1 x Rad = cold at bottom/hot at top

[steadyfriend]

SOME AIRLOCKS ARE REALLY DIFFICULT TO REMOVE !


Well you have done something wrong for sure but what... ok the boiler you say it’s a
Combi? Boiler the Pipe work is it 10 mm or 15 mm to?
I am trying to work out in my mind the room and how the rad is fitted...
Is it in the same room you say it (was tee-d off another rad about two feet away, along the skirting board)
What size is the new rad you fitted
How did you shut the system down what did you do?
Again is it an open vented system or a closed system
There could be too many rads on the system could be! You say you have 13? Already

Removing recently fitted radiator. Dose the rest of the system have a problem example air in the other 13 or one of them, rads not getting the heat they need anything unusual

What is the boiler rating? Btu’s watts whatever!


Try turning the pump down on the heating side variable pump I would assume it will have three settings on it try tuning it down to 1, 2, 3, see what happens on say 2 then move up then see what happens.


Also do the same with the domestic pump on the boiler turn it down if it on three set it to 2



The heating pump could be Caviatating.. .. have a nice weekend

Ray, thanks for responding so quickly.
First your answers:

1) The boiler pipework is fine: -- 22mm out of the boiler. Then 15mm everywhere else. Nothing smaller.
2) The new rad was small, about 3 feet, single and with fins. It was tee-d off a nearby old rad (about 3 ft., double without fins) in the same through-lounge because the customer reckoned there was a ‘cold spot’ near the bay window. Yes, it was 2 ft. away from the nearest rad. The pipework off the existing rad to the new one was clipped along the skirting, for the customer did not want the floor lamination and boards taken up.
3) Yes, there are a total of 14 rads(inc. the new one) in the system but most of them are small about 3 ft. each. So, really it does not matter how many rads a system has, it is the boiler heat output which should match the total rating of all the rads in the system.
4) Now, none of the rads have any airlock problems.
5) It is a sealed fully pumped system with a combi boiler.
6) The system has a Valliant ecoTEC 831 boiler, output about 28 to 30 kW, adequate for all the rads.

Now for my analysis:-

The system is okay but too spread out with a long piped network, as the house is quite long.
I did not check if the boiler had a variable-speed or a single-speed pump, but it does not matter now, for the problem has been solved.
I had bent the pipe (with a pipebender) to go into the thermostatic rad valve, instead of using a 15mm elbow. And this bend stored a stubborn airlock which could not be pushed out by the force of the pump alone, as it was too far away from the rad concerned. Removing the new rad and opening the closed thermostatic valve slightly allowed this massive airlock to come out with a loud hissing noise.

We all learn new things everyday !