A combination unit like the Gradient syncFURNACE does two jobs from one appliance and one vent: it
heats your home and it makes your hot water. A traditional setup uses a furnace and a separate hot
water tank, two appliances with two vents. The combination unit wins on space, on venting, and on
avoiding the standing heat loss of a tank. The traditional pair wins on simplicity, on redundancy,
and on being serviceable by any heating company in the city. Which one is right depends on your
house rather than on which is better in the abstract, and this page is written to help you tell.
180 Plumbing and Heating installs and services both across southeast Calgary. Call
403-404-9975.
The short version
| Combination unit | Furnace plus tank | |
|---|---|---|
| Appliances | One | Two |
| Vents | One vent set | Two |
| Floor space | Gradient states about half | Full mechanical room in most homes |
| Standing heat loss | None. Water is heated on demand | A tank of water kept hot all day |
| Hot water supply | Continuous, but flow limited | Limited by tank size, then you wait |
| If it fails | You lose heat and hot water together | You lose one, not both |
| Who can service it | A technician who knows the platform | Almost any heating company |
| Annual service | More involved. Includes a water system flush | Conventional furnace tune up plus tank check |
Where the combination unit is genuinely better
Space. This is the biggest practical difference. Gradient states a typical syncFURNACE
installation needs a closet rather than a mechanical room of a hundred square feet or more. In a
townhome, a laned home or a home with a suite, that difference is not a convenience. It is often
the difference between having the space and not having it.
One vent instead of two. In an older Calgary home with a single chimney, running a second vent
for a new appliance can be awkward and expensive. Gradient states the syncFURNACE can be retrofit
inside an existing B-vent and terminated vertically out the roof, which also avoids the side wall
termination that ices up in this climate.
No standing loss. A hot water tank keeps forty or fifty gallons hot around the clock whether
you use it or not. Gradient’s efficiency case rests largely on removing that, and it is a sound
argument. Their published figure is that Alberta homeowners typically save between 500 and 900
dollars a year on utility bills compared with traditional or electric heating. That is the
manufacturer’s number, not our measurement, and your result depends on your house.
Deeper modulation. The sFT-202 modulates 12:1, meaning it can run at roughly 8 percent of
capacity. Gradient notes that most traditional furnaces cannot run below about 40 percent. Longer
gentler cycles mean fewer temperature swings and less blower noise.
Hot water does not run out. You can run a bath, then a shower, then a dishwasher, and the
supply does not empty the way a tank does.
Where a separate furnace and tank is the better answer
We install both, so here is the case for the traditional pair, made properly.
Redundancy. This is the strongest argument and it is worth taking seriously. With a combination
unit, one appliance failure takes out your heating and your hot water at the same time, in
February. With two appliances, a dead water heater is an inconvenience and a dead furnace is an
emergency, but you rarely lose both at once.
Simplicity of service. Any heating company in Calgary can service a conventional furnace and
tank. A combination unit needs a technician who knows the platform, and that is a smaller list.
This is the single most common frustration we hear from owners who inherited a combination unit
with the house.
Flow rate at high temperature rise. A tank delivers whatever is in it at full flow. A tankless
system delivers continuously, but the flow depends on how much it has to raise the temperature.
Gradient rates the sFT-202 at 10.5 US gallons per minute at a 35 degree Fahrenheit rise, and 4.8 US
gallons per minute at a 77 degree rise. Calgary’s incoming water is cold in winter, which is
exactly when the rise is largest. For most households that is still plenty. For a house with two
simultaneous showers and a soaker tub, it is a real design consideration and it belongs in the
sizing conversation.
Replacement cost timing. Two appliances fail at different times, which spreads the spending. A
combination unit is one larger replacement rather than two smaller ones.
Hard water. Calgary water is hard, and southeast Calgary is fed from the Glenmore plant at 10.6
to 16.0 grains per gallon, the harder of the city’s two supplies. Scale affects both types of
equipment, but a combination unit’s heat exchanger is doing more work and its annual flush and
descale is not optional. If you are not going to keep up with annual service, a tank is more
forgiving of neglect.
The questions that actually decide it
How much mechanical space do you have, and what else needs to go in it? If the space is a
closet, the decision is close to made.
How many vents can you run, and where do they terminate? Side wall terminations ice up in
Calgary winters. A single vertical vent through an existing chimney is a meaningful advantage.
How many people, and how do they use hot water? Simultaneous demand is what strains a tankless
system. Sequential demand is what empties a tank.
Will annual maintenance actually happen? Be honest about this one. A combination unit rewards a
maintained house and punishes a neglected one more than a tank does.
How do you feel about a single point of failure? Some people would rather have two things that
can each break than one thing that cannot be allowed to.
Are you replacing both appliances anyway? If your furnace and your tank are both near the end
of their lives, a combination unit becomes far more attractive than if you are replacing only one.
What we recommend, in practice
If you are in a newer home, a townhome, or anything with a compact mechanical closet, and both
appliances are due, a combination unit is usually the better answer, provided you are prepared to
have it serviced properly every year.
If you have a full mechanical room, a working furnace with years left in it, and a tank that has
just died, replacing the tank is usually the better answer. Replacing a working furnace to gain a
combination unit is a harder case to make and we will tell you so.
If you already own a combination unit because it came with the house, the useful question is not
which is better. It is whether yours has been serviced and documented, because that is what
protects the ten year heat exchanger coverage. See
the warranty page.
Getting an answer for your house
We will come and look, tell you what you have, how long it has got, and what the realistic options
are. Replacement quotes are free and in writing, and yours to keep whether you use us or not.
How we price this work
We charge by the job, not by the hour. Hourly billing punishes you when a job turns out to be
complicated and punishes us for being quick, so we price the job. You get one number for the
finished work, agreed before anything starts and always in writing. Parts, labour, disposal and
permits are in the number you agreed.
On a replacement you will see three options rather than one: the straightforward like for like
swap, the one we would recommend, and the one that deals with the underlying cause of whatever went
wrong. We will tell you which one we would choose in our own house.
Call 403-404-9975.
Frequently asked questions
What is the difference between a Gradient syncFURNACE and a regular furnace plus hot water tank?
Three practical differences. Space: the syncFURNACE replaces two appliances with one, and Gradient states it fits in about half the footprint, which can mean a closet rather than a mechanical room. Venting: it needs one vent set instead of two, which matters in older Calgary homes with a single chimney. Modulation: it has a 10:1 or 12:1 turndown, so it can run at 10 percent or less of capacity, where Gradient notes most conventional furnaces cannot go below about 40 percent.
Is a combi furnace worth it?
It depends on your house rather than on the technology. It is usually worth it if mechanical space is tight, if venting is awkward, and if both your furnace and your water heater are near the end of their lives. It is usually not worth it if you have a working furnace with years left, plenty of mechanical space, and no plan to keep up annual maintenance.
What happens if a combi unit breaks down?
You lose heating and hot water at the same time, which is the honest disadvantage of combining them. With a separate furnace and tank you normally lose only one. That is a real reason some households prefer two appliances, and it is a reason to stay on top of annual maintenance if you have one appliance doing both jobs.
Does a combi unit run out of hot water?
It does not run out the way a tank does, because it heats continuously rather than storing. What it has instead is a flow limit that depends on how cold the incoming water is. Gradient rates the sFT-202 at 10.5 US gallons per minute at a 35 degree rise and 4.8 at a 77 degree rise. Winter in Calgary is the demanding case, and simultaneous showers are the scenario to size for.
Can I replace just my hot water tank with a combi unit?
Not usefully. A combination unit replaces both the furnace and the tank, because it does both jobs from one burner and one vent. If your furnace is fine and only the tank has failed, replacing the tank is normally the better decision.
Is a combi furnace harder to get serviced in Calgary?
There are fewer companies who work on them, and that is the most common complaint we hear from owners who inherited one with the house. The work is routine once a technician knows the platform. We service them, including units we did not install and units in tight closets other companies have declined.
Written by Desmond Neufeld, Red Seal Journeyman Plumber and Certified Type B Gasfitter. Last updated 23 August 2026.
