Can my 100-amp panel run a whole-home electric tankless water heater?

Almost certainly not. Whole-home electric tankless heats water instantaneously with resistance elements and represents one of the largest single loads in a house, which is why 100-amp services in older Bellingham homes generally cannot support it. A licensed electrical contractor performs the load calculation and the work; we do not hold an electrical licence and will not guess at it.

Is gas tankless available at my address?

Only if Cascade Natural Gas serves your street, because Cascade rather than PSE is the gas utility here. Bellingham, Ferndale and Lynden have gas mains in much of their built area; Deming, Kendall, Maple Falls, Glacier and many rural parcels have no gas main at all, which is why propane and electric dominate there.

Are there rebates for tankless in Bellingham?

PSE does not rebate tankless water heaters of either fuel; its water heating incentive is for heat pump water heaters. Cascade Natural Gas has run residential rebates including tankless, but the current amounts were not verifiable from a primary source, so we will not print a number — confirm with Cascade before you count on one.

Why does a tankless unit deliver less hot water in winter?

Because its job is to raise the temperature of whatever water arrives, and in winter that water arrives much colder. The unit’s rated flow assumes a temperature rise; a bigger rise means fewer gallons per minute. Sizing on a summer inlet temperature is the most common reason a new tankless disappoints its owner in January.

Would a heat pump water heater be better than either?

For most Bellingham houses with a suitable space, yes, mainly because PSE pays $1,000 or $1,100 toward it and pays nothing toward tankless. Tankless stays the right answer where floor space is unavailable, where the surrounding air is too cold for a heat pump water heater, or where the demand is genuinely continuous.

Gas tankless water heater vs. Electric tankless water heater

Gas tankless vs. electric tankless: which one your house can actually support

Whole-home electric tankless needs electrical service most older Bellingham houses do not have. Gas tankless needs Cascade Natural Gas service and a vent path. Point-of-use electric is the case worth understanding.

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The short answer

For whole-home hot water, gas tankless is usually the only one your service can support: electric tankless draws enormous current and most older Bellingham panels cannot feed it. Electric tankless is the right answer at point of use — a shop sink, an ADU bathroom, a remote fixture — where the load is small.

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Gas tankless water heater vs. Electric tankless water heater, line by line

Where one option is genuinely better for a Bellingham house, the cell is marked. Where it is a wash, we say so.

What you are comparing	Gas tankless water heater	Electric tankless water heater
Electrical service required	A modest circuit for controls and the combustion fan. better	Very large. Whole-home electric tankless is one of the heaviest single loads a house can carry, and 100-amp service usually cannot.
Fuel availability at your address	Requires Cascade Natural Gas service, which exists in Bellingham, Ferndale and Lynden but not in the foothills.	Works anywhere PSE serves, which is everywhere in Whatcom County. better
Venting and combustion	Sealed-combustion venting through a wall or roof, plus combustion air and condensate on a condensing unit.	None. No flue, no combustion air, no CO risk. better
Installed cost	Published ranges run roughly $2,100 to $5,600 installed, plus gas line sizing if the existing line is undersized.	Published ranges run roughly $1,400 to $3,000 installed, before any electrical service work, which can dwarf the unit price.
Flow rate on a cold winter inlet	Higher. Gas units have the input to raise 40°F inlet water enough for two fixtures at once. better	Limited. The colder the inlet, the fewer gallons per minute it can deliver, and a Bellingham winter inlet is cold.
Rebates in Bellingham	Cascade Natural Gas has historically rebated tankless, but current amounts could not be verified, so no figure is quoted here.	No PSE rebate. PSE’s water heating money goes to heat pump water heaters.
Space and mounting	Wall-hung but needs vent clearance and service access.	Smallest option, and a point-of-use unit fits under a sink. better
Maintenance on hard water	Annual descaling of the heat exchanger, which is not optional on north-county well water.	Also scales, and the elements are the part that suffers.

Rows with no mark are close enough that the difference will not decide your project.

Choose Gas tankless water heater if

You want whole-home tankless and you have Cascade Natural Gas service with a gas line that can be sized for it.
The household runs multiple fixtures at once in winter, when the incoming water is coldest and flow rate is the real limit.
You already have a suitable exterior wall or roof path for sealed-combustion venting.
Your electrical service is 100 amps and a service upgrade is not in this year’s budget.

Choose Electric tankless water heater if

It is a point-of-use application: a garage shop sink, a detached studio, an ADU bathroom, a fixture at the far end of a long run.
There is no gas at the property at all, which is the normal condition in Deming, Kendall, Maple Falls, Glacier and much of the farmland.
You want no combustion appliance in the building, whether for safety, for indoor air quality, or because there is no vent path.
You already have generous electrical capacity — a newer house on 200-amp service — and the demand is genuinely modest.

What changes this answer in Bellingham

This choice is settled by your panel and your street more than by your preferences. Bellingham’s gas utility is Cascade Natural Gas rather than PSE, so gas tankless is available in the city and the north-county towns but simply is not an option up the Mount Baker Highway or on many rural parcels. On the electric side Puget Sound Energy serves the whole county, but a great deal of Bellingham’s pre-1960 housing is still on 100-amp service, and whole-home electric tankless is one of the few loads that genuinely forces a service upgrade. Winter inlet temperature is the underrated factor: the colder the water arriving, the fewer gallons per minute the unit can raise to shower temperature. All electrical work here is performed and permitted by a licensed electrical contractor, which we are not.

Washington's energy code puts Bellingham's outdoor heating design temperature at 19°F, against 24°F at Sea-Tac, in climate zone 4C (marine). We size from a load calculation against that number, not from the square footage of the house.

Money that moves this decision

Cascade Natural Gas Residential Rebates

Cascade Natural Gas Corporation

Amounts not published in a verifiable form
Check first

Cascade’s rebate pages block automated retrieval and the current offerings PDF renders without its amount table. Figures circulating online (tankless $700, insulation $2.00/sq ft, duct sealing $500) come from a 2024 document and are treated as stale.

Bellingham note: We list this program because Cascade is Bellingham’s gas utility, but we will not print dollar amounts we could not verify. Confirm current figures with Cascade directly.

Paperwork:

You file it

Deadline:

Apply within 90 days of installation

Verified:

2026-09-04 · source
Heat Pump Water Heater Rebate

Puget Sound Energy

$1,000
Available now

$1,100 with Efficiency Boost. Requires a NEEA Tier 3 or Tier 4 model.

Paperwork:

You file it

Deadline:

No published end date — apply within 30 days of installation

Verified:

2026-09-04 · source
Washington State HEAR — Home Electrification and Appliance Rebates

WA Dept. of Commerce via local administrators

Varies by administrator
Income-qualified

Commerce awarded $39.3M across 40 local administrators with no statewide schedule. Whatcom-relevant awards: Sustainable Connections $731,250, Opportunity Council $500,000, Lummi Nation $950,500. Per-household amounts are not published.

Paperwork:

The program files it

Deadline:

While administrator funds last

Verified:

2026-09-04 · source
Federal §25C Energy Efficient Home Improvement Credit

Internal Revenue Service

$0 — terminated
Ended

Historically 30% of cost, up to $2,000/year for heat pumps and heat pump water heaters. Gone. The One Big Beautiful Bill (P.L. 119-21, enacted July 4, 2025) accelerated its termination.

Paperwork:

You file it

Deadline:

Terminated — property placed in service after December 31, 2025 does not qualify

Verified:

2026-09-04 · source

Questions Bellingham homeowners actually ask

Can my 100-amp panel run a whole-home electric tankless water heater?: Almost certainly not. Whole-home electric tankless heats water instantaneously with resistance elements and represents one of the largest single loads in a house, which is why 100-amp services in older Bellingham homes generally cannot support it. A licensed electrical contractor performs the load calculation and the work; we do not hold an electrical licence and will not guess at it.
Is gas tankless available at my address?: Only if Cascade Natural Gas serves your street, because Cascade rather than PSE is the gas utility here. Bellingham, Ferndale and Lynden have gas mains in much of their built area; Deming, Kendall, Maple Falls, Glacier and many rural parcels have no gas main at all, which is why propane and electric dominate there.
Are there rebates for tankless in Bellingham?: PSE does not rebate tankless water heaters of either fuel; its water heating incentive is for heat pump water heaters. Cascade Natural Gas has run residential rebates including tankless, but the current amounts were not verifiable from a primary source, so we will not print a number — confirm with Cascade before you count on one.
Why does a tankless unit deliver less hot water in winter?: Because its job is to raise the temperature of whatever water arrives, and in winter that water arrives much colder. The unit’s rated flow assumes a temperature rise; a bigger rise means fewer gallons per minute. Sizing on a summer inlet temperature is the most common reason a new tankless disappoints its owner in January.
Would a heat pump water heater be better than either?: For most Bellingham houses with a suitable space, yes, mainly because PSE pays $1,000 or $1,100 toward it and pays nothing toward tankless. Tankless stays the right answer where floor space is unavailable, where the surrounding air is too cold for a heat pump water heater, or where the demand is genuinely continuous.

Next steps on this decision

Get this priced both ways

We will quote the option that fits your house and tell you what the other one would have cost, so the comparison is yours to make, not ours.

Ready for a straight answer on your house?

Tell us what you have now and what you want it to do. We will tell you what fits, what it costs, and which rebates you actually qualify for — before anyone comes out.

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