Hello everyone, thank you in advance for your interest!
We are planning to renovate a building from 1936. Ultimately, it will undergo a complete renovation and be well insulated.
For the question at hand:
Underfloor heating is planned for all rooms. At the moment, we are considering an air-source heat pump (unfortunately, alternatives are too expensive right now). The roof will be extensively equipped with photovoltaic panels (14 kWp).
I do not currently have a U-value calculation available. I am mainly interested in your opinion on whether you think my proposed heating system makes sense.
Requirement:
The heat pump should provide heating as well as domestic hot water. Possibly, a wood stove with a water jacket will be integrated in a few years.
My initial thought is that the heat pump runs more efficiently the less work it has to do. This means that if the underfloor heating is operated with, for example, 23°C (73°F) supply temperature, the heat pump should not have to work much harder than 25°C (77°F).
To take advantage of the photovoltaic system, a generously sized buffer tank will be used.
The heat pump would keep the buffer tank at 25°C (77°F), preferably during the day, and depending on solar surplus, the heat pump could also work harder at times and raise the buffer temperature to higher levels (for example, 40°C (104°F)).
That covers the heating system.
Now there is always the question of how to achieve the temperature lift for the domestic hot water, especially considering the risk of legionella bacteria.
My idea is to draw water from the buffer tank in the same way as for the heating system and install two domestic hot water stations. Two units only for the purpose of locating the domestic hot water stations close to the points of use (kitchen and bathroom). I would then place a solar-powered instantaneous water heater before each station, so depending on the buffer temperature, it can raise the temperature from 25°C (77°F) (or possibly higher) to 50–60°C (122–140°F).
In this system, I believe a very simple buffer tank can be used, without heat loops.
According to my concept, this system should have comparatively low installation costs because it is very simple and contains little complex control technology. Therefore, it should also be relatively low-maintenance. I am aware that the instantaneous water heaters will cause costs when operating without solar surplus. However, in my estimation, these costs should be balanced out because the heat pump can continuously operate efficiently within its ideal “comfort range.”
Looking ahead, there is also a plan to connect a wood stove with a water jacket to the system, which would raise the buffer temperature and reduce the workload on the instantaneous water heaters.
Open for criticism and suggestions ;-)
Stefan
We are planning to renovate a building from 1936. Ultimately, it will undergo a complete renovation and be well insulated.
For the question at hand:
Underfloor heating is planned for all rooms. At the moment, we are considering an air-source heat pump (unfortunately, alternatives are too expensive right now). The roof will be extensively equipped with photovoltaic panels (14 kWp).
I do not currently have a U-value calculation available. I am mainly interested in your opinion on whether you think my proposed heating system makes sense.
Requirement:
The heat pump should provide heating as well as domestic hot water. Possibly, a wood stove with a water jacket will be integrated in a few years.
My initial thought is that the heat pump runs more efficiently the less work it has to do. This means that if the underfloor heating is operated with, for example, 23°C (73°F) supply temperature, the heat pump should not have to work much harder than 25°C (77°F).
To take advantage of the photovoltaic system, a generously sized buffer tank will be used.
The heat pump would keep the buffer tank at 25°C (77°F), preferably during the day, and depending on solar surplus, the heat pump could also work harder at times and raise the buffer temperature to higher levels (for example, 40°C (104°F)).
That covers the heating system.
Now there is always the question of how to achieve the temperature lift for the domestic hot water, especially considering the risk of legionella bacteria.
My idea is to draw water from the buffer tank in the same way as for the heating system and install two domestic hot water stations. Two units only for the purpose of locating the domestic hot water stations close to the points of use (kitchen and bathroom). I would then place a solar-powered instantaneous water heater before each station, so depending on the buffer temperature, it can raise the temperature from 25°C (77°F) (or possibly higher) to 50–60°C (122–140°F).
In this system, I believe a very simple buffer tank can be used, without heat loops.
According to my concept, this system should have comparatively low installation costs because it is very simple and contains little complex control technology. Therefore, it should also be relatively low-maintenance. I am aware that the instantaneous water heaters will cause costs when operating without solar surplus. However, in my estimation, these costs should be balanced out because the heat pump can continuously operate efficiently within its ideal “comfort range.”
Looking ahead, there is also a plan to connect a wood stove with a water jacket to the system, which would raise the buffer temperature and reduce the workload on the instantaneous water heaters.
Open for criticism and suggestions ;-)
Stefan
D
Deliverer24 Jun 2022 16:57Havanna86 schrieb:
But not even a small storage unit to save solar energy for the evening hours? You have 10 or 15 tons of screed that can store heat. Compared to that, 100 or 200 liters (about 26 or 53 gallons) of water won’t make much difference. Especially if you want to avoid generating high temperatures.Havanna86 schrieb:
Would a hot water heat pump be the better choice then? No, you only need that if for some reason you don’t have a “proper” heat pump. All current models can easily deliver 50°C (122°F) without running at their limit or becoming too inefficient. (There’s about a 10% efficiency difference between 35°C and 50°C (95°F and 122°F) supply temperatures)Havanna86 schrieb:
Then I would still need the instantaneous water heaters ... That’s unnecessarily complicated again. Just heat the buffer tank to the desired temperature. Almost all heat pump owners do it this way. For efficiency, use a domestic hot water tank sized for one day’s use (e.g., 300 liters (79 gallons) for 4 people) and heat it only once at midday. That’s when it’s warmest and there’s the most sun on the roof. Don’t keep the default setting where the heat pump constantly reheats and has to work around 50°C (122°F) four times a day (and at night).Similar topics