4 ms·

But both of those situations are not normal. He did not ask if it was possible for an AC to run for 22 hours a day. He asked it was normal. If someone asked if

by cglace 8y ago

But both of those situations are not normal. He did not ask if it was possible for an AC to run for 22 hours a day. He asked it was normal. If someone asked if it was normal for a page to take 10 mins to load I would say no. However, I would then list circumstances where that would make sense.

Waterluvian 8y ago
Right. I'm not discarding the value of the details. But right now I just want to know, "does it seem like I might have a problem?" As a non expert I wouldn't have been surprised if someone said, "yeah it's pretty common for furnaces to run non stop in cold winters. That's their design."
- dsfyu404ed 8y ago
  >As a non expert I wouldn't have been surprised if someone said, "yeah it's pretty common for furnaces to run non stop in cold winters. That's their design." This was not uncommon in rich (big houses) older (built up before WW2) towns in MA because the houses are big and old and state law regarding who can perform plumbing/electrical/hvac work greatly drive up costs and are a massive incentive to always minimum amount of work possible so tons of people would have poorly insulated houses with smaller than ideal heating systems. For the coldest days in the winter many people's furnaces would run all day to keep the house warm (whereas poor people just turn down the heat). This has changed recently because the state is pumping a ton of money into incentives for people to make their homes energy efficient now basically every old house has had insulation blown in everywhere because with state subsidies the cost to do so is now justifiable in the overwhelming majority of use cases.
- thaeli 8y ago
  And if you were asking about air conditioning in the summer, that would be the answer. Moderately "oversizing" a furnace vs. the heat loss calcs doesn't cause major problems; for air conditioning it does, with an oversized unit you don't get adequate humidity control. But for furnaces, to get noticeable negative effects you have to MASSIVELY oversize. The upshot of this (and other factors such as needing to upsize the furnace to get enough air handler capacity for the cooling load in summer) is that no, if your furnace is firing almost constantly all winter, something is probably wrong. That "wrong" is likely to be "the furnace itself is working fine, but you don't have enough insulation and your windows are super drafty", but for purposes of the basic "is this normal".. no. It's not, given common North American residential HVAC practice. Certainly worth further investigation. Importantly in this case, the outside temperature at which your heat or AC runs constantly is the maximum where your house will maintain temperature. So, because of the different tradeoffs of oversizing heat vs AC, normal practice is to put in enough AC for a typical summer (and just let the house get a little warmer during a heat wave) so that dehumidification remains optimal, and to put in enough heating for a worst-case cold snap because, well, it doesn't hurt much and people REALLY complain when their house gets cold in the winter.
dsfyu404ed 8y ago
The edge cases in which it is "normal" are frequent enough that "it depends" becomes a better answer than "no"

by cglace 8y ago

Waterluvian 8y ago

Right. I'm not discarding the value of the details. But right now I just want to know, "does it seem like I might have a problem?" As a non expert I wouldn't have been surprised if someone said, "yeah it's pretty common for furnaces to run non stop in cold winters. That's their design."

dsfyu404ed 8y ago
>As a non expert I wouldn't have been surprised if someone said, "yeah it's pretty common for furnaces to run non stop in cold winters. That's their design." This was not uncommon in rich (big houses) older (built up before WW2) towns in MA because the houses are big and old and state law regarding who can perform plumbing/electrical/hvac work greatly drive up costs and are a massive incentive to always minimum amount of work possible so tons of people would have poorly insulated houses with smaller than ideal heating systems. For the coldest days in the winter many people's furnaces would run all day to keep the house warm (whereas poor people just turn down the heat). This has changed recently because the state is pumping a ton of money into incentives for people to make their homes energy efficient now basically every old house has had insulation blown in everywhere because with state subsidies the cost to do so is now justifiable in the overwhelming majority of use cases.
thaeli 8y ago
And if you were asking about air conditioning in the summer, that would be the answer. Moderately "oversizing" a furnace vs. the heat loss calcs doesn't cause major problems; for air conditioning it does, with an oversized unit you don't get adequate humidity control. But for furnaces, to get noticeable negative effects you have to MASSIVELY oversize. The upshot of this (and other factors such as needing to upsize the furnace to get enough air handler capacity for the cooling load in summer) is that no, if your furnace is firing almost constantly all winter, something is probably wrong. That "wrong" is likely to be "the furnace itself is working fine, but you don't have enough insulation and your windows are super drafty", but for purposes of the basic "is this normal".. no. It's not, given common North American residential HVAC practice. Certainly worth further investigation. Importantly in this case, the outside temperature at which your heat or AC runs constantly is the maximum where your house will maintain temperature. So, because of the different tradeoffs of oversizing heat vs AC, normal practice is to put in enough AC for a typical summer (and just let the house get a little warmer during a heat wave) so that dehumidification remains optimal, and to put in enough heating for a worst-case cold snap because, well, it doesn't hurt much and people REALLY complain when their house gets cold in the winter.

dsfyu404ed 8y ago

The edge cases in which it is "normal" are frequent enough that "it depends" becomes a better answer than "no"