Banging Boiler

[benno99]

I have a Glow Worm Energysaver 40e boiler which is approximately 9years old. A couple of months ago we started experiencing a loud banging noise from the boiler. When I lifted the front cover off I was quite disturbed to see when the banging noise happens a blue spark occurs at the bottom left hand corner of the boiler. The banging is at its worst generally after about 30mins of the CH being on. It does not happen when the hotwater is heating up.

I had a heating engineer around who replaced the pump to the left handside of the cylinder, however this did not work. He then advised that I needed a powerflush as the heat exchanger was being affected by sludge. This seems to be quite expensive to have done.

I have now also noticed a light dripping from the overflow from the loft area.

Would using introducing chemicals to the system help? Any other advice would be appreciated.

 

[JohnD]

a chemical clean might or might not do the trick, but it is a fairly straightforward DIY job and so much cheaper than a powerflush, that it is certainly worth trying. If you use a mild sediment-loosener like Sentinel X400, it is not acidic and is non-aggressive and can be left circulating for up to four weeks before you drain it out. It will cost you about £15 for a typical sized house, and after flushing and rinsing you will need another £15 for the inhibitor. It might take a couple of afternoons of your time.

A powerflush usually costs some hundreds of pounds.

If you see signs of black sediment, it is worth fitting a Magnaclean on a vertical 22mm return pipe as well. it will cost you about £100 if you fit it yourself, fairly easy while you are drained down.

Banging is often caused by sludge and sediment (or thick limescale). I don't know about the blue spark you mention. I am not a pro, just a householder with an old boiler.

 

[benno99]

Many Thanks I will try that. Yes there is black sediment when I drain the system. How do I put the sentimal x400 in. Does it go in the expansion tank once the system is drained?

Failing a chemical clean, what would you suggest?

 

[JohnD]

If you have a Feed & Expansion tank:

Tie up the ball valve

find the drain cock, put a hose on it going outside in case it breaks or jams open, and drain out a bucket or two of water

Go back to the F&E and verify that the water level has dropped by the amount that you drained out (if not, you have a blockage that you must deal with )

bale out the mud from the tank and sponge it clean to avoid washing down the mud to add to your existing sediment.

You may as well give it a drain and plain-water rinse to take out the loose muck.

If you are fitting a Magnaclean (which is very good at trapping circulating black sediment from the water) do it while you are drained

Close the drain cock. If you take out the plug from the cock first you can look at the washer on the end of it to see if it needs changing (I had this problem over the Bank Hol and had trouble buying a washer to fit) or fiot a new one anyway to save trouble later.

add the X400 to the F&E and untie the ball-cock so that the incoming water mixes with it and it is carried down into the system

Bleed rads etc, turn on pump to circulate out air bubbles, bleed again to check system is full, turn on boiler. Turn pump to high speed to encourage good circulation, run it for a few weeks, bleeding frequently and verify that all radiators are heating up all over (it helps to turn on one rad at a time and close the others to encourage good flow through that one).

If you have fitted a Magnaclean, open it daily for the first few days and empty out the accumulated black sludge, you will find the amount drops away after a while, but keep emptying it at intervals. This only takes a few minutes and is very satisfying.

Be aware that the Magnaclean only traps black sludge; not brown, or dead spiders, plumbers' cigarette ends, drowned mice etc so you still have to drain and flush to get rid of them.

After a few weeks, drain it, rinse and flush with plain cold water several times until draining water seems clean, then close drain cocks and give it the final fill, adding the inhibitor during the fill.

Keep emptying your Magnaclean weekly until you are in the happy position of finding no sediment in it for weeks on end.

See if your problem, is now cured. If so, you can share your £x00 saving with me If not, you can have a powerflush or try more aggressive chemicals, but ask advice here first and describe what the results were.

 

[benno99]

Many Thanks.

Anyone who can confirm that this blue spark I am seeing is not about to blow my house up, would put my mind at rest. Also why I am now experiencing a drip from the overflow. Both ball cocks are fine?

 

[JohnD]

You say you had a heating engineer round to look at it, was he a proper Corgi or equivalent? What did he say about the blue spark?

 

[benno99]

yes he was corgi reg. I have cover with my bank for boiler repairs and parts. The first lad they sent was going to change the heat exchanger, however when the man came out the following day he said this would make no difference as I needed a power flush!

 

[JohnD]

What did he say about the blue spark?