I wonder if anyone can help me?

At night in cold weather both my frost stat and pipe stat switches close and the boiler comes on, as I would expect.

The boiler runs for about 6 minutes and when the return water temperature rises, the pipe stat switch opens and the boiler cuts out. The boiler stays off until the return water pipe cools again, then the pipe stat switch closes and the cycle repeats.

Here is my problem. The boiler ‘on’ time seems to be virtually constant at 6 minutes and does not vary if I change the temperature setting on the pipe stat. The ‘off’ time varies from about 30 seconds with the pipe stat set to 25 °C up to about 2 minutes with the pipe stat set to 5 °C.

When my plumber first fitted the pipe stat he told me to expect an ‘on’ time of about 20 minutes followed by an ‘off’ time of about an hour. (Before the pipe stat was fitted the boiler and the radiators would run constantly all night and the house was like a sauna).

I can’t sleep because of the noise and the worry about the size of the gas bill! Is there anything I can do?

Thanks

Sounds like possibly a fault or incorrect wiring of the frost and/or pipe stat somehow.

I certainly wouldn't expect the boiler to cycle this often on the pipe stat

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Dave

www.drlgas.co.uk

The cycle time will depend on the heat loss from the system, are all the pipes lagged.

But in any case, if the system is that noisy it wants looking at.

Pump speed too high.
Pump too big.
Pipes under sized.
By-pass wants adjusting if you have one.

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I have now looked at the boiler manual, and I think the pipe stat may have been connected wrongly.

The boiler is a Worcester Bosch Greenstar Ri and the pipe stat is connected to the vertical pipe closest to the flue connection. If I read the manual correctly, this is the FLOW pipe, not the RETURN.

If so, I guess the pipe stat is seeing a very fast rise in temperature and switching off quickly, then the flow pipe cools again quickly and causes the cycle to restart?

So if I move the pipe stat to the return pipe (next to the flow pipe but closer to the outside edge of the boiler) will that do the trick?

Thanks for your help.

Yes, the left pipe is the flow, so swapping the pipe stat over may do the trick.

If you turn the frost stat right up, the boiler should click on by turning the pipe stat up.

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