Can't get all rads working on new system

[KingDoey]

Good evening all.

Last job today to repair a leak on a brand new heating system. Is a combi boiler.

Drained down. Repaired leak and refilled. Vented and ran system. On 5 of 8 rads getting hot. Tried balancing system and no better. Ran boiler on max. Still 3 stone cold rads.

EngIneer before me says system was running hot all round before leak. Any ideas why 3 rads stone cold. Have removed all air from system. Set boiler on purge programme several times. Just can't get it to circulate.

Even with every radiator off bar the three cold ones the boiler just cuts off.

Any ideas?

 

[ShaunCorbs]

Moved some rubbish about blocking those 3 ??

 

[Scott_D]

Did you check trvs and lockshields open?
Are you sure it worked before?

 

[KingDoey]

Thanks chaps

Yeah the guy who had it running before said it was defo working like a dream. I trust him aswell as I know him.

Shaun I thought a blockage, yet the 3 radiators affected are at different stages of the run if that makes sense. They are in between hot radiators.

I am literally stumped....

 

[ShaunCorbs]

I would pull the rads and see if you have flow then both valves but won't be quick

Trv pins arnt stuck ??

 

[Harvest Fields]

Definitely not an air lock?

 

[Chuck]

Tell us where the 3 cold radiators are and about the path the pipes to/from them take.

Could they be on a separate zone with a zone valve hidden somewhere non-obvious?

Are you sure the pump is running and pumping effectively, could the 5 hot ones be being kept warm by gravity circulation (unlikely with a modern boiler) or a weak pump that is on the way out?

 

[king of pipes]

Shut the valves off to the rads let the pressure off take out the plug opposite the manual air vent and pipe up to a hosepipe run to a drain open up trv and filling loop and flush through do this on the 3 rads and refill and vent, see if this improves the situation . cheers kop

 

[KingDoey]

Turns out the apprentice had messed about with the lockshields. Didn't even think to check them since 2 hours before the other engineer had the system hot. Funny how you overlook the simple things!

Cheers for all the advice!

 

[ShaunCorbs]

hope the apprentice is still in the world of the living