PowerFlush Best Practices

Hi,

For reference this is off the back of another post regarding my WB 28i here:
https://www.diynot.com/diy/threads/worcester-bosch-greenstar-28i-junior-combi-boiler-help.564499/

I am going to borrow a power flusher and have an engineer set it all up for me so that I don't goof it up! The plan is to carry out the cumbersome labour involved myself as I know its essentially a full days work.

So, putting pragmatism and economics aside, I wanted to seek out the board's advice on the absolute best practices on Powerflushing.

I googled it, found this link as an example and found it informative:
http://www.powerflushassociation.com/recommended_procedures_and_practices_power_flushing_uk.html

Appreciate there are also videos on youtube on it - feel free to link.

Specifically interested in recommendations on:

1. Cleaning chemical [Fernox, Sentinel or anything else that is awesome?]
2. Recommended % of chemical used for a 9 Rad System - is 1 litre bottle enough or what's ideal?
3. Should I inject some cleaner in prior and let it work its magic for a few days?
4. How long should I flush for / Cleaning times per rad?
5. Definitely go full bore?
6. Full system blast first with all valves open, then each rad individually or any better suggestions?
7. Best way to dislodge any sludge from the bottom of the rads - Adey bit for the kango the best or is there anything better?
8. inhibitor recommendations and % of inhibitor post flush
9. General do's and dont's
10. Anything else?

Want to compile a bit of a checklist so that this sludge gets absolutely smashed.

Thanks for your help!

Thanks for all the replies and useful tips... lol.. only joking..

Anyway, I ended up doing what I said I would do in the last post and wanted to share the results should any one care...

As per the thread in the last post I had replaced my Heat Exchange Plate with a refurbished part which started fail, and failed twice before I turned down the dial on the boiler from the 'Max' to just below the 'Max'.

When I did that, it stopped failing.

The reasonably suspected cause of constant failure has been attributed to a dirty/rusty TRV. Picture of it below which I took today.



Rusty TRV #1
https://ibb.co/sC40YQC

Rusty TRV #2
https://ibb.co/FnwTjmh

Rusty TRV #3
https://ibb.co/x286W1n

It's dried out now obviously but at the time it was quite sludge-y. Not completely blocked but, when I put my finger in and touched it, it came back fairly black.

That was replaced around the 5th of March 2021 and at the same time I put two doses of cleaner in the system, Fernox F3 and Fernox F5, both rapid/express doses, which was left in the system until I flushed it on the 20th of March 2021, so a good couple of weeks.

During the couple of weeks there were absolutely no problems of failure and I turned the dials on the boiler back up to 'Max' as well, so it's fair to say that the cleaner worked through the plate as well when showers were being had etc.

For flushing I'm pretty sure I was using a Kamco CF190, although not completely sure, along side the Magnacleanse RapidFlush (MACK01) magnets.


Powerflush Machine
https://ibb.co/mzDZyFZ

On the day, after switching off the boiler etc, the machine was attached straight onto to a downstairs radiator which made up one of the nine (1/9) total radiator's in the house. I did not drain the system prior to flush but took a sample which is in the sample photo.

I added 3x 1 liter X800 Sentinel doses and let it mix around for a while before going Rad to Rad.

Going Rad to Rad I initially only turned off the TRV's but then I went back and turned off all the Lockshield valves as well, which meant I had the machine working completely focused on one rad and one rad only. Was told that would make no difference but that's what I did anyway.

When each rad was the focus, I banged along the fins with a mallet in order to try and dislodge any sludge and then went back and reversed the flow every 5 minutes for about 30minutes each rad, before then spending about a minute going back and forward for about 10seconds each for 2-3minutes. Then when I returned to the Rad, I'd give it another few whacks with the mallet before shutting off each side and moving onto the next Rad.

I did that for all 9 rad's in the house, so that was about 4-5hours. After each rad got its fair share of the flush machine and mallet whacks, I then started to dump/refill with fresh water until it run clear, per rad - carrying out a similar enough exercise as previous; going rad to rad and giving them some whacks along the way for good measure.

I kind of messed up because I was filling and dumping on a side which was not isolated. Stupid of me, yeah, but ultimately it didn't matter because I was regularly reversing the flow and the balance of the new fresh water intake and the dumping meant that when I dumped, it dumped faster and but when I was pushing it round the system, the fresh water was going through anyway.

Bit daft of me to just fill fresh water and dump it simultaneously and also may have been giving me a false representation of the cleanliness at that particular moment but again, it ultimately didn't matter too much because at the end, I did it properly and it run completely clear, as you'll see in the photos. The last two samples which aren't completely clear are a result of my stupidity.

Samples:


Samples
https://ibb.co/myQVhcM

Whilst the magnets didn't pull back an astronomical amount of sludge, it still caught a fair bit, and I'm glad it's on the magnet and not in my system.

MACK01 Results



Magnaclean Magnet #1
https://ibb.co/wpNhqD0

Magnaclean Magnet #2
https://ibb.co/gTp3thx

After all that, I wrapped up, cleaned my own Adey magnacleanse filter myself and filled it with two liters of X100 Sentinel inhibitor, bled all the rads and made sure the system was sitting at about 1-bar cold.

I had abit of a scare because when the boiler fired up and was kicking out hot water - they weren't going to my Rads. At first, I thought it was because the Lockshield valves were all fully open, and completely unbalanced, so I closed them all except one, still to no avail.

Completely freaking out, I left it overnight until this afternoon where it was established the magnacleanse filter was left closed... lol

After another spell of stupidity, once I opened that up, the system started heating up nicely and I went rad to rad and balanced the lockshield valves.

Mad heat off most of the Rad's except maybe two - and I also think those two Rad's gave out the most trouble during the flush, so I'm thinking I'm going to replace them now. One of the Rad's I'm referring to had the dodgy TRV valve on it - so may very well be time to get replaced!

Anyway, it's been some journey - I'm very glad I did it and got to see how it works and exactly what is being paid for in a powerflush. I'd say with a bit more experience there are things I would have liked to have done better, such as drain the system off first prior to flush, maybe connect straight onto the pipework directly as to collect more debris.
However, for the first time I feel like I did alright and I am happy with it. It was quite a cumbersome task and, not that I ever disagreed with it in the first place but, the prices charged for a powerflush seem to be justified as there is a fair bit of labour involved with going rad to rad, opening them up, closing them off, keeping an eye on the machine, reversing the flow, examining the water etc, and I'm sure the professionals have a few more tricks up their sleeves too with use of specialized thermal equipment etc.

Anyway, hopefully anyone who's reading this has found my perils useful..


Magnaclean Magnet #1
https://ibb.co/wpNhqD0

Magnaclean Magnet #2
https://ibb.co/gTp3thx

Powerflush Machine
https://ibb.co/mzDZyFZ

Samples
https://ibb.co/myQVhcM

Rusty TRV #1
https://ibb.co/sC40YQC

Rusty TRV #2
https://ibb.co/FnwTjmh

Rusty TRV #3
https://ibb.co/x286W1n