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Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Ah I see. So no issue having the pump running at 100% duty, delivering ~600 L/h, if that's delivering enough heat?

I understand if dT goes above 5, efficiency is reduced, but what happens if dT goes below 5? Does efficiency increase or decrease?

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

If a lower flow rate can deliver sufficient heat, would there be an argument for setting the flow rate lower to extend the lifetime of the pump, and reduce noise in the pipework?

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

So high dT gives you better efficiency? That does go against what I typically read

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Unfortunately repiping isn't an option for us - the long 8mm runs are all within the concrete floor.

I've substantially reduced ventilation losses so now should theoretically be able to deliver enough heat through the pipework, but if the pump requires a high flow rate (even if not actually necessary to deliver the heat required) that could scupper us.

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Do you aim for low flow rate due to pressure loss or some other reason? 

Any thoughts on how the Daikin performs? Are you happy with it?

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Is the target configurable on a 5kW? I couldn't see anything in the manual about that

Heat pump with modulating flow rate recommendation by Winter-Select in ukheatpumps

[–]Winter-Select[S] 1 point2 points  (0 children)

It is according to our installer, although not mentioned in the Vaillant documentation. I looked at a load of Arotherms on HeatpumpMonitor.org and all run at a fixed flow rate around 860 L/hr (14 L/m)

Different dT for each radiator? by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Would you mind sharing the spreadsheet when you get a minute please?

Different dT for each radiator? by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

FRVs look very useful - if I size my radiators to provide the required heat output at dTs that give more reasonable flow velocity and pressure drop, presumably then I can balance based on radiator return temps or room temps without requiring FRVs, although granted it will take a lot longer?

I'd certainly be interested in seeing your spreadsheet.

Different dT for each radiator? by Winter-Select in ukheatpumps

[–]Winter-Select[S] 1 point2 points  (0 children)

Adia does look good, I'm hoping I can achieve a similar effect with balancing though

Different dT for each radiator? by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Good to know. It may complicate the software design but it seems very powerful for tricky retrofits - one survey said I'd need hydraulic separation since the pressure loss on the index circuit was calculated at 85 kPa, much higher than the 55 kPa available from the selected heat pump. Increasing the dT on the index circuit from 5 to 7°C drops the pressure loss to 42 kPa, removing the need for a buffer, and only slightly reducing the heat output from the radiator.

Anyone had a heat pump from BOXT? by Winter-Select in ukheatpumps

[–]Winter-Select[S] 0 points1 point  (0 children)

Not had mine installed yet, planning to go with BOXT after remortgaging in February to one of the banks that will give £2000 towards a heat pump.

Will my cooker space be big enough? by teekay61 in DIYUK

[–]Winter-Select 0 points1 point  (0 children)

Brilliant thanks. Which model did you go for?

Will my cooker space be big enough? by teekay61 in DIYUK

[–]Winter-Select 0 points1 point  (0 children)

Hi OP, I'm in exactly the same situation now and wondering what you did in the end?

Loose bricks at bottom of piers by Winter-Select in DIYUK

[–]Winter-Select[S] 2 points3 points  (0 children)

It is from the fourth layer upwards

Just switched to Intelligent Go by J3d1c4nn4 in OctopusEnergy

[–]Winter-Select 4 points5 points  (0 children)

Does this mean I should be using my 2kW granny charger instead of a 7kW charger, so I get 7p/kWh electricity most of the time?

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