There is a assumption built into a lot of heat pump conversations: all-electric is the real version, and keeping the gas furnace is the half-measure you settle for.
That gets the engineering backwards often enough that it is worth spelling out properly.
What dual fuel actually is
A dual-fuel system pairs an electric heat pump with your existing gas furnace on the same ductwork. The heat pump does the heating for most of the year. When the outside temperature drops below a crossover point — where gas becomes cheaper or more effective per unit of heat — the control switches over and the furnace takes it.
You are not running both. You are running whichever one is the better tool at that temperature, automatically.
Why it suits Lower Mainland houses
Three reasons specific to here:
The cold snaps are short. We spend most of the winter in the range where a heat pump is efficient, and a genuinely hard week or two where it is working harder. Dual fuel gives you the heat pump’s efficiency for the long stretch and the furnace’s brute output for the short one.
The ductwork is already there. Most houses with a gas furnace have ducting sized for that furnace. A dual-fuel retrofit uses it. An all-electric conversion sometimes needs duct modification because heat pumps move more air at lower temperature — the constraint we cover in do heat pumps actually work in Lower Mainland winters.
The electrical service. A whole-home all-electric heat pump, in an older house on 100A service, often needs a panel upgrade. That is real money and real disruption. Dual fuel usually asks less of the panel because the furnace is still carrying the peak load. We cover how to assess this in will your electrical panel take a heat pump.
Where all-electric is clearly right
Dual fuel is not the answer to everything. Go all-electric when:
- You do not have gas, or you are on oil or propane. Then there is no furnace worth keeping and the conversation is simpler.
- Your furnace is at the end of its life anyway. Keeping a 22-year-old furnace as backup means you have bought a heat pump and inherited a failure waiting to happen.
- You want off gas on principle. That is a legitimate reason and we will not argue you out of it. Just go in knowing what the panel and duct implications are.
- Your house is well insulated and modestly sized. Less peak demand means less need for a backup with that much output.
Where dual fuel is clearly right
- Your gas furnace is relatively new and working. Throwing away a functional eight-year-old furnace to avoid using it twelve days a year is not obviously good economics or obviously good for anything else.
- Your panel is tight and a service upgrade would add materially to the project.
- Your ductwork is marginal for full heat pump airflow.
- You want cooling, primarily. A lot of people arrive at heat pumps because of summer, not winter. Dual fuel gets you air conditioning without touching the heating system that already works.
The rebate dimension
Dual fuel sits in its own incentive category through FortisBC, separate from the all-electric streams. There is also an income-qualified version.
We are not going to quote you an amount here, for reasons we set out at length in why every BC rebate calculator shows a bigger number than you will get — the short version being that the issuing bodies do not publish flat tables and anyone who gives you a confident total is guessing on your behalf.
What we will say is that the rebate structure should not drive this decision on its own. Choosing the wrong system to chase an incentive is how people end up with equipment that does not suit their house. Work out what the house needs, then find out what is available for it. Our rebate tool will tell you which programs your situation points at.
The crossover point matters and nobody sets it
One practical thing that separates a good dual-fuel install from a mediocre one: the crossover temperature.
Set it too high and the furnace takes over more than it needs to, and you have bought a heat pump you barely use. Set it too low and you are running the heat pump inefficiently in weather it should have handed off in. The right setting depends on your gas rate, your electricity rate, and your specific equipment’s performance curve — and it can be revisited when rates change.
Ask any contractor quoting dual fuel how they will set the crossover. If the answer is vague, that is informative.
Straight version
If you have a working gas furnace, existing ductwork and a tight electrical panel, dual fuel is probably the better answer and it is not a compromise. If your furnace is old, your insulation is good and your panel has room, all-electric is cleaner.
Either way the sizing and the ductwork matter more than the label. We do both, out of one Surrey showroom, and the assessment is the same either way: look at the house first.