and here comes the next question^^
We currently have a setup with a 180 L (48 gallons) hot water tank. What are your experiences— is this size sufficient, or is a larger one recommended?
Background information:
Ground source heat pump Nibe Fighter 1245 with the 180 L (48 gallons) tank
Currently a household of 2 people (but it may grow in a few years^^)
Mainly showering habits, but there is also a large spacious bathtub
(either 200 L (53 gallons) or maybe even one with 350 L (92 gallons), although I understand that I can’t fill it completely hot with a 180 L (48 gallons) tank ^^)
What do you think about Nibe?
Best regards
We currently have a setup with a 180 L (48 gallons) hot water tank. What are your experiences— is this size sufficient, or is a larger one recommended?
Background information:
Ground source heat pump Nibe Fighter 1245 with the 180 L (48 gallons) tank
Currently a household of 2 people (but it may grow in a few years^^)
Mainly showering habits, but there is also a large spacious bathtub
(either 200 L (53 gallons) or maybe even one with 350 L (92 gallons), although I understand that I can’t fill it completely hot with a 180 L (48 gallons) tank ^^)
What do you think about Nibe?
Best regards
A heat pump cannot produce 62 degrees Celsius (143.6°F) without generating a high electricity consumption, unless you live in Dubai.
Heat pumps usually operate with a flow temperature of 30-35 degrees Celsius (86-95°F). At this range, heat pumps have a good efficiency. If you want 60 degrees Celsius (140°F), the electricity consumption unfortunately increases not linearly, but exponentially. This means your heat pump becomes uneconomical.
Heat pumps usually operate with a flow temperature of 30-35 degrees Celsius (86-95°F). At this range, heat pumps have a good efficiency. If you want 60 degrees Celsius (140°F), the electricity consumption unfortunately increases not linearly, but exponentially. This means your heat pump becomes uneconomical.
Der Da schrieb:
A heat pump cannot produce 62 degrees without generating high electricity consumption, unless you live in Dubai Correct! Der Da schrieb:
...Heat pumps generally operate with a flow temperature of 30-35 degrees. This is where heat pumps have good efficiency. If you want 60 degrees, the electricity consumption unfortunately increases not linearly, but exponentially. That means your heat pump becomes uneconomical. That’s correct, although the flow temperatures for domestic hot water are somewhat higher (50...55°C (122...131°F)). That’s why properly designed hot water storage tanks for heat pump systems look quite different (volume, heat exchanger surface) compared to, for example, gas condensing boilers! Combination systems mostly fail here! In my designs, I usually rely on external, “heat pump-friendly” suppliers for this! Best regards.
Der Da schrieb:
A heat pump cannot produce 62 degrees without generating high electricity consumption, unless you live in Dubai No one is saying that.
Der Da schrieb:
Heat pumps usually operate with a supply temperature of 30-35 degrees. At this range, heat pumps have a good efficiency. If you want 60 degrees, the electricity consumption unfortunately increases not linearly, but exponentially. That means your heat pump becomes uneconomical. We are talking about water for the shower here, right? Because I definitely won’t shower at 30°C (86°F). I need 40°C (104°F). That has nothing to do with the underfloor heating, which I understand will have a supply temperature around 30°C (86°F).
Hi,
this discussion is about sizing the heat pump and its efficient operating range.
The primary role of the heat pump is space heating. It can do this cost-effectively with low supply temperatures, which is what it is designed for.
The secondary role is domestic hot water production. This requires higher temperatures, which creates less favorable conditions for the heat pump. As a result, heat pump storage tanks are usually heated only to a temperature that balances comfort and cost. Temperatures of 62°C (144°F) and above are well beyond what constitutes a reasonable compromise. Such temperatures often can only be achieved using an electric heating element. If the heat pump does manage it directly, it does so with such poor efficiency that the electricity costs become disproportionately high compared to the delivered performance.
In that case, the higher upfront investment for a heat pump compared to, for example, a gas condensing boiler would not pay off, which is already quite challenging in practice.
It is better to have a larger storage tank optimized for this type of use at lower temperatures than a standard tank operating at higher temperatures.
this discussion is about sizing the heat pump and its efficient operating range.
The primary role of the heat pump is space heating. It can do this cost-effectively with low supply temperatures, which is what it is designed for.
The secondary role is domestic hot water production. This requires higher temperatures, which creates less favorable conditions for the heat pump. As a result, heat pump storage tanks are usually heated only to a temperature that balances comfort and cost. Temperatures of 62°C (144°F) and above are well beyond what constitutes a reasonable compromise. Such temperatures often can only be achieved using an electric heating element. If the heat pump does manage it directly, it does so with such poor efficiency that the electricity costs become disproportionately high compared to the delivered performance.
In that case, the higher upfront investment for a heat pump compared to, for example, a gas condensing boiler would not pay off, which is already quite challenging in practice.
It is better to have a larger storage tank optimized for this type of use at lower temperatures than a standard tank operating at higher temperatures.
P
perlenmann29 Sep 2013 10:20Sorry, Explosiv:
You don’t really have much experience yet, do you?!
The hot water storage tank (I would call this a user requirement) isn’t simply made bigger just because you have a heat pump.
And the hot water consumption of a heat pump is insignificant compared to the heating demand (unless you take a daily whirlpool bath).
The ground source heat pump easily reaches temperatures of 70°C (158°F) WITHOUT an electric heating element.
How do I know this? Because I have one, perform weekly legionella protection, and can compare the summer/winter months on the display.
You don’t really have much experience yet, do you?!
The hot water storage tank (I would call this a user requirement) isn’t simply made bigger just because you have a heat pump.
And the hot water consumption of a heat pump is insignificant compared to the heating demand (unless you take a daily whirlpool bath).
The ground source heat pump easily reaches temperatures of 70°C (158°F) WITHOUT an electric heating element.
How do I know this? Because I have one, perform weekly legionella protection, and can compare the summer/winter months on the display.
Perhaps it should be mentioned that the Vaillant heating system is a complete solution. It is called the geoTHERM heat pump system. As far as I understand, it is a combined unit that generates low-temperature heating water while also integrating a 175L (46 gallons) hot water storage tank, which can be heated up to a maximum of 62°C (144°F) using a 6kW electric heating element. The latter, however, does not make much sense if 175L is sufficient. In that case, around 44°C (111°F) or similar would probably be enough. The question is, how far can you get with 175L of hot water, and how fast is the heating element?
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