Plate heat exchanger keeps clogging up

[Moluskman]

Hi all,
my radiators work fine but every 6 months or so my water starts running cold (Halstead Ace High Gas combi). I get the heat exchanger changed and it's great again for another 6 months. When I drain the radiators the water that comes out is a little dark but not sludgy as such but there is visible black particles in the heat exchangers that are taken out. Incidentally, the system is always filled with inhibitor and a few years ago I got the system flushed but it didn't seem the have any lasting effect; there is a magnetic filter too.

My question is, what is causing this?, is one of the radiators disintegrating some how?, if so how can I ascertain which one?, I've considered getting a new boiler but am concerned that the problem may still be there and that will clog up too.

Any advice would be much appreciated.

Thanks.

 

[Madrab]

Is it clogging up on the Ch side or the mains water side, are you in a hard water area? How old are the radiators?

 

[Moluskman]

Hi, thanks for the reply.
So I guess your asking which side of the heat exchanger is clogging up, truth is I don't know, until I looked at an unblocking video today I didn't realise the 2 sides had separate flows. I'm in a hard water area.

 

[Moluskman]

PS. most radiators are of a newish type- double wall with vent thing over the top edge, there are a few which are the older type but nothing ancient.

 

[ianmcd]

Suppose you could try installing a magnetic filter on the return to the boiler, but to have to fit a new plate heat exchanger every six months would indicate a very dirty system which you dont seem to have