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Thread: Evohome + intergas xclusive. Low heat demand

  1. #11
    Automated Home Jr Member
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    Old thread but i just want to send a quick update.

    It appears the main reason why my rads were not getting hot was an issue with trvs.

    It appears that when there were open at 20-30 they were not getting a flow. Im not sure if its a fault with valves or hr92 design issue but i have unscrewed all hr92 about 2mm. So when they are open at low flow the vavle is open probably in half which makes a flow much better.

    I have also set them at full stroke but dont think it actually matters

  2. #12
    Automated Home Legend top brake's Avatar
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    what trv bodies do you have?
    I work for Resideo, posts are personal and my own views.

  3. #13
    Automated Home Legend
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    Quote Originally Posted by m112 View Post
    Old thread but i just want to send a quick update.

    It appears the main reason why my rads were not getting hot was an issue with trvs.

    It appears that when there were open at 20-30 they were not getting a flow. Im not sure if its a fault with valves or hr92 design issue but i have unscrewed all hr92 about 2mm. So when they are open at low flow the vavle is open probably in half which makes a flow much better.

    I have also set them at full stroke but dont think it actually matters
    20 to 30 what ? If you're talking about the valve pin position as reported by option 10 in the HR92 menu that is normal - the valve is not expected to start flowing until 30% pin position. This is taken into account by the design of the system which doesn't start calling for heat until an HR92 pin position is >30.

    See the following graph I derived which shows the relationship between HR92 valve pin position and heat demand:



    Heat demand here is reported in the system summary page of the Evotouch.

    If you're having to unscrew your HR92 adaptor by 2mm then your valve bodies are not compatible with the HR92 - probably the pin is too long. You're never going to get completely satisfactory results with these valve bodies with the adaptor partly unscrewed.
    Last edited by DBMandrake; 7th March 2020 at 07:36 PM.

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