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Zero Degree Heating

zero degree heating

Everybody knows there’s no such thing as zero degree heating when it comes to a heat pump. An energy efficient heat pump might work for mild temperatures, but they rapidly lose efficiency as the temperature drops. Everybody knows you need a gas furnace to stay warm in severe winter weather.


I’ve got some news for you. What everybody ‘knows’ is about to change.

Zero Degree Heating is Real

The conventional wisdom that a heat pump won’t work for really cold winter days used to be 100% right. Previous generation heat pumps simply could not function in freezing conditions. As I’m sure you know, technology does not stand still. Right now it’s entirely possible for a modern heat pump to deliver zero degree heating. In fact, some heat pumps can continue heating at 100% efficiency past -10 degrees.

Okay, so that’s great. Heat pumps can heat better, terrific. What, however, does it mean for the average American homeowner?

Expanding Regional Utility

Not too very many years ago keeping your house heated with just a heat pump was not a great idea for most people. Heat pumps were unable to heat effectively at low temperatures, so only people in very mild winter climates could reasonably rely on one. If you didn’t live in South Florida or Hawaii, you were probably not going to use a heat pump for zero degree heating.

This is no longer the case.

Being able to heat effectively down to -10 degrees means using a heat pump for summer cooling and winter heating is a real option for many more homeowners than it used to be. If you live in Alaska and routinely experience temperatures around -40, you’re still going to need a furnace. On the other hand, if you live in a region, the American South for example, where zero degree days are not too common, you can now depend on an energy efficient heat pump for all your air comfort needs.

Like I said before – what everybody ‘knows’ just changed.

32 thoughts on “Zero Degree Heating”

  1. We live in north western Pennsylvania. We would like a unit for heating purposes. We need help deciding which one. The hyper heat looks like it might be it. How efficient is the unit at 0°. Or how low Can the temperature go and still supply heat.

    1. A Hyper Heat is definitely a better option for winter heating than other ductless heat pumps. The AHRI only rates down to 17 degrees, and the Hyper Heat performs at around 65-70% capacity. The lowest it will operate is around -5 degrees.

    2. North West Pennsylvanian here. We did purchase and install a Hyper Heat last year and flat out LOVE it. We do have a fireplace but only had to use it a total of 5 days last Winter when the temps went below -10. It was one cold Winter; with an average of 15 for Nov-Dec 2018 with a low of -17.

      That said has there been an update in the efficiency of the units better than -5?
      Also who is the manufacturer of these units?

  2. So we live in upstate New York we see temps as low as 10 below but not a normal average is between 10,15 we need a system to heat and cool 750 sg.ft which unit will be best and how efficient are they

    1. A 24k Hyper Heat unit would probably be the best fit. It is an 11.5 HSPF unit and will perform effectively in below freezing temperatures.

  3. I live in the Boston area and would prefer to be able to install my own DIY Mr Cool system. Being that it will be my only heating system, will this work during the cold winter months?

    1. The DIY will heat in cold conditions. However, like all heat pumps, it does lose efficiency as the outside temperature drops lower and lower. Capacity is significantly impacted between 32 degrees. It will continue operating down to around 17 degrees (as rated by AHRI).

  4. What should the air temp be coming out of my DIY 24,000 mini be if inside temp is 80 outside is 110 and a setting of 70?
    Thanks in advance

    1. That depends. Air conditioners reduce indoor air temperature in 15-20 degree increments. For example, if you set your unit on 70 and the interior temperature is 100, the air coming out of the air conditioner will probably be 80-85 degrees. It takes time for any air conditioner, MRCOOL or otherwise, to reach equilibrium during hot weather.

    1. The exact components in a product package can vary from dealer to dealer. In our standard Olympus product, we include a condenser, a variable number of air handlers (depending on specifications), Smart Controller, remote control, and a wall sleeve.

        1. The MRCOOL DIY comes with a 25′ line set, and cannot increase or decrease length. For the Advantage and Olympus, choose the length appropriate for the amount of space between where the interior components must be installed and the outside components must be installed.

  5. Is there much difference in heating between the hyper heat and the advantage I have a 40 foot 5th wheel I want to install in

  6. Can you get a 5 zone hyper heat? And if not, what operating temperature can the five zone get down to? Does the hyper heat also include air conditioning for summer months?

    1. Hyper Heat is not available in a multi-zone system at the present time. An Olympus multi-zone will continue to function down to 5 degrees. Hyper Heat does have air conditioning.

  7. What is the lowest temperature the 1200k btu Mr Cool advantage heat pump will continue to heat? Also when the HVAC contractor installed my system he talked about installing a drain pan heater for the indoor unit as well as some sort of heating device for the outdoor unit compressor. Can’t remember what he called it. He said there was also electrical hookups in the indoor unit for both of these. Is this correct? I live in central Indiana and we can get some pretty cold days during the winter months. Do you sell these products he was talking about and if not can you recommend any 3rd party ones that would work?

      1. How do I run it in the winter without a drain pan heater and crankcase heater? Are there any other manufactures that make compatible crankcase and drain pan heaters that can hook up to another power source?

    1. No, it won’t necessarily shut itself off, but heat production on the DIY is very low at that rate. For serious cold weather heat pump heating we would recommend an Olympus Hyper Heat.

  8. Looking to install your 12k diy in our 500 sq ft lake house,used mostly in summer,but occasionally it would be used in the winter,when temperatures would be 20 or above.Can I count on this unit giving us comfortable temperatures?

    1. DIY unit heating functions best above freezing, but it is AHRI rated to 17 degrees. It will produce 6800 BTUs at that temperature.

  9. I purchased a 4 ton 48,000 btu 3zone 1 24,000 2 12,000 btu units. The box that the indoor units came in say hyper heat on them. The box the outdoor unit came in says Olympic series multi-zone 48k. Is this a hyper heat system?

    1. It is not a Hyper Heat system. The air handlers for the Olympus Hyper Heat and the Multi-zone are compatible with both condensers.

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