Pipe thermostat

[squiff]

Can someone please explain the purpose of a pipe thermostat? I have a Potterton Suprima 40 located in my garage with a Honeywell pipe thermostat on the return pipe.

The control ranges between "MIN" and 40. Any suggestions as to what it should be set to?

Thanks.

 

[Bahco]

This is a control which turns off your boiler (after the frost stat has turned it on) when the temp of the return water reaches its set temperature which is set at 25 degrees.
This control removes unnecessary boiler cycling and saves you money.

 

[squiff]

BAHCO, thanks for your reply.

The thermostat has been set on minimum for over a year, without any problems. However recently the boiler started turning off too early and I had to increase the setting on the thermostat. Any ideas?

Are you suggesting I set the thermostat at 25 degrees?

 

[Bahco]

Are you suggesting I set the thermostat at 25 degrees?

Yes.
This will be the most economical setting for your pocket as it will prevent the boiler cycling unnecessarily

 

[ChrisR]

No no no no nono yes. The stat on the pipe only comes into use in freezing conditions - it plays no part normally so there's no point adjusting it. SOunds like you have a problem with the boiler. Suprima by any chance??

Oh yes so it is I just looked. Probably needs a new circuit board but needs diagnosing.

 

[squiff]

I had the PCB changed for the new style recently. The boiler fired ok and ran for about 5 minutes, then shut off (LED continuous orange). I could only get it to restart by turning up the pipe thermostat.

Does this imply the pipe thermostat may be faulty?

 

[Bahco]

A pipe thermostat works in conjunction with a frost stat. If a boiler is fitted in an outbuilding or garage, you need both these controls.
The F/S switches the boiler on when the temp goes below 5 deg and the P/S swiches it off when the return flow reaches 25 deg. That is how they are designed to work.
As Chris said their function only comes into play when freezing conditions arise