Central plant
Boiler or tank plant
One or more gas boilers or commercial water heaters feed storage tanks and a recirculation loop. Suits mid-size and large buildings with a mechanical room.
Water Heaters for California Apartment Buildings
Choosing a water heater for an apartment building starts with how the building makes hot water today. We help California owners and managers compare central plants, boilers and in-unit heaters, then connect them with a qualified contractor.
For owners, managers and authorized representatives of California multifamily buildings.
- California multifamily onlyApartment, condo and affordable housing buildings.
- Central plants and in-unit heatersWater heaters, DHW boilers and central heat pumps.
- Incentive check includedCurrent program status reviewed for your address.
- Free, no-obligation assessmentFor owners, managers and authorized representatives.
Three ways an apartment building makes hot water
Almost every building fits one of these. Which one you have decides what a replacement involves.
Central plant
Central heat pump plant
Heat pumps heat water into larger storage. Suits owners electrifying a central system who have outdoor or ventilated space and electrical capacity.
In each apartment
In-unit tank or tankless
A heater serves each home, often in a closet or on a balcony. Suits buildings without central piping, but every replacement needs access to the unit.
Central or in-unit: how to tell what your building has
Five quick checks answer most of it. If the answers conflict, the building may have a mix, which is common after partial renovations.
- Mechanical or boiler room with large tanks and a pump on a return line points to a central plant.
- A water heater closet in each apartment, or units on balconies, points to in-unit equipment.
- Gas meters: one large meter for the building often serves a central plant; a meter per apartment often serves in-unit heaters.
- Who pays for hot water fuel. Owner-paid usually means central; resident-paid usually means in-unit.
- Nameplates and permits. Model numbers and past permits confirm type, input rating and age.
| Question | Central plant | In-unit equipment |
|---|---|---|
| Where is hot water made? | A shared plant supplies many apartments through distribution piping. | A dedicated heater serves each home. |
| Where does work happen? | At the plant and its connections; a cutover affects many residents at once. | Inside each home, with access appointments and repeated installs. |
| What changes for a heat pump? | Equipment location, storage and recirculation need a coordinated design. | Each location needs a check for space, airflow, sound and power. |
Choosing the best water heater for an apartment building
For a central system there are three common routes. None is best everywhere; the building's space, gas and electrical service usually decide it.
| What to compare | Gas condensing heaters with storage | Tankless array | Central heat pump water heater |
|---|---|---|---|
| First cost | Depends on whether venting, gas piping and tanks can be reused. Condensing units usually need new venting and a condensate drain. | Several units on a manifold, often with a buffer tank. Gas supply size and venting for each unit drive cost. | Heat pumps, larger storage, a recirculation strategy and often electrical work. Usually the largest scope. |
| Operating cost | Set by gas prices and how efficiently the plant runs at part load. | Set by gas prices; short, frequent firing can add maintenance. | Set by electricity rates and the time of day the system heats. |
| Space | Similar footprint to an existing gas plant. | Compact wall-hung units; buffer tank if used. | Outdoor or ventilated space for heat pumps, plus more storage than a gas plant. |
| Electrical need | Controls and pumps only. | Controls and pumps only. | A dedicated electrical service review. Panel or service upgrades are common questions. |
Compare central heat pump equipment How central systems are sized
Signs the system is near the end of its life
- Water on the floor around a tank, or rust at fittings and seams
- Residents running out of hot water at morning and evening peaks
- Rusty or discolored hot water
- Repeated ignition, burner or control faults
- Replacement parts that are hard to find or discontinued
- Service calls getting more frequent and more expensive
One symptom is not proof. A failed mixing valve or recirculation pump can look like an undersized heater, so the survey checks the whole system.
What a replacement project involves
The same five stages apply whether you replace like-for-like or convert to a heat pump. The occupied-building cutover is where most of the planning goes.
- Site survey. Equipment, piping, recirculation, venting, gas and electrical service are recorded, along with the access route.
- Sizing and design. Demand, storage and recovery are worked out for the building, not copied from the old nameplate.
- Permits. The contractor pulls the local permits the scope needs and checks equipment against current code.
- Occupied-building cutover. Resident notice, phasing and any temporary hot water are agreed before the shutdown date.
- Commissioning and handover. The new system is tested and adjusted, and your team receives the operating and maintenance records.
Who we help
The form asks for these details, so a contractor can tell quickly whether the project fits.
A good fit
- Apartment, condo/HOA, senior and affordable housing buildings
- Typically 20 or more apartments
- Anywhere in California
- A central plant, DHW boiler or heaters in each unit that have failed, are failing or are due for replacement
Not what this is for
- Single-family homes
- Tenants: please talk to your property manager
- Restaurants, offices and other non-residential buildings
- Same-day emergency repair dispatch
How an assessment request works
The assessment and quote are free, with no obligation. Nothing is booked until you agree a scope with the contractor.
Send the building details
Two short steps: the equipment, unit count, location and who should receive the follow-up.
We check the fit
California, multifamily, and an owner, manager or authorized representative making the request.
A contractor follows up
With your consent, a qualified California contractor partner contacts you about the property and a site survey.
Compare complete scopes
The survey informs the proposal: options, the cutover plan and any incentive open for the property.
Guides for owners and managers
Commercial water heater replacement
Replacing central or multi-unit water heaters in an occupied building.
Boiler replacement cost
What drives the price of a boiler or water heater replacement, and how to get a firm quote.
Commercial water heater sizing
The inputs a designer needs to size central water heating for apartments.
Multifamily water heater rebates
California programs to check, with dated status and an eligibility checklist.
Planning a replacement at an occupied building?
Send the building details once. Qualified requests go to a California contractor partner for a free, no-obligation assessment and quote.
Owner questions
Apartment building hot water questions
How do apartment building boiler systems work?
In a central domestic hot water system, a boiler or commercial water heater heats water that is held in one or more storage tanks. A pump moves it around a recirculation loop so hot water reaches distant apartments quickly. Some older buildings also have a boiler for space heating through radiators or fan coils. That is a separate system with different replacement questions.
How big of a hot water heater does a multifamily building need?
There is no single size per apartment. A designer works from peak demand (occupancy and fixtures), the balance between storage and recovery, and the heat lost in the recirculation loop. The sizing guide explains each input, and the assessment confirms the numbers for your building.
Is central or in-unit hot water better for an apartment building?
It depends on what the building has now. Central plants keep equipment and maintenance in one place but rely on distribution piping. In-unit heaters avoid long pipe runs but need access to every home for service and replacement. Switching between the two changes piping, venting, electrical and utility arrangements.
Can hot water stay on during a replacement?
Often the cutover can be staged, or a temporary water heater or boiler can carry the building. Whether that works depends on the plant room, connections and access. The contractor confirms the plan after a site survey.
Two short steps
Request a free assessment
The assessment and quote are free, with no obligation. Tell us about the building and the hot water equipment that serves it. An uncertain equipment age is fine.
- Central plants, DHW boilers and in-unit heaters at California multifamily properties
- With your consent, details go to a qualified California contractor partner who follows up
- Helpful later: nameplate photos, recent service notes and access constraints
This form is not an emergency dispatch service. If hot water has stopped, use the building's existing maintenance contacts.