ᐅ Heating System Replacement in an Existing Property Built in 1993 – Evaluation of Quotes

Hello dear home building community.

I have been a silent reader so far and have already gained one or two very useful tips from this forum. Now I need your help.

We have purchased an existing property built in 1993. Currently, the old oil boiler with 20 kW is still installed, which urgently needs to be replaced, as the entire installation in the heating cellar has also "aged."

Here is some background information:

80 m² (860 sq ft) with underfloor heating dating from 1993 (ground floor). The ground floor also has radiators in every room.

80 m² (860 sq ft) with radiators (upper floor)

According to the energy consumption certificate, about 3000 liters (790 gallons) of heating oil were used per year, with 450 liters (119 gallons) for hot water demand. Additionally, 3500 kWh from the tiled stove were used annually for supplementary heating.
We have already renovated the tiled stove (warm air) with 9–18 kWh storage capacity.

Building information:

Double-glazed PVC windows
36 cm (14 inches) exterior wall made of Pori-Klimaton blocks
Fully basemented. One room in the basement is developed as potential living space.

Insulation status:

Attic and roof: rafter insulation with about 16 cm (6 inches) of glass wool.
The roof windows are in poor condition and will need to be replaced soon.
Not beneficial for the house’s energy balance is an open basement staircase/gallery leading from the basement to the upper floor.
There is also a fire protection door on the basement staircase leading outside, which acts as a significant thermal bridge.
Additionally, the wooden house door is in poor condition (warped) and will also be replaced soon. The windows are in excellent condition.

Possible future investments:
- Basement ceiling insulation
- Closing off the basement stairwell (drywall) to prevent cold air drafts from the basement in winter; alternative would be replacing the basement door (more complex)
- Photovoltaic system (9–12.5 kWp)
Longer term: roof insulation, window replacement

Unfortunately, we do not yet have reliable personal experience with the house, and due to the failure of the heating system, we are now forced to take action. Otherwise, the condition of the house is very good, so we do not plan major renovations.
The heating room is very large, and storing pellets is not a problem. Installing a heat pump is also feasible given the property. There is no gas connection.

The following options were offered to us by different heating installers:

1) Air-source heat pump with 10 kW plus 800-liter (210-gallon) fresh water tank, including renovation of all radiators for low-temperature heating. (50% subsidy)
2) Pellet boiler Ökofen condensing with ZeroFlame plus electric heater for fresh water tank 800 liters (210 gallons) (55% subsidy) → currently our favorite
3) ETA PU 14 plus electric heater for fresh water tank 1000 liters (260 gallons) (50% subsidy)

Investment costs for both projects are around 38,000 (minus subsidies). Both offers include a water softening system.

After reading extensively here in the forum, I am now considering prioritizing the photovoltaic system as an investment, to possibly cover the pellet heating during summer months with a hot water heat pump.
I would install this in the basement to increase self-consumption.

I look forward to your opinions. Many thanks in advance!

myDoering schrieb:

1) Air-source heat pump with 10 kW (Wolf) plus 800-liter (210-gallon) domestic hot water tank plus renovation of all radiators to low-temperature operation. (Subsidy 50%)
2) Pellets boiler Ökofen condensing with ZeroFlame plus electric heating element in 800-liter (210-gallon) domestic hot water tank (Subsidy 55%) → Currently our favorite
3) ETA PU 14 plus electric heating element in 1000-liter (260-gallon) domestic hot water tank (Subsidy 50%)

How do you qualify for such high subsidies? Aren’t you usually 5% too high?

P.S. Without additional energy improvement measures, I wouldn't choose a heat pump, and photovoltaic panels are always worth considering—regardless of the heating system you have (pellet heating combined with domestic hot water is of course a double investment, which a heat pump alone can handle better in summer).

Why is the replacement urgently necessary? Is it really urgent? Because everything is old and looks outdated, or is something actually broken?

First, I would carry out all planned energy efficiency upgrades during the upcoming summer months. Additionally, focus on adjusting the heating curve and supply temperature and implement these changes. Then, throughout the winter, measure the actual energy consumption and determine the lowest possible supply temperature.

Actions should be taken in spring next year.

Otherwise, if it is an urgent matter, I would avoid opting for heat pumps, as they tend to be inefficient and therefore costly at presumably high supply temperatures. Also, I consider €38,000 (€38,000) to be an outrageous price.

Pellets are a possible alternative in principle. However, you don’t gain any space.

Is gas not available?

Photovoltaic systems can be chosen completely independently from the heating system.

Basic funding of 45%
We are currently having the iSFP prepared +5%
With pellets, the Ökofen Condens with Zeroflame would qualify for the Innobonus.

Reasons for the replacement:
- Expansion vessel is broken.
- System is losing water and must
- Exhaust values are okay.
- During maintenance, detachment of the burner base and critical condition of the fan were detected.

myDoering schrieb:

We are currently having the iSFP created +5%

OK – I didn’t consider the schedule. In that case, you are required to follow and complete all the tasks on the schedule.