Central Heating Blocked Pipe !

[Monkey Wrench]

About 10 years ago a customer had a two storey extension built onto their house which added four radiators to the system. The boiler is located in the garage and the installer teed directly off the main 22mm flow and return in the garage for the additional radiators. The system is vented and the pump is on the return. Apparently, only three of the four additional radiators have ever got up to temperature with one of them only remaining only luke warm. The radiators in the rest of the house (there are 9 of them) all heat up normally.

Recently, the radiators in the extended part of the house stopped working but all the other radiators still work perfectly and so I was called to take a look. The first thing I did was to turn all 9 radiators off leaving just the four in the extension on but after twenty minutes they were still cold anbd, although the flow pipe to the extended radiators was hot the return pipe was cold. I therefore removed one of the
four radiators and found that the flow side had a reasonable flow of water when the valve was opened but the return had virtually nothing at all. Both sides showed the presence of black magnetite/dirt/sludge so this could have caused a blockage in the return.

My question is, how to clear it ? I suggested a Power Flush to the customer (which I do not do) but they were shocked by the estimated cost. The only accessible pipework to the four radiators is in the garage as all other pipework is under wooden floors which the customer does not want taken up if at all possible. I have thought about breaking into the flow and return to the four rads from the garage and blasting mains water through the flow (leaving the return open with a hose connected) which may "hopefully" clear the blockage but the risk is that it may also expose a weakness in the pipework (its all push fit with 10mm tails to the rads) and consequently cause a leak ! I don't think there's any point in adding a cleanser/sludge remover as circulation to the four rads is virtually non-existent.

Any helpful advice would be appreciated.

Thank You

 

[Paulus]

They should have taken this up with the original installer.

You could be messing about with this for days and still not cure the problem. Would they be happy to pay your bill?

I think the only way you will sort this is with a power flush but this may also expose a weakness in the pipework. The only thing you can do is explain your concerns to the customer and place the ball back firmly in their court in the nicest possible way.

If they don't want to pay for the job or don't want to take the risk, then it is their problem.

 

[M.Joshi]

I recently circulated X800 in our system for a week which has very old pipework. It is stronger than the other cleansers/sludge removers and is normally used prior to PowerFlushes. You could also use Fernox F5 etc. which is similar.

It seems to have loosened up quite a bit of sludge/magnetite which I then drained out.

Have a look at this thread:

http://www.ukplumbersforums.co.uk/c...aled-central-heating-system-3.html#post289933

 

[SafeGasInstall]

rip out as much as you can to find where is the blockage , very likely power flush will not do any good as pipe looks like is solid block

 

[WHPES]

My best advice would be to break into the pipes in various locations to try and narrow it down. You're probably going to have to locate the blocked section and strip out and replace as if its really caked, a powerflush won't shift it and neither will chemical cleaning.

Sometimes a magnet will stick against the pipes with the suspected blockage

The customer needs to be aware that due to the nature of it, you can only give an hourly rate

 

[SimonG]

Is it plastic or copper thats been installed to the extension. If one of the rads has never worked from the off then maybe it's a kicked pipe thats clogged up over the years.

I'd be with SGI and WHPES on this .

 

[smtplumbing]

would not powerflush as well due to the fact it is plastic 10mm try find out where the 22mm tees of to the 10mm manifold i bet it is blocked there. ps is it a vented system as i had a problem like this few months ago and the 10mm had burst under the floor

 

[TerryH]

I had a similar problem in my own house. The downstairs circuit is all covered in concrete and fed by 1 15mm flow and a return pipe. I used Sentinel x400 for ten days which cleared out some sludge but I suspected there was more. I drained down, cut the dedicated flow and return then capped one side off, connected a mains fed hose to the other side and flushed through using the drain off to vent the water. Then I swapped over the cap and hose (i.e. hose on feed/ return capped off then hose on return/feed capped off) and reversed the flush, turning off radiators to concentrate the flush.
A fair bit of work but successful.
Saves a lot of expense but not as powerful as a power flush.
Might be worth a try?
Terry H.

 

[Monkey Wrench]

Thank you for all the posts.

Just to reconfirm, the extension pipework has 10mm plastic feed tails to the rads and is connected to the main CH flow and return in the garage in plastic so I'm assuming all the hidden pipe work is also in plastic. The system is gravity fed.

This is the second one of these I've had recently! Another customer called a couple of months ago to say that the kitchen radiator wasn't getting hot. After diagnosing the problem to be a blocked 10mm flow to the rad I added X400 to the F&E tank drained a tanks worth of water out of the system and left it for a month. A month later, the radiator is still not working and so I've told the customer that the only solution is to break into the floor above the kitchen and run a new flow pipe to the radiator (the kitchen has a concrete floor and the pipes to the rad are dropped from the room above). However, the room above has a wooden floor that they don't want to disturb and so they've decided to leave the radiator as it is. I now have to go back to drain/flush the X400 out of the system, refill and add inhibitor. A total of about four hours labour plus inhibitor/cleanser without resolving the problem but the customer is still going to get a bill !

Im starting to think this one may go the same way as this customer also has solid wooden floors and also does not want to take them up !

I think I'll forget the idea of adding water of any kind to the system under pressure as, if there is a weakness/leak it would be a recipe for disaster. I'll check the F&E tank to see if it's constantly refilling but I think it's probably a blockage.

As Paulus suggested, I think that I'll have to throw it back to the customer, clearly explain the situation to them and let them decide !

TerryH, is your system plumbed in copper or plastic ?

Thanks again.

 

[TerryH]

Monkey wrench.... mine's copper 15mm.
TerryH

 

[stevetheplumber]

why is every one thinking blocked pipework if its never worked from day one its either not connected corectly of the pipe work has a physical fault in itive had tees that are pushed right through and a half inch elbow inside a 22mm one and soldered my advice would be it needs repiping end of anything else is a may or may not work after which youll have to repipe anyway

 

[Monkey Wrench]

Monkey wrench.... mine's copper 15mm.
TerryH

I would definitely try blasting with the cold main if it was all copper but the extension heating pipe work is all plastic and, as I didn't install it, I'm not sure I'm willing to risk it.

 

[Monkey Wrench]

why is every one thinking blocked pipework if its never worked from day one its either not connected corectly of the pipe work has a physical fault in itive had tees that are pushed right through and a half inch elbow inside a 22mm one and soldered my advice would be it needs repiping end of anything else is a may or may not work after which youll have to repipe anyway

thank for the post stevetheplumber.

It's only one of the four rads in the extension that didn't work from day one but, as the other three all worked until recently, a blockage must now be the most likely cause.

However, I agree that re-piping the extension will probably now be only way to solve the problem.

 

[peteheat]

Remember as soon as you put your hand to it all problems past and present are now yours.