COP heatpump air/water

[Seair]

Hi to everyone

My question is about COP

I now that the manufacturers calculate
Different out side temp for instance
+7, 0, -5, -10 and so on, +7 best and -10 worst COP

But if the outside temp is
+ 7, + 10, + 15

And we calculated

I suppose the COP is going to decrease

Please help me to come to conclusion

[frank]

COP or coefficient of performance is a measure of energy input v energy output.
It relates to how energy efficient the apparatus is at design conditions.
Obviously, as outdoor temperatures increase the efficiency increases.
Manufacturers COP figures are produced in controlled conditions and may not represent real life but allow you to make a choice when making a decision on which make to buy.

[Seair]

COP or coefficient of performance is a measure of energy input v energy output.
It relates to how energy efficient the apparatus is at design conditions.
Obviously, as outdoor temperatures increase the efficiency increases.
Manufacturers COP figures are produced in controlled conditions and may not represent real life but allow you to make a choice when making a decision on which make to buy.


Thanks for the answer.

But let me give a concrete example.

When is COP going to better? for a same model heat pump different outdoor temp.


Heatmode
Unit one outdoor temp +7 celsius
Unit two outdoor temp +15 celsius

[Seair]

Thanks for the answer.

But let me give a concrete example.

When is COP going to better? for a same model heat pump different outdoor temp.


Heatmode
Unit one outdoor temp +7 celsius
Unit two outdoor temp +15 celsius

I suppose the unit will give more heat
But the power consumption will increase
And COP decrease

But i like to hear from the pro…

[RANGER1]

COP not as good, but it is not “only” thing to focus on.
heating a lot better with higher SCT
could run less time to achieve required water temperature
water in could also be warmer, if ambient warmer

Heat pump in cold climate not always ideal

[Seair]

COP not as good, but it is not “only” thing to focus on.
heating a lot better with higher SCT
could run less time to achieve required water temperature
water in could also be warmer, if ambient warmer

Heat pump in cold climate not always ideal

Hi my question

is COP
Better in 7 or better in 10 celsius

Thanks

[frank]

Obviously, as outdoor temperatures increase the efficiency increases.

With more heat energy available outdoor then less energy input into the heat pump is required to achieve the required conditions indoor. This will increase the COP.

[Seair]

With more heat energy available outdoor then less energy input into the heat pump is required to achieve the required conditions indoor. This will increase the COP.


I understand that, but still not have the answers i like to hear,
The total cost for heating is decreasing when is warm outside but i like to no where is the break even.

For instans COP at +7 is 6
How is COP at + 14 maybe 8 or 9

Should not increase I think

[Rob White]

.

There is a simplistic kW in to kW out ratio but that is generally used in sales and advertising.

The more technical would be calculations from a pH chart and that involves far too many parameters
to be able to give you the quick answer that you want.

The quick answer you want is "yes" if the ambient temperature rises then the COP will but only to a point
and not under all circumstances.

If you want water at say 45 degsC then your refrigerant in the condenser would be at least 7 or 8 degs higher
to get the heat flow, if the system was less efficient then that difference might be near 10 or 12 degs higher.

If you are condensing in the region of about 55 degsC average and you air ambient outside was 10 degsC
then you would need to evaporate at about 0 degsC.

The lift or difference between 0 degsC and 55 degsC is 55 but if you were in an outside temp of 14 degsC the the evaporator would be at about 4 degsC so the lift now or the difference now between +4 and +55 is 51.

There is less lift so the comp won't have to work as hard and therefore the power used will be slightly less.

The trouble is with air sourced is the ambient. The ambient very rarely stays exactly where you want it to so the COP is referred to as Energy Efficiency Ratio or EER and EER is calculated by dividing the input into the output. Because heat and electricity can both be measured in kW that means you can get a ratio of efficiency (EER) by dividing input power into output heat. The EER can now be used more realistically because EER then can allow for seasonal variations such as spring, summer, autumn and winter. Averaged over the year the EER becomes a SEER
Seasonal Energy Efficiency Ratio. and now you have a ratio of seasonal performance that can be compared like for like with other systems.

Not easy answer I'm affraid.

Rob

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