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!
W
WilderSueden5 Feb 2021 18:52meowmeow schrieb:
I'm still not sure what to make of the heat pump electricity tariffs.The real question is what your grid operator thinks about it. In many grids, a heat pump is only allowed behind a separate meter, so you have no choice. Otherwise, these tariffs tend to be rather unprofitable.Hmm, my first small heat pump simulation from a few weeks ago:
Outside temperature: -3°C (27°F)
Supply temperature: Boiler temperature 45°C (113°F) (controlled by a slope of 0.8)
Radiator in the living room fully opened. Other rooms not yet. Circulating pump unchanged.
Room temperature in the living room: 20°C (68°F)
The idea behind the instantaneous water heater was as follows:
I also want hot water during summer and transitional periods. With an electric heating element in the sanitary storage tank, I would have to run the supply temperature higher than necessary and would lose the option to cool in summer (even though this has never actually been an issue so far).
Do I absolutely need a water softener system for our hard water (21°dH)? So far, one has never been installed and we have not really been bothered by limescale.
Here is a small monitoring setup I created for my apartment:
[MEDIA=imgur]a/7eyF7qm[/MEDIA]
Unfortunately, I haven’t found any radiator valves that can really have their opening controlled via API. With mine (tado), I can only set the target temperature. When it is reached, the radiator closes. This would be exactly the opposite of what I want in summer when cooling.
Many heat pumps apparently always keep radiators fully open and control temperatures centrally via the heating curve. I understand the approach—it’s supposedly better to reduce the fuel supply rather than regulate speed by applying the handbrake. However, in our house extension, there is a kitchen and guest room that are hardly heated so far because the kitchen has a wood stove, so there is generally less heating demand there, and the guest room is located above it.
Outside temperature: -3°C (27°F)
Supply temperature: Boiler temperature 45°C (113°F) (controlled by a slope of 0.8)
Radiator in the living room fully opened. Other rooms not yet. Circulating pump unchanged.
Room temperature in the living room: 20°C (68°F)
The idea behind the instantaneous water heater was as follows:
I also want hot water during summer and transitional periods. With an electric heating element in the sanitary storage tank, I would have to run the supply temperature higher than necessary and would lose the option to cool in summer (even though this has never actually been an issue so far).
Do I absolutely need a water softener system for our hard water (21°dH)? So far, one has never been installed and we have not really been bothered by limescale.
Here is a small monitoring setup I created for my apartment:
[MEDIA=imgur]a/7eyF7qm[/MEDIA]
Unfortunately, I haven’t found any radiator valves that can really have their opening controlled via API. With mine (tado), I can only set the target temperature. When it is reached, the radiator closes. This would be exactly the opposite of what I want in summer when cooling.
Many heat pumps apparently always keep radiators fully open and control temperatures centrally via the heating curve. I understand the approach—it’s supposedly better to reduce the fuel supply rather than regulate speed by applying the handbrake. However, in our house extension, there is a kitchen and guest room that are hardly heated so far because the kitchen has a wood stove, so there is generally less heating demand there, and the guest room is located above it.
N
nordanney6 Feb 2021 09:19meowmeow schrieb:
The idea behind the instantaneous water heater was this:
I also want warm water during summer and transitional seasons. With a heating element in the hygiene tank, I would have to set the supply temperature higher than necessary and lose the option to cool in summer (even though this has never really been an issue before)? I don’t understand any of that. Normally, the heating element is off since that’s what the heat pump is for. And how do you plan to cool in summer?
meowmeow schrieb:
Many heat pumps apparently have radiators 95% of all heat pumps don’t have radiators at all. Even if they do, the thermostats are turned up, but only with hydraulic balancing and controlled flow similar to underfloor heating.
Hmm, maybe I’m making a mistake in my thinking. But during the transitional periods, I might need a supply temperature of about 35°C (95°F), so 35°C (95°F) in the domestic hot water tank. Does that mean the water from the tap would be around 33°C (91°F)? That seems a bit cool for showering.
In summer, I won’t need to heat for several months, but I still want to bathe and shower with warm water. So, should I heat the entire domestic hot water tank?
In my opinion, the house can be cooled in summer by circulating water through the radiators at a temperature lower than the room temperature.
In summer, I won’t need to heat for several months, but I still want to bathe and shower with warm water. So, should I heat the entire domestic hot water tank?
In my opinion, the house can be cooled in summer by circulating water through the radiators at a temperature lower than the room temperature.
N
nordanney6 Feb 2021 15:59meowmeow schrieb:
Hmm, maybe I’m also making a mistake in my thinking. But during the transition period, I might need a supply temperature of around 35 degrees, so 35 degrees in the hygienic storage tank. That means the water from the tap would come out at about 33 degrees? You have 50 degrees in the storage tank. The supply temperature refers to the heating water, not the domestic hot water.
With a heat exchanger, you get water hot enough to burn your skin.
In summer, the tank is still heated. Using the heat pump, which creates four units of heat from one unit of electricity, is much more economical than an electric instantaneous water heater (which works 1:1). Storage losses are negligible.
meowmeow schrieb:
Hmm, in my opinion, you can cool the house in summer by circulating water cooler than the room temperature through the radiators. Keep dreaming...
Even with underfloor heating, a temperature drop of about 2 degrees is possible in a well-insulated new building. With radiators, the cooling effect will be close to zero.
First, read up on how heat pumps work, the different types of hot water tanks, and cooling options in houses. You’re still a complete beginner on these topics. No offense intended.
Yes, I am definitely still at the beginning of my journey. That’s why I’m especially grateful for posts that I can learn from. Hmm, there are some users here in the forum who say they also use their radiators for cooling, but cooling is not really an issue for us. I think it might make sense to involve an energy consultant for our project, who can hopefully also handle all the subsidy applications. When we replaced the roof two years ago, there was briefly a consultant involved, but he kept insisting on wrapping the entire house in plastic, and we couldn’t really agree.
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