Frost Stat Question

[ChizzDoha]

Great...I may know someone then who is a real handy man, who I trust and has done other work for us. My husband and I are not great at DIY sadly...we've done a bit of painting/stripping wallpaper/can wire a plug, but that's as far as it goes. Thanks

 

[ChizzDoha]

@MJN - yes, I am amazed that you all spend so much of your free time giving free advice to people online! So thanks to you all for that.
I'm also amazed (and saddened) that there appear to be so many so-called "professionals" operating in the heating field that do not know what they are doing.

 

[MJN]

@MJN - yes, I am amazed that you all spend so much of your free time giving free advice to people online! So thanks to you all for that.

Ah, well actually I'm one of the amateurs asking more questions than giving answers!

 

[ChizzDoha]

lol...sorry, I didn't read your other forum posts, but good that you're asking lots of questions and being interested in learning more, as well as contributing to the forum.

 

[ianmcd]

can wire a plug, but that's as far as it goes.

if you can wire a plug you can wire a pipe stat , it is actually easier to wire the pipe stat

 

[stem]

As @ianmcd the wiring is straight forward. Here's how it's done.

The tricky bit is locating the pipe stat in the best place:

• It should be on the return pipe to the boiler so that the heated water has circulated through the heating system before reaching it.
• Not too close to the boiler such that residual heat from the boiler is conducted along the pipe thus keeping it warm and preventing it switching on.

And what temperature to set it at:

• If the pipe stat is in a normally heated part of the home I usually set it at 5 to 10 degrees above ambient room temperature. So for example if the ambient temperature where it is located when the heating was off overnight remained at around 16 to 18 degrees, and the pipe stat was set to 15 degrees it would never switch on and no frost protection to any external at risk pipes would be provided.
• If the pipe stat is in an unheated area, a much lower setting of 10 to 15 degrees would probably be sufficient. [remember the pipe stat is primarily measuring the temperature of the water in the pipe, not the room temperature]

 

[ianmcd]

A frost stat is simply a switch, and the pipe stat is simply another switch wired in series, nothing complicated at all

 

[ChizzDoha]

if you can wire a plug you can wire a pipe stat , it is actually easier to wire the pipe stat

am sure I could mess it up!

 

[ChizzDoha]

As @ianmcd the wiring is straight forward. Here's how it's done.

View attachment 222811

The tricky bit is locating the pipe stat in the best place:

• It should be on the return pipe to the boiler so that the heated water has circulated through the heating system before reaching it.
• Not too close to the boiler such that residual heat from the boiler is conducted along the pipe thus keeping it warm and preventing it switching on.

And what temperature to set it at:

• If the pipe stat is in a normally heated part of the home I usually set it at 5 to 10 degrees above ambient room temperature. So for example if the ambient temperature where it is located when the heating was off overnight remained at around 16 to 18 degrees, and the pipe stat was set to 15 degrees it would never switch on and no frost protection to any external at risk pipes would be provided.
• If the pipe stat is in an unheated area, a much lower setting of 10 to 15 degrees would probably be sufficient. [remember the pipe stat is primarily measuring the temperature of the water in the pipe, not the room temperature]

Thanks for the info!

 

[ChizzDoha]

A frost stat is simply a switch, and the pipe stat is simply another switch wired in series, nothing complicated at all

You've convinced me, but I'm electronically challenged

 

[Bon]

Hi all. I've come across this post from a Google search as I seem to have the exact same problem as the OP.

We moved into a mid-90's built property in October last year after ~12 years of living in new builds so I am well and truly back on this forum

We've got a Baxi 400 heat only boiler that is connected to an open system. Pump and valves are in the airing cupboard and the boiler is in our garage. There is also a Honeywell frost stat installed directly above the boiler.

The symptoms of the problem we have is a knocking/rattling noise that is loud enough to wake me up (although I am a fairly light sleeper) and constant (but not regular) enough to keep me awake .

From what I can tell, the frost stat is wired to switch the boiler and circulation pump on and they were running constantly until I turned the stat down to its lowest setting (which I believe to be ~3degC. That was fine last week, and the knocking stopped and I got a full night's sleep however the weather in Lancashire has dropped over the last few days and it has returned.

It seems entirely plausible that the temperature in the garage is dropping below 5 degrees overnight and therefore the pump and boiler are switching. The issue I have is that the heating and hot water are both set to "OFF" on the Tado programmer I have installed so the valves are closed.

My plan is to install a pipe-stat (or I may just buy the Honeywell set someone posted further up, just in case the frost stat isn't working properly). The mains from the boiler run through the garage roof-space and above the roof insulation so the plan would be to set the pipe stat to around 5 degC

I also need to check for a bypass in the airing cupboard and make sure that is working properly as the DAB pump appears to be set to proportional control, but never seems to ramp down - although admittedly the pumps I am used to working with are bigger than me and make notably different noise when the inverters ramp them up/down.

I was just wondering if the amazing guys & gals on here have anything else I should be considering??

Thanks

 

[stem]

Usually with your type of system having motorised valves, the frost stat is connected to the central heating motorised valve (in series with a pipe stat). So when the frost stat and pipe stat are calling for heat, that opens the valve which then starts the pump and boiler exactly as it would when the heating was running under Tado control.

The frost stat would be fed from a permanent live, and not come via the Tado meaning it would work when the normal heating schedule was off.

 

[Harry Bloomfield]

My plan is to install a pipe-stat (or I may just buy the Honeywell set someone posted further up, just in case the frost stat isn't working properly). The mains from the boiler run through the garage roof-space and above the roof insulation so the plan would be to set the pipe stat to around 5 degC

No, your pipe stat, needs to be set higher than that, high enough to ensure it allows the boiler to need to run, when the frost stat demands it. The pipe stat needs to be fitted, to the return pipe, a few feet from the boiler, and set to a higher temperature than the frost stat. Setting it to 10 C, with the boiler located in the garage, or if indoors, set it to your home's usual indoor night temperature, plus 10C.

Idea is, your frost stat detects the temperature near your boiler, is falling below 5C, and starts the boiler. The pipe stat then, measuring the temperature of the returned heated water, stops the boiler. Many/most/all modern boilers include such frost sensing, to run the boiler, but that only protects the boiler. If you have other exposed pipework, then additional precautions might be needed.

 

[Bon]

OK, so the pipework rises up from the boiler and then runs across the width of the double garage (in the garage’s “loft” space)

On that basis I put the pipe stat in the garage loft and set it to 10degC?

Thanks for help

 

[Harry Bloomfield]

On that basis I put the pipe stat in the garage loft and set it to 10degC?

On the boiler return pipe in the loft. You have two CH pipes exiting the boiler, the flow, and return. The flow will heat up quickly, the return much slower. Fitting the pipe stat, to the return, ensures some warmth gets through to your entire system, before it shuts the boiler back down.