central heating - frost stat

[jie49]

In tracing an electrical fault in my heating system, I've found that it only works when I short out the frost stat. Presumably, the frost stat should only close in extremely low temps and this is what I'm simulating. Of course, the system is then on even if the programmer is set to off.

When I remove the short from the frost stat, the heating system shuts down.

The boiler is in the garage and has a frost and a pipe stat alongside.

Can anyone advise

 

[doitall]

Not from the information so far.

Is it a new install ?

 

[jie49]

No, it's been in 5 years

 

[doitall]

So has the problem just started or always been there.

The frost stat simply over-rides the controls.

You need to go back to the programmer, room and cylinder stat and any motorized valves.

 

[jie49]

More info: At the moment, the frost stat is shorted so the gas burner is on, pump is running, programmer is off, room stat is off. Only some rads are hot and others are stone cold.

Very confusing

 

[doitall]

The problem will not be the frost stat.

Is the system filled with water and at the right pressure (sealed system)

Why is the programmer and room stat off, the heating will never work.

 

[jie49]

That last post was misleading about some rads being cold, my grandson's been playing with the TRVz!

 

[jie49]

The system is full and the pressure is ok. I was pointing out that with the programmer off and room stat off, the boiler is on even though I'm not calling for heat but if I'm understanding correctly I've got the frost stat calling for heat because I've linked it out.

If I remove the link and turn on programmer and room stat, the system won't come on at the moment

 

[doitall]

So has the problem just started or always been there.

The frost stat simply over-rides the controls.

You need to go back to the programmer, room and cylinder stat and any motorized valves.

Thats why I replied above.

 

[jie49]

The problem is recent

 

[jie49]

Many thanks, I'll go back to the programmer and stat

 

[doitall]

You need to ID the components then fault find them one at a time.

Post the makes and models and a few system/control details.