When tankless is not your best choice
We do not install water heaters, so we have nothing to gain from talking you into the expensive option. Here are six situations where converting to tankless is the wrong call, written plainly because almost nobody else in this market has a reason to write it.
Your household barely uses hot water
One or two people who rarely run two hot taps at once will never recover the conversion cost. Tankless earns its money on continuous demand. Without that demand you have paid a premium for a capability you do not use, and the payback period can outlast the unit.
Your gas line cannot carry it
A whole-home tankless unit needs far more gas than a storage tank. If your existing line or meter cannot supply it, you are paying for gas work before you pay for the water heater. This one line item regularly adds hundreds to a couple of thousand dollars, and it is the single most common reason a tankless quote lands far above what the homeowner expected.
Your heater has already failed
A conversion needs permits, venting, possibly gas and electrical work, and sometimes a second trade. A like for like tank swap can often happen the same day. Deciding to convert while your family has no hot water is how people end up rushing a decision they later regret. Replace the tank now, and plan the conversion properly for next time.
You will not keep up with descaling
Tankless units need periodic flushing, and hard water shortens the interval. Skipped maintenance shows up as reduced flow, error codes and a shortened life. If nobody in the house is going to book that service, a storage tank is the more honest choice.
The venting run is awkward
Condensing tankless units need their own venting, and an interior location a long way from an exterior wall makes that expensive. If the unit can go outside or on an exterior wall, the maths changes considerably. If it cannot, price the venting before you commit to the idea.
A heat pump would suit you better
This is the one most often missed. If you have a garage or utility room with room to breathe, a heat pump water heater is usually much cheaper to run than gas tankless and may attract a utility rebate that tankless does not. Homeowners arrive set on tankless because it is the upgrade they have heard of, not because it is the best fit for their house.
What does tankless cost is the wrong question
The unit is frequently the cheapest line on a tankless quote. Gas line work, venting, a dedicated circuit and condensate routing regularly add more than the appliance. That is why two identical houses on the same street can get quotes thousands of dollars apart, and why a national average price tells you almost nothing about your own home.
The question worth asking is what would tankless cost in my house, and the answer depends on things a contractor can only establish by looking at your gas line, your venting route and where the unit would sit.
A tankless heater costs what it costs. The distance from it to an exterior wall, to your gas meter, to your panel and to a drain does not — and that is the entire reason two identical houses on the same street get quotes thousands of dollars apart.
Venting
Sealed and dedicated. It cannot reuse the flue the old tank vented through, so the cost is however far the unit sits from an exterior wall. On an outside wall this is cheap. In an interior closet it is not.
Gas supply
A tankless burner asks for several times what a storage tank does, because it heats on demand instead of slowly. If the existing line cannot carry that, it gets upsized — and not just at the unit. Back to the meter.
Dedicated circuit
Even a gas unit needs power for its controls and fan. The cost is the run from your panel, plus whatever the panel needs if it has no room left.
Condensate drain
A condensing unit produces acidic water as it runs. That needs a drain within reach, often a neutraliser, and sometimes a pump if the unit sits below the nearest drain.
A like-for-like tank swap reuses all four — the existing flue, a gas line already sized for it, no new circuit, no condensate. That difference is the conversion cost, not the appliance.
Who genuinely should go tankless
This is not an argument against the technology. In the right house it is clearly the better buy, and we will tell you so.
- Households where showers, laundry and dishes regularly overlap
- Homes where the existing gas line is already adequate
- Units that sit outside or on an exterior wall, which cuts the venting cost sharply
- Anyone who wants the floor space a tank occupies
- People staying in the house long enough to see the longer service life pay off
- Homeowners who will actually book the annual descaling
How to pressure test a tankless quote
If you are already holding a quote, these four questions separate a real number from an optimistic one. A good contractor will answer all of them without hesitating.
- Is my existing gas line adequate, or does it need upsizing, and is that in this price?
- What venting does this unit need, and is the full run included?
- Does it need a dedicated electrical circuit, and who is running it?
- Is the permit included, and will you schedule the inspection?
A quote that goes quiet on any of these is not a quote. It is an opening position.