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Heating system flush?

(5 Posts)
JingleCatJingle Thu 17-Sep-20 00:20:44

We have an oil fired central heating system with a 10 year old condensing boiler. The heating has stopped working and the boiler man reckons there is something caught in the coil in the cylinder.
He is going to remove the cylinder tomorrow and check.
The little tank in the attic that feeds the heating (I think?) has a load of crap in the bottom. I have suggested to DH that perhaps the crap could also be dealt with as otherwise won’t it just happen again.
DH was astounded. He had never heard of removing or flushing a heating system.
Boiler is 10 years old, plumbing is well over 20 years old.
Is heating system flushing a regular house maintenance thing?
House is 1930s.

OP’s posts: |
JingleCatJingle Thu 17-Sep-20 00:22:12

That was meant to be ‘removing crap’ from heating system.

OP’s posts: |
TheHighestSardine Thu 17-Sep-20 01:24:01

With a closed loop system the only things that enter are metal particles from the inside of the pipes. We have a magnetic trap which catches enough that flushing shouldn't be necessary.

If you have a little tank in the attic that feeds the heating... yeah, get that checked out. Your boiler man will be able to tell you if action is needed.

PigletJohn Thu 17-Sep-20 01:37:04

ha ha, yes it is

if the small "feed and expansion" tank has brown mud in the bottom, that is sediment of fine rust particles caused by the water inside your steel radiators. So is black water and sludge in the radiators.

Things you can do to reduce the sludge, scale and sediment:

Have a filter (usually magnetic) fitted in the large return pipe to your boiler. It will gradually trap circulating particles from the water so they can't collect together and form a blockage. The trapped sediment can be emptied out periodically. It is no harder than emptying a vacuum cleaner, once you know how.

Add an corrosion inhibitor to the circulating water (this scavenges spare oxygen from the water which accelerates the corrosion). Over time it gets used up. If fresh water is added to the system, especially due to a fault or blockage causing pumping-over, but also to replenish minor leaking, it gets used up sooner.

Assuming you have not done these things, it will be dirty and sludgy.

If you are having your boiler person round, ask what they would charge to fit a filter. They typically cost around £100 plus fitting. It is usual to drain the system down before cutting the pipes. Preferably a sludge-loosening chemical is circulated beforehand, so that draining will wash away some of the old sludge.

if you are fond of simple plumbing jobs, you can give it a chemical clean yourself. This is best done before a blockage has occurred. It will cost a couple of half-days of your time, plus around £32 for chemicals. In a hard-water area, an extra £32 for the limescale cleaner. If not, you can pay the boilerperson to do a powerflush. This will be quicker and more intense, and will cost hundreds of pounds.

I'd suggest starting with the filter, because it will stop things getting worse. Magnaclean is very effective on a dirty old system, and the newer ones seem to have got over the earlier leaks trouble.

more modern, sealed systems (with no feed and expansion tank) are less prone to sludge unless you have a leak necessitating frequent top-ups.

Bwlch Thu 17-Sep-20 06:36:09

My husband has flushed ours out a couple of times and fitted a filter. I think modern boilers are more sensitive to sludge in the system than old ones.

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