HEATING FAULT

[buildclean]

Our heating system has developed a fault in the last week or so.

It is a sealed system with a primary circuit to heat the water and a few rads, and a secondary circuit to heat the remaining rads. The hot water is controlled with a cylinder stat on the storage tank and the heating is controlled with a (|Heatmiser) room stat in the hall. Both circuits are controlled with a 7 day programmer - drayton LP722. The boiler is a potterton 100e. The radiators all have trv's.

The problem is that the boiler is on all the time (until the boiler overheat thermostat kicks in) and it is not switched off by the cylinder / room stat or the programmer. The only way we can reduce or increase temperature in the house is by using the boiler thermostat knob or turning off the electrical supply to the boiler completely.

Can anyone give us some advice as to what the most likely problem is??

Thanks

Peter

 

[simond]

Yep, motorised valve end switches are stuck closed.

Seized motrorised valve most likely.

 

[buildclean]

Cheers Simon - is it possible to replace this without draining the whole system down?

Peter

 

[xr4x4]

so if you turn down the boiler stat, does the boiler cycle on and off as it reaches temperature?

 

[simond]

It depends on the type of motorised valve you have, some have detachable power heads. I also depends whether the water bearing part of the valve has seized, obviously if this is the case then it will be a drain down.

 

[buildclean]

xr4 - yes it does

 

[xr4x4]

oh i see, ive re-read your post and im guessing it doesn't overheat, which is what i first thought.

also, do you know how many valves you have?

 

[buildclean]

xr4 - just one

 

[xr4x4]

as been said then, sounds like a fault in your 3 port valve.

 

[buildclean]

honeywell is the most expensive...is it the best?

 

[Agile]

Its the easiest to repair so I like systems with them.

But most of the others are just as reliable but just more difficult or impossible to repair.

Tony