central heating works for 40mins and then stops

Postby sinnet » Wed Nov 14, 2007 4:20 pm

I have a fully pumped CH system with a timer control panel on an ideal classic boiler (boiler and water tank are 5yrs old). When the heating is set to come on it only does so for 40mins and then goes off and the pump stops working. At the front of the pump is a nut which i think is used to bleed it, i've tried to remove it but it just keeps rotating after a while (with a tiny bit of black water coming out).

Does anyone have this style of pump and know how else to access it so I can see if it's siezed. The pump has 3 settings and it's on 3.

Or does anyone know what else maybe causing my heating to stop after 40mins?

Thanks for reading.
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Joined: Wed Nov 14, 2007 3:21 pm


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Postby Thorpy » Fri Nov 16, 2007 6:53 pm

I have the same problem but I no solution yet. The heating goes off before the house is warm and won't come back for a couple of hours.

Have you solved it yet?
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Joined: Fri Nov 16, 2007 6:44 pm

Postby slr1981 » Sun Nov 18, 2007 3:31 pm

I've also got a similar problem, but also no solution yet,

With mine, the CH stops working when the thermostat in the HW is reached. i.e. after about 40 mins. If i run the hot tap, and the HW starts to flow again, the boiler fires up, and the CH becomes hot again. is this the same for you?

I think this is something to do with a flow sensor in the boiler (CH alone not enough flow to fire), but i haven't found anything about this.

Can anyone else offer advice etc?
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Joined: Wed Nov 14, 2007 5:49 pm

Postby sinnet » Thu Nov 22, 2007 11:44 am

Yes I have now resolved this problem. Under the pump by my hot water cylinder is an actuator (in my case it was a rectangle shape with three settings on the side (H M W) attached to a 3way valve. This houses the motor that drives a quadrant that fits on the valve spindle. First of all I checked the valve spindle to make sure it was working this is done by slowly turning the spindle with a small spanner to check it moves easily. It was moving so this indicated that the motor in the actuator wasn’t working. I had already organised for a plumber to come round but phoned to cancel as I had identified that the actuator was the problem. The plumber kindly told me I wouldn’t need to replace the actuator but just the motor inside. I have done this and my CH is now working. I purchased the motor from PTS £10 it is easy to replace - it is just attached with 3 screws and 2 orange cables that plug into a circuit board.

Hope this helps.
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Joined: Wed Nov 14, 2007 3:21 pm

Postby Thorpy » Sat Nov 24, 2007 10:05 pm

Thanks Sinnet - I will have a look.
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Joined: Fri Nov 16, 2007 6:44 pm

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