Powerflush Problem

Hi all, got a problem with powerflushing.

I had a customer who I installed a boiler for & powerflsuhed come back to me some months after complaining that he had bled a rad and a load of black water came out. I assured him it was just a small amount at the top of the radiator and nothing to worry about. i then had to go back to add a new radiator 2 months after, and on cutting into the pipework I got a LOAD of jet black water come out, full of magnetite & sludge deposits.

I've got a Kamco CF30 DDV model, an Adey Magnaclean powerflush filter, and I only use Ferroquest at the reccomended doses. I use these whenever installing a new boiler as standard. I do the powerflush after all soldering & plumbing installation work has been completed (so no flux or jointing compounds are left behind), from the point where the flow & return connect to the new boiler, but without the boiler connected so as not to contaminate it with whatever dirt was in the system before.

Powerflushes take me about 4-8 hours in total depending on system, and I do them the way that they are supposed to be done. I flush & dump the whole thing out for 30 mins to get the worst out & check for leaks, then add chemicals, then run the chemicals around pipework & each radiator individually for around 10 mins per rad whilst agitating rads with a rubber mallet & reversing flow regulalrly, then dump & flush with clean water again around pipework and 10 mins per rad, repeating till water runs clean. I clean the 2 magnets on the Magnaclean filter every 30-60 mins, getting varying amounts of Magnetite each time.

I take samples from the dump hoses in a white container which show up any remaining deposits being purged, and I absolutely do not finish until all are gone and the water being dumped is crystal clear.

Just finished another boiler, this time for a relative in a renovation project, 8 radiators & towel rail. Powerflush here lasted about 6 hours, and the cleaning process was done with 2 bottles of Ferroquest, approx 50 degree water, same procedure as above. Finished up and left pressurised. Had to remove all radiators a couple of days later as decorating plans changed, and lo and behold, some pretty grimy stuff coming out of every one!!!

What the hell am I doing wrong here?! One could have drank the water coming from the dump hoses towards the end of the purge, but somehow this lengthy procedure is not doing what it should be doing. I am tempted to try FX2 or another acid based product as I feel that im wasting my time trying to do things the right way here.

I'm sure that many of the contributors to this site powerflush in the correct way, as I do. But I wondered how many of you have ever removed radiators / cut into pipework afterwards to find that the extensive powerflush done with expensive chemicals & equipment has not cleaned as thoroughly as you would have hoped?

I've seen what system deposits can do to condensing boilers with narrow waterways and its not good, and I'd rather not use acid based products when powerflushing, but I feel that i have no choice but to try doing so on my next boiler job...

Surely you should have been using heat from the boiler to better activate the chemicals? The CF30 is safe up to 50 degrees.

Don't like to attach the boiler to systems full of sludge & magnetite. I pipe up to the boiler, remove the flow & return tails, and attach powerflush machine from right underneath the boiler. I then powerflush before physically connecting boiler once procedure is done.

Besides, then one has the problem of attaching the machine. If you use the Kamco pump adapter you are flushing through the heat exchanger which is essentially microbore pipe, and if you connect at a radiator you are reducing the flow by flushing from a 15mm pipe. The CF30 works on flow, not pressure.

However, as I said I did use heated water in the second powerflush I mentioned so it shouldn't have been an issue anyway...

You seem to be doing everything right. Have you done a pre survey on the system before powerflushing or do you use the same technique for each job tha you. Because if a system is heavily sludged up then I normally add a sludge remove a couple if weeks prior to powerflushing. This can give me a head start as the magnetite begins to be dislodged by the chemicals by the time I come around to Powerflush the system. It may also be the case that if you have dumped foul water several time then the chemical is too weak. Have you added further dose of chemicals.
In essence each job has to be evaluated and dealt with on a case by case basis. You can also check the system water with a tds meter and that would indicate if the water is clean or not...

Wow - more than 7 years old.... how far back are you going to troll?