Blocked heat exchanger

[GaryH]

Hi,
I have a Baxi Duo Tech Combi 33 boiler fitted to my small bore system in 2010. When the boiler was fitted I suspect no corrosion inhibitor was added to the system. Over a period of time I lost flow to a radiator, this was resolved by renewing a completely blocked section of pipework and inhibitor added. I now have one radiator that does not get as hot as the others, the problem does not appear to be getting worse and may be resolved by correct balancing. The main issue now is that I get repeated blocking of the secondary plate heat exchanger resulting in a loss of hot water, large flakes are being removed. The plumber who has been cleaning out the heat exchanger recommended replacing the Fernox TF1 filter on the return to the boiler with a Adey Magnaclean, this has been carried out, however the problem remains.
I am unsure if the primary heat exchanger has been contaminated and the rust is slowly been carried forward and blocking the secondary?
Today I removed 2 radiators to assess the level of debris, the radiators were significantly contaminated and when I agitated the radiators, more rust was removed. I am considering removing all the radiators and giving them a thorough flush/agitation to remove a large proportion of the debris, when the radiators are replaced, will the corrosion build up again?
I understand that power flushing is not effective with a small bore system? I am reluctant to replace the small bore pipework as I have concrete floors and chipboard floors upstairs.
Any thoughts/suggestions?

 

[Scott_D]

Is it copper or plastic pipework?
You could have a mains flush and a magnacleanse to clean the system.

 

[GaryH]

Is it copper or plastic pipework?
You could have a mains flush and a magnacleanse to clean the system.

Hi, pipework is copper.
I have watched a few youtube magnacleanse videos, they appear to show sludge removal, my problem is with large flakes, my magnaclean is relatively clean (minor sludge deposits). I have spoken to Adey, apparently they do a video magnacleanse Q&A session, I'm going to join next week.

 

[Scott_D]

You could remove and flush each radiator it even better replace them.
Fit a strainer next to the magnaclean

 

[Ric2013]

Personally, I feel Adey's promotion of the Magnacleanse is OTT. I do own one, but cannot see how it can possibly work unless used in conjunction with a powerflushing pump - there simply isn't enough flow to shift much debris IMO.

Removing radiators (this is where most of thr dirt will lodge) and flushing out in the garden with a hose is old-school, but cheap, effective, and very satisfying. More satisfying in summer than in winter.

I must say I had a customer who was in almost exactly the same boat as you, and the heat exchanger was replaced by Baxi under warranty, as the Baxi installed had neither flushed nor added a filter. The customer paid me to fit a filter on the return and I think this has prevented further blockages. As a point of interest, I did run the system with my Magnacleanse unit (didn't try a flush as such, but wanted to see how dirty the circulating water was) and it picked up very little, so the water running through the boiler must have been relatively clear.

 

[GaryH]

Thank you for your replies.
I am wondering if my major contamination is rust or lime scale, I live in a hard water area but do have a combi mate fitted. If it is scale that would explain the debris passing the magnaclean and choking the secondary heat exchanger and suggest a filter may be the solution.
I intend to flush out a radiator and check if the flakes are magnetic.
Thanks again, I'll let you know what I find.

 

[Scott_D]

Are the flakes magnetic or non magnetic?