Boiler firing up during the night

Mr. Fancypants

I have a Intergas Combi Compact HRE 24-18 (about 5 years old) boiler and got a Nest installed in December last year.

Since having the Nest installed I have found that the boiler will fire up during the night every so often. The Nest is not aware that the boiler is on when this happens. The motorized valve does not have a light on it when it happens either. The only way turn off the boiler when this happens is to turn off the power on the boiler itself using the power switch.

It could fire up at any stage during the night. I have had it happen at anytime between 10pm-4am. Just happened at 3am this morning. It may not happen for days or weeks at a time and other times it may happen 2 or 3 days in a row.

I haven’t been able to get through to my regular boiler service company. Boiler has been regularly serviced prior to this. Could anyone point me in the right direction? Boiler is in my bedroom so losing sleep due to this!

jimf

most likely a sticking micro switch on motorised valve

If the boiler has a preheat on it and it’s been activated it could be firing to preheat your hot water which means the boiler can fire for short periods erratically more noticeable at night, if it gets cold enough it can fire for short periods also at night.


Two test that may help:

Turn the heating off at the selector switch on the boiler for one night, if it fires again it’s not your external controls.

Turn your boiler off from the on/off switch on a second night, if it fires its most likely frost protection, if it doesn’t fire it’s mos likely your hot water pre-heat.

TitianGerm

mbroaders wrote: »

I have a Intergas Combi Compact HRE 24-18 (about 5 years old) boiler and got a Nest installed in December last year.

Since having the Nest installed I have found that the boiler will fire up during the night every so often. The Nest is not aware that the boiler is on when this happens. The motorized valve does not have a light on it when it happens either. The only way turn off the boiler when this happens is to turn off the power on the boiler itself using the power switch.

It could fire up at any stage during the night. I have had it happen at anytime between 10pm-4am. Just happened at 3am this morning. It may not happen for days or weeks at a time and other times it may happen 2 or 3 days in a row.

I haven’t been able to get through to my regular boiler service company. Boiler has been regularly serviced prior to this. Could anyone point me in the right direction? Boiler is in my bedroom so losing sleep due to this!

There's a setting on the Nest to fire the boiler if the water temperature is below a certain temperature. When we got ours installed it'd for up once a week or so and it took me ages to figure out why.

Kencollins

My money is on the "bacteria protection" function. If nest thinks the hot water hasn't been at 70 degrees for a few hours in a 24 hour period it will fire the boiler to heat the tank. It doesn't show in the status lights or on the display, it just does it itself. When I disabled that function the phantom boiler firings went away!

It’s a combi boiler so it doesn’t have a hot water cylinder so it’s a function that shouldn’t be operating “hopefully” ��

DGOBS

https://www.youtube.com/watch?v=tCZhd0mWIRc

Turn on/off Intergas pre-heat

Mr. Fancypants

Thanks for all the feedback, really appreciate it!

DGOBS wrote: »

https://www.youtube.com/watch?v=tCZhd0mWIRc

Turn on/off Intergas pre-heat

That looked promising but when i checked it is off already. Thanks though!

Kencollins wrote: »

My money is on the "bacteria protection" function. If nest thinks the hot water hasn't been at 70 degrees for a few hours in a 24 hour period it will fire the boiler to heat the tank. It doesn't show in the status lights or on the display, it just does it itself. When I disabled that function the phantom boiler firings went away!

Just turned that off and will see how it goes, good to hear someone else had a similar issue!

jimf wrote: »

most likely a sticking micro switch on motorised valve

Would i not see the motorized valve turn on if this was the case? When the boiler comes on normally i see an orange light on the motorized valve but not when it comes on outside of schedule.

HeidiHeidi

Kencollins wrote: »

My money is on the "bacteria protection" function. If nest thinks the hot water hasn't been at 70 degrees for a few hours in a 24 hour period it will fire the boiler to heat the tank. It doesn't show in the status lights or on the display, it just does it itself. When I disabled that function the phantom boiler firings went away!

I was driven demented by this! It's to protect from Legionnaire's disease (or so I was told) Nest were very helpful in fairness, the setting is buried deep in the thermostat gizmo, I'd never have sussed it by myself.

Mr. Fancypants

2 night so far and no random boiler firing up. Will update again to confirm if the issue is sorted in a few weeks.

Mr. Fancypants

Just as an update in case anyone else experiences this issue. I haven't had a problem since disabling the bacteria protection function. Has been 6-7 weeks with no sign of the boiler firing up in the middle of the night. My sanity is restored. Thanks again Kencollins!

blackbox

mbroaders wrote: »

Just as an update in case anyone else experiences this issue. I haven't had a problem since disabling the bacteria protection function. Has been 6-7 weeks with no sign of the boiler firing up in the middle of the night. My sanity is restored. Thanks again Kencollins!

Are you not worried about legionella?

blackbox

blackbox wrote: »

Are you not worried about legionella?

It’s a combi boiler and has no stored hot water so legionella isn’t a issue.