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Discuss ASHP not compatible with existing CH (cast iron) pipework? in the Renewable Energy area at PlumbersForums.net

megalithic

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5
Hello,
We were due to have an air source heat pump installed on a grant scheme on Monday, with radiator size upgrade, but retrofitting using the existing pipework.
The calculations have been done to show it's viable etc...

However their engineer has just (!!) looked at the photos taken by the surveyor and thinks some of our pipes are 'not copper' so not compatible with ASHP (they say).

It's not clear but I presume this means they think some of the pipes are cast iron?
It is a very old system and certainly a couple of the radiators are cast iron.
The pipes around the existing cylinder (which was upgraded about 20 years ago) are copper.

Is this true that ASHP is only compatible with copper pipework?
I will be talking to them on Monday but thought I'd try to get some info first...

The ASHP is planned to be a Mitsubishi Ecodan R32 with compatible Mitsubishi cylinder being fitted also.
Many thanks for the help.
Andy
 

ShaunCorbs

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any pictures of said pipework?
 

megalithic

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5
any pictures of said pipework?
Hello Shaun,
A bit dark currently but here you go -
1. one end of hallway rad and 2 & 3 both ends of the rad in the front bedroom.
Thanks
 

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ShaunCorbs

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That’s a one pipe system not compatible with any new boiler or heat pump needs a re pipe

Also if the inspector missed that I would be questioning his calcs as if you get it wrong you will be paying / the elec meter will be going round like anything
 

megalithic

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5
Hello Shaun,
A bit dark currently but here you go -
1. one end of hallway rad and 2 & 3 both ends of the rad in the front bedroom.
Thanks
That’s a one pipe system not compatible with any new boiler or heat pump needs a re pipe

Also if the inspector missed that I would be questioning his calcs as if you get it wrong you will be paying / the elec meter will be going round like anything
OK thanks, yes I was aware of that and of the upgrade difficulties to a new gas boiler, but wasn't aware that applied to ASHP also.
As I say it was all surveyed and so on months ago.
Oh well so much for that.
I'll post in the CH forum about what we have at present.
Dear me... Thanks again...
 

megalithic

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OK thanks, yes I was aware of that and of the upgrade difficulties to a new gas boiler, but wasn't aware that applied to ASHP also.
As I say it was all surveyed and so on months ago.
Oh well so much for that.
I'll post in the CH forum about what we have at present.
Dear me... Thanks again...

... out of interest, how come an ancient boiler can power a 1 pipe system absolutely fine when no modern one can?
 

ShaunCorbs

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hotter temps eg 80 dc which is more inefficient modern ones are 60dc or less and heatpumps are 45dc or even better 30dc as your cop will increase and you will get more efficiency out of what your put in
 

megalithic

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5
hotter temps eg 80 dc which is more inefficient modern ones are 60dc or less and heatpumps are 45dc or even better 30dc as your cop will increase and you will get more efficiency out of what your put in
Interesting yes they did feel damn hot when running - OK I'll be back on the other forum another time - cheers.
 

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