Is this short cycling?

ARainyDay

I didn't end up touching the programme, and left it on 6 cycles (which was what was there originally). However, I've now noticed that when my boiler is working up to reach a set temperature it is now shutting down every 8 minutes for approximately 1-2 minutes. It's never done this before- does anyone know what the cause could be? I wonder if there's a button I accidentally pushed when going through the set-up this morning

EDIT- I don't think it's ever done this before when the thermostat has been calling for heat, but there is a chance it has and I've just not noticed it. So I guess what I'm asking is it usual for a boiler to cycle not only when it is maintaining a temperature, but when it is heating up to reach one?

markin

If rads close it will shut of to prevent over heating the heat exchanger or other boiler parts

Ballymoney

@ARainyDay can I ask why you decided against changing the cycle program? Did you decide it’s more efficient to cycle every 10 mins rather than 20? 

Yorkshire_Pud

Is regular cycling a normal and necessary occurrence when running a CH combi boiler?

If so what is a desirable frequency?

Or does a mythicaly perfect system never cycle or exhaust vapour as it has the perfect 20c flow return where the boiler can condense optimally?

Reason I ask is I read that when the water vapour is seen exhausting from the flue it means the boiler is failing to return the heat energy for re use back into the system so the less times this is seen to happen the better the system is operating and cheaper the bill?

BUFF

Yorkshire_Pud said:

Is regular cycling a normal and necessary occurrence when running a CH combi boiler?

If so what is a desirable frequency?

Or does a mythicaly perfect system never cycle or exhaust vapour as it has the perfect 20c flow return where the boiler can condense optimally?

Reason I ask is I read that when the water vapour is seen exhausting from the flue it means the boiler is failing to return the heat energy for re use back into the system so the less times this is seen to happen the better the system is operating and cheaper the bill?

Imo a mythical perfect system would modulate to exactly the heat demand (so wouldn't cycle) but that may well need modulation ratio of 10:1 or more (certainly on your typical combi that was sized for dhw demand rather than heating demand) whereas most boilers are ~5:1.

You are never going to get 100% of the energy out of the flue exhaust. With the outside temperature as low as it has been for the last week or so the plume is going to be more visible as the difference in temp. between the exhaust gases & ambient is larger than usual.

Reed_Richards

Yorkshire_Pud said:

Is regular cycling a normal and necessary occurrence when running a CH combi boiler?

In my old house I had a gas boiler than never seemed to cycle.  It could do both Weather Compensation and Load Compensation and the modulation range was sufficient that it could keep going.  A gas boiler using an OpenTherm controller should be able to behave similarly.