ᐅ Different Statements from General Contractor / Construction Supervisor Regarding Heating
Created on: 25 Apr 2018 08:21
Y
Yoschi
Hello dear forum,
I know this topic has been discussed many times, but due to differing statements, we are quite confused.
We are currently planning a single-family house, 120-130 sqm (1292-1399 sq ft) which is enough for us,
2 full floors, turnkey,
solid construction, no basement.
Now the topic of heating has come up.
A brief note about the companies:
Company 1: Does everything in-house or has the trades within the company.
Company 2: Works only with subcontractors from the region.
Which heating system should we choose?
We had a brief explanation about the options and how they work.
Gas vs. geothermal
Company 1: Said geothermal would not be worthwhile. Gas costs are about 70 to 80 euros per month (about $)
Electricity costs for heating about 50 to 60 euros per month (about $).
That makes a difference of about 20 euros.
But since the initial investment for the geothermal heat pump is too high, it would not be worth installing one.
Company 2: What kind of heating do you want?
Gas!
Why?
I explained to them what Company 1 told me.
They said that is wrong, often such statements are made because people don’t know better or are not allowed or able to install it.
Also, Company 2 told me that gas heating should only be used with underfloor heating because the new gas heating systems have an extremely low "supply temperature" (I hope you understand what I mean) of 38°C (100°F), so my radiators would never get properly warm.
And they would probably sell me an old technology system.
Company 1, for example, did not tell me that.
Company 2 offered me an air-source heat pump, which would be cheaper in the long run since I would save the gas connection, and the pump or the fan outside would only run in the mornings and evenings.
Is that correct?
Best regards
I know this topic has been discussed many times, but due to differing statements, we are quite confused.
We are currently planning a single-family house, 120-130 sqm (1292-1399 sq ft) which is enough for us,
2 full floors, turnkey,
solid construction, no basement.
Now the topic of heating has come up.
A brief note about the companies:
Company 1: Does everything in-house or has the trades within the company.
Company 2: Works only with subcontractors from the region.
Which heating system should we choose?
We had a brief explanation about the options and how they work.
Gas vs. geothermal
Company 1: Said geothermal would not be worthwhile. Gas costs are about 70 to 80 euros per month (about $)
Electricity costs for heating about 50 to 60 euros per month (about $).
That makes a difference of about 20 euros.
But since the initial investment for the geothermal heat pump is too high, it would not be worth installing one.
Company 2: What kind of heating do you want?
Gas!
Why?
I explained to them what Company 1 told me.
They said that is wrong, often such statements are made because people don’t know better or are not allowed or able to install it.
Also, Company 2 told me that gas heating should only be used with underfloor heating because the new gas heating systems have an extremely low "supply temperature" (I hope you understand what I mean) of 38°C (100°F), so my radiators would never get properly warm.
And they would probably sell me an old technology system.
Company 1, for example, did not tell me that.
Company 2 offered me an air-source heat pump, which would be cheaper in the long run since I would save the gas connection, and the pump or the fan outside would only run in the mornings and evenings.
Is that correct?
Best regards
Domski schrieb:
- Geothermal energy: Actually the "best" option, but usually the most expensive due to the high costs of deep drilling. If you are interested and skilled, building a trench collector yourself can also be cost-effective.Gas was not an option for us because there is no gas line available.
Regarding the difference between an air-to-water heat pump and a geothermal heat pump:
The heat pump unit itself for geothermal costs about the same as for an air-to-water heat pump.
However, there is no outdoor unit at all.
That saves money.
The expensive part is the ground probe, in our case about 10,000€ (approximately 10,000 euros).
BUT:
There is a BAFA subsidy of 5,000€ (about 5,000 euros) if the heat pump is Smart Grid Ready.
Additionally, you save the cost of the outdoor unit (around 3,000€ (about 3,000 euros)?).
You also save the construction work for the foundation of the outdoor unit and the trench between the outdoor unit and the heating center, so in my opinion, the overall costs are roughly the same. Our ground probe is located directly under the slab in the boiler room, so there is no trench outside.
In terms of energy consumption, the geothermal heat pump is cheaper because in deep winter it operates with a supply temperature of about 10°C (50°F), compared to outdoor air temperatures often around 0°C (32°F).
Then there are the noises from the outdoor unit during normal operation to consider. The regular defrost cycle also produces noticeable clattering sounds, which would have bothered us.
By the way, the BAFA subsidy also applies to trench collectors. That makes them very attractive compared to the costs of a ground probe.
Best regards
Ekki
B
Bieber081525 Apr 2018 21:53Sorry, I seem to have confused it with surface collectors. There are many more types... ("Guide to using geothermal energy with ground collectors" would be great if it could be directly linked online...). Therefore, I take back everything and claim the opposite!
Oh, one more brief note. My acquaintance built about 200 m² (2,150 sq ft) to KfW 55 standard. At -12°C (10°F), he has a heating load of 5.5 kW. Under similar conditions, you will probably have a heating load of around 3 to 4 kW. Keep in mind, this is at the design temperature. That's almost nothing.
So, whatever system you choose, make sure it offers deep modulation. That means the heating system can adjust its output down to a very low level. This greatly improves the technology’s efficiency.
So, whatever system you choose, make sure it offers deep modulation. That means the heating system can adjust its output down to a very low level. This greatly improves the technology’s efficiency.
The 5.5kW is probably without hot water and includes a controlled ventilation system with heat recovery. Still, the direction is clear.
Modulating heat pumps are a good option but you have to be willing to pay for them. These are the top models; according to my previous research, there is often a difference of about €5,000 (approximately $5,500) between a standard model and the modulating version. This cannot be justified by lower energy consumption. The hope remains for better durability.
Modulating heat pumps are a good option but you have to be willing to pay for them. These are the top models; according to my previous research, there is often a difference of about €5,000 (approximately $5,500) between a standard model and the modulating version. This cannot be justified by lower energy consumption. The hope remains for better durability.
Including domestic hot water without controlled mechanical ventilation. However, internal gains were taken into account, so the calculation was based on Passive House standards. Even in the first winter, there were still issues with solar radiation.
For me, having calculated the heating load myself, I was still 1 kW below the calculated heating load this winter.
Yes, modulating systems are more expensive. But they can be worth it. And if you are considering a trench collector with some DIY work, it might fit the budget.
But here I am speculating too much again. First, there should be a bit more input.
For me, having calculated the heating load myself, I was still 1 kW below the calculated heating load this winter.
Yes, modulating systems are more expensive. But they can be worth it. And if you are considering a trench collector with some DIY work, it might fit the budget.
But here I am speculating too much again. First, there should be a bit more input.