Howdy, just a little enquiry to see if there is anybody who can guide me in the right direction. Had a Grant outdoor boiler [not combi] fitted couple of years ago. Cycles on and off approx every 2 mins on central heating. Thought it might be 70000/90000 output too much for present system which comprises only seven rads. However when the hot water only comes on for an hour each day, the boiler runs for about ten mins to bring the water back up to temp then cycles approx every 10/12 mins. What are the possible causes of this?
oil boiler problem
- Thread starter ranger
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a) Probably. You could fit a digital eg: Honeywell CM 907 series room stat and set a delay to offset the cycling. Has your room stat got an anticipator and is the neutral connected? Cycling would be more significant were this the case.
b) You could fit an ACV fast recovery HW cylinder, that could take all the heat from the boiler in one burn.
b) You could fit an ACV fast recovery HW cylinder, that could take all the heat from the boiler in one burn.
You have a 24 kW boiler supplying about 7 kW of rads. Obviously its going to cycle when the flow temperature gets up to the set value of about 80° C until the room stat turns the boiler off.
On HW you say it gets up to temperature in 10 minutes and then it cycles every 10/12 minutes. That implies that the water is heated but the stat on the cylinder is either set too high or is not turning the boiler off. It should be set about 55-60°.
If I was a barrister then I would be suing your installer for fitting a boiler which is grossly over rated for yor needs which results in much lower efficiency and thus greater running costs.
There used to be retrofit devices to increase the cycling delay on heating to 5-12 minutes to improve efficiency but I dont know if they are still available. Easy to knock up for an electronics enthusiast though.
In theory it might be possible to adjust the boiler stat to increase the differential but I would not recommend that as a DIY activity!
Tony
On HW you say it gets up to temperature in 10 minutes and then it cycles every 10/12 minutes. That implies that the water is heated but the stat on the cylinder is either set too high or is not turning the boiler off. It should be set about 55-60°.
If I was a barrister then I would be suing your installer for fitting a boiler which is grossly over rated for yor needs which results in much lower efficiency and thus greater running costs.
There used to be retrofit devices to increase the cycling delay on heating to 5-12 minutes to improve efficiency but I dont know if they are still available. Easy to knock up for an electronics enthusiast though.
In theory it might be possible to adjust the boiler stat to increase the differential but I would not recommend that as a DIY activity!
Tony
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