central heating off but on!


Postby mart39 » Sun May 04, 2008 6:02 pm

Hi there,
Now summer has arrived i have turned the central heating slider switch to off but left the hot water on timer, yet when the timer kicks in to heat water up i have found all the upstairs radiators heating up even though the c/h is turned off.
thanks
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Postby ericmark » Sun May 04, 2008 8:04 pm

Much depends on the system you are running. Thermo siphon will sometimes allow upstairs radiators to heat up and many systems have motorised valves to stop this happening.
ericmark

Postby rosebery » Sun May 04, 2008 10:02 pm

It sounds like a failed actuator on your motorised valve (assuming you have one) or the valve gummed up with goo so the actuator can't actually operate it properly.

Can you give some more data about your system please? As ericmark says much will depend on that answer.

Cheers
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Postby mart39 » Mon May 05, 2008 12:04 pm

Thanks, the boiler is downstairs in the kitchen and has myson orion on the front, the control panel is potterton and has individual switches for water and c/h, hot water tank is airing c-board and looks like there is a a pump attached to it, and another oblong silver bos with honeywell coming off it, hope that helps if not let me know what more info you need
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Postby htg engineer » Mon May 05, 2008 3:25 pm

The oblong silver box will be the actuator, probably a Honeywell V4073 or similar.

Remove the actuator, check the 3 port valve turns freely, and check the actuator turns when HW or CH selected. If it's not turning - replace.

I think you might have to change the whole three port valve though, normally if the actuator fails, all of the radiators will heat up when hot water only selected. If only upstairs radiators heat up it sounds like the valve is turning but not fully closing off the heating side. Therefore letting water/pressure through but not enough to reach downstairs.

Hope this helps
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Postby rosebery » Mon May 05, 2008 4:50 pm

Just had to do the same with my own system as it happens. Actuator working fine but valve itself just didn't want to play at all.

Quicker just to exchange the whole thing. Watch out though that your actuator wiring might be slightly different. Older Honeywells had 6 wires the newer ones have 5. There's data on the Honeywell Site about the wiring differences to save repeating it here.

Cheers
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Postby GrahamW » Wed May 21, 2008 7:01 am

Hi all

I have a similar problem. Potterton Suprima Combi boiler.

When the termostat is turn right down, the radiators are boiling hot and I've run out of hot water. Sounds like the Actuator to me. In my airing cupboard I have black Honeywell box with a manual and auto lever and I also have a Myson Power Extra which also has a manual lever. Any ideas of which would would be causing the problem??

Cheers

Graham
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Postby htg engineer » Wed May 21, 2008 6:30 pm

"When the thermostat is turn right down, the radiators are boiling hot and I've run out of hot water."

Run out of water ? hot tap stops running ? if yes then it's the tank not filling as fast as it's emptying - renew ball valve.

If you can have Hot water only, Central Heating only or Central heating and hot water - actuator/3 port valve fine.
Turn heating on only, radiators too hot ? thermostat problem.

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