Heating problem

Hi guys,

A couple of months ago we had a new boiler (Potterton Suprema condensing) installed. Since then one of our 12 radiators has been pretty much stone cold. The only way we have found of making it work is by turning off all the other radiators - that makes it piping hot.

The plumber who installed the system has been back a couple of times but failed to fix it. He is convinced there is a blockage and therefore replaced some piping today. I can't understand how it can be a blockage if it works when we turn off the other rads.

We've had some advice from a maintenance bloke who did some tiling for us. He said the pump is set to high and that by default a new pump would be set to medium on the basis that it would go to high when an extension/more rads were added to the system. His suspicion is that the pump is not powerful enough - the installer disputes this.

Any comment would be fantastic - I am a complete novice when it comes to these issues. One thing I note is that for the rad in question one pipe feeding it is hot, one cold. We have tried putting cleaning agent through the system. Another thing to note is that the boiler was moved to our garage from the kitchen which has added quite a bit of pipe length to the system.

Thanks in advance, James.

Reply to
James
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If there's hot water getting to the rad, and all other rads, then it's not the pump. It sounds like a blockage in this rad, take it off and clean it out with a hosepipe, it's probably full of sludge.

Reply to
Phil L

Have you tried balancing the system as per the FAQ?

Reply to
Dave Plowman (News)

There could be a partial one due to sludging etc., but it is more likely that either the system is out of balance or that as you say the pump is not powerful enough. It may even be that there is a partial airlock (i.e. a bubble) in the pipework to the miscreant radiator, although normally turning everything else off and this one up full would clear it.

Really the system should have been thoroughly cleaned when the boiler was replaced. Often it is a warranty condition for the boiler.

Did he quote for and do this?

Extending the pipes substantially will have increased the flow resistance and that may well also be playing a part. The installer should have done the sums and worked out the implication of extending them. Possibly a larger size should have been used between the new position and the connection point to the rest of the system.

You could try opening the lockshield valve on the miscreant radiator and see if it begins to work with some radiators turned off but not all. If it does, then balancing the system would be a good move. This is easy but time consuming to do which is why installers often don't do a very thorough job. However, if you can only get the miscreant radiator to work by closing off all other radiators and with both valves on it full on, then other issues such as blockage, trapped air and inadequate pipework from boiler and pump power are in the frame.

Reply to
Andy Hall

It can be, because the pipe lengths have been increased.

That could be.

Reply to
Andy Hall

If I open up all the lockshield valves fully here the rads on the top floor don't get hot. Even with the pump on max. I do have a fixed bypass circuit, though. With the system balanced the pump is on minimum.

Reply to
Dave Plowman (News)

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