On 3 Nov 2003 14:06:05 -0800, (Danny)
wrote:


To combat the problem so I can at least have some heat in the house I
have to open by-pass fully and open the 22mm gate valve feeding the HW
coil to 3/4 - full. but the rads don't get to full temp with this
config. I set the HW circuit to approx 1/4 open, rads getting piping
hot, room thermostat pops off, boiler safty cut-out soon follows!!

Could it be the boiler thermostat? If so, can I replace just the
thermostat, and approx how much are they?

It sounds like it could be and normally you can. Did you say which
boiler you have? If the thermostat is one of the capillary type then
it is pretty easy to replace - push on connectors normally.
I replaced one on a Glow Worm about two years ago and IIRC the
replacement was about £30.

If you have a boiler with electronic controls, then Geoff at CET is
your man - his company reconditions them.





BTW, temp of pipes is approx 65 degrees

Do you mean flow or return? 65 on a return is within spitting
distance but on a flow is too low. If anything, you should be
closing the bypass to encourage more water around the heating circuit.

Have you checked the diverter or other motorised valves? Does the
situation improve with higher pump speed?

If the boiler has good flow and is cutting out with a flow of 65
degrees then evidence does point to the thermostat or possibly an over
temperature sensor.





Regards,

Danny


..andy

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