In short
A heat pump balance point is the outdoor temperature where the heat pump's output equals the house's heat loss. Above it the heat pump heats alone; below it, backup heat makes up the gap. If the balance point is at or below your local winter design temperature, the heat pump can carry the house. It is found from a CSA F280 heat-loss calculation and the unit's capacity table.
Two lines on a graph decide how much backup heat a house needs. What is a heat pump balance point? It is the outdoor temperature where those lines cross: the house's heat loss, which rises as it gets colder, and the heat pump's output, which falls as it gets colder. At that temperature the heat pump, running continuously, exactly keeps up.
How a heat pump balance point is worked out
The balance point is calculated, not guessed, and it takes two documents. The first is the heat loss of the house at the local winter design temperature, produced by a CSA F280 heat-loss calculation. The second is the manufacturer's capacity table for the exact outdoor and indoor model, showing heating output at several outdoor temperatures. Plot both against outdoor temperature and read off where they meet.
The design temperature comes from the Ontario Building Code's climate data (Supplementary Standard SB-1), listed by municipality. Across Burlington, Hamilton and the west GTA it sits well below -15 °C, and it is typically colder inland than along the Lake Ontario shore. Your designer should name the figure used on the calculation.
Decision rule: if the balance point is at or below the design temperature, the heat pump can heat the house alone on all but the rarest nights. If it is above, every degree of gap is load the backup has to cover. The backup is sized with that gap in mind, and many designers size it to carry the whole house in case the outdoor unit is down.
Thermal balance point vs economic balance point
The crossing described so far is the thermal balance point, a capacity question. A home with a gas furnace as backup has a second number, the economic balance point: the outdoor temperature below which a unit of heat from gas costs less than a unit of heat from the heat pump. It depends on your Enbridge Gas rate, your electricity rate from Burlington Hydro, Oakville Hydro, Milton Hydro, Alectra or Hydro One, the furnace's efficiency and the heat pump's COP at each temperature.
- Thermal balance point: set by the equipment and the house. It moves only if you change the heat pump, add insulation or air-seal.
- Economic balance point: set by energy prices. It moves every time rates change and should be rechecked when they do.
- All-electric homes have only a thermal balance point, since the alternative is strip heat, which costs more to run than a working heat pump.
In a hybrid system the installer programs a switchover based on these two numbers. That setting has its own entry: dual-fuel changeover temperature.
What a wrong balance point looks like in the house
- Auxiliary heat running in mild weather: the heat pump is undersized for the house, or the thermostat's lockout was set without reference to the calculation.
- A heat pump sized only for the cooling load: common when an air conditioner is swapped like-for-like, leaving a balance point near freezing and a backup that runs much of the winter.
- A grossly oversized unit chosen to push the balance point down: on single-stage equipment it short-cycles in mild weather. Inverter models tolerate oversizing far better.
- Backup heat strips too small: the house slowly loses temperature during a cold snap even with everything running.
The balance point is not the temperature at which a heat pump stops working. A cold-climate unit keeps producing heat well below it, just less than the house needs. That separate question is answered in at what temperature a heat pump stops working.
What to ask for on a heat pump quote
Ask for three things in writing: the design heat loss and the design temperature it was calculated at, the heat pump's capacity at that temperature, and the resulting balance point. A contractor who sized the unit by square footage alone cannot give you the third. For reference, a 3-ton cold-climate heat pump installs for $9,500–$15,000 in the GTA, and the right size for your house comes from the calculation. Ask us for these numbers when we quote your heat pump installation; you can request a quote through the contact page or browse related terms in the HVAC glossary.
Questions people ask about Heat pump balance point
What is a good balance point for a heat pump in Ontario?
For a home that wants to heat almost entirely with the heat pump, a balance point close to the local design temperature is the target, and that takes a cold-climate inverter model sized to the heating load. For a hybrid system with a gas furnace, a higher balance point is acceptable because the furnace covers the coldest hours of the winter.
Can I lower my heat pump's balance point without replacing it?
Yes, by reducing the house's heat loss. Attic insulation, air sealing and better windows flatten the heat-loss line, so it crosses the heat pump's capacity line at a colder temperature. Duct sealing helps as well, because heat lost from ducts in unheated spaces never reaches the rooms. The equipment's own capacity curve cannot be changed.
Is the balance point the same as the auxiliary heat lockout setting?
No, but one informs the other. The balance point is a property of the house and the heat pump. The lockout is a thermostat setting that stops auxiliary heat from running above a chosen outdoor temperature. Setting the lockout a little above the calculated balance point keeps the strips off in mild weather while still allowing them when they are needed.