Replies

1. 
   Walter Ahlgrim|Jun 14, 2020 07:14pm|#1

   Given you cold temps you should consider one of the units that compress part of the gas twice this allows them to operate at colder temp without much reduction in output.

   I think most manufactures have models with this technology marketed under different trade names.

   Mitsubishi call it” Hyper Heat”
   https://www.mitsubishicomfort.com/benefits/hyper-heating

   Fujitsus calls it xltH
   https://www.fujitsugeneral.com/us/residential/technology/xlth-low-temp-heating.html

   Walta

2. 
   Kye Ford|Jun 14, 2020 07:53pm|#2

   Thanks Walta I was planning on using the cold temp units from Fujitsu. I have one in my house now and have been real happy with the performance, but I am still not sure how to size the units as the max. heating capacity starts to fall off below 20F.

3. Expert Member
   Akos|Jun 14, 2020 09:38pm|#3

   You can search through here:

   https://ashp.neep.org/

   They provide specs down to 5F for the units, any of the ones have good maintenance capacity between 47F and 5F will typically deliver 90% of rated down to 0F. Most cold climate units are rated down to -15F but will deliver heat at reduced cacpity even bellow that.

   Once you find a unit you like, you'll have to do a bit of digging for the engineering manual for it on the company's site. This will have tables for capacity vs temperature (ie:https://nonul.mylinkdrive.com/files/M-Series_Engineering_Manual.pdf)

4. 
   Kye Ford|Jun 17, 2020 09:32am|#4

   Thanks Akos, so I checked ASHP and found a Fujitsu AOU30RLXFWH with a rated capacity of 32,000 BTU/h at -15F delivers max but of 22860. My design temp is -7F so I am figuring at this temp my heating capacity would be around 26,000 BTU/hr.