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Does it explain somewhere that I missed how the different size units translate to sq. ft.? I would think that would be a great way to convey which size might wo

Does it explain somewhere that I missed how the different size units translate to sq. ft.? I would think that would be a great way to convey which size might work for people, but I might be missing some other factor that doesn't allow for that conversion?

heatpumpfan 4y ago
Sizing heat pumps by the sq. ft. is hairy reasoning. Load calculations take into account climate zone, insulation, building materials, orientation, ceiling height, etc. Any recommendation based on 2D area is sketchy. For replacement of existing professionally installed systems, going by the capacity of the installed unit is a better shortcut.
- simplyaccont 4y ago
  There is actually good reason to bump up capacity by half a ton to ton, unless currently installed unit was sized recently. The reason for this it's that design temperatures jumped up, sometime in a big way in a recent ashray published design conditions (and many companies don't even know that this is the case and use those from 10 years ago or more). And even the published numbers tend to be off and they usually use one specific weather station in a region that may or may not have same weather as you. When I replaced hvac a couple of years ago, I retained company to make manual j calcuation as none of hvac contractors were willing to do it. I provided it with design temperatures that I calculated after scrapping data from a bunch of private weather stations in few miles radius
cmui 4y ago
In the process of building out a tool that allows you to do just that on the website. You need some basic info about the home + a recent energy bill to do this. You can also go more bottoms up where you have all the geometric/thermal + air leakage properties of the home and the local weather, this is more involved.
- obituary_latte 4y ago
  Ah, very cool (LOL). Even if it's not totally accurate, getting a ballpark sense of what the costs might be would be huge. Thanks!
simplyaccont 4y ago
it doesn't translate. there is a thing called "manual j" calculation, that take into consideration size of house, orientation, insulation, number of rooms. windows in each room, type of windows, appliances, a bunch of other parameters and then how many people live in house. topped of with required temperature inside during winter/summer and outside temperature during winter/summer. after this you get unit sizing

heatpumpfan 4y ago

Sizing heat pumps by the sq. ft. is hairy reasoning. Load calculations take into account climate zone, insulation, building materials, orientation, ceiling height, etc. Any recommendation based on 2D area is sketchy. For replacement of existing professionally installed systems, going by the capacity of the installed unit is a better shortcut.

simplyaccont 4y ago
There is actually good reason to bump up capacity by half a ton to ton, unless currently installed unit was sized recently. The reason for this it's that design temperatures jumped up, sometime in a big way in a recent ashray published design conditions (and many companies don't even know that this is the case and use those from 10 years ago or more). And even the published numbers tend to be off and they usually use one specific weather station in a region that may or may not have same weather as you. When I replaced hvac a couple of years ago, I retained company to make manual j calcuation as none of hvac contractors were willing to do it. I provided it with design temperatures that I calculated after scrapping data from a bunch of private weather stations in few miles radius

cmui 4y ago

In the process of building out a tool that allows you to do just that on the website. You need some basic info about the home + a recent energy bill to do this. You can also go more bottoms up where you have all the geometric/thermal + air leakage properties of the home and the local weather, this is more involved.

obituary_latte 4y ago
Ah, very cool (LOL). Even if it's not totally accurate, getting a ballpark sense of what the costs might be would be huge. Thanks!

simplyaccont 4y ago

it doesn't translate. there is a thing called "manual j" calculation, that take into consideration size of house, orientation, insulation, number of rooms. windows in each room, type of windows, appliances, a bunch of other parameters and then how many people live in house. topped of with required temperature inside during winter/summer and outside temperature during winter/summer. after this you get unit sizing