Author Topic: Furnace sizing Daikin  (Read 871 times)

Offline BenBear

  • ***
  • Posts: 7
Furnace sizing Daikin
« on: January 02, 2019, 04:25:48 PM »
New to forum. Currently have two 17 yr old Lennox gas furnaces mid efficency in 2200 sq ft 1973 home...70 btu and 90 btu. Two separate Lennox HVAC shops in and each stated should go down to 45 and 70 btu.
Question..looking at the Daikin DM97DC. Only issue is minimum BTU is 60. What should I do?
Thanks

Offline Admin

  • Administrator
  • *****
  • Posts: 2356
    • HVAC TECH GROUP
Re: Furnace sizing Daikin
« Reply #1 on: January 02, 2019, 05:41:04 PM »
That seems like alot of BTU’s for a 2200 sq ft house.  Where do you live and what is the approximate sq ft each furnace heats?

I think you mean Daikin DM97MC or DC97MC.  You could just lock the 60,000 in low fire and it will run at around 30,000 BTU’s.  Or go with the 80,000 BTU model and low fire would be around 40,000 BTU’s.

Are there AC’s installed on both furnaces?  You will want to make sure the new furnaces have enough airflow for the existing AC’s.  That 90,000 may have an AC larger than 3 ton in which case you have to be careful the new furnace can support an AC larger than 3 ton.

Offline BenBear

  • ***
  • Posts: 7
Re: Furnace sizing Daikin
« Reply #2 on: January 02, 2019, 08:13:46 PM »
Not sure what you mean by “furnace heats”

The here is a Lennox 1.5 ton AC on each furnace...July 2017. We should be OK? Very good observation.

The house is a split/two storey. 560 sq ft upstairs . 1160 sq ft main.
Small furnace feeds upstairs 560 and 110 sq ft office main..total 670 sq ft.
The large furnace feeds main(1160-110) 1050 plus basement 1200 ...insulated R12.
Calgary House built 1973, original windows, added insulation attic, home in good condition.

I’m going to get at least two more quotes so will get comfortable with sizing...but any observations/recommendations are appreciated. Looking for independent , unbiased approaches.
Thanks for the help.