Please help, overheat thermostat problems!

[deepi1985]

Hi,
I wonder if you could be of assistance. I have had problems with my boiler for about a month now, went xmas without any heating - nightmare!
The radiators stopped heating up when I turned on the boiler. This problem has now been solved when I changed the pump..but can not fix this one problem: the overheat thermostat keeps coming on and cutting off the boiler, I have changed the boiler thermostat AND also the overrun thermostat for the pump. This does not seem to solve the problem.

It is a potterton neatheat profile boiler 60e.

 

[deepi1985]

Can Someone help? I have already changed the pump, and both thermostats (Boiler and overheat). How do I find out if it is airflow problems???

 

[twgas]

have you checked the actual temp of the boiler?

 

[deepi1985]

how can we check the temperature of the boiler? We can only put the temperature knob at the minimum and it still overheat button is coming on.. with HW and CH, but most usually the HW.

 

[twgas]

which stats have you changed first post says boiler and pump overrun, second post says boiler and overheat.

 

[deepi1985]

Hi Mick,
Sorry working with my dad on this (getting very confused).. He has changed the pump over-run thermostat and the over heat thermostat.

 

[twgas]

so how hot is the boiler when the overheat trips?
and is any heat going round the system

 

[deepi1985]

when i put the central heating on all the radiators gets hot and after for a while the overheat thermostat button comes on, but on the hot water as soon as the boiler comes on after a few minutes the thermostat button comes on.
We have changed the BOILER THERMOSTAT and PUMP OVERRUN THERMOSTAT, and PUMP, and 3 WAY VALVE MOTOR AS WELL as still get the same problem.
Please help.
I do not know how hot the boiler gets, there is no way of me being able to tell.

 

[twgas]

when, and if, you changed the boiler stat-thats the one that has the control knob on-did you smear the phial with heat sink compound?

 

[deepi1985]

Hi,

No we did not. What is heat sink compound and where it should it be put on - on the capillary? What effect would this have?
Ignore other thread sorry.
Thanks you

 

[twgas]

its a paste that helps transfer heat from system to thermostat, goes on phial (bulbous bit at and of capilliary). Overheat problem could be solely down to this.

 

[baxpoti]

Have you checked the pump actually runs on after the flame shuts down?

 

[deepi1985]

The pump works fine after the flame turns off, however no paste was applied at all. no paste came with the stat so was wondering where I could grab hold of it?

cheers

 

[baxpoti]

After changing the pump.
Is the water going through the boiler the correct way?
e.g. the flow pipe gets hot first!

 

[ChrisR]

Does the Return pipe get almost as hot as the flow pipe, when it turns off?
If not, you have a circulation problem.