ᐅ Prefabricated House Heating: Gas / Air Source Heat Pump / Underfloor Heating
Created on: 11 Sep 2015 01:45
G
GathoHi!
We are currently planning a prefab house and are undecided between Bien-Zenker and Weberhaus. Both strongly promote the Proxon air-to-air heat pump. However, this option is no longer suitable for us. The more we research, the less convincing it seems.
We are now considering an air-to-water heat pump (with underfloor heating) combined with a mechanical ventilation system, or a gas condensing boiler system (also with underfloor heating), likewise combined with mechanical ventilation. Both options should allow for future preparation for a photovoltaic system, which can be installed later. Ground source heat pumps or pellet heating systems are unfortunately not an option due to the high initial investment costs.
The thermal insulation in prefab houses is generally quite good/high. For Bien-Zenker, we would build to KfW 70 standard, and for Weberhaus even to KfW 55.
We are unsure whether it is worth investing the extra cost in an air-to-water heat pump (e.g., LWZ 304 from Stiebel Eltron or THZ 304 from Tecalor), or if a well-established and proven gas condensing boiler might also be a good solution. What about the ongoing costs for maintenance and repairs?
The house will be built in Dortmund, will have no basement, and will have a living area of 130 to 140 m² (1400 to 1500 ft²).
At Weberhaus, the LWZ 304 (with underfloor heating) from Stiebel Eltron currently costs 8555 EUR (including mechanical ventilation) as a "special anniversary offer." We have not yet received an offer for a gas condensing boiler system—only for the air-to-air heat pump from Proxon, which we have already excluded. I have some concerns about the electricity costs in winter and the potential noise from the air-to-water heat pump. Of course, both gas and electricity prices are rising, but modern gas condensing boilers are also very efficient, and with a well-insulated prefab house, gas heating could be a cost-effective solution.
What would you recommend? Is there anything else we should consider? How significant are the maintenance costs in this comparison?
I would greatly appreciate any tips, suggestions, and opinions.
Best regards and thanks!
Gatho
We are currently planning a prefab house and are undecided between Bien-Zenker and Weberhaus. Both strongly promote the Proxon air-to-air heat pump. However, this option is no longer suitable for us. The more we research, the less convincing it seems.
We are now considering an air-to-water heat pump (with underfloor heating) combined with a mechanical ventilation system, or a gas condensing boiler system (also with underfloor heating), likewise combined with mechanical ventilation. Both options should allow for future preparation for a photovoltaic system, which can be installed later. Ground source heat pumps or pellet heating systems are unfortunately not an option due to the high initial investment costs.
The thermal insulation in prefab houses is generally quite good/high. For Bien-Zenker, we would build to KfW 70 standard, and for Weberhaus even to KfW 55.
We are unsure whether it is worth investing the extra cost in an air-to-water heat pump (e.g., LWZ 304 from Stiebel Eltron or THZ 304 from Tecalor), or if a well-established and proven gas condensing boiler might also be a good solution. What about the ongoing costs for maintenance and repairs?
The house will be built in Dortmund, will have no basement, and will have a living area of 130 to 140 m² (1400 to 1500 ft²).
At Weberhaus, the LWZ 304 (with underfloor heating) from Stiebel Eltron currently costs 8555 EUR (including mechanical ventilation) as a "special anniversary offer." We have not yet received an offer for a gas condensing boiler system—only for the air-to-air heat pump from Proxon, which we have already excluded. I have some concerns about the electricity costs in winter and the potential noise from the air-to-water heat pump. Of course, both gas and electricity prices are rising, but modern gas condensing boilers are also very efficient, and with a well-insulated prefab house, gas heating could be a cost-effective solution.
What would you recommend? Is there anything else we should consider? How significant are the maintenance costs in this comparison?
I would greatly appreciate any tips, suggestions, and opinions.
Best regards and thanks!
Gatho
The LWZ system requires relatively low maintenance – basically, you just need to replace the ventilation mats 2-3 times a year and that's it. You can opt for professional servicing (we currently pay about 200 euros per year), but it’s not mandatory. Many people do the maintenance themselves.
Our system runs on about 65 € of electricity per month (average) for a similar house size, covering hot water, heating, and ventilation.
The LWZ has a relatively small tank – with four people, the last person to shower sometimes experiences colder water. A gas heater can supply hot water on demand.
Our system runs on about 65 € of electricity per month (average) for a similar house size, covering hot water, heating, and ventilation.
The LWZ has a relatively small tank – with four people, the last person to shower sometimes experiences colder water. A gas heater can supply hot water on demand.
We are facing exactly the same issue; the price from Weberhaus is already very good. Fingerhaus offers an Energy Plus promotion (which includes underfloor heating, explaining the higher price), but the Viessmann system with an outdoor unit is €6,000 (about $6,500) cheaper, which makes you think. However, we would prefer one without an outdoor unit.
Geothermal energy is expensive, but first, there is a €4,500 BAFA subsidy, and second, you save on consumption later, even if the insulation is only standard. With an air-to-water heat pump, I would recommend very good insulation because otherwise the heating consumes large amounts of expensive electricity. As far as I know, the benefit of a photovoltaic system strongly depends on whether the roof has a favorable south orientation. If so, it is definitely worthwhile. I recommend a website on the topic of "heating comparison" by the energy consultant Alois Zimmermann, where different heating systems are calculated based on an example house. This is my layperson’s assessment.
A gas boiler itself should generally be significantly cheaper than an air-to-water heat pump.
However, you need to consider:
- The gas connection also costs money
- The chimney also costs money
- You might need to install solar panels on the roof (for hot water or photovoltaics) to meet primary energy requirements
In the end, additional costs may arise — or maybe not.
To compare running costs, you need to find out the gas and electricity prices in your area. Also, consider the costs for the chimney sweep. Don’t forget the fixed fees for the meters!
Furthermore, a gas boiler requires some electricity as well, and the "annual performance factor" (seasonal efficiency) is not quite 1 but around 0,... because there are also losses.
For the heat pump, I would estimate the annual performance factor to be about 3 to 3.5, depending on how much you invest in the technology.
Have fun calculating.
Oh yes:
I would always recommend underfloor heating or another type of surface heating. ALWAYS!
However, you need to consider:
- The gas connection also costs money
- The chimney also costs money
- You might need to install solar panels on the roof (for hot water or photovoltaics) to meet primary energy requirements
In the end, additional costs may arise — or maybe not.
To compare running costs, you need to find out the gas and electricity prices in your area. Also, consider the costs for the chimney sweep. Don’t forget the fixed fees for the meters!
Furthermore, a gas boiler requires some electricity as well, and the "annual performance factor" (seasonal efficiency) is not quite 1 but around 0,... because there are also losses.
For the heat pump, I would estimate the annual performance factor to be about 3 to 3.5, depending on how much you invest in the technology.
Have fun calculating.
Oh yes:
I would always recommend underfloor heating or another type of surface heating. ALWAYS!
Umbau-Susi11 Sep 2015 09:13Ask DocSchnagels. If I remember correctly, he has had the Tecalor system running in his Weber house for six months and can probably provide some information about it.
Sylvia
Sylvia
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