    James
     
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