Has anyone heard of a plate flush?

[kron77]

Hi there. Ecodan 11.5 kw and 3 years old. Mitsubishi service technician came out and noted low flow. He isolated the ashp and it was achieving 20l. When not isolated it’s reporting max 2l. Normal is above 5 I think. System was warning LP and a few times it went to L9 when on dhw. 
 

so here’s the thing. Service guy is saying the solution is a plate flush because apparently it’s clogged with gunk cause the system was not installed correctly by the installer. 
 

I fell off my seat when they quoted £1200 for a plate flush, drain system, add anti freeze (which was not done originally). 
 

anyone seen this before? And I getting my pants pulled down here? 

[Onoff]

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/flushing-an-ashp-system-and-ufh-questions

[sharpener]

Sound like you are being taken for a ride.

 

For a dT of 5K you need approx 3 l/min per kW so ideally 30 or more. If the flow is 2l (presumably /min) round the circuit but 20 on an isolated HP (how did he bypass it to test that?) then the problem does not lie within the HP so a plate flush will not help. Unless you have an external plate HX as well.

 

DIY with Fernox F8 would be my course of action, supposing I believed the diagnosis.

• What kind of filter have you got and is it in the return line immediately upstream of the HP?
• How often has it been cleaned out and what did you find?
• What does the water look like?
• Did he test it with e.g. Adey diagnostics?
• Does it smell?
• If you leave a few nails in it for three days do they go rusty?

 

If it has anti-freeze valves you do not need to add antifreeze anyway, and you are probably better off without it. Just use an HP inhibitor, and maybe a biocide as well if bio-fouling has been identified as a problem.

 

 

Edited October 31, 2024 by sharpener

[JohnMo]

Sounds a rip off.

 

Explain your system, is this the heat exchanger in the outdoor unit or one inside the house?

 

[James Logan]

We were advised to do the same thing and did pay out £1200. The plate flush did not help at all. Within 10 minutes of the engineer leaving the system resorted back to the L9 fault. 
 

he is now saying that the system was badly fitted and needs all the pipework changing. Can I ask which part of the country do you live.