Gas heating + solar & controlled residential ventilation or air-water heat pump Energy Saving Ordinance 2016

Hello everyone,

since I am quite new here, I would like to give some background information about my concern. I apologize in advance for any missing knowledge and am happy to provide further information if needed.

I own a fairly flat plot of land with 400 sqm (gas connection available) on which a Kfw 70 solid single-family house made of bricks on a slab (no basement) with about 134 sqm of living space or 144 sqm of total area spread over 1.5 floors is to be built. Gable roof with a 30° pitch, knee wall 1.50m. Since there is a railway line nearby, there is increased soundproofing, so the exterior wall must be constructed with a thickness of 36.5 cm.

Construction is being done with a local general contractor who has provided me with two offers as follows:

Offer 1: Thermo Planziegel S9 36.5 cm thick, reinforced insulation in the roof/attic, gas condensing wall unit type Viessmann VITODENS 200-W with a 500l storage tank and Viessmann VITOSOL 200-F flat-plate solar collectors. Four ventilation units with heat recovery (decentralized) as controlled residential ventilation and normal compact radiators throughout the house are planned. Airtightness test using blower door test. Executed according to Energy Saving Ordinance 2014 with tightening in 2016

Offer 2: Thermo Planziegel SX 10 36.5 cm thick, Bartl air/water compact heat pump ECO 3-6 LCI for indoor installation and an 800l storage tank. Underfloor heating throughout the entire house. Vento ventilation systems on all windows and patio doors in the living areas. Preparation for a photovoltaic system to be installed later. Executed according to Energy Saving Ordinance 2016

In terms of price, the second offer is exactly €3000 more expensive, which is offset by the gas connection required in offer 1.

Since I am very uncertain which heating system would be, I’ll put it cautiously, the “better” one for this house and more economical in the long term, I am asking the group here what you would recommend to me? A second side question I have is whether the compact heat pump makes sense, or if a split unit from the same manufacturer would be the better choice?

However, I do not want to start a fundamental discussion about whether gas or air-water heat pumps are better in advance and explicitly refer only to the air-water heat pump.

My general contractor’s recommendation clearly tends towards the air-water heat pump. Here is a link to the technical data of the air-water heat pump.

Best regards

Filstal

Air-to-water heat pump with indoor installation is better than split, as long as you have the space for it inside. In terms of appearance and noise level, it is more pleasant. The 800l storage tank with a heat pump is not only unnecessary but above all nonsensical and does not fit into the system at all. What's that supposed to be? Take a compact unit or a 200-300l external storage tank and that's it. Then another 500€ can be deducted from the price. If he plans a buffer storage tank, remove that too, another 500€ saved.

Soundproofing made with thicker Poroton bricks from the commercial sector ... well, if it makes it look nice. It's probably due to the region.

Here is a link to the technical data of the air-water heat pump:

It will probably be removed soon, external links are not desired here.

In terms of price, the second offer is exactly €3000 more expensive, which is offset by a necessary gas connection in offer 1.

This only applies if you really do not have to take the gas connection (keyword: mandatory connection).

That will probably be removed soon, external links are not desired here.

Yes, I was already informed about this by the admin today.

I also find the 800l quite a lot, it almost reaches the dimension of a cubic meter. However, this is even specified by Bartl himself. I see on the original price list from 2016 that it is included as standard. So there must be a deeper reason why it is dimensioned so large?

What do you think about these offers, which would you consider the more sensible option?

I have also considered adding controlled residential ventilation to offer 2, although there is also debate about central versus decentralized systems.

where opinions also differ between centralized or decentralized.

Not only there. Even if one might think that this is about facts – opinions still differ just as much as if one were talking about football.

That is why I said elsewhere that it can be helpful to decide without "religious reservations" between a provider with red bricks and one with white bricks, which one you want to have build your little house.

Are compact radiators even an option? I would start with underfloor heating designed for low flow temperature (<=30 °C) and central controlled residential ventilation. Everything else should be determined afterwards (construction method, heating system). For the small plot, gas might be better, as the outdoor unit of the air-water heat pump would then be omitted. Is a basement to be built? For sound insulation, sand-lime brick is actually recommended, but the exterior walls will not be any thinner (the interior ones will).