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Digital RoomStat

  • 16-10-2021 3:49pm
    #1
    John.G
    Registered Users, Registered Users 2 Posts: 3,623 ✭✭✭



    Purchase one of these a few days ago, its a FantiniCosmi CH110 stat with no fancy controls, just settable winter and summer settings and settable differential, default setting 0.3C, max 2C.

    Problem is that it doesn't switch off at the chosen set point but if you change the SP setting around the actual displayed temperature (which is accurate, checked with digital thermometer) then it switches on/off at the differential setting. It is battery controlled which switches a switched live to the boiler, have changed to new batteries but still same problem.

    Has anyone any experience of these stats? or did I just get a faulty unit I wonder.

    The aperture in the back is up against the wall, not conducive to proper measurement either?.

    Stat Backplate.JPG




Comments

  • #2
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,380 Mod ✭✭✭✭Wearb


    Are you saying e.g. that if the room is at 18C and if you set your stat for 19C, it works fine. But if room is at 10C and you set your stat for 19C it doesn't work?

    Please follow site and charter rules. "Resistance is futile"



  • #3
    John.G
    Registered Users, Registered Users 2 Posts: 3,623 ✭✭✭John.G


    Take any digital roomstat...............assume SP is 20C and the differential is set to 0.3C. the contacts will close once the room temperature falls to 19.7C (SP-3) and will reopen once the temperature hits 20C. Mine isn't doing this and the contacts stay closed (sometimes) even when the room temp is a few degrees higher than the SP. The display also doesn't sometimes increase in 0.1C steps but takes a jump of 1 to 2 C and then the contacts may open.

    This morning, (old "mechanical"stat back in place) the room temp was 19.3C and the digital (battery powered) closed the contacts when I increased the SP to 19.6C, and reopened when I decreased the SP to 19.0C, perfectly normal way of testing.

    Apart from all that I can't see how this stat can properly monitor the room temperature when attached to the wall.



  • #4
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,380 Mod ✭✭✭✭Wearb


    Seeing as it's working properly when not mounted, you should try making a mount that might give it more circulation. Then mount beside your old one (currently in use), using bluetack or something. Monitor it for a while, then you'll see if it's faulty.


    I've a digital wifi Chinese one (what's not Chinese nowadays) and I'd a bit of trouble getting it to work as I wanted. I set the hysteresis at .5 and it way over shot. In the end I set it to 0 and it now works fine.

    Please follow site and charter rules. "Resistance is futile"



  • #5
    John.G
    Registered Users, Registered Users 2 Posts: 3,623 ✭✭✭John.G


    Apparently these digital ones don't need air slots, I returned mine and just replaced it with electro/mechanical EPH CM2 which seems to have a switching hysteresis of ~0.75C which is fine for me. It replaces a very old Imit stat, my 15 year old Firebird 90S also has this make of boiler control stat and hi limit stat.



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