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Not all heat pumps are equal

When it comes to the efficiency ratings of centrally ducted heat pump systems there is a specific criteria set forth by the American Heating & Air Conditioning Institute (AHRI) that must be followed.  The way the systems are tested in the lab is based on two different outdoor temperatures known as the “high heat capacity” and “low heat capacity”.  Each heat pump sold in North America must submit testing for each of their heat pump systems at these outdoor temperatures to AHRI and other energy efficiency rating authorities like Energy Star.

The High Heat Capacity is the heat pumps total heating output value at +8.3C and the Low Heat Capacity is the heat pumps total heating output value at -8.3C.

Even though you may receive an estimate for the same size system (TONS) the total heating output value can range significantly from brand to brand.  This is why it is so important to understand the numbers and hire an experienced contractor that has the know how to properly size and provide a heat pump system for your homes specific needs.  In other words your home may need a 3TON Carrier heat pump but if looking at a Daikin or Gree brand you might need a larger system to offer the same heating output value or you’ll be relying heavily on the back up electric, gas or oil system to do bulk of the work.

We have prepared a comparison between the leading brands sold in Nova Scotia to show how one heat pump system is not equal to another.  We used a 3TON model as our example since that is the most common size for the average home in Nova Scotia.

We took the highest efficiency INVERTER models from the most popular heat pump brands sold in Nova Scotia.  We compared Carrier, Daikin, GREE, Trane, General Electric, LG and 


At an outdoor temperature of -8.3C the leading 3TON heat pump inverter systems range dramatically in total heating output capability.

Carrier Infinity (25VNA436A0031)

Heating Capacity at +8C – 35,000BTU/HR

Heating Capacity at -8C – 33,000BTU/HR


11.5HSPF (Region 4)

LENNOX (SL25XPV-036-230A) 

Heating Capacity at +8C – 36,000BTU/HR

Heating Capacity at -8C – 34,000BTU/HR

22 SEER 

11 HSPF (Region 4)

LG (LUU368HV) 

Heating Capacity at +8C – 40,000BTU/HR

Heating Capacity at -8C – 25,600BTU/HR


10HSPF (Region 4)

Trane (4TWV8036XVA1) 

Heating Capacity at +8C – 28,600BTU/HR

Heating Capacity at -8C – 25,400BTU/HR


10HSPF (Region 4)


Heating Capacity at +8C – 36,000BTU/HR

Heating Capacity at -8C – 24,000BTU/HR


10HSPF (Region 4)


Heating Capacity at +8C – 36,000BTU/HR

Heating Capacity at -8C – 24,000BTU/HR


10HSPF (Region 4)

Daikin FIT (DZ17VSA36)

Heating Capacity at +8C – 27,400BTU/HR

Heating Capacity at -8C – 22,000BTU/HR


10HSPF (Region 4)


These are all INVERTER systems and all deemed a 3TON model; however you can see the wide variance in actual heating capability quite clearly.  

Do your research and look into the actual performance and capability of the heat pump system you are considering.  

SEER and HSPF ratings are important but as the example above shows the actual heating capacity of that system may not be what is needed for your home and the sizing of your system may be drastically off if your HVAC contractor isn’t aware of the heating output capability of the systems they sell.

The Carrier Infinity 24, 3TON model would have an output of 33,000BTU/HR at -8.3C (17F)

The Daikin DZ17, 3TON model would have an output of 22,000BTU/HR at -8.3C (17F)

The Carrier system has 50% more heating output value versus the Daikin which means that you will rely SIGNIFICANTLY more on your back up heating source to heat your home with the Daikin model than you would the Carrier.

If we look at a larger size Daikin DZ17  4TON model the total heating output at -8.3C is 29,400BTU/HR and a 5TON offers 34,400BTU/HR.  

As you can see, one INVERTER heat pump system is NOT comparable to the other. In our example it takes a 5TON Daikin DZ17 INVERTER system to match the heating output of the Carrier Infinity 24 3TON model at -8.3C

When you’re considering the purchase of a new ducted heat pump system for your home you should ask each one of the contractors to provide you with some heating information about the system(s) they are offering so that you can do a direct comparison of the brands you are considering. DO NOT just rely on the system TONNAGE, SEER or HSPF numbers.

If you are gathering estimates from numerous HVAC contractors that are all suggesting the same heat pump size (tonnage) for your home, we would strongly suggest you question them on the actual heating BTU/HR output rating at the AHRI low heat output temperature of -8.3C (17F).

Understanding how much heating will be from the heat pump VS the auxiliary heat source is crucial in making the decision on what heat pump is best for your Nova Scotia home.  

In certain cases you may come to find that some HVAC contractors are possibly undersizing your heat pump system.

Heat pump systems are not a cheap purchase. Before making your purchase many questions need to be asked and information needs to be transparent and forthcoming. 

If questions cannot be answered clearly and professionally and/or information and data cannot be provided then it is best to find a contractor who has this knowledge and experience instead of risking tens of thousands of dollars on something that may just increase your heating costs.

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