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Thread: Suitable Remote Thermostatic Valve For HeatLeak Rad

  1. #1
    Automated Home Lurker
    Join Date
    Nov 2010

    Default Suitable Remote Thermostatic Valve For HeatLeak Rad

    Hi All,

    Have recently put in a wood-burning stove (with back-boiler) and a small thermal store (~300L). The stove heats the thermal store by thermo-syphon.

    As the cold weather moves in, I have been using the stove for a greater proportion of the day and, later in the day, the store has been approaching 100C. The installer put a heatleak rad in, but I have to manually open this heatleak circuit using a normal rad valve. The rad is located within one metre of the cupboard holding the thermal store.

    What I am looking for is a remote system, whereby, as the store reaches approx 99C, the rad valve will open automatically. Preferably, I would like this to be a passive system, so I'm not reliant on batteries or mains electricity, but will look at such options if there is nothing else. The closest I've come to finding anything is this Danfoss AVTA Thermostatically Operated Valve With Capillary Sensor (Link) However, there are a few problems with this - in descending order of importance: (a) The price! ~60 (b) the sensor is too big for the pockets in my store (14.5 mm vs. 7mm - although there is a spare 22mm connection currently with blanking disk inserted, (c) its sensor range is only up to 95C so I lose ~5% of my store's potential, (d) I would like something that shows the temperature as the sensor will have to replace the current gauge in its pocket.

    So, has anybody got any alternative solutions for me to consider? Any help would be much appreciated. Thanks.


  2. #2
    Automated Home Jr Member Simon300's Avatar
    Join Date
    Apr 2010


    Quote Originally Posted by horatiog View Post
    So, has anybody got any alternative solutions for me to consider? Any help would be much appreciated. Thanks.
    Another alternative might be a high-limit stat (e.g. I have two on my unvented cylinder) with a normally-closed contact which powers a (normally open) zone valve to keep the radiator isolated. Then if the stat high temp was reached (or there was a power cut) the zone valve would open flow to the rad. My high limit stats need a manual reset and operates at 85C I think, but alternatives should be available.

    Regarding sensor pockets, Klaus over on the Navitron forums, made one for a 22mm boss from a reducer or two and short piece of pipe/end cap ("poking into the cylinder" if you see what I mean).

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