Tank, tankless or heat pump water heater?
Whether yours just quit or you're planning ahead, here's how to tell which water heater fits your home.
Updated October 2026 by the Green Core Heating & Air teamA standard tank is the fastest, lowest-cost replacement, and we can often swap one the same day. A tankless heater gives you hot water that doesn't run out and lasts the longest, but costs more and may need gas line or venting work. A heat pump water heater uses the least energy and may qualify for rebates, but it needs the right spot, or a split system that puts the heat pump outdoors.
The three options at a glance
Standard tank
A gas burner or electric elements keep a tank of water hot and ready.
Best for
- Getting hot water back today
- The lowest upfront cost
- Running several taps at once
Good to know
- Our standard gas or electric tank replacement starts at $2,850 installed.
- Lasts about 10 to 15 years, per the Department of Energy.
Tankless
Heats water only when you open a hot tap. Mounts on the wall.
Best for
- Households that run out of hot water
- Freeing up closet or garage space
- Staying in the home long term
Good to know
- Lasts about 20 years, and puts out about 2 to 5 gallons per minute, per the DOE.
- Gas models often need a bigger gas line and new venting.
Heat pump water heater
Pulls heat from the air into the water, like a fridge in reverse.
Best for
- The lowest energy use
- Homes with solar, or moving off gas
- Planned replacements, before the old tank fails
Good to know
- Can be 2 to 3 times more efficient than a standard electric tank, per the DOE.
- All-in-one models need about 1,000 cubic feet of air around them. Split systems put the heat pump outside.
Find the line that sounds like your home
Ifyour water heater just failed and you need hot water fast
Standard tankIfkeeping the upfront cost low matters most
Standard tankIfthe last shower of the morning always runs cold
TanklessIfyou want your closet or garage corner back
TanklessIfyou want the lowest energy use, or you have solar
Heat pump water heaterIfyou want efficiency but your heater sits in a tight closet
Split heat pump water heaterThings homeowners often hear
"Tankless means unlimited hot water for the whole house at once."
It won't run out, but it can only heat so much at one time: about 2 to 5 gallons per minute, per the DOE. We size it to how many showers and appliances you run together.
"A heat pump water heater won't fit in my house."
All-in-one models need room to breathe, but split systems put the heat pump outdoors, so the tank can go where a regular tank would.
"New air district rules mean I have to replace my gas water heater."
The Bay Area Air District's zero-NOx standard for new gas water heaters starts in 2027 and applies at replacement, not to heaters already installed. As of October 2026 the rule is up for changes, including a later date.
"If it still makes hot water, it's fine."
Tanks often fail with a leak, not a cold shower. Rusty water, popping noises or moisture at the base are early warnings. See our 7 warning signs.
How a Green Core water heater visit works
- Tell us what's happeningNo hot water, a leak, high bills or just curious. Call (707) 988-5858 any time.
- We check your setupGas line, venting, electrical, space and how much hot water your household uses.
- You pick from clear optionsTank, tankless and heat pump side by side with upfront pricing, plus help with rebates.
- We install and haul awayPermits, code updates and removal of the old heater, then a walkthrough of the new one.
Quick answers
Which water heater is cheapest to run?
A heat pump water heater uses the least energy. Whether it's cheapest for you depends on your gas and electric rates and whether you have solar.
How much does a new water heater cost?
Our standard gas or electric tank replacement starts at $2,850 installed. Tankless and heat pump models are priced to your home after a free estimate.
Can you replace my water heater today?
Often, for a standard tank, when our schedule allows. Tankless and heat pump installs are usually scheduled, since they can involve gas, venting or electrical work.
How long do water heaters last?
About 10 to 15 years for tank and heat pump models and about 20 for tankless, according to the Department of Energy.
More on water heaters
Need hot water back, or planning ahead?
Call for a same-day tank replacement when our schedule allows, or book a free estimate to compare all three for your home.
(707) 988-5858 Book a free estimate