GSHP on renovation project - circulation pumps?

[andyfen]

Hi, [FONT=&quot]I have installed a Ground Source Heat Pump connected to a 120l accumulator in a renovation project.[/FONT]
[FONT=&quot]The accumulator is in turn connected to the original radiators which are 2x oversize at 40C MWT with TRVs, utilising an Alpha 2 15/50 pump set to adaptive setting 2 (for rads)[/FONT]
[FONT=&quot]There is a total of 88 metres of 15mm OD flow and return pipework a 50/50 mixture of copper and plastic and 34 metres of 22mm Plastic from the plant room to the centre of the attic.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]The furthest rad is 29 metres away from the accumulator and has difficulty getting enough flow, which I have addressed by throttling back individual rads using the lockshields to force flow thru this rad.[/FONT]
[FONT=&quot]Unfortunately restricting the flow reduces the total heat available, which on a low temperature design will cause problems is severe cold weather.[/FONT]
[FONT=&quot]For efficiency I wish to achieve the lowest possible flow temp from the accumulator to the rads. I believe this requires the water to circulate unrestricted and swiftly in the radiator circuit. [/FONT]
[FONT=&quot]Delta T is important Heat Pump side of the accumulator but relatively unimportant in the rad circuit, except that return temps should be balanced so as to be as low as possible after blending.[/FONT]

[FONT=&quot]Would you recommend a 2nd 15/50 circulation pump fitted at the furthest point in the rad circuit?[/FONT]
[FONT=&quot]What other advice do you have please?[/FONT]

 

[Gray0689]

IMHO sounds like you may have undersized your pump sounds like long runs is all pie work lagged?
Need the house super lagged in this type of installation and also pipe work can be easily undersized to use of rads in these conditions

 

[andyfen]

Hi Gray

Any chance you could address the points I made please?

The plumbers sized the pump.

I could fit a bigger pump but thought it would be inherently more balanced, with one at each end of the system

 

[eaton]

I'd of used a minimum pump of 25/55 on that

 

[andyfen]

Has anyone got a view on fitting a 2nd Alpha 2 15/50 half way round?

 

[Gray0689]

How many pumps have you got on system
There should be a pump from buffer tank to manifolds then 1 for underfloor heating side
Sorry re read no underfloor then as said should probably of been a bigger pump
Why have you not had your installer back to address all these points ????

 

[andyfen]

What about a 2nd pump!!!!

I would love to get the plumbers back - looks like small claims court!!!

 

[eaton]

If you just had underfloor up and down you'd get away with one system pump but the main pump on yours I still thInk needs to be 25/55 then underfloor manifold pumps should be ok

 

[andyfen]

There is no UFH - this is a 7 large rad system on one floor.

What about a 2nd pump!!!!

 

[Gray0689]

Second pump is not a good idea ideally should be a bigger pump
Sounds like to big a runs on just 15mm pipework

 

[eaton]

Then no 2nd pump needed as said. Just put a bigger pump in, how many times do we need to say it, grundfoss 25/55. If you won't listen then don't ask

 

[eaton]

Just re read your original post. Are you an installer? 15/50 on 28m of pipework set to speed 2, your taking the **** surely.

 

[ecowarm]

Just re read your original post. Are you an installer? 15/50 on 28m of pipework set to speed 2, your taking the **** surely.

Its an alpha pump its adaptive, and the OP has said it was installed by a plumber.

 

[eaton]

Still no where near big enough, I'd have him back to change it, issue is 15/50 is around £60-70 25/55 is £180 upwards

 

[Gray0689]

25/55 is not (180 plus)
A 25/80 is about that prize

 

[eaton]

Where from, last 25/55 I had priced at that from 3 places

 

[Gray0689]

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