Hello everyone,
We just had a conversation with the company responsible for our heating and plumbing installation.
First of all – we are building a large single-family house with a basement, two full floors, and a hipped roof with a 22° (22 degrees) pitch. Wall construction is 17.5 cm (7 inches) sand-lime brick, insulation with mineral wool, plus a brick façade.
We are building according to the 2012 Energy Saving Ordinance (EnEV 2012) and are not aiming to achieve a higher standard.
Our original plan was:
- Gas heating with underfloor heating on all levels, no wall-mounted radiators, and a central mechanical ventilation system with heat recovery.
Now, after the discussion, I’m totally confused. The company recommends:
- Heating via an air-to-air heat pump, solar thermal for hot water, plus gas to support hot water
- Underfloor heating only on the ground floor and first floor, excluding children’s rooms and bedrooms (to avoid overheating during sleep), with the rest heated by wall-mounted radiators on a second heating circuit
- No mechanical ventilation system with heat recovery due to noise issues
I can understand reconsidering the mechanical ventilation system because of potential constant noise and airflow, so we might want to think that over.
But I’ve never heard of combining a heat pump, gas, and solar thermal in one system!
Solar thermal is said to be uneconomical anyway, especially with a roof pitch of only 22° (22 degrees), right? We also don’t have a direct south-facing roof orientation. Does anyone have links or information about the economic viability?
Our main priorities are comfort; cost and economic efficiency are not the primary focus, but I don’t want to end up building something completely pointless either. The problem is, we need some sort of renewable energy source to comply with the Energy Saving Ordinance. The thermal protection report is not available yet, but I definitely need some concrete information for the next meeting. It would be great if someone could help!
We just had a conversation with the company responsible for our heating and plumbing installation.
First of all – we are building a large single-family house with a basement, two full floors, and a hipped roof with a 22° (22 degrees) pitch. Wall construction is 17.5 cm (7 inches) sand-lime brick, insulation with mineral wool, plus a brick façade.
We are building according to the 2012 Energy Saving Ordinance (EnEV 2012) and are not aiming to achieve a higher standard.
Our original plan was:
- Gas heating with underfloor heating on all levels, no wall-mounted radiators, and a central mechanical ventilation system with heat recovery.
Now, after the discussion, I’m totally confused. The company recommends:
- Heating via an air-to-air heat pump, solar thermal for hot water, plus gas to support hot water
- Underfloor heating only on the ground floor and first floor, excluding children’s rooms and bedrooms (to avoid overheating during sleep), with the rest heated by wall-mounted radiators on a second heating circuit
- No mechanical ventilation system with heat recovery due to noise issues
I can understand reconsidering the mechanical ventilation system because of potential constant noise and airflow, so we might want to think that over.
But I’ve never heard of combining a heat pump, gas, and solar thermal in one system!
Solar thermal is said to be uneconomical anyway, especially with a roof pitch of only 22° (22 degrees), right? We also don’t have a direct south-facing roof orientation. Does anyone have links or information about the economic viability?
Our main priorities are comfort; cost and economic efficiency are not the primary focus, but I don’t want to end up building something completely pointless either. The problem is, we need some sort of renewable energy source to comply with the Energy Saving Ordinance. The thermal protection report is not available yet, but I definitely need some concrete information for the next meeting. It would be great if someone could help!
D
DerBjoern8 Jun 2015 13:05I also find 8cm (3 inches) of mineral wool quite insufficient...
Maybe 16cm (6.3 inches)? I can't even do the math right now, sorry. The wall will be about 46cm (18 inches) thick, with 17.5cm (7 inches) of sand-lime brick, the rest being mineral wool, an air gap, and a facing brick. Sorry.
Regarding the heat pump – we definitely want to have a gas connection installed in the house because of the fireplace (we don’t have enough distance from the neighbor for wood). So it would make no sense not to use it for heating as well. From what I understand, it’s possible to switch to a heat pump later on (in 15 or 20 years or whenever).
Regarding the heat pump – we definitely want to have a gas connection installed in the house because of the fireplace (we don’t have enough distance from the neighbor for wood). So it would make no sense not to use it for heating as well. From what I understand, it’s possible to switch to a heat pump later on (in 15 or 20 years or whenever).
S
Sebastian799 Jun 2015 08:52Why calculate? Everything is described in detail in the calculation anyway.
You can always switch to a heat pump – but use gas mainly because of the chimney (which then – sorry – isn’t a real one)? In that case, I would rather operate the fireplace with a gas cylinder – since it’s only used a few days a year.
At least, if I wasn’t opposed to a heat pump…
You can always switch to a heat pump – but use gas mainly because of the chimney (which then – sorry – isn’t a real one)? In that case, I would rather operate the fireplace with a gas cylinder – since it’s only used a few days a year.
At least, if I wasn’t opposed to a heat pump…
From the beginning, we said that we would prefer to heat with gas.
If a heat pump could be used without solar panels, we might reconsider that. But the installer also said that with a heat pump, in severe winters you would still need to heat additionally with gas, as a heat pump alone would not be sufficient. I have also read several times that the calculations are complicated (with this annual performance factor or whatever it’s called), and as a result, the system might either be oversized or too small, meaning you end up heating with expensive electricity.
The problem is that everyone seems to say something different, perhaps because heat pumps have not been around for that long. With a gas heating system, we are definitely on the safe side in terms of heating.
If a heat pump could be used without solar panels, we might reconsider that. But the installer also said that with a heat pump, in severe winters you would still need to heat additionally with gas, as a heat pump alone would not be sufficient. I have also read several times that the calculations are complicated (with this annual performance factor or whatever it’s called), and as a result, the system might either be oversized or too small, meaning you end up heating with expensive electricity.
The problem is that everyone seems to say something different, perhaps because heat pumps have not been around for that long. With a gas heating system, we are definitely on the safe side in terms of heating.
D
Doc.Schnaggls9 Jun 2015 14:19Panama17 schrieb:
If it were possible to use a heat pump without solar support, we might have to reconsider. In fact, our air-to-water heat pump works perfectly fine without solar assistance.
Panama17 schrieb:
But the installer said that with a heat pump you would need additional gas heating during severe winters, because a heat pump alone wouldn’t be sufficient. I have to disagree with your installer. We don’t have a gas connection, and yet our house stayed comfortably warm all winter, even at outdoor temperatures as low as -24°C (-11°F).
Panama17 schrieb:
I’ve also read several times that the calculations are difficult (with the seasonal performance factor or whatever it’s called), and that the system would either be oversized or too small, resulting in heating with expensive electricity. So far, we’ve only used the electric backup heater (immersion heater) once, and that was during the initial start-up of the system at the end of November 2014. It was around -15°C (5°F) then, and the backup heater ran for its only 2 hours immediately after the system was switched on.
I’m afraid your installer might not have much experience with heat pumps and is therefore recommending the “tried and tested” solution.
Please don’t get me wrong—I’m not trying to put down gas heating—but perhaps you should consult with an installer who is well versed in this technology before making a final decision.
Best regards,
Dirk
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