ᐅ Heating System Upgrade for Existing Buildings – Condensing Boiler / Air-to-Water Heat Pump / Air Source Heat Pump
Created on: 9 Apr 2022 10:12
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Chrizz72
Hello dear forum,
I am new here and this is my first post. I would be very grateful if anyone could help me with my question/problem.
Starting point:
We are about to buy a single-family house (built in 1959/60; living area approx. 170sqm (1830 sq ft) – 65sqm (700 sq ft) first floor, 65sqm (700 sq ft) second floor, 40sqm (430 sq ft) attic). The windows were replaced in 2005 (Uw-value 1.2), we will reroof and insulate the roof (U-value 0.14), possibly also insulate the basement ceiling – everything else is still in the “original condition.” Four of us will live in the house (2 adults + 2 children). The attic will be converted into living space. There is an old gas boiler (not condensing) in the basement and old cast iron radiators throughout the house. Additionally, we will renew the electrical system and renovate all the floors.
The key question now is: What heating system should we choose?
Since the house was previously occupied only by an elderly lady, there is no reliable data to estimate our future heating demand. Naturally, we would prefer to move away from fossil fuels and install an air-to-water heat pump combined with underfloor heating and photovoltaic panels (without subsidies, this would definitely cost about 65K) – however, this would exceed our budget. Without photovoltaic, I am also quite worried that the electricity costs could skyrocket. As a compromise, we have now focused on the following option: installation of a gas condensing boiler for heating and a domestic hot water heat pump (DHW HP) for hot water production – the ability to reduce the condensing boiler’s use during warmer months seems very attractive. Besides the cost aspect (which is completely acceptable to us, both initially and ongoing), the sustainability aspect also plays a role here (of course, a DHW HP alone is not a huge lever). At the same time, we are thinking about switching to underfloor heating on the ground floor and low-temperature radiators on the first and second floors. The idea behind this is to create an infrastructure that would allow us to switch to a heat pump fairly easily in the future. We would also gain reliable data regarding heat and heating demand. We wouldn’t have to install photovoltaic on the roof immediately but could add it later, either gradually or all at once.
How do you assess my approach? Does it sound realistic and reasonable to you, especially considering the current context (war, energy transition/costs, etc.)? I understand there is no perfect solution, but I would like to make a well-informed decision that makes economic and ecological sense in the short and long term. Maybe there are alternatives I haven’t considered yet.
A little about me: I am unfortunately not very skilled technically and have very little experience. However, I have noticed that I can quite quickly get to grips with unfamiliar topics and have a steeper learning curve than expected 🙂
I look forward to your feedback.
Best regards,
Christian
I am new here and this is my first post. I would be very grateful if anyone could help me with my question/problem.
Starting point:
We are about to buy a single-family house (built in 1959/60; living area approx. 170sqm (1830 sq ft) – 65sqm (700 sq ft) first floor, 65sqm (700 sq ft) second floor, 40sqm (430 sq ft) attic). The windows were replaced in 2005 (Uw-value 1.2), we will reroof and insulate the roof (U-value 0.14), possibly also insulate the basement ceiling – everything else is still in the “original condition.” Four of us will live in the house (2 adults + 2 children). The attic will be converted into living space. There is an old gas boiler (not condensing) in the basement and old cast iron radiators throughout the house. Additionally, we will renew the electrical system and renovate all the floors.
The key question now is: What heating system should we choose?
Since the house was previously occupied only by an elderly lady, there is no reliable data to estimate our future heating demand. Naturally, we would prefer to move away from fossil fuels and install an air-to-water heat pump combined with underfloor heating and photovoltaic panels (without subsidies, this would definitely cost about 65K) – however, this would exceed our budget. Without photovoltaic, I am also quite worried that the electricity costs could skyrocket. As a compromise, we have now focused on the following option: installation of a gas condensing boiler for heating and a domestic hot water heat pump (DHW HP) for hot water production – the ability to reduce the condensing boiler’s use during warmer months seems very attractive. Besides the cost aspect (which is completely acceptable to us, both initially and ongoing), the sustainability aspect also plays a role here (of course, a DHW HP alone is not a huge lever). At the same time, we are thinking about switching to underfloor heating on the ground floor and low-temperature radiators on the first and second floors. The idea behind this is to create an infrastructure that would allow us to switch to a heat pump fairly easily in the future. We would also gain reliable data regarding heat and heating demand. We wouldn’t have to install photovoltaic on the roof immediately but could add it later, either gradually or all at once.
How do you assess my approach? Does it sound realistic and reasonable to you, especially considering the current context (war, energy transition/costs, etc.)? I understand there is no perfect solution, but I would like to make a well-informed decision that makes economic and ecological sense in the short and long term. Maybe there are alternatives I haven’t considered yet.
A little about me: I am unfortunately not very skilled technically and have very little experience. However, I have noticed that I can quite quickly get to grips with unfamiliar topics and have a steeper learning curve than expected 🙂
I look forward to your feedback.
Best regards,
Christian
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Benutzer20010 Apr 2022 20:46Chrizz72 schrieb:
I will commission a heat load calculation as well as the design of underfloor heating and low-temperature radiators.Don't bother with that and just go with underfloor heating. In my opinion, radiators only have disadvantages.Benutzer200 schrieb:
Just skip that and only install underfloor heating. In my opinion, radiators have only disadvantages.Disadvantages in what sense? Because then we could only replace the radiators in four rooms and keep the existing floor or screed in place.B
Benutzer20011 Apr 2022 10:51Chrizz72 schrieb:
Disadvantages in what sense? Because then we could only replace the radiators in four rooms and leave the floor or screed as it is. They get in the way.
They don’t fit well with the hydraulics of the heat pump.
Different heat than underfloor heating.
Higher flow temperature needed for the radiators (I’m renovating to a KfW55 standard house – ground floor apartment with underfloor heating and a maximum flow temperature of 30°C (86°F), upper floor apartment with new radiators and a maximum flow temperature of 40°C (104°F). This doesn’t matter to me since each apartment will have its own heat pump).
D
Deliverer15 Apr 2022 10:55If there is even the slightest possibility to replace radiators with underfloor, wall-mounted, sloped ceiling, or ceiling heating, I would do it.
However, low-temperature radiators will also work, just not as efficiently or comfortably.
However, low-temperature radiators will also work, just not as efficiently or comfortably.
Deliverer schrieb:
If there is even the slightest possibility to replace radiators with underfloor, wall, sloped ceiling, or ceiling heating, I would do it.
It will also work with low-temperature radiators, just not as efficiently or comfortably. We will install underfloor heating everywhere except in the attic. Since there is only the bedroom up there, the effort and cost would simply be too high for us. In our opinion, a less efficient/comfortable low-temperature radiator serves its purpose there...
D
Deliverer15 Apr 2022 12:26If it’s not a problem—and it probably isn’t—for the bedroom to be one to two degrees cooler than the floor below, then that works perfectly. The heating circuit can be connected directly to the supply line of a small heating loop without any efficiency-reducing mixing.
It’s like with many things: once you understand the rules (and the reasons behind them), you can break them occasionally. ;-)
Edit: Additional idea: install an air conditioner in that room. It helps to sleep well during the summer, can partially cool the floor below when doors are open, and can also provide heating upstairs in emergencies.
It’s like with many things: once you understand the rules (and the reasons behind them), you can break them occasionally. ;-)
Edit: Additional idea: install an air conditioner in that room. It helps to sleep well during the summer, can partially cool the floor below when doors are open, and can also provide heating upstairs in emergencies.
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