Descaling my heat exchanger

[andycharger]

Hi everyone,

I had my boiler engineer out last year as our hot water decided to stop working. After trying a few bits, he decided it was the heat exchanger that was faulty on my combi boiler. Replaced it with a brand new one and hey presto, it all worked fine again.
Hot water Pressure is never as good as the water mains pressure but i can live with that. Plus the shower in our loft conversion was flowing at a decent rate.
Roll the clocks on 6 months and its started to have sporadic hot water issues and the flow rate is not as good. Therefore im going to take the heat exchanger off (done it before) as I now have a spare one while i attempt to descale the one i take off.

Before i set about this task, can someone tell me the best product/way to descale my heat exchanger? There are obviously descaling products in the shops some of which i guess are not as powerful as others.

Can someone tell me in the plumbing trade the best chemicals to use for descaling and where i can buy them from?

 

[grahamgas]

Depending on which boiler you have, there might be a strainer in the cold inlet valve that maybe blocked.
as for chemicals for descaling I use Kamcos scalebreaker.
This also depends on what material your heat exchanger is made of.
This needs to be ascertained before any chemicals are used.
The Kamco website gives a list of boilers with aluminium heat exchangers.
Hope this helps

Graham

 

[Alanka]

To prevent scaling up of combi heat exchangers in hard water areas I always fit a water conditioning unit on the mains water supply to the boiler. I've found the polyphosphate type units work well. They need the cartridge renewing annually (or the 'crystals' refilled - depending on type of unit), which is usually an easy job. Certainly far easier than having to descale the heat exchanger!

Note that these conditioners do not remove anything from the water, they only prevent the calcium salts from forming an adherent scale on the hot pipes in the exchanger.

I personally have found the 'no contact' magnetic or electronic type of conditioners to be ineffective for this job, unfortunately, because they would require no servicing at all.

By the way, an alternative to completely removing the heat exchanger to descale it, is to fit a couple of tees and valves to the pipes leading to/from the heat exchanger, and use a flushing pump with descaler solution to wash through the exchanger tubes - in both directions alternately - until all scale is removed (no more fizzing - suppliers give instructions). The tees/valves can be left in position in case it needs doing again in the future.

 

[oldplumber]

I used to live in portsmouth area and you cant find harder water anywere, when I fitted a combi into an old heating system I added a magnetic descaler. It worked so well that we had blue/green baths for several months as all the old built up calcium bits fell off. So much so that 2metres of 22mm vertical HW pipe blocked with all the sedimentation. Anyway, chopped it out and cleared the blockage, replacing it with comp fittings. The combi heat exchangers never blocked at all in the time I lived there, despite all my friends and neighbours having constant problems and most eventually switching to magnetic or electric coil water treatment solutions.

Both magnetic, including the electric coil water treatment devices work ok as do the system using polyphosphates, but magnets dont need topping up/changing regularly. They all work on the same principles of preventing the calcium being able to build up by changing the ionisation of he particles, I understood once! and I was more than happy with the performance of the magnetic sytems.

 

[Blackcatgas]

It could be full of black maganatite (sp) rather than scale .

 

[stevetheplumber]

It could be full of black maganatite (sp) rather than scale .

agreed unlikley to scale up in a year but can fill with magnetite in days take the heat exchanger out and look for black particles in one side