I have a frost stat in the garage (where my boiler is) and a normal room stat (set to 20degrees). When the frost stat kicks in the manual room stat seems to become useless as the boiler contiues to heat the radiators up untill piping hot . I turn the room stat down but nothing happens (the room stat clicks at over 30degrees). I eventually have to turn the mains switch off for an hour or so then wait for the radiator temperature to come down. Then switch it on again, untill the same thing happens. It makes no difference if the heating is either on or off?
Any clues please?

Simon, December 2008

check if the frost stat is a frost stat or a faulty one as it will only start the boiler when danger of became frost as under 6 degrees.

albto, December 2008

Hi Peccavi and AN Other

Thanks for the information. Reading between lines, there is a pipe control sensor/thing and a frost stat that do the same job? Would it be easier if I disconnect the frost stat and just rely on the pipe control?
My bolier is a Potterton Suprima 40L if it makes any difference!
As you can tell I may not know what I'm talking about!

Simon, December 2008

why did people do that, a sole room thermostat in a un-heated space, it'll never be satisfied til july???? whats the point. we always used pipe control and were always trained that way from day 1. frost stat and pipe control to turn off, simple.

., December 2008

It's being discussed here - pipe stat on boiler return controling the frost stat seems to be the consensus. Pipe below nominal 6deg C *and* garage temp close to freezing turns on boiler

http://www.screwfix.com/talk/thread.jspa?forumID=25&threadID=32230&messageID=313627

Peccavi, December 2008