Residential plumbing · Denver Metro, Colorado

Water heater installation in the Denver Metro

A good water heater installation starts with the right size and type, then gets the gas or electrical supply, venting, relief valve, expansion tank and permit right. Since 2026, new gas models sold in Colorado also have to meet HB23-1161 low-NOx limits.

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Owned by John Kuykendall, Colorado Master Plumber License #03002471

Tank water heater in a basement with white PVC vent piping overhead and an expansion tank above it.

Installing a water heater is more than swapping a tank. It's a gas or electrical appliance, a pressure vessel and, for gas, a combustion appliance with a vent, all in one. The pair of heaters pictured here is one of our installs: two gas tanks with their own expansion tanks, copper piping and venting.

Picking the right heater

First-hour rating. How much hot water the heater delivers in its first hour starting full. Match it to your busiest hour, not your average day.
Fuel. Usually what the house is set up for. Switching between gas and electric means new supply work; see gas vs. electric.
Venting. Atmospheric (natural draft), power vent (fan-assisted, often PVC) or direct vent. The existing chimney or flue and the room decide what works.
Efficiency. Higher-efficiency models cost more up front and save energy over their life.
Tank or tankless. Covered in tank-to-tankless conversion.

Colorado's low-NOx rule

Under HB23-1161, from January 1, 2026, most new natural-gas water heaters sold in Colorado must meet a low-NOx emissions limit (10 nanograms per joule for typical home units under 75,000 BTU per hour). ENERGY STAR-certified models are treated as compliant. SB26-002 later exempted propane water heaters until 2031. Practically, that narrows the models available and can change dimensions or venting compared with your old tank, so we confirm fit before ordering.

What the install includes

Draining, disconnecting and removing the old heater
Setting the new heater, level and with required clearances
Water connections with shutoff, dielectric protection where needed, and a thermal expansion tank where the system is closed
Temperature and pressure relief valve with a properly sized and routed discharge pipe
Gas connection with a shutoff and sediment trap, or the electrical connection on electric models
Venting connected, pitched and checked for draft
Drain pan where the location calls for one
Startup, temperature setting and a walkthrough

Permits and inspections

Water heater replacement is permitted work in metro cities. Thornton lists water heater installation or replacement among projects that need a permit, and a like-for-like swap is processed without plan review. Denver's Community Planning and Development and Aurora's Building Division also handle these permits. Colorado's carbon monoxide alarm law (C.R.S. 38-45) requires a working CO alarm near sleeping rooms when a fuel-fired appliance is replaced under a permit.

When it's time for a new water heater

Your current heater is leaking from the tank
It's past 10 to 15 years and needs a major repair
You regularly run out of hot water
You're remodeling or adding a bathroom
Your heater's venting or setup doesn't meet current code

How a visit goes

Look at the existing setupFuel, venting, location, piping and household use.
Recommend size and typeWith the options and trade-offs explained.
Install to codeWater, gas or electric, venting, relief valve, expansion tank and pan.
Start up and walk throughTemperature, shutoffs and basic maintenance.

Colorado notes

What's different here

Altitude. Gas burns with less oxygen along the Front Range, so burners and venting have to be set up for elevation per the manufacturer.
Winter demand. Colder incoming water in winter means the heater works harder and recovers more slowly, which exposes weak parts.
Low-NOx rule. Under HB23-1161, new gas water heaters sold in Colorado since January 1, 2026 must meet low-NOx limits, which matters when repair turns into replacement.
CO alarms. C.R.S. 38-45 requires a carbon monoxide alarm within 15 feet of sleeping rooms when a fuel-fired appliance is replaced under a permit.

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.

Size and modelCapacity, efficiency and low-NOx compliance.
Venting changesFitting the vent to the new model, or switching vent type.
LocationBasement, closet, garage or attic.
Code updatesExpansion tank, pan, relief valve discharge and gas shutoff.
Fuel changeSwitching gas to electric or the reverse adds supply work.
PermitRequired for replacement in most metro cities.

Questions we hear

How long does a water heater installation take?

A straightforward like-for-like replacement is usually done in a single visit. Venting changes, moving the heater or switching fuel take longer.

What size water heater do I need?

Look at first-hour rating rather than gallons alone, and match it to your busiest hour of hot water use. We'll help you work it out.

Do new gas water heaters have to be low-NOx in Colorado?

Yes, most new natural-gas water heaters sold in Colorado since January 1, 2026 must meet HB23-1161 low-NOx limits. Propane models have until 2031 under SB26-002.

Do I need an expansion tank?

If your home has a pressure-reducing valve or check valve that makes the system closed, a thermal expansion tank is usually needed so pressure doesn't build each time the heater runs.

Do I need a permit?

In most metro cities, yes. Ask when you call and we'll go over what your city requires.

Can I move my water heater to a different spot?

Often, but it means new water, gas or electrical, and venting runs, which add cost. Tankless units give more placement options.