What's your monthly SCOP

matt_drummer

I have had two minor defrost today,

But at much lower temperatures than I used to see with my old 9kW Daikin, that would be defrosting like crazy at 5c and below.

This 8kW doesn't start until -2c or so.

It has average about -1c here today.

My COP so far is 4.20 with a flow temperature of 29.3c Average power consumption is 736W

It will have cost about £1.30 to heat the house today so that is about 5.30p per hour

The defrosts consumed 0.70 kWh of heat in total.

My house is at design temperature including the all glass conservatory, so 20c downstairs and 18c in the upstairs bedrooms.

I have needed 3.1kW of heat to maintain design temperatures at -1c.

So Octopus were miles out with their heat loss calculation and my heat pump is still more than twice the capacity I actually needed.

That is why I turn it up as the outside temperature increases. It will run at 28/29c in this weather quite happily but need 31 to 33c when it is warmer.

I get too much heat when it is warmer but it is actually less at 33c than I get at 28c due to the effect of the outside temperature on my heat loss and therefore my radiators ability to deliver heat.

If I had another brand of heat pump that could run below 30c when warmer then my SCOP would be above the 5.0 that it is now.

michaels

Whereas I have averaged a cop of about 2.4 today with outside temp of zero and flow of 46.  No idea of defrost events although for one hour last night the unit used 3.4kwh whereas generally it was around 2.5kw.  House is taking about 6kw to keep at 21 which is actually slightly less than I estimated based on our modulating gas boiler using a steady 7.5kw on similar days last winter.  Obviously if our rads were larger allowing the same heat transfer with a lower flow then the COP would be better, whether it is worth the capital cost of me changing 9 rads is less clear a we will soon be back to higher temps and thus 3x flow rates and higher COP.  One good thing is I hav ento yet had to turn the heat pum poff its limited output but quieter night more setting.  On the plus side out v2h means that our average electricity cost is only 8p per unit.

Spies

Found a sneaky setting which has been turned on called "increase around 0c", which from reading the manual seems to only apply to homes in colder locations that have snow on their roofs, as it naturally draws out heat from the house

I did wonder why the LWT seemed to not be following my curve around 2c as it was set to "increase around 2c span 4c". Now set it to 0c and put it back on LWT control with an overshoot of 4c

matt_drummer

5.03 for November

Includes space heating and dhw, and includes circulation pump and controller as usual. MID certified obviously!

NedS

I've been away, so late reporting for November, but 4.4 excluding circulation pumps and controller, drops to 3.9 including them.

matt_drummer said:

5.03 for November

Includes space heating and dhw, and includes circulation pump and controller as usual. MID certified obviously!

That really is exceptional @matt_drummer

matt_drummer

6 hours early!

SCOP for December is 5.05

Includes space heating, DHW, circulation pump and controller as usual. MID certified also as usual.

Electricity consumed is 425kWh at a cost of £29.75 (at 7p per kWh on IOG)

Gas would have cost about £155 (including the standing charge) at 6p per kWh and a boiler efficiency of 90%

Heat produced is 2,147kWh

Average outdoor temperature was 6.9c and the room temperature measured in a bedroom was 20.9c, downstairs is about 2c warmer.

NedS

Few hours early here too...

SCOP of 4.4 for Dec for ASHP only - dedicated MID electricity meter for ASHP (only) usage and heat generated as reported per Samsung controller. In my mind this gives me a more direct comparison to the oil boiler it replaced, which also had electric oil and water circulation pumps,

SCOP of 4.0 for Dec as reported by Samsung controller Energy generated / Energy consumed.

For reference, the Samsung controller consistently reports ~11% higher electricity usage including the two circulation pumps and controller compared to the MID class meter which only measures ASHP usage.

Electricity consumed by ASHP only (MID meter) 292.87kWh (roughly £58.60 at ~20p per kWh)

Energy generated (not verified) 1,290kWh (we were away for a large part of Dec).

Gas would have cost £102.32 (including the standing charge) at 6.45p per kWh and a boiler efficiency of 90%

Our average cost of electricity was around 20p per kWh for the month of Dec. We were on Octopus Agile, but panicked and switched to Cosy on 12th Dec after a couple of VERY expensive days on Agile. Agile prices have since dropped/stabilised, but so far we have been able to average under 20p per kWh on Cosy so I'm happy with that, given the certainty in pricing. We may switch back to Agile again at some point in the future. With a SCOP of 4, electricity prices of around 29p per kWh would roughly equate to the price of gas (at 90% efficiency), so anything around 20p per kWh is going to be substantially cheaper than a gas boiler to run as long as we can achieve a SCOP of 4 or above.

Spies

Setback just kicked in at 10pm so it won't be on again before midnight

This is via the Daikin controller and it rounds down (so I'm told) where electrical energy is concerned...

Heating: 1980kWh produced using 557kWh of electricity so a COP of 3.5

Hot Water: 170kWh of heat for 70kWh of electricity so a COP of 2.4

Water runs at 2-4am so no great surprise its pretty poor but its on the IOG rate of 7p so it doesn't overly matter, AHSP is basically running from when the water is done heating, so 20 hours a day or so, I average around 21p/kWh over that time.

So overall, each unit is costing me 6p and for Heating, and for Hot Water - as I only run it during IOG (no reheat scheduled), that's costing me 2.9p a unit, those two combined averages 5.75p/kWh of heat energy

So pretty much on par with gas but comfort levels are way higher

Strummer22

EcoForest GSHP, figures for heating + hot water.

Dec: ~3,500 kWh heat, ~700 kWh electricity. COP 4.8.
Annual: 16,200 kWh heat, 3,200 kWh electricity, COP 5.1. 

Spies

Worst days COP so far was Thu 9th Jan, generated 124kWh of heat for 52kWh of electric = 2.38, average unit rate for that day was around 19.5p meaning 8.19p per unit of heat so slightly more expensive than gas on that day.