If you live in Nova Scotia, the “best” ducted heat pump is NOT always the one with the highest HSPF2 rating.

It’s the one that delivers the most usable heat when it’s -10°C, -15°C, or colder.

Many homeowners are told to look at HSPF2 numbers alone.

That’s a BIG mistake.

HSPF2 measures seasonal efficiency — but it does not tell you how much heat the system can actually produce when you need it most.

In Nova Scotia, cold-weather performance matters more than marketing numbers.

HSPF2 vs Real Cold-Weather Heating Output

Let’s compare a few real 3-ton heat pump systems:

• Carrier 37MUHAQ36AA3

  • HSPF2: 10.3 (Region IV)

  • Heating Output Rating at +8C: 37,000BTU/Hr

  • 105% Heating Output at -15°C: 38,850 BTU/hr

• Lennox SL22KLV-036

  • HSPF2: 8.5 (Region IV)

  • Heating Output Rating at +8C: 32,800BTU/Hr

  • 103% Heating Output at -15°C: 33,784 BTU/hr

• Daikin Fit DH7VSA3610A

  • HSPF: 8.5 (Region IV)

  • Heating Output Rating at +8C: 35,000BTU/Hr

  • 81% Heating Output at -15°C: 28,350 BTU/hr

• Trane 5TWV0X36A1

  • HSPF: 10.5 (Region IV)

  • Heating Output Rating at +8C: 33,200BTU/Hr

  • 74% Heating Output at -15°C: 24,568 BTU/hr

On paper, the Trane has a higher HSPF2 Rating than any of the other models. But at -15°C, the Carrier produces over 36% more heating capacity. That difference determines how often your electric backup heater turns on. And electric backup heat is expensive.

The less your system relies on backup heat, the lower your winter power bills.

Why Cold Climate Certification Is Not Enough

In order to qualify as a cold-climate system, a heat pump must meet certain minimum performance thresholds. But “Cold Climate Certified” does not mean “Best for Nova Scotia.”

Some certified systems lose significant heating capacity as temperatures drop.

That means:

• More reliance on electric back up heat

• Higher power consumption

• Less comfort during extreme weather

Certification is a starting point — not the final decision factor.

Capacity Maintenance at -15°C (What Actually Matters)

Because we live in a heating predominant climate the most important metric for Nova Scotia homeowners is:

Heating output at -15°C and below.

You may see the term “Capacity Maintenance.”

This measures how much heating output a system maintains at -15°C compared to its rated capacity.

Example:

The Carrier 37MUHAQ36AA3

• Rated Capacity: 37,000 BTU/hr

• Capacity at -15°C: 38,850 BTU/hr

• Capacity Maintenance: 105%

That means the system maintains 105% of its heating ability during true winter conditions.

That’s real performance.

Understanding Tonnage vs Real Output

Heat pumps are sized in “tons.”

1 ton = 12,000 BTU/hr.

But here’s what most homeowners don’t realize:

Two different 3-ton systems can have drastically different heating outputs at -15°C.

A 3-ton system from one manufacturer may deliver far less usable winter heat than a 3-ton system from another brand.

That’s why proper system selection matters.

In several instances a 3-ton system in one brand/model can outperform even a 5-ton in a different brand/model 

Example:

The Carrier 37MUHAQ36AA3 (3TON)

• Rated Capacity: 37,000 BTU/hr

• Capacity at -15°C: 38,850 BTU/hr

• Capacity Maintenance: 105%

The Daikin Fit DH7VSA4810A (4TON)

• Rated Capacity: 47,500 BTU/hr

• Capacity at -15°C: 33,250 BTU/hr

• Capacity Maintenance: 70%

The Trane 5TWV0X60A1 (5TON)

• Rated Capacity: 52,500 BTU/hr

• Capacity at -15°C: 37,800 BTU/hr

• Capacity Maintenance: 72%

Choosing the wrong system can cost you alot more upfront for equipment and force your home to rely heavily on backup heat.

That’s where operating costs increase dramatically.

Our 3-Ton Cold Climate Heat Pump Comparison

We analyzed several of the most common cold-climate ducted systems sold in Nova Scotia in the 3-ton category which is the most popular size for the average Nova Scotia Home.

The differences in low-temperature heating output were significant.