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Thread: Boiler runs every 5 minutes since installing Evohome kit

  1. #1
    Automated Home Lurker
    Join Date
    Oct 2020
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    2

    Default Boiler runs every 5 minutes since installing Evohome kit

    Hi everybody and I hope that you are all keeping well in these strange times. I am a new member to the site but you have helped me already in fixing a very troublesome install of a full Evohome kit. Please bear with me as I am working long hours so replies and further information may be slow coming back to you.

    My heating system is as follows:-
    Boiler - Vaillant EcoTEC Plus 430 (Approx 2yrs old)
    S Plan sytem with a Grundfoss Alpha 2L pump. Hot water tank is an 206Ltr horizontal RM Insulated copper cylinder.

    My Evohome kit consists of Controller, 2 x BDR91 Wireless Relay Box, one each switching the zone valve on CH and HW. Wireless Cyl Stat CS92. 9 x HR92 Radiator controllers.
    I have left the bathroom towel rail without a HR92 for the moment until Ive got the system running satisfactory.

    My problem is the the boiler is starting up and running for a few minutes every five minutes. Under normal heating up circumstances like bringing the hot water cyl or radiators up to temperature the boiler runs ok. Once the requested temperature is attained the the boiler shuts down then goes onto this 5 minute (approx)
    cycle. Once it gets to 22:30 and all the rooms drop back to a night time temperature, the boiler stops this frequent run cycle. I have tried reading up on other posts but there always seems to be other problems or systems.

    Go easy with me as I struggle to grasp some technical terms. Thank you for taking the time toread this post and an even bigger thank you to anyone responding.

  2. #2
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    2,205

    Default

    Sounds like it's working normally to me. What you describe is TPI (time proportional integral) control. Google it.

    If maximum heat is required the heating relay will come on continuously. If no heat is required it will stay off continuously. However if there is a partial heat demand it will cycle on and off in (by default) 10 minute cycles. (The cycle time can be changed to 5 or 20 minutes but 10 is usually best for a gas boiler)

    So every 10 minute cycle it will come on from some period of time between 1 minute and 10 minutes. In your example it is coming on for 5 minutes out of every 10 minutes indicating a heat demand of 50%.

    You can check the heat demand if your controller firmware is up to date by long pressing on the settings button to get into the installer menu then go into the System Information section. You'll see a table of heat demands from the zones and the heat demand sent to the boiler.

    Your system will only demand maximum heat from the boiler when zones are warming up, once all zones are warmed up there will only be a small heat demand to maintain the status quo hence the reduced heat demand and the partial cycling of the boiler.

    Nothing to worry about.
    Last edited by DBMandrake; 8th October 2020 at 10:10 AM.

  3. #3
    Automated Home Lurker
    Join Date
    Oct 2020
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    2

    Default

    Many thanks for your assistance DBMandrake and confirmation that everything is working ok. I intend to accurately record the length of time the boiler runs on each occasion and the interval. I know my firmware is out of date but I have only just got myself registered on the App due to a problem with my email address at Honeywell.
    I didnt realise that the Controller had disconnected from the Wifi so I have been waiting for the firmware to up date. I am currently on App Version - 02 00 11 21 and the Wifi version is - 02 00 11 00.

    Once I get further information do you mind if I ask further questions in order to get my boiler working as efficient as possible.

    In the short time that Ive been home tonight, the boiler only seems to have run half as much and I dont think there is any difference in the outside temperature.

    Once again, many thanks DBMandrake for your help.

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