Airlock in end 2 radiaotrs

[drew.boi]

hello all,

I am after some advice if anybody has it??

My problem stems from 2 radiators upstairs in a bedroom that aren't getting warm at all. The boiler is a Worcester greenstar combi 25 si so the system is a fully sealed system but the radiators are the old sinlgle panel variety. All the other radiators in the property are fine and heat up ok but these 2 dont and neither does the flow or return pipes leading to the radiators. I have tried bleeding the problem rads as well as all the others and no air is apparant and have also tried turning off all the other radiators to force the water around these 2 rads. When i do this the flow pipe does get very hot on the first rad but going into the second rad it cools off to nothing and nothing into the rad or the return pipes. I have also tried to crack the last nut on the 2nd rads trv and it does seem like there could be an airlock because after releasing some of the water the flow pipe comes warm.

Does this sound like an airlock on the second rad and if so what is best way to get rid of it as i have tried bleeding it etc. Dont think there is a problem with the boiler as it works the rest of the rads fine except these 2.

any suggestions would be gratefully recieved.

cheers drew

 

[Rickster123]

Have the two radiators worked since the combi was installed? How old are the trvs on the rads?

 

[drew.boi]

hey app,

No its a new combi boiler, with brand new trvs and the radiators are newly installed even tho there are old to, customer got given these 2nd hand rads to put in instead of buying new.

cheers

 

[Rickster123]

How many rads on the 25si mate? Are they being run off of 15mm? I would start by shutting off all other rads and pushing any air into the faulty ones.

 

[drew.boi]

The main flow and return pipes are 22mm from the boiler being branched off in 15mm to rad positions as and when they come. There are 11 rads running on the 25si which includes a towel rail and a small 300x600 rad. I have tried switching the other off and do get the flow pipe hot but it doesnt go around the 1st rad on the line and flow pipe gets cold by the 2nd trv.

 

[Rickster123]

Sounds a bit undersized mate IMHO. You could try having the rads off the wall and check flow through both valves and through the rad itself.

 

[drew.boi]

ryt o thanks for advice!!! all the others heat up fine and are so hot can hardly touch them. I just cant seem to see why when all other rads are switched off why it wont force round these 2!!! i think i need take the rads off and investigate further!!!

thanks for the advice