Heating system failure (long sorry!)

[Coldtoes]

I am a complete novice to plumbing, but learning fast! We moved into an old house (1930's) 18 months ago and got thru the 1st winter with no probs. This winter however our downstairs radiators cooled down then stopped working all together. The boiler was making the most almightly cracking and banging noises and hot water was pumping over into the feed and expansion tank.

Our boilerman came round and checked the pump, which he said was working. He diagnosed a blockage possibly caused by a build up of silt and sludge in the system. Following his directions we used chemicals (Sentinel) to clean the system out. We left the chemicals in for about a month then flushed the system out completely. Some of the radiators came on during the period when the chemicals were in - but remained firmly cold after we flushed everything out. On our second visit from our boilerman he recommended a powerflush - but suggested one last go with a different brand of chemical (Fernox). This has been in the system for about 10 days. On draining down the system this time around the water coming out of the system was the colour of strong tea - red/orange colour. One of the radiators downstairs is full of black liquid.

I came home from work to find our very noisy boiler completely silent. Its now cut out completely. The hot water cylinder is still very hot and the pump appears to be whirring around, although Im not sure that its making a very happy noise. THe upstairs radiators which so far have been hot, are now cold apart from one. On bleeding the radiators (in a futile attempt at doing something useful) I found that most of the radiators are now full of the tea coloured water.

Can anyone help diagnose what is wrong so I know what to do. Is this situation irredemable and are we going to have to fork out for a new boiler and heating system - I really hope not. Im pregnant and this is about the last thing that I need to be worrying about just now!

Any advice at all will be most gratefully received. Thanks in advance! Coldtoes.

[Owain]

It is possible that the sludge has killed the pump, the boiler has overheated and cut out.

If the system has worked in the past it will probably work again, but it needs a proper clean out. You can hire the powerflush machine and DIY or alternatively take the radiators out into the garden and hose them out. A new pump is usually quite cheap.

See Andy Hall's postings on this subject [1] and when he warns that radiator sludge is indelible on carpets he means it :-)

Owain

[1] eg

[john2]

If one radiator and the tank is hot the boiler and pump are probably OK, the rest are blocked. Could the system be half full of air after draining and refilling. Bleed the radiators properly and try opening up any balancing valves or thermostatic valves on the radiators.

john2

[Ed Sirett]

This is a sick heating system.

I diagnose pump failure and/or serious sludge and corrosion.

[meow2222]

replacement pump and flushing can both be done yourself for well under =A3100 all in. Expect to get soaked :)

NT

[Capitol]

I don't disagree about radiator sludge on carpets, but in a previous existence, I accidentally emptied out the black dregs of a radiator onto the middle of a white carpet. The rapid application of some gallons of warm water and a wet and dry vac did actually remove the stain, to the point where she didn't notice.

Regards Capitol

[Andy Hall]

This is where you say to a very worried looking customer:

"Mrs. Jones....... It's yer pump"

and Mrs. Jones asks (as though you are an eminent cardiac consultant)

"Will it be all right?"

and you nod and smile reassuringly that it will; while the orchestra rises and the apprentice tags along behind in admiration.

[The Natural Philosopher]

I am not so sure. When I commissioned my system here , I had a huge problem in getting some remote rads to actually fill with water at all.

The solution was to turn off (using the balancing valves).. all radiators apart from the highest one that always seemed to trap air, and the offending ones, and crank the pump up to 11...;-)

That finally blew the air out and back to where it could be bled properly.

[Owain]

You were lucky. You could have been in for a nasty thumping if her husband had come home and found sludge on the carpet.

Owain

[marble]

Not so, they could be heated by convection, as the only working radiator is on the 1st floor this would be a symptom of either a broken pump or a mid position valve stuck in the mid position and the water taking the path of least resistance through the cylinder.

[Ed Sirett]

Sorry, I rarely work on header tank installations now and I forget just how difficult it can be to get the air out.

[Ed Sirett]

I spent a pleasant evening with a consultant surgeon friend discussing the parallels between heating diagnoses and medical ones.

The parallels go much further and deeper than either of us would have anticipated.

Here are some of the things we talked about:

1) People refer to the problems with their own terminology which you have to tune into. 2) Some people are embarrassed about certain aspects of medical matters or plumbing (think muslims and WCs) and will parry around the subject. 3) Sometimes a wrong diagnosis has been given (even by those who could do better). Then the ramifications of getting the wrong one over turned and the correct treatment instigated. 4) Quack remedies, which are nevertheless very popular. 5) People whose knowledge is out of date and therefore reject and/or are suspicious of more recent developments. 6) What to do when the cure is much worse than the problem. 7) The iceberg problem: presenting symptoms apparently small, real problem huge, breaking the news.

[Pete C]

8) Get a second opinion for something drastic/expensive (relates to 3 and 5 too!)

cheers, Pete.

[adder1969]

On mine the pump itself was blocxked with bit of rust and the sludge made it turn too slow. I had to clean it frequently until the system was clean.