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My pet peeve is when people claim that heavy old cast iron radiators are "always better" than new flimsy steel ones. Yes those are better for old houses with o

by ozim 5y ago

My pet peeve is when people claim that heavy old cast iron radiators are "always better" than new flimsy steel ones. Yes those are better for old houses with old insulation or no insulation because then you wanted radiator to keep warm so you can sit close to it and get yourself warm. Where with new thing ones you want to heat up the air so you don't want radiator to be warm but air in well insulated building.

littlestymaar 5y ago
> here with new thing ones you want to heat up the air so you don't want radiator to be warm but air in well insulated building. This is more complicated than this, and the construction industry has actually gone back and forth on this topic for the past 40 years. A few consideration against your point: - When you heat air, you dry it up, which can be pretty uncomfortable for the inhabitants. - Air stratification is a big concern: when you heat air up, it raises up to the ceiling, warming nobody but the spiders in the corners. It's not uncommon to have a multiple Celsius degree difference between floor and ceiling, even in an air-tight room. - A house cannot be air-tight because you need to bring new air for breathing, but also to avoid excess moisture in wet rooms, which means your precious warmed-up air is being vented away, and you bring cold air from outside instead. There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous. - Under standard conditions, thermal comfort comes in roughly equal part from the radiative flux (from the walls) and conduction/convection (from the air) one. So you can achieve a similar level of comfort with lower air temperature when you have a warm radiative surface in a room. At the end of the day, old cast-iron radiators are pretty good from a heating standpoint. (But they have multiple drawbacks, like being really big, and so heavy you can't move them when you want to refresh the room paint, etc. which means that nowadays, people usually prefer underfloor heating instead)
- ozim 5y ago
  Yes that is what I am describing as well - that it is more complicated. I am not saying that new steel radiators are somehow superior.
- theluketaylor 5y ago
  > There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous. Energy recovery ventilation units are not that expensive and are required by code for new construction here in Ontario as of 2017. Adds some cost to the HVAC of a new build, but not that much.
  - littlestymaar 5y ago
    > Energy recovery ventilation units are not that expensive […] Adds some cost to the HVAC of a new build, but not that much. I've recently had my (individual) house built, and it was 3-4 times more expensive than a regular system. It's not a prominent part of the entire budget for a house, but the difference still made me chose the regular one. But maybe a significant part of the price difference was just a premium for having the high-end tech, more than a real cost difference for the builder. > are required by code for new construction here in Ontario as of 2017 Interesting. Even for individual houses? Maybe that's a good idea to make it mandatory, if the premium hypothesis above turned to be true.
    - theluketaylor 5y ago
      I believe the requirement that came in earlier for large apartments and condos, but 2017 was the date for detached homes (sadly by far the most common form of development here) I’m not a super expert, but I believe HVAC here in new builds is about 20-30k, split fairly evenly between parts and install. ERVs are around 1-2k for parts and another grand or so for installation (and significantly easier when done at build time). It likely helps we have such extreme climate our HVAC costs are already quite high, so an extra $1000 here or there isn’t a big deal. Places more moderate it could easily be a much bigger percentage of the budget and come with reduced ROI. Right now over night I’m heating about 30C temperature difference and I live in one of the most mild parts of the country. Recovering energy is a big deal, as is capturing moisture to reduce load on the humidifier (evaporating water is far from free).
      - littlestymaar 5y ago

by ozim 5y ago

littlestymaar 5y ago

> here with new thing ones you want to heat up the air so you don't want radiator to be warm but air in well insulated building. This is more complicated than this, and the construction industry has actually gone back and forth on this topic for the past 40 years. A few consideration against your point: - When you heat air, you dry it up, which can be pretty uncomfortable for the inhabitants. - Air stratification is a big concern: when you heat air up, it raises up to the ceiling, warming nobody but the spiders in the corners. It's not uncommon to have a multiple Celsius degree difference between floor and ceiling, even in an air-tight room. - A house cannot be air-tight because you need to bring new air for breathing, but also to avoid excess moisture in wet rooms, which means your precious warmed-up air is being vented away, and you bring cold air from outside instead. There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous. - Under standard conditions, thermal comfort comes in roughly equal part from the radiative flux (from the walls) and conduction/convection (from the air) one. So you can achieve a similar level of comfort with lower air temperature when you have a warm radiative surface in a room. At the end of the day, old cast-iron radiators are pretty good from a heating standpoint. (But they have multiple drawbacks, like being really big, and so heavy you can't move them when you want to refresh the room paint, etc. which means that nowadays, people usually prefer underfloor heating instead)

ozim 5y ago
Yes that is what I am describing as well - that it is more complicated. I am not saying that new steel radiators are somehow superior.
theluketaylor 5y ago
> There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous. Energy recovery ventilation units are not that expensive and are required by code for new construction here in Ontario as of 2017. Adds some cost to the HVAC of a new build, but not that much.
- littlestymaar 5y ago
  > Energy recovery ventilation units are not that expensive […] Adds some cost to the HVAC of a new build, but not that much. I've recently had my (individual) house built, and it was 3-4 times more expensive than a regular system. It's not a prominent part of the entire budget for a house, but the difference still made me chose the regular one. But maybe a significant part of the price difference was just a premium for having the high-end tech, more than a real cost difference for the builder. > are required by code for new construction here in Ontario as of 2017 Interesting. Even for individual houses? Maybe that's a good idea to make it mandatory, if the premium hypothesis above turned to be true.
  - theluketaylor 5y ago
    I believe the requirement that came in earlier for large apartments and condos, but 2017 was the date for detached homes (sadly by far the most common form of development here) I’m not a super expert, but I believe HVAC here in new builds is about 20-30k, split fairly evenly between parts and install. ERVs are around 1-2k for parts and another grand or so for installation (and significantly easier when done at build time). It likely helps we have such extreme climate our HVAC costs are already quite high, so an extra $1000 here or there isn’t a big deal. Places more moderate it could easily be a much bigger percentage of the budget and come with reduced ROI. Right now over night I’m heating about 30C temperature difference and I live in one of the most mild parts of the country. Recovering energy is a big deal, as is capturing moisture to reduce load on the humidifier (evaporating water is far from free).
    - littlestymaar 5y ago