ᐅ What to replace an oil heating system from 1989 in an old, characterful house with?
Created on: 9 Jan 2021 14:19
M
meowmeow
Hello dear forum,
we have an old timber-framed house in the Alpine foreland. Built around 1910 with an extension from the 1960s, the original building has a basement, the extension does not. The insulation is rather poor, and the windows are either double-glazed or old. A hailstorm completely destroyed our roof, so a new roof with good insulation has now been installed.
Currently, we have a Viessmann oil heating system from 1989 with a 2000l (528 gallons) oil tank in the basement, which has caused no major problems so far. The hot water is also centrally supplied by this system. With the old roof, we used about 1900-2500l (502-660 gallons) of oil in winter, depending on the season. With the new roof, we don’t have experience yet, but I expect some improvement. The house has about 115m2 (1238 square feet) of living space, heated by radiators.
Since the heating system is getting old and there are currently larger subsidy programs, we are considering modernization. From my research so far, a heat pump seems to be out of the question because we would need a better-insulated house and underfloor heating? Other types of electric heating seem even less economical?
The least invasive option would probably be a new condensing oil boiler, but these are not subsidized, so I could just wait until the old one breaks down?
A pellet heating system seems too complicated to operate? My mother will soon be 70 and often lives alone in the house. In her old age, I don’t want to put too much strain on her. We frequently visit with our child for several days, but mostly in summer. Also, the long transition phase with low heating loads appears to speak against a pellet system.
I can’t really estimate the costs for gas. A gas connection might be possible with the local supplier if the neighbors join in. We would need about 60-70m (197-230 feet) of gas pipeline on our own property. What costs should I roughly expect? Alternatively, a tank could be buried in the garden, but we are not very enthusiastic about that idea. We are somewhat confused by current politics: on the one hand, fossil fuels are supposed to become much more expensive to promote renewable energy, but on the other hand, gas condensing boilers are heavily subsidized?
For sentimental reasons, we could imagine installing a water-bearing wood stove in the living room. We already have a wood-burning stove in the kitchen where we occasionally cook, and which also provides some heating in winter.
However, it would have to connect to the same chimney currently used by the oil heating system – or the future gas heating system – and from what I understand, this is not allowed, so I might have to give up that dream, right?
We are considering a photovoltaic system on the roof, but we plan to remove the attic floor and renovate the upstairs room within about 5-10 years to get higher ceilings. This would also include adding a few skylights. I should probably wait for these renovation measures first.
What would you recommend? How should the new heating system be sized – I assume this can be calculated quite well based on previous energy consumption?
Thank you very much for your time and help!
we have an old timber-framed house in the Alpine foreland. Built around 1910 with an extension from the 1960s, the original building has a basement, the extension does not. The insulation is rather poor, and the windows are either double-glazed or old. A hailstorm completely destroyed our roof, so a new roof with good insulation has now been installed.
Currently, we have a Viessmann oil heating system from 1989 with a 2000l (528 gallons) oil tank in the basement, which has caused no major problems so far. The hot water is also centrally supplied by this system. With the old roof, we used about 1900-2500l (502-660 gallons) of oil in winter, depending on the season. With the new roof, we don’t have experience yet, but I expect some improvement. The house has about 115m2 (1238 square feet) of living space, heated by radiators.
Since the heating system is getting old and there are currently larger subsidy programs, we are considering modernization. From my research so far, a heat pump seems to be out of the question because we would need a better-insulated house and underfloor heating? Other types of electric heating seem even less economical?
The least invasive option would probably be a new condensing oil boiler, but these are not subsidized, so I could just wait until the old one breaks down?
A pellet heating system seems too complicated to operate? My mother will soon be 70 and often lives alone in the house. In her old age, I don’t want to put too much strain on her. We frequently visit with our child for several days, but mostly in summer. Also, the long transition phase with low heating loads appears to speak against a pellet system.
I can’t really estimate the costs for gas. A gas connection might be possible with the local supplier if the neighbors join in. We would need about 60-70m (197-230 feet) of gas pipeline on our own property. What costs should I roughly expect? Alternatively, a tank could be buried in the garden, but we are not very enthusiastic about that idea. We are somewhat confused by current politics: on the one hand, fossil fuels are supposed to become much more expensive to promote renewable energy, but on the other hand, gas condensing boilers are heavily subsidized?
For sentimental reasons, we could imagine installing a water-bearing wood stove in the living room. We already have a wood-burning stove in the kitchen where we occasionally cook, and which also provides some heating in winter.
However, it would have to connect to the same chimney currently used by the oil heating system – or the future gas heating system – and from what I understand, this is not allowed, so I might have to give up that dream, right?
We are considering a photovoltaic system on the roof, but we plan to remove the attic floor and renovate the upstairs room within about 5-10 years to get higher ceilings. This would also include adding a few skylights. I should probably wait for these renovation measures first.
What would you recommend? How should the new heating system be sized – I assume this can be calculated quite well based on previous energy consumption?
Thank you very much for your time and help!
N
nordanney6 Feb 2021 16:34meowmeow schrieb:
Wrapping the house in plastic Wrapping the house itself is actually a good idea. It fits well with the heat pump – I am currently renovating to KfW 55 standard, with one apartment using a heat pump. I already need a flow temperature of 40°C (104°F) for the radiators. And you first have to be able to install 33 cm (13 inches) deep radiators. Without insulation, this wouldn’t have been possible or would have required a much higher flow temperature, leading to a poorly performing heat pump.
meowmeow schrieb:
I think it might make sense to involve an energy consultant for our project, They’re not expensive, often subsidized, and definitely worth it!
Hmm, we already have some 33 cm (13 inch) thick partition walls, which could still be easily doubled in height since they are only 30 cm (12 inch) tall.
I’m not a big fan of the insulation craze. In our apartment, for example, the old beautiful wooden windows were replaced with modern plastic windows. When we came back from vacation, there was mold on the wall because, of course, we didn’t ventilate while we were away. Before, with the wooden windows, this was never a problem because they always allowed some air exchange. The cost of mold removal and repainting has been higher than what we would save in heating costs over the next 10 years. Not to mention the installation costs of the new windows. A low-energy house makes sense in my opinion, but the overall concept has to be right, including a proper ventilation strategy. In my view, you can never turn an old farmhouse into a low-energy house.
The father of a friend owns a construction company and advised me against insulation. This year, they replaced insulation on several houses that was less than 8 years old. We also have a neighbor who insulated his house, but ever since woodpeckers took a liking to the insulation, he’s not so happy about having woodpeckers in his garden.
I’m not a big fan of the insulation craze. In our apartment, for example, the old beautiful wooden windows were replaced with modern plastic windows. When we came back from vacation, there was mold on the wall because, of course, we didn’t ventilate while we were away. Before, with the wooden windows, this was never a problem because they always allowed some air exchange. The cost of mold removal and repainting has been higher than what we would save in heating costs over the next 10 years. Not to mention the installation costs of the new windows. A low-energy house makes sense in my opinion, but the overall concept has to be right, including a proper ventilation strategy. In my view, you can never turn an old farmhouse into a low-energy house.
The father of a friend owns a construction company and advised me against insulation. This year, they replaced insulation on several houses that was less than 8 years old. We also have a neighbor who insulated his house, but ever since woodpeckers took a liking to the insulation, he’s not so happy about having woodpeckers in his garden.
Pessimistic Back-of-the-Envelope Calculation
I am assuming a cold winter with a heating oil consumption of 2400 liters (634 gallons). Rounded, heating oil has an energy content of 10 kWh per liter, so that’s a heating demand of about 24,000 kWh.
If I understand correctly, I should still multiply this by the efficiency of the heating system? That would roughly be 24,000 kWh * 0.85 efficiency = 20,400 kWh?
Now, I’m assuming my heat pump only achieves a seasonal performance factor (SPF) of 2.4 (the worst heat pump in the Fraunhofer study managed 2.6, although almost all of them were paired with underfloor heating).
So I would need 24,000 kWh / 2.4 = 10,000 kWh of electricity to heat the house. I pay about 25 cents per kWh for electricity (currently less). The result would then be about 2,500 euros in heating electricity costs per year, which is quite a substantial amount. Is this calculation correct so far?
I believe there are several ways to reduce this amount:
* Achieve a better seasonal performance factor than 2.4
* Use a wood stove on cold days and enjoy the fire
* Generate electricity with a solar system, especially in the transitional seasons, to supply the heat pump
* Milder winters due to climate change (even with the old, uninsulated roof, we often used significantly less than 2400 liters)
* Consider the efficiency of the current heating system in the calculation?
On the other hand, 2400 liters of heating oil currently cost around 1400 euros, but with the 2000-liter (530-gallon) tank, two deliveries are needed. A modern condensing boiler would certainly reduce consumption somewhat. However, I think maintenance costs for a condensing boiler would be somewhat higher than for a heat pump?
The advantages of the heat pump include:
* No more stress with heating oil in the future
* Save space in the basement (though currently the space is not needed)
* Legal security—my heating system won’t be banned in the near future
* A wood stove in the living room (warm your feet by the fire after kitesurfing!)
* Heating system replacement every 15-20 years is cheaper than with oil
* Hopefully a less climate-damaging heating system
What the above calculation does not account for are the initial investment costs. I roughly estimate about 15,000 euros for replacing the oil burner and repairs. The same amount for switching to a heat pump.
However, the latter is heavily subsidized, so the higher heating costs compared to oil would likely be covered by the savings within a few winters. Additionally, the heat pump enables further optimization measures in the house (e.g., better windows, photovoltaic system) that may also benefit from increased subsidies.
Am I just trying to make the numbers look better? Where am I going wrong?
I am assuming a cold winter with a heating oil consumption of 2400 liters (634 gallons). Rounded, heating oil has an energy content of 10 kWh per liter, so that’s a heating demand of about 24,000 kWh.
If I understand correctly, I should still multiply this by the efficiency of the heating system? That would roughly be 24,000 kWh * 0.85 efficiency = 20,400 kWh?
Now, I’m assuming my heat pump only achieves a seasonal performance factor (SPF) of 2.4 (the worst heat pump in the Fraunhofer study managed 2.6, although almost all of them were paired with underfloor heating).
So I would need 24,000 kWh / 2.4 = 10,000 kWh of electricity to heat the house. I pay about 25 cents per kWh for electricity (currently less). The result would then be about 2,500 euros in heating electricity costs per year, which is quite a substantial amount. Is this calculation correct so far?
I believe there are several ways to reduce this amount:
* Achieve a better seasonal performance factor than 2.4
* Use a wood stove on cold days and enjoy the fire
* Generate electricity with a solar system, especially in the transitional seasons, to supply the heat pump
* Milder winters due to climate change (even with the old, uninsulated roof, we often used significantly less than 2400 liters)
* Consider the efficiency of the current heating system in the calculation?
On the other hand, 2400 liters of heating oil currently cost around 1400 euros, but with the 2000-liter (530-gallon) tank, two deliveries are needed. A modern condensing boiler would certainly reduce consumption somewhat. However, I think maintenance costs for a condensing boiler would be somewhat higher than for a heat pump?
The advantages of the heat pump include:
* No more stress with heating oil in the future
* Save space in the basement (though currently the space is not needed)
* Legal security—my heating system won’t be banned in the near future
* A wood stove in the living room (warm your feet by the fire after kitesurfing!)
* Heating system replacement every 15-20 years is cheaper than with oil
* Hopefully a less climate-damaging heating system
What the above calculation does not account for are the initial investment costs. I roughly estimate about 15,000 euros for replacing the oil burner and repairs. The same amount for switching to a heat pump.
However, the latter is heavily subsidized, so the higher heating costs compared to oil would likely be covered by the savings within a few winters. Additionally, the heat pump enables further optimization measures in the house (e.g., better windows, photovoltaic system) that may also benefit from increased subsidies.
Am I just trying to make the numbers look better? Where am I going wrong?
The roof was completely rebuilt and insulated to modern standards after a hailstorm destroyed the old one. However, we do not yet have any experience with energy consumption because this is our first winter with it. The effect of the insulation inside the house is clearly noticeable. Under the sloping roof sections, it is now much warmer.
The attic conversion was done in a way that allows me to remove the attic floor later to gain room height on the upper floor.
The attic conversion was done in a way that allows me to remove the attic floor later to gain room height on the upper floor.
meowmeow schrieb:
The roof was completely rebuilt and insulated with modern materials after a hailstorm destroyed the old one. However, we don’t yet have any experience with energy consumption because this is our first winter with it. The effect of the insulation inside the house can definitely be felt. Under the sloping roof areas, it is now much warmer.
The attic conversion was done in a way that allows me to eventually remove the attic floor to gain ceiling height on the upper floor.That sounds good. Replacing the oil heating system should cost less than 10,000 euros (about $10,000) I think. At the moment, you would be paying around 900 euros (about $900) more per year with a heat pump. If you subtract chimney cleaning and maintenance costs, it might be closer to 700 euros (about $700).
With that, you could initially fix small issues, like air leaks around the windows, unless that was already done—I don’t remember.
Since there is no consumption data yet, wait through the winter first and set the forward temperature to an absolute minimum. The lower, the better for the heat pump.
You might also consider replacing or adding radiators.
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