All radiators fully on but thermostat is off

macman

As above-I supect that the frost protection is kicking in-go measure the garage temp at the time it's doing that with the programmer off.

southcoastrgi

penrhyn wrote: »

Interesting, its a programmable thermostat after all with a hot water timer.
Here is the manual, might well be worth a study.
http://danfoss-randall.co.uk/PCMPDF/6578_2.pdf

i suspect that the thermostat in the hall may not be connected to anything.
If a room is too hot turn the dial on the TRV to a lower setting.:rotfl:

yeh that's gonna work, but not quite the answer the op was looking for me thinks

Dan_Iggulden

penrhyn wrote: »

Interesting, its a programmable thermostat after all with a hot water timer.
Here is the manual, might well be worth a study.
http://danfoss-randall.co.uk/PCMPDF/6578_2.pdf

i suspect that the thermostat in the hall may not be connected to anything.
If a room is too hot turn the dial on the TRV to a lower setting.

I have read the manual thanks, but that doesn't answer my question as to why the boiler unit is coming on even though the controller isn't set to come on.

Thanks for other helpful answers here. Cheers guys.

jennifernil

http://www.plumbnation.co.uk/site/honeywell-l641b1004-low-limit-pipe-thermostat/

This is what we have fitted to over-ride the frost stat. It sits on the return pipe to the boiler and is set to 10 degrees C. You need something similar, the low level 10-40 degrees version.

macman

Because the frost protection overrides all the other controls (programmer and stat), unless you switch off the power supply to the boiler.
It's there to protect you from a very expensive freeze up and burst.

southcoastrgi

jennifernil wrote: »

http://www.plumbnation.co.uk/site/honeywell-l641b1004-low-limit-pipe-thermostat/

This is what we have fitted to over-ride the frost stat. It sits on the return pipe to the boiler and is set to 10 degrees C. You need something similar.

i think that's what i said

the pipe stat doesn't over ride the frost stat it works in conjuction with it, in an unheated space in this case the garage you will never get enough heat in there to turn the frost stat off, the frost stat is there to protect the boiler & heating pipework nothing else, but without a pipe stat the heating will keep going trying to switch the stat off, the pipe stat senses when the pipe is hot enough ie wont freeze & therefore switches the boiler off, which is why it should be fitted on the return pipe & not the flow.

btw there are two types of pipe stat a low & high one you need the low one.

macman

You might check where the frost 'stat is (on boiler or programmer) and if on the latter then it should be possible to go into the installer menu and change the default-normally it is set around 5C.
But I wouldn't drop it any lower than that. If outside it is minus 6C (which it was here in the SE this morning) then your garage could well be down to 5C or lower where the boiler is.

Dan_Iggulden

I have this next to it:

http://imageshack.us/photo/my-images/141/photoihq.jpg

What is that?

notbritishgas

Dan_Iggulden wrote: »

I have this next to it:

http://imageshack.us/photo/my-images/141/photoihq.jpg

What is that?

Yes that looks like the frost stat, can't quite make out the calibration, what is the range and what is it set at.

As others have said 5 degree C is about the norm for a garage.But yours may be set higher than that.

macman

Can't read the label but it looks like a standard room stat?