Pipestats

Zapata123 · 5 January 2019 at 3:29PM

I have a froststat and pipestat connected in series to protect boiler and pipes both of which are in the garage.
Looking at the Worcester wiring diagram it seems that as long as there is a risk of low tempeature ie the froststat has switched due to low temperature and the water return temperature is too low, they will override the normal controls eg roomstat 24/7
As a result temperature cannot be controlled ‘ til the outside temperature rises OR the water return temp increases.

Am I missing something????

Cardew · 5 January 2019 at 5:41PM

Welcome to the forum.

Not sure of your question.

The froststat is 'normally open' and closes to switch on the boiler if the air temperature drops below a certain set level - normally 2C to 4C.

Why would that affect the 'normal' operation of the boiler?

Zapata123 · 5 January 2019 at 6:10PM

Thanks for your reply,

unfortunately as a new user I am not allowed to include a link in my reply, which linked to the wiring diagram.
It was on the Worcester Bosch website “Greenstsr series Wiring diagrams”. Page16 was the relevant page.

This showed that when the froststat and pipestat BOTH switched there would be a heating and pump demand overriding All other controls.

Do you happen to know when I can include links in MSE?

Thanks

Zapata123 · 5 January 2019 at 6:11PM

Thanks for your reply,

unfortunately as a new user I am not allowed to include a link in my reply, which linked to the wiring diagram.
It was on the Worcester Bosch website “Greenstsr series Wiring diagrams”. Page16 was the relevant page.

This showed that when the froststat and pipestat BOTH switched there would be a heating and pump demand overriding All other controls.

Do you happen to know when I can include links in MSE?

Thanks

AndyPK · 5 January 2019 at 6:20PM

you are largly correct.

It doesn't take long for hot water to leave the boiler and return warm at which point the pipe stat will deactivate.

It will only function in practice at night or when away

ianto11 · 5 January 2019 at 6:34PM

You are correct, the froststat is there to protect the whole property, not just the garage, so does override any other control but doesn't affect the normal operation of the boiler per se, and as AndyPK says, once the pipestat reaches it's set point it'll turn the boiler off

Zapata123 · 5 January 2019 at 7:28PM

Thanks for all your replies, most helpful.

The functioning is as I expcted.

The issue for me is that the only temperature control when both stats “engage” is the boiler temperature setting, particularly if the pipestat fails closed. So the house heats up until the rad thermostats close, so the boiler is firing until the froststat opens which may take all night or many days if you are away, if the weather is particularly cold.

So the design is failsafe for the boiler and pipes but not for the gas- bill. I hope all stats are a simple but highly reliable design.

AndyPK · 5 January 2019 at 7:34PM

Honestly don’t worry!

What temp is the pipe stat set at?

If the boiler does run for a couple of hours it will heat the garage and bring it above the frost stat point

Zapata123 · 5 January 2019 at 7:52PM

Thanks Andy,

Setting is 15C.

These modern boilers are very efficient , casing stays very cool, unlike my old boiler which you could barely touch last winter ( was in house), additionally, pipes in garage are lagged, but maybe, just maybe temperature will go over the set point. I guess that is the fail safe for the pipe stat failing!!!!

Regards

Mister_G · 5 January 2019 at 9:53PM

I suspect that the extra gas used will be far less than replacing the boiler if it freezes up!

Zapata123 · 5 January 2019 at 10:32PM

I suspect you are totally correct

Pipestats

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