Froststats (again!)

djm1972

My central heating / hot water boiler is in the garage, and has a froststat attached to it which is on the wall inside the garage just above the boiler. There are 2 wires protruding from the box, 1 ring-main looking cable heading off into the roof, and a white cable heading down into the boiler, which I guess is something to do with a pipe-stat that i've read about elsewhere...

For the last few days during this cold snap i've noticed my boiler kick in under the demand of, I presume, the "frost protection" system; but so much so that it seems to be having a laugh, turning on the heating (if it's not "OFF" on the control the panel) for about 10 minutes in every half an hour, which is going to cost me a fortune if it keeps this up. If both heating and hot water are OFF on the control panel, it brings up the hot water circuit when the froststat kicks in - presumably therefore overheating the hot water as it does not turn off if I turn the thermostat on the tank down below its trigger point.

So there I was at about 2AM this morning putting a thermometer in the garage, and it got down to about 5°c - surely the froststat shouldn't be kicking in when it's still 5 above freezing, should it? OK, it's freezing outside I guess....

Thanks!

Premier_2

What temperature would you expect a froststat to be set up to prevent the water in the pipes & boiler from freezing?

I'm not sure what type of froststat you have, but with Honeywell ones (a very common make) you can take the cover off and set the temperature to what you want. The Honeywell ones are adjustable between 0-20C, with a recommened indicator mark at 5C.

Set it too low and you could have an expensive damp mess and and even more expensive replacement cost for a new boiler!

djm1972

Thanks....

I just removed the cover and it was set, as you mentioned, at just above 5°c (and triggered) whereas the thermometer I put in the garage was reading about 8°c so have lowered it to 3°c (indicated) and will see how it goes...