Our central heating is serviced by British Gas & last year they recommended a powerflush that I did not take up with BG because of the charge they were quoting. I was recommended to Powerflush Ltd who provided a cheaper quotation that I agreed to & they carried out the work earlier this year. I might add that we've been in this house almost 25 years & have not had the system flushed in that time. When the Powerflush operative carried out the work he mentioned that the 2-port valve for the heating was faulty causing the vibration that was audible when the heating shuts down.
I had occasion to call out BG for an electrical fault on the boiler (that they fixed) & in the course of conversation they mentioned the powerflush & I advised them that Powerflush had already done it. They (BG) placed a magnet on the pipes around the hot tank & advised that there was still iron/steel deposits in certain parts of the pipes. (I also checked with the magnet to confirm this). They (BG) also stated that the bypass valve needed cutting out & replaced with a 28mm zone valve & pump. This (the powerflush & valve) would cost me £849.08.
I rang Powerflush Ltd & they advised that whilst the powerflush would remove most of the sludge & deposits there was a likeliehood of some remaining.
So my question is, Are Powerflush correct in staitng that some deposits would remain the pipes (I've no reason to believe they were lying). I've no intention of having another BG initiated powerflush but I reckon they would not replace the bypass valve without carrying out the powerflush.
Hi the deposits you are finding with a magnet are often encountered on a fully pumped system. There would be a build up around the area of pipework where the cold feed enters the system. If left the pipework could completely block. The method of removal would be to cut out the section, and clear by hand. the deposit is similar to limescale, but softer and black. easily removed, but messy. A power flush will not remove this type of build up. So the question is why was a power flush recommended in the first place ? Perhaps the other work recommended is not required. a proper clear out may be all that's needed.
thank you for that link - says it all ! I would urge you though to get that partial blockage removed before it causes a problem. It's not as big a job as it might seem. When I was working, I'd think nothing of doing two a day, and not rushing. Had to be plenty of tea and bickies though. Back to the main subject. I've never done a powerflush, or found the need. Yes sludge can build up over time, but there are other ways of removing it, that in my opinion are far more reliable. There again, perhaps I'm just old fashioned.