ᐅ Replacing the Heating System in an Older Home: Which Option Is Best?

Hello everyone,

I need your advice on choosing the heating system for the planned replacement of our heating installation.

Facts:

- Semi-detached house with two separate living units, built in 1972, purchased by us in 2014
- Approx. 220 sqm (2370 sq ft) of heated space, 186 sqm (2002 sq ft) of living area, 95 sqm (1023 sq ft) on the ground floor, 91 sqm (979 sq ft) on the upper floor
- Building envelope insulated with 10 cm (4 inches)
- New triple-glazed windows, conservatories with full glazing on both ground and upper floors
- Roof not insulated
- Heating distribution: (We are currently planning to replace the old tube radiators with low-temperature radiators)

• Basement: One old tube radiator and about 40 sqm (430 sq ft) of underfloor heating (old system – probably pipes will be reused)
• Ground floor: Underfloor heating with 9 loops, installed in 2014, conservatory still with old underfloor heating system like in the basement
• Upper floor: Six old tube radiators

- Replacement of old oil heating from 1989 (low temperature), oil tank with 6000 liters (1585 gallons) steel tank, current consumption about 2500 liters (660 gallons) per year
- No gas connection available
- Additional planned project: photovoltaic system with about 8 – 9.9 kWp on the south side of the roof with a 10 kWh battery storage
- Ideally BAFA subsidy of 40% – 45% per system utilized

There have been many considerations regarding the options for the new heating system:

Option 1: Gas hybrid with solar thermal system of 8.5 sqm (91 sq ft) and 600-liter (160-gallon) water buffer tank
(Offers from Buderus or BOSCH systems)

Option 2: Gas hybrid with 400-liter (105-gallon) water tank and small supplementary air-water heat pump (possibly combined with the rooftop photovoltaic system)
(Offers from WOLF systems)

Option 3: Air-water heat pump with integrated domestic hot water preparation in the indoor unit and outdoor unit (possibly combined with the rooftop photovoltaic system)
(Offers from Vaillant systems)

Each option has its pros and cons, but I am also interested in your opinions and experiences. In particular, I am uncertain about the noise level of the outdoor units of the heat pumps. How loud are they really?

Or maybe some of you are currently planning a replacement with a similar setup. I would be glad to hear your experiences with these systems and which you would recommend for my situation.

Thank you very much for your help!!!

Best regards,
Chippy

Uh, maybe a silly question. Why choose a gas hybrid system if you don’t even have a gas connection yet (aside from the hybrid concept itself, which I don’t find very good or sensible)? Insulate the roof and basement (if necessary) and install a heat pump. Today’s units are efficient and quiet.

Insulate the roof in ANY case. Or insulate the ceiling of the top floor. You can easily save 20% this way.
Then remove the radiators upstairs and, if possible, have underfloor heating installed.
After that, consider moving towards a heat pump.

So you generally don’t consider GAS hybrid solutions to be worthwhile?

What does having underfloor heating milled mean? What are the approximate costs? Until now, we have avoided these extra expenses for a new underfloor heating system because we would also have to replace the floor coverings.

What costs should we expect for floor slab insulation?

Would these measures also be eligible for funding through BAFA?

Thanks.

Best regards

What costs can we expect approximately for insulating the floor/ceiling between stories? Alternatively, could we do it ourselves and only have the material subsidized?

Why is a gas hybrid system not sensible in our specific situation? Gas hybrid with solar thermal is quite commonly installed in new buildings, or am I mistaken? Or did you mean the gas hybrid version combined with a heat pump? I have wondered about that as well and tend to lean more toward a purely heat pump solution.

A standalone heat pump operates efficiently and economically only at low flow temperatures around 30°C (86°F). If we keep low-temperature radiators on the first floor, they will need at least 55°C (131°F) flow temperature, and wouldn’t the heat pump then consume a lot of electricity?

BAFA funding is available for heat pumps and also for:

- energy efficiency improvements in heat distribution (e.g., insulation of pipes) and heat transfer (e.g., replacement of old standard radiators with low-temperature radiators)

- domestic hot water production, as well as necessary renovations or modifications of heating/technical rooms and chimneys required for the new eligible heat generator.

Simply check the BAFA website for the document listing eligible costs.