It’s sometimes easier to just call it efficiency, but like you say, once you go into the nitty gritty it falls apart.
It depends. It’s certainly economically and CO2 efficient. Thermodynamically? That’s something for physicists and engineers to worry about, not J. Random Bloke.
leave your old furnace in as backup
I’ve seen plenty of old houses over here in Germany which did have a gas furnance that was somehow under-dimensioned – the idea is that in the real cold days you’d still have the good ole fireplace (or coal oven), as well as not so old houses which still have one because sitting in front of it.
Gets a wee bit more complicated with heat pumps and maximising the efficiency of everything as the fireplace needs to be hooked up to the heat exchanger or there won’t be any hot water and modern units are closed and look rather different, but you still get a window and plenty of infrared radiation.
Then, last but not least, there’s insulation. Especially up in the arctic you should be doing your darnedest to build passive houses. Certainly possible in Kiruna, I’ve heard that the Norwegians are trying on Svalbard.
gas furnance that was somehow under-dimensioned – the idea is that in the real cold days you’d still have the good ole fireplace
Oddly enough I’ve never encountered that in Germany, I only ever see catastrophically oversized furnaces that start cycling in March… Seems to me plumbers never really worry too much about correct dimensioning, they just put the same 20 kW furnace that they know and love to install in every apartment and single family home. For some it will be somewhat adequate, for some it’ll be oversized, who cares, customers never complain when the furnace cycles, but when it’s too cold, you’ve got a problem. Same as they’re never too worried about finding suitable supply water temps. Just set it to 80 and you’re good, it’s the customer who pays horrendous gas bills, not you lmao. That’s also why everyone thinks their Altbau has to have 80°+ supply water when they have never really tried anything lower to see if it maybe suffices. My parents had their oil-furnace on 80C supply for the past 40 years and last winter when everybody was trying to save as much energy as possible they figured out you can set it to 55 as well.
It depends. It’s certainly economically and CO2 efficient. Thermodynamically? That’s something for physicists and engineers to worry about, not J. Random Bloke.
I’ve seen plenty of old houses over here in Germany which did have a gas furnance that was somehow under-dimensioned – the idea is that in the real cold days you’d still have the good ole fireplace (or coal oven), as well as not so old houses which still have one because sitting in front of it.
Gets a wee bit more complicated with heat pumps and maximising the efficiency of everything as the fireplace needs to be hooked up to the heat exchanger or there won’t be any hot water and modern units are closed and look rather different, but you still get a window and plenty of infrared radiation.
Then, last but not least, there’s insulation. Especially up in the arctic you should be doing your darnedest to build passive houses. Certainly possible in Kiruna, I’ve heard that the Norwegians are trying on Svalbard.
Oddly enough I’ve never encountered that in Germany, I only ever see catastrophically oversized furnaces that start cycling in March… Seems to me plumbers never really worry too much about correct dimensioning, they just put the same 20 kW furnace that they know and love to install in every apartment and single family home. For some it will be somewhat adequate, for some it’ll be oversized, who cares, customers never complain when the furnace cycles, but when it’s too cold, you’ve got a problem. Same as they’re never too worried about finding suitable supply water temps. Just set it to 80 and you’re good, it’s the customer who pays horrendous gas bills, not you lmao. That’s also why everyone thinks their Altbau has to have 80°+ supply water when they have never really tried anything lower to see if it maybe suffices. My parents had their oil-furnace on 80C supply for the past 40 years and last winter when everybody was trying to save as much energy as possible they figured out you can set it to 55 as well.