APUS vs EcoSmart: the gas-versus-electric tankless decision, priced properly
These get compared because they occupy the same price shelf. They are not the same purchase — one is a combustion appliance and the other is the largest electrical load in your house.
The short answer
APUS if you have gas or propane; EcoSmart only if you do not, and your service can carry it. The appliances are close on purchase price. The installed costs are not: APUS needs a gas line and, indoors, venting; EcoSmart needs 112.5 amps across three breakers and frequently a service upgrade. On running cost, gas wins by roughly three to one per delivered BTU almost everywhere in the US.
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These two products end up on the same comparison lists because they cost roughly the same to buy. That is the only thing they have in common.
APUS builds gas tankless heaters. EcoSmart builds electric ones. So the real question is not which brand is better — it is which fuel your house can support, and what each one costs once it is installed rather than in the box.
The specification comparison
| APUS AP-AWH-W26LPG | EcoSmart ECO 27 | |
|---|---|---|
| Fuel | Liquid propane (NG trim available) | Electric |
| Output | 190,000 BTU | 27 kW ≈ 92,000 BTU |
| Max flow, 45 °F rise | 8.1 GPM | 3.5 GPM |
| Max flow, 70 °F rise | ~4.9 GPM | ~2.6 GPM |
| Appliance price | ~$700 | ~$600 |
| Venting | None (outdoor) or $600–$1,500 indoor | None, ever |
| Gas line | 3/4 in, $400–$900 | Not applicable |
| Electrical | 120 V outlet | 3 × 40 A breakers, 8 AWG ×3 |
| Service requirement | Standard | 200 A minimum, often an upgrade |
| Typical installed total | $1,500–$3,200 | $2,000–$7,000 |
| Physical size | 22 × 16 × 7 in | 17 × 17 × 4 in |
| Warranty, exchanger | 5 years | Lifetime, limited |
Two rows carry the whole comparison. Flow rate — the gas unit delivers nearly twice the hot water at any given temperature rise, because 190,000 BTU is simply more energy than 27 kW. And service requirement, where the electric unit's 112.5 amps is the constraint that decides most of these projects.
Why the electric unit's flow rate is so much lower
It is not a design failing. It is what 27 kilowatts is.
27 kW converts to about 92,000 BTU per hour. The APUS is 190,000 BTU. Even accounting for electric resistance being effectively 100% efficient at the appliance against gas at roughly 82%, the gas unit still delivers around 155,000 usable BTU against the electric unit's 92,000.
Run both through the sizing equation at a 70 °F rise:
- APUS: 155,800 ÷ (70 × 8.34 × 60) = 4.9 GPM — two showers
- ECO 27: 92,100 ÷ (70 × 8.34 × 60) = 2.6 GPM — one shower, and not a generous one
To match the gas unit's output electrically you would need roughly 45 kW, which is 187 amps at 240 V. That is not a residential appliance in any practical sense. The full arithmetic is in how to size a tankless water heater.
Running cost, over a decade
Assume a household using 60 therms-equivalent of water heating energy a year — a reasonable figure for a family of three or four.
| APUS (propane) | APUS (natural gas) | EcoSmart (electric) | |
|---|---|---|---|
| Energy price basis | $2.80/gal | $1.40/therm | $0.17/kWh |
| Effective efficiency | 82% | 82% | 100% |
| Annual energy cost | ~$420 | ~$205 | ~$500 |
| 10-year energy | $4,200 | $2,050 | $5,000 |
| Installed cost | $2,200 | $2,800 | $4,500 |
| 10-year total | $6,400 | $4,850 | $9,500 |
Natural gas wins comfortably. Propane is more expensive per BTU than natural gas but still lands ahead of electric resistance on these assumptions. Electric loses on both axes at once — higher installed cost and higher running cost.
The assumption most likely to overturn this is the electricity price. At $0.09/kWh, which some hydro-served regions genuinely see, the electric column drops to about $265 a year and the ten-year total becomes competitive. Check your own rate before accepting the table.
The electrical capacity question, which usually settles it
This is where the EcoSmart conversation ends for most houses.
The ECO 27 needs three 40-amp double-pole breakers — six panel spaces — fed by three separate runs of 8 AWG copper, drawing a combined 112.5 amps at 240 V. On a 200 A service, that is over half your capacity dedicated to one appliance, before the range, the dryer or the air conditioning.
Whether that fits is decided by a load calculation under NEC Article 220, and in a typical all-electric house with a range, dryer and central air, it frequently does not. The remedy is a service upgrade at $4,000 to $8,000, which is not a rounding error on a $600 appliance. The complete breakdown, with the tables, is in the electrical requirements for electric tankless units.
Where EcoSmart is genuinely the right answer
We have been hard on the electric option, so here is where it wins outright.
No gas supply and no propane practicality. Rural properties without a gas main, where a propane tank installation is not wanted or not permitted. Electric is available everywhere.
Point-of-use. This is the strongest case for electric tankless by a distance. A 6 to 11 kW unit at a remote bathroom, a workshop sink or a guest suite is one breaker, no venting, no gas run, and it eliminates the long pipe wait entirely. EcoSmart's smaller models are very good at this and the gas alternative makes no sense at all.
Apartments and condos. Combustion appliances and outdoor mounting are typically not options. Electric is often the only option.
Substantial solar generation. If you are producing your own electricity, the running-cost objection weakens considerably and the no-combustion, no-venting simplicity becomes attractive.
Mild climates with modest demand. In Florida at a 45 °F rise, the ECO 27 delivers about 4.1 GPM, which is a genuine two-shower capability. The same unit in Minnesota is a one-shower heater. Geography changes this comparison more than anything else.
Installation timelines and who can do the work
Something the price comparison hides: these two products put you in front of different trades, with different lead times.
Gas means a licensed gas fitter in most jurisdictions, plus a permit and an inspection in many. If the gas line needs upsizing to 3/4 inch — common when converting from a tank — that is pipe work through a building. Typical timeline from decision to hot water is two to four weeks, and the cost is dominated by labour rather than parts.
Electric means a licensed electrician, and possibly a load calculation, a panel upgrade and a utility service change. A straightforward install where capacity already exists is a day. A service upgrade involves the utility company and runs four to twelve weeks depending on their queue.
That second path is where electric tankless projects stall, and it is the reason the honest comparison is not $600 against $700 for the appliances. It is the total project, and the totals are frequently a factor of two apart.
Get the load calculation done before ordering anything electric. It costs a couple of hundred dollars and it is the piece of information that determines whether the project is a day or a season.
Our recommendation
If you have natural gas at the property, buy gas — the running-cost gap is large enough that nothing else in the comparison matters much. If you have propane and a mild climate, gas still wins, and the outdoor-mounted APUS is a strong value once you have accounted for the freeze-protection caveat covered in our APUS tankless water heater review.
If you have neither, get a load calculation done before you buy anything. It costs a couple of hundred dollars from a licensed electrician and it is the single piece of information that determines whether an electric tankless heater is a $600 purchase or a $6,000 project.
And if your supply is electric and the goal is genuinely to spend less: a heat pump water heater beats both of these on running cost by a wide margin, for reasons laid out in the ten-year cost comparison against a tank.
Questions people actually ask
Is the APUS tankless water heater electric or gas?
Gas. APUS builds the chassis in liquid propane and natural gas trims, indoor vented and outdoor unvented. The flagship is a 190,000 BTU outdoor propane unit. If you specifically need an electric tankless heater, APUS is not the brand and EcoSmart is one of the mainstream options.
Is EcoSmart a good tankless water heater brand?
For electric tankless, EcoSmart is one of the established names and the ECO 27 is the model most people end up looking at. The hardware is sound — self-modulating elements, a simple digital setpoint, a compact wall box. The limitation is not the brand, it is the physics of electric resistance heating and what it demands from your panel.
Which is cheaper to run, gas or electric tankless?
Gas, in almost every US market. At roughly $1.40 per therm and $0.17 per kWh, a delivered BTU from natural gas costs about a third of one from electric resistance. Electric wins only where electricity is unusually cheap, or where the household has substantial solar generation and net metering.
Can I replace a gas tankless heater with an electric one?
Physically yes, practically rarely. You would be adding 100 to 150 amps of load to a panel that was not sized for it, and the electrical work typically costs more than both appliances combined. The reverse swap — electric to gas — is usually the easier retrofit if a gas supply exists.
Does EcoSmart really need three breakers?
The ECO 27 does — three 40 A double-pole breakers, six panel spaces. Smaller units in the range need fewer: the ECO 18 needs two, and the point-of-use models need one. The breaker count follows directly from the kilowatt rating, and there is no way to reduce it for a given output.