Hello forum community,
My wife and I are planning an extension to our home and are currently considering the possible heating options.
Just to explain, we are extending an existing house (built in 1975). My parents-in-law live on the ground floor, and we live upstairs. The entire building’s existing heating system (storage heaters) and hot water supply will be renewed. It is already decided that we will not install underfloor heating, and that heating and hot water will be produced centrally. The windows and insulation are all up to modern standards.
One option would be a gas boiler, but the question is how expensive the gas connection would be. For a heat pump, only an air-source heat pump would be possible because we don’t have enough space on the property for ground-source heating.
I am somewhat skeptical about air-source heat pumps. From what I understand, heating is not a problem, and hot water for showering or similar purposes up to 40°C (104°F) should still be energy-efficient. But what about the kitchen sink, where you sometimes need really hot water? To avoid constantly heating the entire hot water system to 60°C (140°F) just for the sink, I had the idea of installing an instantaneous water heater under the kitchen sink, connected to the hot water line coming from the central heating system. This way, you would have hot water immediately without delay, and since the water is preheated to 40°C (104°F), the instantaneous heater would only need to raise the temperature by about 20°C (36°F) from 40°C to 60°C.
Would that work?
How practical would it be?
Do you have any other ideas?
Thank you,
Peter
My wife and I are planning an extension to our home and are currently considering the possible heating options.
Just to explain, we are extending an existing house (built in 1975). My parents-in-law live on the ground floor, and we live upstairs. The entire building’s existing heating system (storage heaters) and hot water supply will be renewed. It is already decided that we will not install underfloor heating, and that heating and hot water will be produced centrally. The windows and insulation are all up to modern standards.
One option would be a gas boiler, but the question is how expensive the gas connection would be. For a heat pump, only an air-source heat pump would be possible because we don’t have enough space on the property for ground-source heating.
I am somewhat skeptical about air-source heat pumps. From what I understand, heating is not a problem, and hot water for showering or similar purposes up to 40°C (104°F) should still be energy-efficient. But what about the kitchen sink, where you sometimes need really hot water? To avoid constantly heating the entire hot water system to 60°C (140°F) just for the sink, I had the idea of installing an instantaneous water heater under the kitchen sink, connected to the hot water line coming from the central heating system. This way, you would have hot water immediately without delay, and since the water is preheated to 40°C (104°F), the instantaneous heater would only need to raise the temperature by about 20°C (36°F) from 40°C to 60°C.
Would that work?
How practical would it be?
Do you have any other ideas?
Thank you,
Peter
First of all, I am not an expert.
It may work with large low-temperature radiators. However, air source heat pumps are only suitable for very well-insulated houses. Otherwise, it becomes uneconomical, and in winter you might end up heating purely with electricity because the heat pump, under normal conditions, cannot compensate for the heat losses through the walls, roof, and floor slab.
Of course, it is possible with a significant financial investment to insulate an old house from all sides so that an air source heat pump can function properly. I just don’t believe that this is the case here.
It may work with large low-temperature radiators. However, air source heat pumps are only suitable for very well-insulated houses. Otherwise, it becomes uneconomical, and in winter you might end up heating purely with electricity because the heat pump, under normal conditions, cannot compensate for the heat losses through the walls, roof, and floor slab.
Of course, it is possible with a significant financial investment to insulate an old house from all sides so that an air source heat pump can function properly. I just don’t believe that this is the case here.
P
peterbocholt30 Oct 2014 13:04When it comes to really dirty pots, very hot water is definitely useful!!! However, I only realized a potential issue with hot water in heat pump systems because a colleague had exactly that problem. To run his heating system with hot water (heat pump with ground collector) efficiently, he was supposed to lower the heating water temperature—and promptly his wife complained...
We generally keep the water heater at 54°C (129°F) with a capacity of 270 liters (71 gallons), which provides enough buffer when everyone is showering or bathing, etc.
I also use this water at the sink when cleaning greasy and dirty tools from car repairs, for example... though that’s already pushing the limit of what’s bearable, even with thick dishwashing gloves. 😉
Legionella bacteria only become a concern if the water stays in the tank for a long time or during extended absences, such as when you have a weekend house, for example...
I also use this water at the sink when cleaning greasy and dirty tools from car repairs, for example... though that’s already pushing the limit of what’s bearable, even with thick dishwashing gloves. 😉
Legionella bacteria only become a concern if the water stays in the tank for a long time or during extended absences, such as when you have a weekend house, for example...
P
peterbocholt4 Nov 2014 11:11@illo What kind of heating system do you have?
P
peterbocholt4 Nov 2014 11:12And how many people are there in your household?
E
ErikErdgas29 Dec 2014 11:11Hello Peterbocholt,
How large will the extension be, and is it intended solely to expand your apartment? What energy standard will it meet? Energy saving regulation, KfW 70, or better? What exactly is meant by “windows and insulation up to the latest standards”? Has a defined standard been achieved here? Once the parameters are set, a heating load calculation should be carried out. It is also important to clarify how many people will live in the building. Assuming 5 people (2 parents-in-law plus 3 others) in your case, the hot water demand will be approximately 160 to 300 liters (42 to 79 gallons), which is quite significant. Therefore, a centralized hot water supply should definitely be considered. This should be taken into account when planning the extension, as it might be possible to reduce pipe lengths and, consequently, the renovation effort in the existing house. One option is a gas condensing boiler system combined with solar collectors, which can provide both hot water and heating support. If the two parts of the building have significantly different energy levels, the gas condensing system can deliver sufficiently high flow temperatures that can be managed via two separate heating circuits (old building, new building).
Best regards, Erik
How large will the extension be, and is it intended solely to expand your apartment? What energy standard will it meet? Energy saving regulation, KfW 70, or better? What exactly is meant by “windows and insulation up to the latest standards”? Has a defined standard been achieved here? Once the parameters are set, a heating load calculation should be carried out. It is also important to clarify how many people will live in the building. Assuming 5 people (2 parents-in-law plus 3 others) in your case, the hot water demand will be approximately 160 to 300 liters (42 to 79 gallons), which is quite significant. Therefore, a centralized hot water supply should definitely be considered. This should be taken into account when planning the extension, as it might be possible to reduce pipe lengths and, consequently, the renovation effort in the existing house. One option is a gas condensing boiler system combined with solar collectors, which can provide both hot water and heating support. If the two parts of the building have significantly different energy levels, the gas condensing system can deliver sufficiently high flow temperatures that can be managed via two separate heating circuits (old building, new building).
Best regards, Erik
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