Plz help Boiler & UFH pump not switching off - timer off

7 Jan 2015
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United Kingdom
Hi all

I have a Vaillant Ecotec 624 System boiler with uniSTOR 210L cylinder. also have a 3 channel hortsmann programmer which controls:
a- Hot Water
b- Heating Zone 1 - Radiators downstairs
c- Heating Zone 2 - Radiators upstairs

(both radiator zone are controlled via 2 separate honeywell thermostats)

In addition to the above, I also have an UFH circuit which has its seperate thermostat/programmer (Heatmiser)

Since yesterday, the UFH pump is constantly running despite the thermostat/programmer off. Worst, the boiler is also running constantly and supplying hot water to the UFH system.

Can someone advise as to what I need to check to troubleshoot this?

Thanks in advance
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I do see one on the UFH circuit underneath the pump (looks like its on the return flow), one on the rads pipe going upstairs, one near the water cylinder. Havent seen the 4th one but will check.

Is there anything I can check on the UFH valve to confirm if its faulty?

I also have switched off the entire system from the spur which has caused the boiler + UFH to switch off. After few mins, I switched it back on and the pump instantly came back on and so did the boiler and so did the flame on the boiler :(

Currently running the boiler flow temp on a low value like 40 degrees and only ramp it up to 65 degrees when I want to CH or HW to come on for an hr or two.
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There is a switch inside the valve that I think maybe stuck, you could try switching the whole system off and on a couple of times but the valve head will probably need to be changed.
I have switched it off 2 times already.

Do I need to wait for specific time before switching it back on?
The valves are closed by a spring and take about 3 seconds to close, if the switch isin't opening after a couple of trys chances are it wont, where abouts in london are you ?
No luck. Tried once more.

For now, I have lowered the boiler flow temp to 38 as I think the water in the circuit is higher and the boiler isnt running at the moment, but the pump is.

There is some kind of pump/fan running inside the boiler it seems.

I am btw in Harrow
I am in london tomorrow and friday if you would like me to have look my number is on my profile (just click on my user name).

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