This afternoon we had a nice man come to fix our heating.  He’s been round before to fix our central heating system actually, and from what he said today the two may well be connected.  The first time he came round because the water pump was making a horrible noise, as if it was running dry.  When he inspected it he saw that it was indeed dry, and the water system wasn’t refilling itself from the tank in the loft.  Turns out the pipe had become clogged up with gunk, and it took a lot of prodding to shift the blockage.

Today he came round again, this time to solve the problem of the heatless radiators.  Two of the radiators in our house have been cold for some time now, the one in the kitchen and the one in the study.  I bled them both before Christmas, and the thermostats were turned up full, but they just weren’t getting any hot water to them at all.  So not a problem with the radiators themselves, but rather an issue somewhere else in the system.  And Mr Plumber confirmed my suspicions.

After listening to the symptoms he went and got his ladder from his van and went up into our loft to take a look around.  Meanwhile I rearranged the furniture in the study so that he could get to the radiator if he needed to.  As it turns out he didn’t, and within a matter of a few minutes he was back on the landing.  As I had suspected, there was another blockage in the system, this time stopping water getting round part of the system.

The cause is actually fairly straightforward, though not what you might expect.  It’s a build up of silt, not from dirty water or malfunctioning or worn parts, but from a chemical reaction between the steel and copper pipes.  The residue, which is a by-product of the reaction, is quite normal and shouldn’t cause too many problems; it certainly won’t wear holes in your pipes!  But saving a few pennies during installation and not coating the insides of the pipes with a non-stick coating means that years down the line that build-up of silt will start sticking to the inside of the pipes, and in some cases block it all off completely, as in our case.

The solution, at least in the short term, is thankfully straightforward and painless, though he wasn’t able to start the process today.  All he needs to do is put a bottle of some fancy chemical into the tank in the loft, which dissolves all that silt.  A week later he can then flush the system, refill it, and check the progress.  Hopefully it’ll only need a couple of flushes to clear the blockage.  If it doesn’t… well, we’ll cross that bridge when we get to it!  I don’t envy whoever gets that job, if it needs doing – first of all you’d have to find the location of the blockage, then try to unblock it with something, and just getting to the pipe in the first place could mean taking up floorboards or taking down walls…

Our plumber also enlightened me on another component of central heating system maintenance, and that was to do with why you need to bleed the radiators.  I had just assumed that the air that was inside got there through the boiler, heating the water until it bubbled and then sending those microscopic bubbles round the system until they found somewhere to congregate.  Apparently not.  It’s all to do with that chemical reaction agaiin, between the copper and the steel.  Another bi-product of the reaction is a gas, and it’s that that collects in the radiators.  Which is why when you bleed the radiators it smells so foul – it’s not air at all!

So there you go, it’s the reaction between different types of pipe that cause both the muddy black water and the air in your radiators.  You learn something new every day.  And I understood the principle thanks to GCSE Chemistry.

Our plumber will be coming back tomorrow with the bottle of de-silting liquid, and then again a week later to flush the system and see how healthy it all is.  Hopefully before too long I’ll actually be able to do some work without three layers on and needing to rub my hands every five minutes to keep them warm…


Dad · 16 January 2009 at 11:59 am

I hate plumbing when it goes wrong. Particularly if it involves leaks. Remember the new bathroom at our old house? Arrrgh!
I presume your landlord will pick up the bill for the work done to his infrastructure?

Matthew · 23 January 2009 at 6:25 pm

Hi Dad. Yes I do remember the old bathroom, though I don’t think I was quite old enough to grasp the full extent of the headache – I just found it annoying that I couldn’t use the loo.

Yes, the landlord will be picking up the bill. It’s going to be a length process though – the plumber is coming back next week to drain the system, and even that’s not guaranteed to solve the problem.

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