Residential plumbing ยท Denver Metro, Colorado
Tank-to-tankless water heater conversion
Converting from a tank to tankless means more than swapping equipment: the gas line often needs upsizing, the venting changes, a condensate drain and outlet may be needed, and the unit has to be sized for winter. Done right, you get continuous hot water and the floor space back.
Most people consider a conversion when their tank is near the end of its life. It's a good time to do it, since you're paying for an install either way. Here's what changes and what to plan for.
What changes
- Gas line: a tankless burner draws much more gas than a tank. Upsizing the run is common.
- Venting: the old metal flue usually isn't used; condensing units vent through PVC to an outside wall or the roof.
- Shared chimney: if the old tank shared a chimney with a furnace, removing the tank can leave the furnace's venting oversized; that has to be checked.
- Condensate: condensing units need a drain and usually a neutralizer.
- Power: an outlet near the unit.
- Water connections: isolation valves added for future descaling.
Is it worth it?
The U.S. Department of Energy reports tankless units can be 24 to 34 percent more efficient than storage tanks for homes using 41 gallons or less a day, and 8 to 14 percent for heavier users, with most lasting more than 20 years. The up-front cost is higher. For households that run out of hot water, want space, or plan to stay a long time, it often makes sense. For others, a new tank is the better value. Read tank vs. tankless in Colorado homes.
Planning the conversion
We look at where the unit can mount, the gas supply path, the vent route and condensate drainage before recommending a model. If any of those are difficult, it shows up in the price, and sometimes it tips the decision back toward a tank. Better to know before you commit.
How the project runs
- Site visit: we measure the gas run, look at vent routes, check for an outlet and a condensate drain path, and talk through your hot water use.
- Recommendation: a unit size and the work the house needs, so there are no surprises on install day.
- Permit: water heater replacement is permitted work in most metro cities.
- Install day: old tank out, unit mounted, gas, water, venting and condensate connected, then startup and a walkthrough.
Living with tankless
Most people notice two things. Showers don't run out, and the utility room has space again. A few also notice that a quick off-and-on at the tap can bring a short burst of cooler water while the unit relights, and that very low flows, like a trickle at a bathroom sink, may not trigger the burner. Both are normal for tankless and usually fade into the background within a week.
Signs a conversion makes sense
- Your tank is 10+ years old or leaking
- You run out of hot water
- You want the utility room floor back
- You're remodeling
- You plan to stay in the home long term
How a visit goes
- Site assessmentGas, venting, condensate, power and mounting.
- RecommendationUnit size and what the house needs.
- Remove the tank and installIncluding any gas, venting and chimney corrections.
- Startup and walkthroughSettings and descaling.
What's different here
- Cold incoming water. Winter supply water is much colder, which lowers a unit's flow at a given temperature. Size for winter.
- Altitude. Follow the manufacturer's altitude settings or derating.
- Low-NOx rule. New gas water heaters sold in Colorado must meet HB23-1161 limits.
- Shared chimneys. Many older metro homes vent the furnace and water heater together; removing the tank changes the chimney's draft.
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.
- Gas upsizingDistance and pipe size.
- Vent routeNew penetration through wall or roof.
- Chimney correctionsIf a furnace is left alone in an oversized flue.
- Condensate and powerDrain and outlet.
- Unit sizeOutput for your demand.
- Tank removalAccess and disposal.
Questions we hear
How much does a tank-to-tankless conversion involve?
Usually gas line work, new venting, a condensate drain and an outlet, plus the unit. The exact scope depends on your house.
Can I keep my old vent?
Usually not. Tankless units use specific vent materials and routes from the manufacturer.
Will tankless lower my energy bill?
The Department of Energy estimates 8 to 34 percent better efficiency depending on use. Savings depend on your rates and habits.
Is tankless good for a big family?
Yes, if it's sized for simultaneous use in winter. Large households sometimes need a larger unit.
What happens to the space where the tank was?
It's yours. Many people use it for storage once the unit is on the wall.
Does it need a permit?
Yes, in most metro cities a water heater replacement is permitted work.
Will my showers feel different with tankless?
Mostly no, except they don't run out. You may notice a brief cool burst if a tap is turned off and on quickly while the unit relights.
Can I convert to tankless if I have propane?
Yes, propane tankless models exist. The gas supply, regulator and venting have to suit the unit, and propane water heaters have their own Colorado NOx timeline under SB26-002.
Related services
Water Heater Repair & Replacement
Tank water heaters that leak, run out of hot water or won't light. Repaired when it makes sense, replaced when it doesn't.
Tankless Water Heaters
Wall-mounted tankless installs sized for Colorado winters, plus repair and descaling for the units you already have.
Tank-to-tankless water heater conversion near you
We're based in Thornton and work across the Denver Metro:
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