Day & Night C5H8T36*K*AAA*
ducted heat pump · ~3 ton (36,000 BTU/h cooling) · indoor unit EA*5X43M21A*
A ducted heat pump that still moves 2.4× more heat than the power it draws at 5°F.
Buy this system
Sold through HVAC contractors
This unit isn't stocked for DIY online. It's installed by a licensed pro, who also handles the refrigerant charge, permit and warranty. Get a few local quotes so you can compare the installed price.
Get install quotesAt a glance
Who it's for
Replacing a central system when you want lower running cost than resistance heat.
The standout number
COP 2.4 at 5°F — it keeps working efficiently when it's frigid.
The catch
Sold through contractors, so the installed price depends on local labor — get a few quotes.
The Verified Label — every certified spec
certified 2025-01-30
status: Active
Efficiency ratings — source: AHRI / ENERGY STAR
Capacity & the cold-climate truth — source: AHRI
Operating cost — computed by Verified HVAC Data
Heating cost
per MMBtu of delivered heat, at U.S. average electricity prices
Vs. electric resistance
cheaper to run than baseboard / strip heat ($55.19/MMBtu)
Computed from this unit's HSPF2 × EIA U.S. average electricity price. Your local price changes the answer — run it with your rates →
Refrigerant, staging & identity
How it ranks
Where this unit sits among the 12,239 heat pumps we track, on the two numbers that decide a heat pump. Percentiles are computed from our corpus (higher = better).
COP at 5°F
Better than 97%
of the 11,972 units with a published COP at 5°F
HSPF2
Better than 18%
of the 11,928 units with a published HSPF2
Rebates & incentives
This unit is ENERGY STAR certified, which many utility rebates ask for. The federal 25C tax credit expired on December 31, 2025; the live money now is state and utility programs plus HEEHRA. Check what applies where you live on our rebates page.
Compare similar heat pumps
Frequently asked questions
Does the Day & Night C5H8T36*K*AAA* still heat in cold weather?
At 5°F it runs at a COP of 2.4, meaning it delivers 2.4 units of heat for every unit of electricity it uses. Its certified heating output at 5°F is 19,100 BTU per hour. It is not on the ENERGY STAR Cold Climate list, so check sizing for very cold weather.
What does the Day & Night C5H8T36*K*AAA* cost to run?
About $22.15 per MMBtu of delivered heat at the U.S. average electricity price, roughly 60% less than electric resistance heat. Your local electricity price changes the number — use our operating-cost calculator to run it with your rate.
What refrigerant does the Day & Night C5H8T36*K*AAA* use?
R-454B, which has a global-warming potential (GWP) of about 466. This is one of the lower-GWP refrigerants replacing R-410A.
Where can I buy the Day & Night C5H8T36*K*AAA*?
Day & Night sells this line through HVAC contractors rather than DIY retail, so the way to buy it is to get installed quotes from local pros. Compare the installed price, not just the equipment price.
Sources. Performance ratings from the AHRI Directory (cited by reference number 216358219; not a verbatim mirror) and ENERGY STAR certification data. Operating-cost ($/MMBtu), savings and percentile figures are computed by Verified HVAC Data from published ratings and EIA U.S. average energy prices — see our methodology. Refrigerant GWP is the IPCC value for that refrigerant. We publish no star ratings and take no payment for placement. "Not published" means the source registry doesn't disclose it — we never fill a spec with a guess.
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