Tank or tankless water heater?

Start with your busiest normal hot-water use

Write down which showers, faucets and appliances normally need hot water together. Explain whether the existing problem is running out, waiting at one outlet, changing temperature or no hot water anywhere. Those observations are more useful than asking for the biggest unit.

A tank stores heated water. Tankless equipment heats water as it passes through, within the capacity of the selected unit. Neither label alone establishes how the system will serve your household. If the current unit is leaking, use the water-heater leak guide before treating this as a planned upgrade.

How should the installer explain capacity?

For a storage heater, ask how the proposed model supplies the household's peak use and recovers afterward. Tank volume alone does not describe the whole performance.

For tankless equipment, ask for the flow available at the temperature rise your installation needs. That rise is the difference between incoming water temperature and the required heated-water temperature. Building America guidance specifically includes colder winter incoming water when sizing gas tankless units. A headline flow figure without its conditions is not enough to compare two proposals.

Describe the fixtures actually used together. Ask what would happen if another outlet is opened, rather than accepting an unqualified promise of unlimited hot water.

What changes besides the heater?

For a gas tankless conversion, Building America guidance calls for checking gas supply capacity, equipment and vent clearances, and condensate removal for a condensing model. Ask which of these are included in your quote. Do not assume an existing connection is suitable for a different unit.

For either option, request the exact model and a drawing or written description of its location and access. Ask who handles any required electrical, venting, plumbing, permit or inspection work. Clarify removal, disposal and finish repairs. Different energy sources and buildings need different assessments; this is not a conversion procedure.

A storage tank can also be a heat-pump model

“Tank” does not mean only a conventional gas or resistance-electric heater. ENERGY STAR explains that a heat-pump water heater transfers heat from surrounding air into water stored in a tank. It is another option to discuss when the property can accommodate the selected model.

Ask which space and operating conditions the recommendation assumes. Compare the exact equipment rather than treating every storage design as having the same energy use. A tank-versus-tankless sales comparison may leave out a suitable third option.

Compare ownership costs on the same basis

1. Installed total, with the exact equipment and all required changes.
2. The energy rate and household-use assumptions behind any savings estimate.
3. Model-specific maintenance, its expected cost and who performs it.
4. Equipment coverage separately from installation labor and call-out terms.
5. The assessment fee and how additional work needs your approval.
6. Documents, operating instructions and commissioning checks handed over at completion.

Before deciding

Ask each proposer to explain how its recommendation addresses the same use pattern and building constraints. If one quote assumes fewer simultaneous outlets or leaves conversion work out, resolve that difference before comparing totals.

ENERGY STAR's gas tankless guidance explains reduced standby loss, but that does not establish your installed payback or bill saving. Request the assumptions in writing and compare them with your actual energy tariff. The estimate checklist helps you ask for like-for-like work; the water-heater overview covers current repair symptoms.

For a Topeka address, the local water-heater guide explains why the address jurisdiction matters when arranging replacement work. For a Lawrence property, the water-heater replacement guide sets out the local approval and installed-scope questions. Use the guide for the property’s location rather than applying one city’s process elsewhere.

Call about water-heater replacement

Have the current model and the household's normal hot-water use ready. Ask for an assessment and a written installed scope before choosing equipment.