Question about frost thermostat control

lam2222

Hello

I have what could be a very simple and silly question but I was wondering if one of you lot could enlighten me.

I'm having a combi boiler installed in the loft space and because it's insulated it can get pretty cold up there so I've been advised to get a froststat, specifically they are fitting a Honeywell T4360.

Fair enough but I'm thinking there also needs to be a pipe thermostat otherwise the central heating will be on constantly during the winter months trying to keep the loft warm so I'm looking at a Honeywell L641B.

Are these 2 devices supposed to work in conjunction with each other? What I'm thinking will happen is the pipe stat will kick the boiler on if the water in the pipe starts to freeze over, which is fine but wouldn't the room stat ignore all that and kick in the boiler regardless, constantly? Or am I missing something obvious here?

Thanks

Peter

gas4you

Yes you are correct, you should have a frost stat and a pipe stat fitted.

These will be linked in series so when the frost stat kicks in, often about 3-5c, the boiler won't fire unless the pipe stat is registering a low water temp in the pipe, usually about 10c.

This way the boiler only needs to fire long enough to warm the pipes. The frost stat is always fitted to the return on the boiler.

lam2222

Ah thanks for that.

When you say 'linked in series', does that means the pipe stat is wired into the room/frost stat so they are aware of each other temperatures or they are just both wired directly into the boiler and it (sorry, not i'm that knowledgeable about these subject, I just want to make sure the installer does a proper job)

Thanks

gas4you

Yes, the power from the frost stat goes into the pipe stat, then to the wiring center or boiler controls.

If they were wired as your second suggestion they would both work independently of ech other.

DVardysShadow

peterwhitehead2 wrote: »

... When you say 'linked in series', does that means the pipe stat is wired into the room/frost stat so they are aware of each other temperatures or they are just both wired directly into the boiler and it (sorry, not i'm that knowledgeable about these subject, I just want to make sure the installer does a proper job)

Linked in series means that both must switch on for the boiler to run.