Residential plumbing · Denver Metro, Colorado

Tankless water heaters in the Denver Metro

A tankless water heater heats water only while a tap is open, so it doesn't run out the way a tank does, as long as it's sized for how many fixtures you run at once. We install tankless units and service the ones you already have in homes across Thornton and the Denver Metro.

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Owned by John Kuykendall, Colorado Master Plumber License #03002471

White wall-mounted tankless gas water heater in an unfinished basement, with copper water connections and a yellow gas line below, white PVC vent pipes and red and blue PEX lines overhead.

A tankless water heater (also called on-demand) is a wall-mounted unit with a burner and heat exchanger inside. When you open a hot tap, water flows through, the burner fires and heats it as it passes. When you close the tap, it shuts off. There's no tank of water being kept hot all day, which is where the efficiency comes from.

Sizing is the whole game

The limit is flow, not volume. Each unit can raise a certain number of gallons per minute by a certain number of degrees. The U.S. Department of Energy says tankless heaters typically deliver 2 to 5 gallons per minute, with gas-fired models producing more than electric.

Two things set the size you need: how many hot fixtures run at once, and how cold the water is coming in. A shower might use around 2 gallons per minute; add a second shower and the dishwasher and you can see how quickly a small unit falls behind. Size it right and you can fill a big tub without running out.

What a proper install involves

Gas supply. Tankless units burn a lot of gas when they fire. The line feeding the unit has to be big enough, which sometimes means upsizing the run to the heater.
Venting. Most units vent through the wall or roof, often in PVC for high-efficiency models. Vent length and terminations follow the manufacturer's rules.
Condensate. Condensing units make acidic condensate that needs a drain, usually through a neutralizer.
Isolation valves. Service valves on the water lines make it possible to flush the heat exchanger without cutting pipe.
Power. The controls need an electrical outlet nearby.

The unit pictured above is one of our installs: wall-mounted, with copper connections and service valves below and PVC venting above. Details are on tankless water heater installation.

Efficiency and lifespan

According to the U.S. Department of Energy, for homes that use 41 gallons of hot water or less a day, tankless units can be 24 to 34 percent more energy efficient than conventional storage tanks; for homes that use a lot more, around 86 gallons a day, the gain is 8 to 14 percent. The same source says most tankless heaters have a life expectancy of more than 20 years, compared with 10 to 15 for tanks.

The trade-off is cost up front. Tankless units and their installation cost more than a tank, especially when the gas line or venting needs work. For many families the deciding factors are space, endless showers and how long they plan to stay. We lay it out in tank vs. tankless in Colorado homes.

Repair and descaling

Already have a tankless unit? Common problems include error codes, ignition failures, fluctuating temperatures and reduced flow, and many trace back to scale in the heat exchanger or a clogged inlet filter. Periodic descaling with the isolation valves and a pump keeps the unit working the way it should. See tankless repair and descaling.

Signs tankless is a good fit (or needs service)

Your tank is due for replacement and you'd like the floor space back
You run out of hot water with back-to-back showers or a large tub
You're adding a bathroom or finishing a basement
You plan to stay in the house long enough for the efficiency to pay off
Your existing tankless shows error codes or the water swings hot and cold

How a visit goes

We talk through how you use hot waterHow many bathrooms, how many people, whether you fill a big tub, and what runs at the same time.
We look at the space and the supplyWhere the unit can mount, how it will vent, the size of the gas line, where condensate can drain, and whether there's power nearby.
You get a recommendation and optionsThe unit size that fits your household, and anything the house needs to support it.
Install, startup and a walkthroughWe set the temperature, show you the controls and the service valves, and explain what maintenance the unit needs.

Colorado notes

What's different here

Cold incoming water. In winter, supply water arrives much colder, so the unit has to raise the temperature further. That lowers how many gallons per minute it can deliver. We size for January, not July.
Altitude. Gas appliances lose some output at elevation. Many tankless units have altitude settings or published derating; the install has to follow them.
Minerals. Scale builds up in the heat exchanger over time. Isolation valves and periodic flushing keep it from choking the unit.
Freezing. Units, vents and condensate lines in garages or near exterior walls need protection from Colorado cold snaps.
Low-NOx rule. Colorado's HB23-1161 emission limits apply to new gas water heaters sold in the state, which narrows the models available.

What affects the cost

Every home is set up differently, so we price the job after we've seen it. These are the things that move the number.

Unit size and typeHigher-output and condensing models cost more up front.
Gas supplyWhether the existing line can feed the unit or needs upsizing.
Vent routeA short run through an exterior wall is simpler than a long one through the roof.
LocationMounting where the old tank was, or moving it.
Condensate and powerWhether a drain and an outlet are already nearby.
Removing the old tankAccess and what it takes to get it out.

More about tankless water heaters

Questions we hear

Will a tankless water heater ever run out of hot water?

It won't run out the way a tank empties. It can fall behind if you ask it for more gallons per minute than it's sized for, especially in winter when incoming water is coldest. Correct sizing is what prevents that.

What size tankless water heater do I need?

It depends on how many fixtures you run at once and how cold the incoming water gets. A household that runs two showers and a dishwasher together needs a larger unit than a couple in a condo. We size it with you.

Does a tankless water heater work during a power outage?

Most don't. The controls, igniter and fan need electricity, even on gas models.

How often does a tankless water heater need maintenance?

Plan on flushing the heat exchanger periodically to remove scale; how often depends on your water and how much you use. The manufacturer's manual gives a schedule. Cleaning the inlet filter screen is part of it too.

How long do tankless water heaters last?

The U.S. Department of Energy says most have a life expectancy of more than 20 years, versus 10 to 15 for storage tanks. Regular descaling is a big part of reaching that.

Can a tankless unit go where my old tank was?

Often it can mount on a wall nearby. Venting, gas line size and condensate drainage decide the final spot. See tank-to-tankless conversion.

Is tankless worth it in Colorado?

It can be, if you'll stay in the house a while and want space and steady hot water. A good tank heater is still the right call for many homes. We lay out the trade-offs in tank vs. tankless in Colorado homes.

Why does my tankless water go cold for a second?

That's often the "cold water sandwich": a short slug of cold water when a tap is turned off and on again quickly while the unit relights. It's normal to a degree. Large or persistent swings point to scale, a dirty filter or a sizing problem.

Tankless Water Heaters near you

We're based in Thornton and work across the Denver Metro:

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