3 ms·

Retrofitting is going to be much more than the cost of the unit itself though. You can't just replace an on-demand gas boiler with a heat pump. The rest of the

by fy20 5y ago

Retrofitting is going to be much more than the cost of the unit itself though. You can't just replace an on-demand gas boiler with a heat pump. The rest of the heating system is completely different between the two, it just wouldn't work. It's especially problematic in apartments where there is limited space.

alkonaut 5y ago
But we (Nordics) replaced all our oil pans. I naively thought it was the same thing just oil instead? A boiler makes hot water in a tank in the basement and showers, radiators and taps use that hot water? I have seen (In Scotland) some extremely weird contraptions where water was heated in the shower by what I can only assume was an flame in a box on the wall. But surely that’s not what Germans and others on the continent are using? They do have a central hot water system? How else is water coming to the radiators? I guess my question is: are there gas lines around a typical home to any other place than the boiler and possibly stove? Why?
- fy20 5y ago
  The main issue is that a heat pump takes a lot longer to heat up water on demand than a gas boiler. A gas boiler as used in the UK typically has a heat output of 25 to 50kW. Where as a heat pump for the same sized home can produce maybe 8kW of heat - given the right outside weather conditions. The gas boiler can directly heat up cold water and provide sufficient flow for a hot shower, but the heat pump cannot. Because of this you need to buffer the heat in a hot water tank, usually something that's a few hundred litres, and heat it up over time. I believe boilers using heating oil work somewhat sim In the UK houses heated with gas usually don't have a hot water tank, or even anywhere to put it. You can get all-in-one heat pump units that are the size of a large fridge which have a built in tank, but I've lived in places where there wouldn't even be space for that. The boxes in the showers used in the UK are electric. They work pretty well (esp. considering most homes in the UK are single phase), but I am always concerned by the fact that an electric wire carrying 30kW of power is running right next to running water :-) Other than a gas boiler older homes may have a gas fireplace, but they are not so popular now. There's also issues of the flow temperature for the heating system. Traditional central heating usually has a temperature of 70-80C, where as underfloor heating systems using a heat pump usually have a max of 35C. With a heat pump the efficiency drops with the temperature delta, so they are optimised to produce lower temperature water. But traditional radiators work better with higher temperatures.
  - alkonaut 5y ago
    Yes by heat pump I mean one of those fridge size things. They include hot water tanks. I have one of those and it’s around €4-5000 eur so within the grant money from a scrapped oil burner. Mine produces both 50deg water for radiators and 35deg for underfloor via an electronic shunt (about €500 extra) because I have underfloor heating on one floor and radiators on the upper floor. It also connected directly to 4 pipes hot/cold tap and hot/cold radiator water making an easy swap. Are you saying the space requirement of 60x60x180cm would really be the problem?

by fy20 5y ago

alkonaut 5y ago

But we (Nordics) replaced all our oil pans. I naively thought it was the same thing just oil instead? A boiler makes hot water in a tank in the basement and showers, radiators and taps use that hot water? I have seen (In Scotland) some extremely weird contraptions where water was heated in the shower by what I can only assume was an flame in a box on the wall. But surely that’s not what Germans and others on the continent are using? They do have a central hot water system? How else is water coming to the radiators? I guess my question is: are there gas lines around a typical home to any other place than the boiler and possibly stove? Why?

fy20 5y ago
The main issue is that a heat pump takes a lot longer to heat up water on demand than a gas boiler. A gas boiler as used in the UK typically has a heat output of 25 to 50kW. Where as a heat pump for the same sized home can produce maybe 8kW of heat - given the right outside weather conditions. The gas boiler can directly heat up cold water and provide sufficient flow for a hot shower, but the heat pump cannot. Because of this you need to buffer the heat in a hot water tank, usually something that's a few hundred litres, and heat it up over time. I believe boilers using heating oil work somewhat sim In the UK houses heated with gas usually don't have a hot water tank, or even anywhere to put it. You can get all-in-one heat pump units that are the size of a large fridge which have a built in tank, but I've lived in places where there wouldn't even be space for that. The boxes in the showers used in the UK are electric. They work pretty well (esp. considering most homes in the UK are single phase), but I am always concerned by the fact that an electric wire carrying 30kW of power is running right next to running water :-) Other than a gas boiler older homes may have a gas fireplace, but they are not so popular now. There's also issues of the flow temperature for the heating system. Traditional central heating usually has a temperature of 70-80C, where as underfloor heating systems using a heat pump usually have a max of 35C. With a heat pump the efficiency drops with the temperature delta, so they are optimised to produce lower temperature water. But traditional radiators work better with higher temperatures.
- alkonaut 5y ago
  Yes by heat pump I mean one of those fridge size things. They include hot water tanks. I have one of those and it’s around €4-5000 eur so within the grant money from a scrapped oil burner. Mine produces both 50deg water for radiators and 35deg for underfloor via an electronic shunt (about €500 extra) because I have underfloor heating on one floor and radiators on the upper floor. It also connected directly to 4 pipes hot/cold tap and hot/cold radiator water making an easy swap. Are you saying the space requirement of 60x60x180cm would really be the problem?