Timer question for boiler experts

mikeyranson

My elderly neighbour has had some issues with his central heating boiler just randomly starting up a couple of times during the night when the timer is not set to. He has it set for morning and evenings. Dont know if this is coincidence or whether there is something else but the question is, are the honeywell timers as per photo sensitive from surges?. I am not by far an expert in boilers but the only thing i can think of are the power cuts of the national grid has caused some sort of surge and possibly damaged the timer. Is that possible?

There was a power cut earlier this year and after that cut, was when his heating was turning on and off in the middle of the night. He doesn't know about the day as he is downstairs or always out during the day but at night, it wakes him up as his bedroom is next to the cupbaord that houses the central heating.

He had a new timer installed by a qualified engineer and it went fine, then another powercut happened last month and again, the boiler was firing up again at night. He has since called an electrician and a boiler engineer and both say that everything is fine electrically with no advice on what it could be.

Is it possible that the timer is damaged from a power surge caused by the power cuts? Are these units sensitive towards these events?

advice appreciated.

thanks

grumbler

If it's a combi boiler with a small tank of hot water built in, I think it's normal for it to switch on periodically for short time. 

elle_may

Some boilers have a preheat on them. Our old ideal boiler came on a few times in the night, got used to it in time. Our new one a Baxi does not. Some you can switch off. They would only be for a few minutes so if on longer then it is something else to look at.

Jeepers_Creepers

Yes, make and model of boiler if possible, please.

As for that timer, if the indicator lights as shown in your photo correspond with the on and off intervals as they should, I'd say it's extremely unlikely it's sending an unexpected signal to the boiler.  Your neighb can check this when he's woken up - are any lights on?!

southcoastrgi

The heating is set to constant so what is the room stat set at ?

Homer_home

As above the heating is set to always on and the hot water is set to off , is this correct or is it the wrong way around ( which would explain the boiler firing during the night)

mikeyranson

Thankyou all for your input. Sorry for the delay getting back on here to answer. I will ask these questions when i see him next and come back to you.

kdotdotdotdot

Two possibilities: my boiler sometimes fires up at random times to get the hot water temperature back up to minimum heat. 

In addition to coming on twice a day, it's also set to automatically go on when the house temperature drops to a certain level.  In my case it's 12 degrees, which never happens, but perhaps your friend's lowest temperature is something like 18 degrees, which may cause the boiler to come on during the night now we're heading into colder weather?

JohnB47

My Worscester Bosch combi boiler runs the pump for 5 minutes every 24 hours, although the boiler itself doesn't fire up. It's to stop the pump seizing through long periods of inactivity (eg during summer months when the central heating (CH) might not be needed). We sometimes hear this while lying in bed - it's really just the noise of a couple of bubbles of air being pumped around the system. It does this all year round, regardless of whether or not the CH is actually being used.