Radiators not working after refitting & bleeding

[JayDee81]

Hi all

Yesterday I had most of my radiators refitted after removing them a around a year ago to replaster & redecorate. This is the first time all the radiators in the house have been connected & its a full central heating system since I had a new combi boiler installed around a year ago. I bled the radiators (bottom to top) & topped up the boiler so the pressure is correct.

2 rads which were removed for a year are not heating up at all,
Another rad which was working until a couple of days ago when it was removed to paint it is not not heating up at all.

On all rads both valves are fully opened to the max.

Any ideas what else I could try myself instead of calling in a plumber? I've been reading up on the net that I may need to temperature balance each radiator using radiator thermometers on the inlet & outlet pipes until the temp difference between the two is 20 degrees.

Also another 2 rads I could not bleed because the bleed screw was too small & neither of my bleed keys could grip it. Is there more than 2 sizes of bleed key? These 2 rads are also not heating up.

Thanks in advance.

 

[stanbowles]

Hi JayDee.

Try shutting down the other radiators just leaving one of the cold rads open. This might push out any air or sludge thats causing a blockage. If this works then do it for the other cold rads. You will then need to balance the system. You do this by regulating the flow of water through the rads that get hot the quickest. Also check that the valves are seized shut.
The air vents are all the same size but there are different styles of vent keys which might work better.
Hope this helps

 

[JayDee81]

Hi there

Thanks great thanks very much. A couple of qustions:

You will then need to balance the system. You do this by regulating the flow of water through the rads that get hot the quickest

How would I do this? using rad thermometers like I said above?

Also check that the valves are seized shut.

I opened them to the max myself & they turned freely enough, does this mean they are not seized? sorry this is my 1st house & I don't have much experience in these things.

Thanks for your help.

 

[stanbowles]

Each rad has two valves. One side a wheelhead or thermostatic valve and the other side a lockshield. A lockshield valve is one which you need to remove the cap to turn on and off. This is the valve that you use to balance the system. If both valves are wheelheads then choose the valve on the left hand side of each rad to balance with. Go to the rad which gets hot first ( usually the first on the circuit or nearest the boiler. ) and shut down the balancing valve. Then open it up just a couple of turns. Make sure the rad is still getting hot. If not open it up a bit more. Then go to the next rad and do the same but open up the valve just a little bit more than the previuos one. This regulates the water through the rads and pushes the flow on to the next one. You dont need a thermometer.
The valves can still be seized even if it is moving freely so turn off the valves remove the rad and open up each valve into a bucket to check that they both still work if your still having problems. Feel free to ask if you have any other questions. Good luck.

 

[JayDee81]

Each rad has two valves. One side a wheelhead or thermostatic valve and the other side a lockshield. A lockshield valve is one which you need to remove the cap to turn on and off. This is the valve that you use to balance the system. If both valves are wheelheads then choose the valve on the left hand side of each rad to balance with. Go to the rad which gets hot first ( usually the first on the circuit or nearest the boiler. ) and shut down the balancing valve. Then open it up just a couple of turns. Make sure the rad is still getting hot. If not open it up a bit more. Then go to the next rad and do the same but open up the valve just a little bit more than the previuos one. This regulates the water through the rads and pushes the flow on to the next one. You dont need a thermometer.
The valves can still be seized even if it is moving freely so turn off the valves remove the rad and open up each valve into a bucket to check that they both still work if your still having problems. Feel free to ask if you have any other questions. Good luck.

Right I'm going to try this now. Will first try shutting all the rads & just leaving one cold one open at a time if no joy will try balancing the rads. I assume I need to balance all the rads not just the ones that aren't working.

As only 3 or 4 of the rads in the house are working I can't say which heats up first so I'll just do them in order of proximity to the boiler.

Thanks again I'll keep you posted.

 

[stanbowles]

If you get a rad working then let it circulate on its own for a bit then move on to another one. Get them working then balance the system.
Once they are all working you can fine tune the balancing by opening / shutting valves accordingly.