Gas price increase as of 1.1.2022

12% cheaper!?! They also explicitly point out that I have a special right of termination even in the case of price reductions.... :)

As I understand it, the Renewable Energy Act surcharge will decrease by about this amount on 1/1. I assume the suppliers have to pass this on.

Can you equate the amount of heat the heat pump produced with the kWh or how do you calculate that?

Theoretically yes. In my former gas bills, the cubic meter was always converted into calorific value in kWh. This is supposedly for comparability.

How accurate that is, of course, is another question: with the gas boiler there are surely losses during combustion and the pump electricity is not considered, and with the heat pump (I believe) the heat amount is calculated and not measured. In short, there will probably be a certain margin of error.

Hello,

Can the amount of heat produced by the heat pump be equated to kWh, or how do you calculate that?

Roughly speaking, you can calculate it like this:
For a gas heating system, the kWh of gas corresponds to the amount of heat you bring into the house.
A heat pump produces heat energy equal to the electricity consumed * the seasonal performance factor (Seasonal Performance Factor).
The seasonal performance factor is the average performance factor over the year; the nice catalog values of COP = 5 or higher are unfortunately the maximum values under ideal conditions and have nothing to do with reality.
It should also be noted with the seasonal performance factor that the electricity consumption for heating rods (either for heating domestic hot water or to support heating during severe frost) is not included. In other words, the actual efficiency can be significantly worse.

Best regards,

Andreas

Hello,

Theoretically yes. In my former gas bills, the cubic meter was always converted into calorific value in kWh. This is supposed to serve comparability.

How accurate that is, of course, is another question: with the gas boiler there are certainly losses during combustion and the pump electricity is not taken into account, and with the heat pump (I believe) the amount of heat is calculated and not measured. In short, there will probably be a certain margin of inaccuracy.

Not quite correct. The calculation on the gas bill simply compensates for different pressures in the gas supply systems and slightly different gas compositions. In other words, in network A, for whatever reasons, the pressure is slightly higher and the gas has a slightly different composition than in network B.

A condensing boiler has efficiencies beyond 100% (yes, not a typo, that is due to the very old definition of the calorific value), so it converts 1 kWh of gas into 1.0x kWh of heat in the house. The flue gas losses are already deducted here.

Pump electricity is of course added on top, but that is also the case with the heat pump; it is ALSO NOT included in the seasonal performance factor.

Best regards,

Andreas

Not quite correct. The calculation in the gas bill simply compensates for different pressures in the gas supply systems and slightly different gas compositions. In other words, for whatever reason, the pressure in network A is slightly higher and the gas has a slightly different composition than in network B.

Sure, I just understood it as meaning that different pressures and composition are normalized via the z-factor in my example to kWh heat quantity. That is, there are regionally different z-factors, but the heat quantity should still be comparable in the end (if only for billing reasons).

A condensing boiler has efficiencies beyond 100% (yes, not a typo, that’s due to the very old definition of the calorific value), so it produces 1.0x kWh of heat in the house from 1 kWh of gas. The flue gas losses are already deducted. The electricity for the pumps is naturally added on top; this is also the case for heat pumps, and it is NOT included in the seasonal performance factor either.

Yes, I know about the 115% efficiencies (back then we switched to condensing boilers, and it was really noticeable). The question is whether you can actually equate the heat quantity contained in the gas with the heat quantity calculated for the heat pump. My metrology understanding says "no." I just don’t know how large the margin of error is.

I wasn’t aware of the seasonal performance factor before, but it makes sense for determining the efficiency of heat generation. The only problem is when the heating load is so low that the pump electricity disproportionately influences the total consumption of the heat pump. But this also applies to gas equally.

Hi,

Of course, I just understood it as different pressures and compositions being normalized to kWh heat quantity via the z-factor in my example.

If I understood correctly, the compressibility factor reflects the different pressures while the calorific value takes the composition into account.

In other words, with the compressibility factor you first normalize to a standard pressure and with the calorific value you normalize to some standard gas.

Then you end up with the delivered kWh energy. What your gas boiler then does with it is another matter.

Best regards,

Andreas

If you really want to know exactly, you have to integrate heat meters. Then you know exactly what has gone into the house.