De-Scaling Full Combi Central Heating System

[1975]

6 weeks ago I moved into a property, and imediately had problems with the central heating. Apparently the previous owners had a few problems before we moved out which had been mis-diagnosed by a plumbing firm in the area. The plumber came and fitted the parts the day after we got the house.

Whilst he was out I mentioned to him that the diverter valve was not functioning properley and asked why he didn't pick this up - his reply was - I wasn't told there was a problem with it. After fitting a RV and a new pressure gauge he mentioned that the diverter valve was infact faulty and needed replacing.

After having a lack of confidence in this guy I decided to buy and fit the diverter, which now works great. Now I had hot water my second problem arose, fluctuating hot water - after a lot of testing and working through the system I come to the conlusion that the DHW exchanger was full of crap, which last night I removed and cleaned with ferroquest. The boiler is now working as it should be.

My concern is the amount of black scale that came out of the exchanger whilst cleaning. I am assuming that the whole system is now full of this crap, which I would like to remove. Can anyone recommend a cartridge type cleaning agent to inject into the system and also an inhibitor to stop the build oup of this crap once the system is cleaned and re-filled.

For info the boiler is a Vaillant TurboMax 824E Combi with 8 rads in the system. I am planning on changing upto 6 of these rads in the future.

Regards.

Dean.

 

[oilman]

To do the job properly, there is no alternative to powerflushing. while you can inject something then drain and refill, there will be lots of stuff left in the system. We don't see any one system for long enough to say what really works and what doesn't, but when it comes to cleaning when a boiler is replaced, the first thing to do is put a cleaner in the system, and perhaps drain and refill, then powerflush. It's a big surprise how much extra crud comes out with the flushing.

 

[JohnD]

And if there's lots of black in it, a Magnaclean will trap it all, whatever circulates during or after you've done the flush. It can be left in place indefinitely and emptied occasionally.

 

[Birmingham_Spanner]

Out of intrest what were the original problems with your CH system when you moved into the property?

 

[Agile]

If you are going to change rads shortly you may be better off fitting a line filter in the CH return for the time being.

Power flushing is always the best way to get rid of dirt in the system.

New rads have their own way that they need to be dealt with!

Tony

 

[1975]

Out of intrest what were the original problems with your CH system when you moved into the property?

The diverter valve was sticking intermitantly so sometimes hot water and no CH other times Ch and no HW other times all OK. Once the diverter valve was replaced I noticed the hot water fluctuated in temp from cold to luke warm, and listening to the boiler I could hear the gas valve modulating to try and keep the temp correct. I removed the DHW exchanger and de-scaled it with feroquest and then give it a good flush through. It is now possible to have a hot bath, and the shower is usable.
I really cannot understand how the previous owners lived with half the problems I have found, some people really amaze me.

Regards.

Dean.