Home / Comparisons / Guides by equipment type
Air-to-water or air-to-air heat pump: heating water, or heating air
Both draw heat from the outdoor air. An air-to-air unit blows it into the house, through indoor units or ducts. An air-to-water unit hands it to water, which then circulates through a radiant floor, radiators or fan coils. To make the difference concrete, this guide follows two MIDEA units of similar size, sold by AirGreen, with what their documents publish.
M Thermal Arctic · 16 kW
MHA-V16WD2MN8-B2 / HB-A160CMDM30GN8-B2 · manufacturer sheet (no AHRI certificate)
View the product page
EVOX G3 · 5 tons
MAUSE-H60B-2A / MO1HE-H60B-2A · AHRI 215471345
View the product pageWhat 1 kWh of electricity delivers, depending on the water temperature
On our other pages, a season’s cost is calculated with the HSPF2 and SEER2 from the AHRI certificate. Those ratings belong to air-to-air heat pumps: the MIDEA M Thermal Arctic has none, so the same method does not apply to it. Here is what MIDEA publishes instead: the heat produced per 1 kWh of electricity, depending on the outdoor air and the water sent into the system, and what that means in dollars at one test point.
Each square = 0.1 kWh of heat obtained per 1 kWh of electricity.
100 kWh of heat, in dollars
At Hydro-Québec’s Rate D average price, 9.104¢ per kWh, taxes included; one coin = $1.
How this amount is calculated
- Electricity for 100 kWh of heat. 100 ÷ COP. The COP is the one MIDEA publishes in the M Thermal Arctic brochure (HA-SA202503V4), for the 16 kW model, at the chosen air and water temperature. For electric baseboards: 100 kWh.
- Price. Hydro-Québec Rate D average price in effect April 1, 2026, 9.104¢ per kWh, multiplied by 1.14975 for GST and QST. The system access charge is not counted.
- What this calculation is not. One test point is not a season: the air and water temperatures change all winter, and electric backup may kick in. This amount helps read the COP in dollars; it does not predict a bill.
AirGreen method, November 9, 2026. The real bill depends on the house, the insulation, the water system, the settings and the use; this amount is not a promise.
One house, cut in two: water on one side, air on the other
On the left, the air-to-water heat pump heats the water of a radiant floor and a radiator. On the right, the air-to-air heat pump pushes air through ducts. Switch to cooling: both reverse their cycle, but cold water needs a system that can distribute it.
On a small screen, swipe the drawing sideways.
- The outdoor unit (photo): 1,118 × 865 × 523 mm, 97 kg, single fan.
- The hydronic module (photo), wall-mounted: 420 × 790 × 270 mm, 40 kg; plate heat exchanger, pump, 5 L expansion tank.
- The refrigerant only goes as far as the module: R-32, 3/8 and 5/8 in lines.
- The water flows from the module to the radiant floor and the radiator: adjustable from 25 to 65 °C in heating, 5 to 25 °C in cooling.
- Two zones of water possible, plus domestic hot water with a tank (20 to 60 °C).
- The outdoor unit (diagram): 37 1/2 × 52 1/2 × 16 3/8 in, 243 lb, per the submittal sheet.
- The air handler (diagram): 21 1/2 × 21 1/2 × 60 1/8 in, 188 lb.
- The refrigerant goes as far as the air handler coil: R-454B, 3/8 and 3/4 in lines.
- The air is blown into the ducts: up to 1,801 CFM at turbo speed.
- Electric backup of up to 25 kW can be added in the air handler as an option.
All four units are to the same scale, that of the 1 m bar. Photos: MIDEA M Thermal Arctic units from the AirGreen product page. On the air-to-air side, the units are drawn as diagrams at their published dimensions; the EVOX G3 photo is in the card at the top. The house itself is not to scale.
Your water system decides almost everything
Natural Resources Canada describes air-to-water as less common in Canada, and a better match for water under 45 to 50 °C: radiant floors, fan coils, low-temperature radiators. High-temperature radiators that need more than 60 °C may exceed what most residential heat pumps produce. Choose your system to see where it falls, next to the range MIDEA publishes.
Below −15 °C: what each sheet publishes
MIDEA’s air-to-water sheet gives a last point at −15 °C, with water at 43.3 °C. NEEP certifies the air-to-air unit at −15 °C and then at −30 °C, with indoor air at 21.1 °C. The two units do not have the same rated capacity (about 54,600 and 55,000 BTU/h according to their documents) or the same test method: read each column on its own.
What MIDEA states for each, line by line
The features come from the air-to-water brochure and the air-to-air submittal sheet. They describe what each unit can do; they do not all compare, since one heats water and the other heats air.
Air-to-water: 8 heating curves, 8 cooling curves and one custom curve; the water temperature follows the outdoor temperature.
Air-to-air: constant airflow up to 1.0 in w.c., adaptive control.
Air-to-water: hot water from 20 to 60 °C with a tank; 60 °C only with the tank’s backup element; disinfection cycle and fast DHW function.
Air-to-air: not applicable, the unit heats air.
Air-to-water: two water zones (zone 2 pump and valve).
Air-to-air: one zone per unit, set by a thermostat.
Air-to-water: 3 kW element in the module, optional.
Air-to-air: backup kit up to 25 kW, optional.
Air-to-water: two levels; minimum outdoor-unit sound pressure of 45 dB(A).
Air-to-air: “quiet” indoor-unit speed, 37 dB(A).
Air-to-water: multifunction wired control and app; power-input limiting.
Air-to-air: two-way wired control with Wi-Fi (120N, X6W), remote or 24 V thermostat.
Air-to-water: not stated by the manufacturer in the brochure.
Air-to-air: base pan heater and crankcase heater as standard.
Air-to-water: the refrigerant stays in the outdoor unit and the module; not stated by the manufacturer in the brochure.
Air-to-air: R-454B refrigerant sensor in the indoor unit (series spec sheet).
Air-to-water: wall-mounted module, 1 in NPT water connections.
Air-to-air: several positions (horizontal left or right, vertical up or down).
How loud each one is, according to MIDEA
The air-to-water brochure gives a sound pressure measured at 1 m; the air-to-air sheet gives levels by speed without stating the measuring distance. The numbers are placed on the same scale for reading, not for ranking.
How to read these numbers. dB(A) measures a noise level as the ear perceives it: the lower the number, the quieter the unit. Each dot is a published value.
Why this is not a ranking. The two sheets do not measure the same way (distance, conditions, speed). Different method: not comparable.
Outside, the outdoor unit
Published values
In the house, the indoor unit
Hydronic module or air handler
Measurements taken by the manufacturer with each document’s own method: read them as reference points, not as a ranking.
What each installation requires, according to MIDEA
Air-to-water adds a water system, with its fittings, pump and expansion tank. Air-to-air adds air ducts. The table lists the published limits for each unit.
| Installation | Air-to-water · M Thermal Arctic | Air-to-air · EVOX G3 5 tons |
|---|---|---|
| Connection inside the house | Water system, 1 in NPT fittings | Air ducts, static pressure up to 0.8 in w.c. |
| Maximum line-set lengthRefrigerant, between the two units | 98 ft | 246 ft |
| Minimum line-set length | 6.5 ft | Not published by the manufacturer in the submittal sheet. |
| Precharged length | Not published by the manufacturer in the brochure. | 25 ft |
| Maximum height difference | 65.5 ft | 98 ft |
| Liquid – gas diameters | 3/8 – 5/8 in | 3/8 – 3/4 in |
| Outdoor unit W × H × D, weight | 44 × 34 1/16 × 20 9/16 in, 214 lb | 37 1/2 × 52 1/2 × 16 3/8 in, 243 lb |
| Indoor unit, weight | Module 16 9/16 × 31 1/8 × 10 5/8 in, 88 lb | Air handler 21 1/2 × 21 1/2 × 60 1/8 in, 188 lb |
| Outdoor unit power supply | 208/230 V, 1 phase, 60 Hz | 208/230 V, 1 phase, 60 Hz; MCA 40 A, MOP 40 A |
| Water or air flow | Water: 0.7 to 3 m³/h (3.08 to 13.21 gal/min) | Air: 1,236 to 1,801 CFM |
| Stated heating / cooling range | −25 to 35 °C / −5 to 43 °C | −30 to 24 °C / −30 to 50 °C |
| RefrigerantGWP per the IPCC (AR4); ASHRAE 34 class | R-32 · GWP 675 · A2L | R-454B · GWP 466 · A2L |
Sources: MIDEA brochure “NA M thermal Arctic Split Series”, HA-SA202503V4 (16 kW model); MIDEA submittal sheet MAUSE-H60B-2A / MO1HE-H60B-2A, Extreme Heat AHU series, undated; 246 ft maximum length: MIDEA EVOX Extreme Heat installation manual, rev. 5 (10/23/2025), the submittal sheet leaving the field blank. The installer always follows the installation manual and the nameplate.
What people ask us about air-to-water
Can my hot-water radiators work with an air-to-water heat pump?
It depends on the water temperature they need in extreme cold. Natural Resources Canada warns about high-temperature radiators that need more than 60 °C. MIDEA publishes heating water adjustable up to 65 °C for the M Thermal Arctic, but its COP drops as the water gets hotter: 4.50 at 35 °C and 2.90 at 55 °C, at 7 °C outside. Compatibility is checked on site, room by room.
My radiant floor is electric. Can an air-to-water unit connect to it?
No. A floor heated by electric cables contains no water. An air-to-air heat pump can be added alongside it.
Does an air-to-water unit cool?
MIDEA publishes a cooling mode, with water from 5 to 25 °C. To cool the rooms, you need a system that can distribute that cold water, such as fan coils. A radiant floor is not designed to blow air.
Can the boiler be kept as backup?
Natural Resources Canada describes hybrid systems where the heat pump uses a backup system, such as a boiler; these systems do not run at the same time as the heat pump. The connection is designed on site with the existing system.
Why no dollar estimate for the season?
Our seasonal estimate, the same on all our comparison pages, relies on the HSPF2 and SEER2 from the AHRI certificates of air-to-air heat pumps. The MIDEA M Thermal Arctic is described by a COP at specific air and water temperatures. Applying the same method would be inaccurate, so the page shows what 1 kWh is worth at each published point.
Is an air-to-water heat pump eligible for grants?
Eligibility depends on the program, its official list on the purchase date and the exact unit. This page promises no amount.
The published values, unit by unit
The air-to-water unit is described by the manufacturer’s brochure; the air-to-air unit by its AHRI certificate, published by NEEP. The test conditions differ: nothing is highlighted.
| Published value | Air-to-water · M Thermal Arctic | Air-to-air · EVOX G3 5 tons |
|---|---|---|
| Heating, under each document’s conditions | ||
| Rated heating capacityDifferent conditions, not directly comparable | 54,589 BTU/h (16 kW), air 7 °C, water 35 °C | 55,000 BTU/h, air 8.3 °C, indoor air 21.1 °C |
| COP at rated capacityDifferent conditions | 4.50 (air 7 °C, water 35 °C) | 3.36 (air 8.3 °C) |
| Capacity at −15 °CDifferent conditions | 33,780 BTU/h, water 43.3 °C | 54,000 BTU/h |
| COP at −15 °CDifferent conditions | 2.06 | 1.90 |
| HSPF2 Region IV / V | Not applicable: a rating for air-to-air heat pumps | 9.5 / 7.7 |
| Cooling | ||
| Cooling capacity | 47,765 BTU/h, air 35 °C, water 7 °C | 54,000 BTU/h at 35 °C |
| Published cooling efficiency | EER 8.37 (air 35 °C, water 7 °C) | SEER2 17.5 · EER2 12 |
| Certifications and refrigerant | ||
| ENERGY STAR / cold climate (NEEP) | Not listed by NEEP | Yes / Yes |
| AHRI certificate · NEEP record | None: manufacturer sheet | 215471345 · 387394 |
| RefrigerantGWP per the IPCC (AR4); ASHRAE 34 class | R-32 · GWP 675 · A2L | R-454B · GWP 466 · A2L |
Nothing is highlighted in this table: the two units are not measured under the same conditions. On our other pages, “higher” marks the higher value of the same measurement under the same conditions; it is never a recommendation.
Both are on the AirGreen website.
To choose for your home, talk to our team: bring the type of system you have (water, ducts or baseboards), the water temperature it needs and the area to heat.
Where every number comes from
Data verified on November 9, 2026. This guide explains two types of heat pumps; it ranks neither the units nor the brands. Air-to-air: AHRI certificate and NEEP database. Air-to-water: manufacturer documents, since the unit has no AHRI 210/240 certificate. When a source contradicts the AHRI certificate, the certificate prevails.
Trademarks. MIDEA, M Thermal Arctic and EVOX are trademarks of their respective owners. Logos are used only to identify the products shown. AirGreen is a retailer of the brand; this page is not produced, sponsored or endorsed by the manufacturer.
Photos: AirGreen and manufacturer, for identification.
Does a figure look wrong? Write to us : every reported figure is checked again.