Best way to find blockage in heating system

shefmarkh

Hi,

We have issues with our downstairs radiators not heating up very much. Boiler has been checked by the boiler manufacturer and they say it's fine + the issue is likely a blockage. They recommend a power flush (but won't do it themselves) to clear any blockage. Our plumber on the other hand suggests randomly cutting pipes open to search for the blockage (and presumably clear it manually). Which is likely to be the best option?

Thanks,

Mark

molerat

A power flush is likely to be the least messy and intrusive but isn't cheap.  Unless your plumber can do it you are likely looking at a £500+ bill.

Draining down and taking radiators off could be cheaper but could get messy, have you seen what comes out of an old radiator ?

markin

Have you turned off all the radiators but 1 at a time?

Is it 8mm, 10mm piping? magnetic filter?

Why would he not try a flush first has he not go a flusher?

M25

How old are the radiators?

A power flush could be the answer but it needs doing properly so get a couple of quotes and maybe a recommendation from someone.

You could also change the first poorly operating radiator for a brand new radiator. Cheap to do but may not give you the results you want (ie the blockage could be in a pipe away from the first radiator).

Also if the plumber could get access to pipes he could use FLIR thermal imaging and that would clearly show a bad blockage immediately.

Lots of options if you're scared of a mess maybe just go with a power flush but if it's a proper job it could take a full day (plumber will leave after setting it up) and may drop into the following morning so you'd have that to contend with.

Also -maybe a plumber could comment- you could have a faulty return or flow valve on one of the radiators. Do you have thermostatic valves?

FreeBear

Unless you have microbore pipes, any blockage is likely to be in a radiator. Cutting random pipes in the hope of discovering where the blockage is sounds like an act of desperation.

Personally, I'd put some central heating cleaner (Fernox F3 or Sentinel X800) in the system and run it for a few days. Drain the system down, and then take each radiator outside and run fresh water through them (plug the ends before taking them off the wall). Before refilling the system, make sure there is a magnetic filter on the return pipe to the boiler. Dose up again with cleaner, run for another day or two, and then give it a real good flush. Clean out the magnetic filter before refilling one last time, making sure corrosion inhibitor is added. Finally, go round and balance all the radiators.

70sbudgie

I would be wary of a powerflush if you've not done it before. We discovered bad welds on a lot of our pipework that hadn't caused problems until the pressure was increased significantly. 

On the other hand, cutting pipes to look for a blockage seems madness 

Reed_Richards

FreeBear said:

Unless you have microbore pipes, any blockage is likely to be in a radiator. 

Radiators should be plumbed in parallel rather than in series.  So a blocked radiators should only affect that radiator, not the whole downstairs.

shefmarkh

markin said:

Have you turned off all the radiators but 1 at a time?

Is it 8mm, 10mm piping? magnetic filter?

Why would he not try a flush first has he not go a flusher?

Yes plumber tried turning on radiators one at a time ages ago and it didn't help.

There is a magnetic filter on one of the pipes to/from the boiler.

No idea why he has not suggested a flush. We are going to get another plumber to look now and see what he recommends.

shefmarkh

M25 said:

How old are the radiators?

A power flush could be the answer but it needs doing properly so get a couple of quotes and maybe a recommendation from someone.

You could also change the first poorly operating radiator for a brand new radiator. Cheap to do but may not give you the results you want (ie the blockage could be in a pipe away from the first radiator).

Also if the plumber could get access to pipes he could use FLIR thermal imaging and that would clearly show a bad blockage immediately.

Lots of options if you're scared of a mess maybe just go with a power flush but if it's a proper job it could take a full day (plumber will leave after setting it up) and may drop into the following morning so you'd have that to contend with.

Also -maybe a plumber could comment- you could have a faulty return or flow valve on one of the radiators. Do you have thermostatic valves?

Radiators are no older than 1980 (when house was built). Some are newer (2010's) when extension was added.

Wouldn't a radiator valve fault only affect one radiator rather than the whole system?

shefmarkh

70sbudgie said:

I would be wary of a powerflush if you've not done it before. We discovered bad welds on a lot of our pipework that hadn't caused problems until the pressure was increased significantly. 

On the other hand, cutting pipes to look for a blockage seems madness 

What was the consequence? Pipes burst and rooms got flooded?

tim_p

shefmarkh said:

There is a magnetic filter on one of the pipes to/from the boiler.

Have you opened this up and checked it’s clear of crud?