ᐅ Interaction between Air-to-Water Heat Pump and Gas Condensing Boiler?
Created on: 19 Dec 2021 09:24
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Forsberg21
Hello,
I recently purchased a newly built condominium (KfW-55 standard) that is equipped with an air-to-water heat pump. During the construction phase, the developer informed me that the HVAC system was supplemented with an additional gas condensing boiler to handle high peak energy demands.
Would it have been possible to heat the domestic hot water for showers, kitchen, and sinks using only the air-to-water heat pump? I understand that a supply temperature of about 35°C (95°F) is sufficient for underfloor heating, but what about the rest? What other alternatives could have been installed alongside the air-to-water heat pump?
I’m asking because air-to-water heat pumps are commonly installed in Germany at the moment, and as far as I know, a separate energy source is needed for hot water; otherwise, the electricity costs for operating the heat pump increase significantly. Gas is becoming more expensive and will probably be increasingly subject to a CO2 tax in the future.
Best regards,
Robert
I recently purchased a newly built condominium (KfW-55 standard) that is equipped with an air-to-water heat pump. During the construction phase, the developer informed me that the HVAC system was supplemented with an additional gas condensing boiler to handle high peak energy demands.
Would it have been possible to heat the domestic hot water for showers, kitchen, and sinks using only the air-to-water heat pump? I understand that a supply temperature of about 35°C (95°F) is sufficient for underfloor heating, but what about the rest? What other alternatives could have been installed alongside the air-to-water heat pump?
I’m asking because air-to-water heat pumps are commonly installed in Germany at the moment, and as far as I know, a separate energy source is needed for hot water; otherwise, the electricity costs for operating the heat pump increase significantly. Gas is becoming more expensive and will probably be increasingly subject to a CO2 tax in the future.
Best regards,
Robert
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Benutzer20020 Dec 2021 13:12Deliverer schrieb:
Hmm. Fancy. I’m curious about the technical background. I personally know five heat pumps from different years – three of them don’t even have a heating element, yet they still defrost.
May I ask which model it is?You’ll have to ask Panasonic. It’s a monoblock – but typical Panasonic.F
Forsberg2120 Dec 2021 18:57Benutzer200 schrieb:
Setting the flow temperature to 60 degrees Celsius (140°F) in single-family homes is rarely done. Most heat pumps can reach up to 60 degrees Celsius (140°F) without needing an electric heating element.
If a heat pump requires the electric heater at an outdoor temperature of -10 degrees Celsius (14°F), then there was likely a planning issue. Normally, you can just turn off the electric heater (except in exposed locations like upland areas)—that’s what I do myself (it only activates during defrost cycles).
The heat pumps capable of this are standard, off-the-shelf units. You don’t need high-tech equipment for that. My €3,000 heat pump manages this easily (60 degrees Celsius (140°F) flow temperature and -20 degrees Celsius (-4°F) outdoor temperature without electric backup).I still don’t quite understand. Running a heat pump with a 60 degrees Celsius (140°F) flow temperature isn’t energy-efficient, is it?
I also own a small multi-family building (2 large apartments built in 1972 and 3 apartments built in 2004). It currently has an oil heating system from 2004, which I want to replace. There is no underfloor heating anywhere, only relatively large panel radiators. Would a heat pump be suitable here? If so, what kind of supplementary heating might be needed? The hot water tank was replaced this year for €3,000. Would I need to replace that as well for a heat pump? Sorry for my basic questions.
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Deliverer20 Dec 2021 19:15Forsberg21 schrieb:
If you operate the heat pump with a 60 degrees Celsius (140°F) supply temperature, isn’t that an energy disaster?Disaster is a strong word... It does require a bit of electricity, but lacking better alternatives, the pump has to manage. In terms of efficiency and CO2 emissions, everything else that heats water is far worse by comparison.Forsberg21 schrieb:
The apartment building has 25 units, and the gas condensing boiler is intended to be used only during really cold outdoor temperatures and in the morning when maybe everyone wants to take a hot shower at the same time.
But how does a heat pump manage to keep the water permanently at 60°C (140°F)? I still don’t understand that. That would require significantly more electricity, and the main advantage of the heat pump would disappear.Then that is a very good solution. Bivalent systems are also available for older buildings.
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Deliverer20 Dec 2021 20:02... where they are not advisable.
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Benutzer20020 Dec 2021 21:11Forsberg21 schrieb:
I still don’t understand. If you operate the heat pump with a 60-degree Celsius (140°F) supply temperature, wouldn’t that be an energy disaster?Yep. But nobody actually does that. You only need 60°C (140°F) for domestic hot water preparation, not for continuous heating. As I said, that usually costs you about 30 to 50 cents per day in a single-family home. So, just a minor disaster. For heating, the supply temperature is mostly around 30°C (86°F) during cold weather.Similar topics