Boiler firing on cold

[DIYSOS2018]

Had an extension fitted, some rads moved and a new boiler fitted and since then my combi system is firing up briefly when there is a cold water draw from either a tap or toilet etc. This happens after the cold draw and I’ve read plenty to indicate it’s likely caused by air being trapped or a dead leg pipe.

I understand to an extent the possible fix in terms of one way valve and expansion vessel but wondered without this how much, if any, damage, this will be doing the boiler?

 

[Jurassicspark]

You need to find the dead leg.

Look behind your washing machine some only have a cold fill ,older ones have a hot as well. You can try seeing if you have a redundant hot water pipe if you got one, turn the isolator valve to off.

Alternatively, you can fit a NRV (non return valve) on the hot water output of the boiler quick job for an average DIYer, you don't need to drain the system down.

 

[DIYSOS2018]

Thanks. There are lots of dead legs hence looking to check whether leaving things as is would be a problem?

 

[gas112]

dead leg although you hear boiler it doesnt usually get to stage were it fires

 

[DIYSOS2018]

dead leg although you hear boiler it doesnt usually get to stage were it fires

So providing I put up with the annoyance no problem doing nothing?