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Valiant Ecotec Plus 637 radiators not heating up fully

Discussion in 'Plumbing and Central Heating' started by Marc118, 12 Oct 2019.

  1. ScottishGasMan

    ScottishGasMan

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    It will speed up and slow down depending on the temperature of the water and output of the burner, when the boilers burner is at 100% the pump will be aswell
     
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  3. Marc118

    Marc118

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    When balancing my rads do I aim for 11 or 20'C DT across each rad?

    I've read that condensing boilers should have 20'C across them but i'm not sure if this is a condensing boiler
     
  4. Gasguru

    Gasguru

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    Aim for 15 to 20 degrees...it's always going to depend on the weather...how cold it is and the heat dissipated by the radiators.
    At low temperatures you will be closer to 20 degrees since the friction through the boiler heat exchanger is so significant on these models.
    11 degrees was based on the old 180/160 Fahrenheit temperatures and cast iron heat exchangers....it no longer applies.
    Condensing boilers often have narrow water ways and a slight pump energy efficiency gain is achieved with the move to 20 degrees.
     
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  5. Marc118

    Marc118

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    all the radiators now seem to be balanced and are giving out a good amount of heat for the first time since we moved in so thanks.

    I've set the pump to 100% and at the minute the D01 setting is 30Kw at 20kw it was struggling to increase the supply water temp.

    I want to try and get it running as efficient as possible so what would you suggest that I leave the pump and D01 setting at or is it a case of playing around with the two of them?
     
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  7. snb

    snb

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    because the boiler is so oversized, when it ramps up to max power the differential between flow and return becomes too great and it either ramps down or more often ramps down and stops and then goes into a waiting mode for 5 mins before repeating the cycle.
    Try reducing the power in D0 down to 15kw. Yes it will take longer to get hot but at least it will run constantly until flow and return get much hotter. Check the d40 and d41 and if you can set the power so that temp diff is less than 10 degrees. You might be able to increase higher but often most bungalows even 4 beds only need 12 ish kw
     
  8. Marc118

    Marc118

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    I tried it on 15 and on 20Kw and it could get the water temp to increase with all raiators on and calling for heating. 25Kw seemed to be about right but even then it took a while to get the temps up which is why I put it up to 30kw but I might try to put it back to 25Kw.
    Our bungalow is 2700 Sq ft and has 17 radiators if this helps.
     
  9. ScottishGasMan

    ScottishGasMan

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    With the pump speed locked on 100% you can run that boiler at any power output, if theres not enough water flowing through the radiators then it will simply bypass through the internal bypass and flow/return temps will be ok, So in reality just set it to the highest setting it works at.

    True Efficiency requires that the boiler/pipework/radiators/controls/balancing is perfect for the house its heating, without the system being designed and speced fully to the house then theres not a great deal you can do to improve the efficiency. But its a big step in the right direction now that its at least working!

    Changing the heat output of the boiler wont make a huge difference as it still has a set volume of water to heat up for the radiators to reach temp to heat the rooms, (the boiler will still modulate to lower rates by its self once they get hot) the output will only change how quick that happens, the efficiency is in the temperature drops and return temperatures through the radiators.
     
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  10. Marc118

    Marc118

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    Another update since the temperatures has dropped.
    The water just doesn't get around the system and even though the pump is on 100% if I have upstairs and downstairs on then the system struggles and when the hot water is on, it makes it even worse.

    Instead i'm going to get a low loss header fitted along with 3 separate pumps. One for upstairs, one for downstairs and one for the hot water.
     
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