Cost guide
What makes a tankless conversion cost more than a tank swap
Tankless is a genuinely different install, not a smaller tank. Most of the price difference comes from three things that happen outside the unit itself: gas supply, venting and condensate.
Equipment pricing is shown in our warehouse. Installed pricing is quoted after we confirm the details below — we do not publish estimated installed prices.
Scope
What's included, and what isn't
Ambiguous scope is where estimates go wrong. Here's the line we draw.
Included in the installed price
- Wall-mounting and securing the unit
- Isolation/service valves for future descaling
- New venting run and exterior termination
- Condensate drain and neutralizer on condensing models
- Commissioning, flow verification and temperature setup
Quoted separately
- Gas line upsizing from the meter, when the existing line cannot carry the BTU load
- Electrical outlet at the unit
- Water treatment where hardness would shorten heat-exchanger life
- Recirculation pump or dedicated return line
- Removal of an abandoned flue or chimney liner work
Cost drivers
What actually moves the number
Two homes on the same street can price differently. These are the reasons why.
Gas capacity
A tankless unit can demand several times the BTU input of the tank it replaces. If the existing line or meter can't carry it, the line gets upsized — this is usually the single largest cost variable.
Can raise the price
Venting path
Tankless units use their own sealed venting to an exterior wall or roof. A short, straight run to an outside wall is inexpensive; a long interior run through finished space is not.
Can raise the price
Condensing vs. non-condensing
Condensing units are more efficient and use less expensive PVC venting, but require condensate drainage and neutralization. Non-condensing units cost less up front and need stainless venting.
Depends on the home
Water hardness
Hard water scales heat exchangers. Treatment or a committed descaling schedule protects the investment; skipping both shortens the unit's life.
Can raise the price
Moving the location
Relocating from a basement corner to an exterior wall means new water, gas and vent runs. Keeping the existing location is always cheaper.
Can raise the price
Long-term operating cost
No standby loss and long equipment life can offset the higher install cost over time, depending on your usage and fuel rates.
Can lower the price
Comparing quotes
Ask every contractor these questions
Including us. A cheaper number often means a smaller scope, not a better deal.
- Ask whether gas line sizing was calculated or assumed.
- Ask whether isolation valves for descaling are included — retrofitting them later costs more.
- Ask where the vent terminates and how it will look on the exterior.
- Ask what the maintenance interval is and what a descale visit involves.
More guides
Keep reading
What a water heater replacement actually costs
An honest breakdown of what changes the cost of replacing a water heater in DC, Maryland and Northern Virginia — equipment, code work, venting, permits and access.
ReadHybrid heat pump water heaters: cost, rebates and the fine print
What a hybrid heat pump water heater install involves in the DMV — electrical, space, condensate and noise — plus how federal tax credits and utility rebates change the math.
ReadWhat a water heater repair costs — and when it stops being worth it
Thermocouples, elements, gas valves and leaking tanks: which water heater repairs are worth doing, which aren't, and what drives the price of a repair visit in the DMV.
Read
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