Radiators cold at bottom/ or not working at all

[pat1mac]

I moved into an old house a few years ago, and inherited an old oilfired boiler feeding about 12 radiators. Only one or two radiators gets very hot (nearest the boiler) rest of them warm, with several cold. Bleeding the rads made no difference In an attempt to improve things ( seemed a good idea at the time), during the summer I drained the system and replaced about 6 of the radiator thermostats, which didn't seem to operating.
I now have some of the radiators hot at the top and cold at the bottom, and still have the problem with a few radiators, mostly remote from the boiler, stone cold. The pump seemed to be working ok, boiler switches on and off, rads have been bled. At the local plumbers shop suggestion, (he said that there may be muck blocking the rads), I drained one and ran water through. Black dirty water came out, but after reconnection, there does not appear to be an improvement. I can't belive most of the rads can be blocked. Any ideas out there before I freeze to death !

 

[corgiman]

you better start believing that the rads are blocked, cos they probably are

quick fix is to take em off and flush the out, but you would be advised to flush the whole system

do a search on it

 

[JohnD]

... I can't belive most of the rads can be blocked...

start believing it!!!

if you don't feel like taking then all off and hosing them through in the garden, add a litre of Sentinel X400 (about £15) to the system, and run it for a month or so. It will break down sludge deposits and the sediment will be carried round in the water (which will go very black). Bale out all the sludge from the F&E tank first, and sponge it clean. You don't want to add that sludge to what is already in the radiators. Make sure the F&E tank has a tightly-fitting lid to keep out dust, spiders, birds etc

You can drain it out after a month or so, give it a rinse, and refill with an inhibitor. X400 is non-aggressive so will not do any damage if you leave it in for longer. It just loosens sediment.

If you can be bothered to flush them, or pay someone else to do it, that will get more out. but the chemical will loosen it so is worth doing anyway.

You might feel more like flushing them out after the winter.

If you can afford an extra £100 or so for a Magnaclean, it will trap some of the remaining sediment after you have cleaned it, as it traps any black particles circulating in the water. It carries on doing this indefinitely.

Youi still have to drain out the dirty water as some of the muck will be non-magnetic, e,g, limescale, drowned spiders, plumber's cigarette-ends etc.

 

[pat1mac]

Thanks for good advice. Where can I get a Magnaclean, and where does it need to be installed ?? If I flush the rads outside how do i know that all the much is cleaned out. ( Do I need to tap them to loosen the muck or something.) Proves how little I know about this doesn't it!
Someone suggested putting in a second pump to improve circulation, Its a long run from the boiler. Any views ?

 

[JohnD]

you can get a Magnaclean from your friendly local plumbers merchant. if they don't sell them go to another. It costs about £100 and is a fairly straightforward DIY fit.

They are mostly 22mm size and you fit them on a VERTICAL 22mm pipe on the return to the boiler (if you fit then horizontal some water will spill out when you take the top off for cleaning).

Youi will want to drain the system to avoid water gushing out when you cut the pipe. If you have any slack on the pipes you can offset them to put the canister more upright.

Put it somewhere easily accessible so you can easily open it for cleaning.

You can get a 28mm size but it is more expensive.

As someone said, it sounds too good to be true, but I fitted one on my mums old system and it is terrific. Some people think I have droned on about it too much I am not a plumber.
//www.diynot.com/forums/viewtopic.php?p=749132#749132

There is a demo film on here http://www.youtube.com/watch?v=uDgegChsLvc
and see http://www.adeysolutions.co.uk/subprofessional.asp?id=246

You can bang radiators with a rubber mallet to shake sediment loose, but you ought to treat it with X400 or similar first for a few weeks to soften and loosen the sediment.

 

[bengasman]

read through faqs and you will find whole process detailed

 

[pat1mac]

Thanks guys for great advice, I think though I'll wait till the weather warms up before starting work on this.