I have a long thin house and I have just discovered that the two radiators furthest from the boiler (at each end of the house) are cold. I've had the pump and diverter valve changed but it has made no difference.

The system has worked fine for 10 years and is a Bosch combi, with 15 radiators. Piped in Hepworth 22mm to manifolds then down to 10mm to rads.

The Bosch service guy recommended a Powerflush. Last year I used a cleaner and had it running for a week before draining and refillig with Fernox, is a Powerclean so much better?

I've been quoted £452 for a Powerclean and £220 to fit a Magnaclean, is this reasonable?

Scruff I have seen you recommended the Magnaclean last year, is this still the best? Is it better than the Fernox total filter?

Final question, the pipework is Hepworth grey pipe, I am wondering if they fitted non barrier pipe, do you know if Hepworth make a non barrier version? The Speedfit barrier pipe has a black layer, this pipe is grey all through.

Thanks

You have my sympathies, WS. Been there. Done that. Got the stains. Sued the company. Won the case.

Would I be correct in saying that you possibly have kept the heat down or even off in these rooms? That is what we did in some of the rooms in our house and like you have plastic pipes fitted - although larger at 15mm. Same problem. Cold radiators.

I did everything that Scruff suggested. In fact you will find my thread on the very same topic here http://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1284813832/13#13

I removed the radiators that were in rooms without carpet, took them outside and flushed them in both directions with a hose connected to mains pressure. Shook 'em, swilled 'em until all the black magnatite came out.  Reconnected.  Still not working.

Drained the system down, took up some floorboards and broke into the 15mm pipe to find this

and this was after I had tried powerflushing it.  I got some of that curtain flexible plastic cased curly-wurly stuff used for hanging curtains - no idea what it's real name is.  I then put that in a drill and spun it as I fed the stuff back into the pipe...a sort of scouring action...but that only worked so far as the curly-wurly just knotted itself up.  So Plan B was to just keep shoving this wire up and back down the pipe trying to get out as much black crud as I could.

So I reckon that this is what you've got.  The strange thing is that in static water flow, the black crud seems to have a preference for blocking up plastic pipe because 15mm copper in the same circuit remains as clean as a whistle.  Maybe this is the dirty little secret that plastic pipe manufacturers would prefer kept quiet.

Did I succeed ?  Nope because to get even further down the pipes would have required taking up the fitted carpets in the bedroom.

The one thing that powerflush advocates and also those who say how wonderful the system cleaner products are forget to mention.  That is that you actually need some flow through the blockage otherwise they do absolutely nothing. If your pipes are really blocked like mine then you'd get more fun out of burning £452 of pound notes then you would from having your system powerflushed.

Interesting article on this subject (or at least on the chemistry of a heating system)..

http://www.energymanagertraining.com/Documents/lecture15.doc

Seems magnetite is good (section 2.4)...

Quote:


but Hematite is bad (section 2.5)...

Quote:


How do you tell the difference? Is it simply a matter of looking at the color?  I wonder why magnetite doesn't appear to be self limiting in domestic heating systems?

Thanks for that Scruff, I will order one later, and get the baby up and running as soon as I get it.

I'll try the maget idea too: Ta.

Good idea about the magnet. Have you got any of those flat rare earth magnets in your workshop?

Keith, whilst the weather is a little warmer, it may be worthwhile shutting off all the radiators except the two that are not heating up and try getting some cirulation through them to get the cleaner in them.  If you get no circulation through them, then you may be able to force the blockage by disconnecting the rad valve from the radiator(collect the water from the rad) and connect a bucket pump to the valve and push water back through the pipe.  Be careful of creating too much pressure though so as not to blow a joint.

Greg, sorry I didn't reply, I've only just spotted your post but I now have a fully functioning system.

We took Scruff's advice and did loads of running the mains through the system. We then fitted a Spirotech to the boiler return, but I must say I am a bit underwhelmed with its performance.

We have obviously been disturbing the magnetite as we have been flushing and found we had more radiators not working after flushing.

In the end half the rads did not work so we bought a Magnaclean which we fitted to the flow from the boiler. Since fitting it this has been collecting about 100 times more bits than the Spiro and with another couple of flushes we were left with just 2 rads which did not work.

I tried compressed air (up to 8 bar) but even that would not shift it so we ran in two new pipes which has obviously solved the problem.

Thanks for all the advice, much appreciated now, and we will be especially grateful when the cold weather comes back.

Yep, 10mm Hepworth which we replaced with copper

woodsmith wrote on Jun 12^th, 2011, 12:04pm:



Magnaclean should be in the return not the flow.

As should other brands.