On Sunday, 4 November 2018 10:14:38 UTC, DerbyBorn wrote:
John Rumm wrote in
o.uk:

On 03/11/2018 18:48, Tim Watts wrote:
On 03/11/18 17:50, DerbyBorn wrote:

After lots of checking a Heating Engineer has decided a mate's
heating system has a partly blocked boiler heat exchanger. Likely?
12 - 15 years old. Has been pressure cleaned a couple of years ago.


Quite possible in that timescale - the heat exchanger sees mains
water all the time, so hard water will scale it up.

You are assuming its a combi, and in a hard water area as well... I
was assuming he was talking about the main HX being (partly) blocked
on the primary side. Perhaps the OP could clarify?



??It is a conventional Boiler - not a Combi

Boiler blockage seems unlikely then. Flow failure is more likely to be down to crud in the pump impellor or settled at the lowest points in the system.

You can get a chemical that blocks holes in heat exchangers. You can run that for 14 years in a system with no filter, where the boiler kettles each time it runs and still not block the exchanger.


NT