Noisy TRVs

Discussion in 'Plumbing and Central Heating' started by GribMoose, 12 Feb 2009.

  1. GribMoose

    GribMoose

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    Hi, I am balancing the heating system in the house I have just bought, I have increased the pump setting (Grundfos Alpha) to get a 12°C drop at the rad furthest from the boiler but I am now getting quite a lot of noise from some of the other TRVs. The TRVs are a mixture of Pegler Terrier & Myson TRV II - the noisy ones are all Terriers.
    Is this likely to be because the valves are towards the cheaper end of what is available? and if I replaced all the TRVs what is the best in terms of noise/sensitivity/hysteresis etc to use, e.g are liquid filled sensors better than wax filled? Thanks.
     
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  3. weareleeds

    weareleeds

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    If there is an arrow on trv then flow of water must go this way you might be as well swapping to other side or rotating through 90 degrees or fitting bi-directional valves
     
  4. GribMoose

    GribMoose

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    I think both types I have fitted are bi-directional.
     
  5. D_Hailsham

    D_Hailsham

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    Liquid sensors are preferable to wax as they have a smaller differential between on and off and do not "age" so quickly. If you want to change them, go for Drayton or Honeywell.

    Which boiler - make and model?
    Which Alpha pump?
    What setting was the pump on?
    What setting is the pump on?
    What procedure did you follow to balance the valves?
     
  6. GribMoose

    GribMoose

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    The boiler is a Trianco Iona, oil fired.
    Pump is an Alpha plus (fixed & variable speeds).
    The pump was set in the centre of the variable range and is now about 3/4 of the way round the range.
    I balanced the valves per the advice generally available on the web; TRVs fully open (but with heads on - is this advisable?), Checked temp drop across all rads, adjusted all I could as close to 12°C drop which left the highest drop at about 20°C with the LSV fully open so I increased the pump speed to bring it down. I havent done another full lap of balancing since turning the pump up though.
     
  7. D_Hailsham

    D_Hailsham

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    Have you checked that your boiler runs with an 11°C differential?
    Do you have a bypass valve?
    If yes, is it auto or manual?
    Has it been adjusted?

    It's better to remove the TRV heads while balancing to eliminate any chance of the TRV working.

    Here is my Balancing Procedure
     
  8. GribMoose

    GribMoose

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    Is the boiler differential the difference between flow & return temps or the variation in flow temp? The flow temp varies as the boiler cuts in & out (between about 85°C and 60°C) and the return varies between about 45 & 55°C.

    There is no bypass valve fitted, the only bypass is a rad in the airing cupboard with a wheelhead valve rather than a TRV.
     
  9. GribMoose

    GribMoose

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    Should I use the average temperatures to calculate the boiler differential or the peak temperatures? (Either way it isnt 11 C at the moment)
     
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  11. D_Hailsham

    D_Hailsham

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    The differential is the difference between flow and return temperatures.

    If you have your boiler installation manual, you should find it in there; if you don't have it, tell me the exact model no and I can look it up.

    That's not too important as your Alpha pump is supposed to remove the need for an auto bypass.

    Balancing should be done with TRV heads removed and the pump on a fixed speed. It's best to turn the room stat up - assuming you have one - so the boiler runs continuously while you balance, otherwise it may cut out or modulate down - which will mess things up.

    The important thing with balancing is that the differential at the radiators should be the same as the boiler's.
     
  12. GribMoose

    GribMoose

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    The boiler is a Trianco Iona 100/125 and I do have the manual, its exactly the same as this http://www.trianco.co.uk/pdf/contractorflooroil.pdf but with a different burner. I dont have a room stat and the boiler is cutting in & out while I am balancing. I think I may have to go back to square one with the balancing, but when I open all the LS valves and take the TRV heads off some of the radiators dont get warm at all (presumably because with all the valves open it is very unbalanced?), if I turn the boiler stat up to full when its like this is it likely to get far too hot?
    Thanks for the help so far.
     
  13. D_Hailsham

    D_Hailsham

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    The online manual on page 1 says this:

    BOILER CONTROL THERMOSTAT
    The boiler control thermostat enables you to select the temperature of the water leaving the boiler. It is calibrated between High and Low in five intermediate settings, corresponding to a temperature range of 82° C
    (high) to 60° C (low).
    Set the temperature by turning the knob to the required temperature. However, the installer should take into consideration that the return water temperature must not drop below 60°C when the appliance is up to full operating temperature


    Note the bit I have put in bold

    The Technical Specification on page 6 has two entries under "Water side Resistance" of 10 diff and 20 diff. These look like temperature differentials to me, suggesting that the boiler can run with any differential between 10°C and 20°C. One advantage of running with a higher differential is that the circuit resistance is lower, so you can run the pump at a lower speed.

    Fit one ASAP; and if you don't have a timer/programmer, consider fitting a programmable thermostat.

    That's OK, provided the water temperature does not drop too far before it relights. The boiler thermostat may have an on/off differential of 10°C, while modern room stats only have a differential of 1°C. The flow temperature will stay more constant if a room stat is fitted.

    So do I :(

    Very unbalanced certainly.

    Could do, the boiler thermostat and overheat control will take care of that.

    Read the Balancing Procedure I gave a link to and you will learn what to do.
     
  14. GribMoose

    GribMoose

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    I have just checked the last readings I took and the boiler thermostat cuts off when the flow temp is 87C and cuts back in when it is 54C, return varies between 43C & 51C, do you think my boiler thermostat is knackered? If so can I fit a room stat and turn the boiler stat up to full, or should I replace the boiler stat as well? (or should I just buy a new condensing boiler !?)
    Am I correct in thinking that I shouldn't fit a room stat anywhere that is controlled by a TRV (which is the whole house at the moment)?
    :confused:
     
  15. D_Hailsham

    D_Hailsham

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    That is a very wide differential on the boiler stat and, according to the manual, they should not go above 82C; so it may be knackered.

    If you fit a room stat, that will effectively control the boiler. Which turns the boiler off first will depend on which heats up quicker - house or boiler.
    No harm replacing the boiler stat.

    That depends on so many factors that no one can give you a definite answer. But, if the boiler is working or not too expensive to repair, the general advice is to keep the old one as the reduction in your fuel bill when you install a new boiler is unlikely to cover the cost of financing a new one - unless a few £k is just small change in your pocket. ;)
    Though with the current economic climate and interest rates very low ...
    But don't forget that £3k in the bank is there for ever earning you money, if you want. But £3k spent on a boiler will only last the life of the boiler - 5 to 10 years - after which you have to find another £3k or £5k, depending on inflation.

    That is correct.

    If you have a room stat and a TRV in the same area they will conflict. If the TRV is set lower than the room stat, the room stat will never turn the boiler off. If the TRV is set higher than the room stat, the room will never reach the temperature set on the TRV.

    You should either replace the TRV with a lockshield valve (prevents someone turning the rad down) or just take the top off the TRV so the valve stays permanently open.
     
  16. GribMoose

    GribMoose

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    Thanks very much for all your input, I now have a plan; new boiler stat, fit a room stat, and rebalance the whole system from scratch. I have been thinking about where the room, stat should go; I have quite a big L shaped hall, one branch of which goes through the middle of the house and has no rads in it - I think I will put it there.
     
  17. D_Hailsham

    D_Hailsham

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    As long as there is a radiator in the hall which the stat can control. Ideally you want the room stat to keep running until all the TRVs have operated. If you find the stat switches off to early, you can reduce the radiator output by closing down one of the valves.
     
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