Gas condensing boiler vs. air source heat pump

Hello everyone,
we are about to undertake a complete new build on a rear-located plot. For the house (1.5 stories + basement) we are desperately looking for arguments to choose the heating technology to be used.

When interviewing various civil engineers, we felt we encountered preconceived opinions (I haven’t installed GAS for more than 10 years or with air heat pumps I am independent). I can hardly make use of such blanket statements.

I question the following points
Regarding air heat pumps:
- Acquisition costs for air heat pumps (compared to GAS)
- Lifespan and the related amortization
- Electricity costs of an air heat pump (electricity price development in the coming years – almost doubled in the last 10 years)
- Appearance

Regarding gas condensing boilers:
- Acquisition costs + connection costs (almost 40m to the house)
- Gas price development (according to an energy supplier comparison site, the development was not particularly volatile except for the years 2007-2009)
- Solar support (here too I question whether this even makes sense, as the support is most needed in winter and at this time the yield is not particularly good)

For gas, you can significantly reduce the final costs with a supply temperature by using an underground gas tank. A few families in our development area have done this because our local supplier does not offer gas there ([mangels Nachfrage!]).

Hello,

.....we are desperately looking for arguments for the heating technology to be used....

For this, the actual demand (capacity, energy) for heating and hot water must have been determined beforehand (basic assessment)!

.....from various civil engineers we have felt like receiving preformed opinions....

Civil engineers and architects are not MEP planners! They lack the technical training for this.

.....
- Solar support (here too I question whether this makes any sense at all,...

The question is certainly justified. One must distinguish between the favorable calculation on paper (Energy Saving Ordinance/ KfW proof) and the actual conditions.
It is possible that compensatory measures suffice and that solar can be dispensed with.
With liquid gas, it must be considered that the important lower modulation stages are not reached as with natural gas!
If applicable, a brine heat pump with an inexpensive trench or surface collector is interesting.

best regards

Hello ferro,

as Nordanny correctly pointed out, the basics for a statement tailored to the specific project are missing. The central contact person for a small single-family house, besides the planner/architect, is the MEP planner or the person who creates the energy certificate. In cooperation with them, your user requirements (number of people, comfort standard), the budget, and the site conditions must be balanced.

In this context, a 40 m gas connection may not be an argument, depending on the offer from the local gas supplier, which may provide special conditions for this.

The gloomy forecasts about solar support in combination with a gas condensing boiler do not want to fade away, and rightly so; if the legal requirements are not met, the renewable share can be omitted. But does that make sense? If I can significantly extend the period during which I do not need my gas heating through solar support and in winter, by choosing a sufficiently large collector area that is not based on the legal minimum requirements and considers the lower solar yield, further decouple myself from external energy supply, one should do this. Then there is no too deep discussion about rising energy costs, which are rightly significantly smaller for gas and for electricity will gain further dynamics not only due to the Renewable Energy Act surcharges.

Best regards, Erik

Hello and thank you!
I am already aware that without a precise needs assessment, no decision about natural gas/air heat pump can be made.

It was only important to me to find basic arguments for and against the heating type. This currently seems very difficult for me. The rough floor plan for the construction project is set, but will probably not be feasible due to budget reasons - hardly any cushion for unexpected costs...

I have already excluded geothermal energy and liquid gas. The reason for this is on the one hand the tank and on the other hand I want to remain flexible on the property (possibly to retrofit a pool later).

I will create a pro/con list once the floor plan is finalized and would be happy to post it here for further discussion.

Regarding solar, I strongly question the technology for single-family homes.
Scenario 1 (solar collectors for heating water):
The water storage is limited and thus also the efficiency of the collectors.

Scenario 2 (photovoltaics):
Here, only self-consumption makes sense, as selling is at a much lower price than what energy providers charge. The problem is that electricity is rather needed at later times. Are there suitable storage options? I have not found any...


Regards
Ferro

...I am already aware that without precise demand planning, no decision can be made regarding natural gas/air heat.
....It was only important to me to find basic arguments for and against the heating method....

How should that therefore be possible based on your own findings? A contradiction in itself!

... will probably not be feasible due to budget reasons - hardly any cushion for unexpected costs...

Every construction becomes more expensive afterwards than initially estimated, assumed, or suspected!
Anyone who financially overextends themselves already in the diffuse preliminary phase will have to expect a more or less obvious money pit in the end!

...
Scenario 2 (photovoltaics):....Here only self-consumption makes sense, since selling is at a much lower price than what energy suppliers pay....

Correct. Therefore, photovoltaics today actually only make sense in connection with heat pumps for heating and hot water. In addition, normal household electricity consumption can be credited.
What always matters is the annual balance, not the momentary event

Best regards.