Best way to clean a heat exchanger

[hallra]

I have a central heating system in a 7yr old ‘Persimmons’ new build, that has several problems related to reduced flow.

A nice retired engineer on these forums, has helped me, through extensive testing, identify the heat exchanger as the culprit.

The boiler is a Glowworm Ultracom 24hxi, 10 Rads, 8 of them on 10mm microbore.

• It wasn’t commissioned for 18 months.
• before the system was commissioned, I took all the rads of the wall and flushed them, small metal fillings came out as well as dirty water.
• subsequent flushing over the years, has been clear, no signs of sludge.

The question now is, how to clean the heat exchanger.

• A main flush, removed nothing, but it did demonstrate restrictive flow.
• The mains return - flow flush, was more restricted than a reverse flow - return flush.

What are the best methods of cleaning the heat exchanger without removing it?
- running Fernox F3 through system for a week made no difference.

What are the likely culprit, limescale/sludge/metal fillings ?

What are the best chemicals to use?

Thoughts?

Thanks in advance.

 

[gmartine]

What exactly do you mean by it wasn't commisioned for 18 months?