4.1 Water Heater Installation, Location, Access, and Clearances
Key Takeaways
- IPC 501.5 requires water heaters to be third-party certified, and IPC 502.1 requires installation in accordance with the manufacturer's instructions.
- IPC 502.3 requires an attic passageway not less than 30 inches high and 22 inches wide, not more than 20 feet long, with continuous solid flooring not less than 24 inches wide.
- IPC 502.3 and 502.5 both require a level working or service space not less than 30 inches by 30 inches at the front or control side of the appliance.
- IPC 501.3 requires a drain valve at the bottom of each tank-type water heater and storage tank, with an inlet not less than 3/4-inch nominal iron pipe size and male garden hose threads on the outlet.
- IPC 503.1 requires a cold water branch line valve located near the water heater, serving only that heater, with access on the same floor level.
Scope and the seven items
IPC 501.1: Chapter 5 governs the materials, design and installation of water heaters and the related safety devices and appurtenances. On the Colorado Journeyworker exam this area carries 7 scored items — more than General Regulations, Traps, Indirect Waste or Isometrics individually. The items concentrate on Section 504 safety devices, which this chapter covers next, and on the installation and access rules below.
Note the boundary. IPC 502.1 routes the fuel-side rules elsewhere: oil-fired water heaters to the International Mechanical Code, electric to NFPA 70, gas-fired to the International Fuel Gas Code, and solar thermal to the IMC and ICC 900/SRCC 300. IPC 502.1.1 sends elevation of ignition sources and mechanical damage protection to the IMC and IFGC as well. The IPC itself does not set the "18 inches above the garage floor" rule; that belongs to the fuel gas and mechanical codes.
Certification, labeling and marking
| Section | Requirement |
|---|---|
| 501.5 | Water heaters shall be third-party certified |
| 501.7 | Storage tanks and water heaters for domestic hot water shall have the maximum allowable working pressure clearly and indelibly stamped in the metal or on a permanently attached plate, positioned for access from the outside so inspection and reinspection are readily possible |
| 501.8 | Hot water supply systems shall have automatic temperature controls adjustable from the lowest to the highest acceptable setting for the intended operating range |
Location and access
IPC 501.4 states the governing principle: water heaters and storage tanks shall be located and connected so as to provide access for observation, maintenance, servicing and replacement. Every specific access rule flows from it.
IPC 502.5 Clearances for maintenance and replacement: appliances must be accessible for inspection, service, repair and replacement without disabling the function of a fire-resistance-rated assembly and without removing permanent construction, other appliances, or any piping or ducts not connected to the appliance being serviced. A level working space not less than 30 inches in length and 30 inches in width must be provided in front of the control side.
Attic installations — IPC 502.3
The most commonly tested set of dimensions in the chapter:
| Requirement | Minimum |
|---|---|
| Opening and unobstructed passageway | large enough to remove the water heater |
| Passageway height | 30 inches |
| Passageway width | 22 inches |
| Passageway length | not more than 20 feet, measured along the centerline from the opening to the heater |
| Continuous solid flooring in the passageway | not less than 24 inches wide |
| Level service space at the front or service side | 30 inches long by 30 inches wide |
| Clear access opening | not less than 20 inches by 30 inches, where those dimensions allow removal |
The pattern to remember: 30 high, 22 wide, 20 long, 24 floor, 30 by 30 service, 20 by 30 opening. Note that the passageway width (22 inches) and the access opening (20 by 30 inches) are different numbers measuring different things.
Prohibited and restricted locations
- IPC 502.2: water heaters using solid, liquid or gas fuel shall not be installed in a room containing air-handling machinery where that room is used as a plenum. Electric heaters are not caught by this sentence.
- IPC 502.4 Seismic supports: where earthquake loads apply under the IBC, water heater supports must be designed and installed for the seismic forces per the IBC.
- IPC 307.4 (from Chapter 2 of this guide) forbids adding loads such as a water heater to a truss without verification the truss can carry it — the rule that governs attic platform framing.
Connections
IPC 503.1 Cold water line valve is short and precise, and each clause is testable:
The cold water branch line from the main water supply line to each hot water storage tank or water heater shall be provided with a valve, located near the equipment and serving only the hot water storage tank or water heater. The valve shall not interfere or cause a disruption of the cold water supply to the remainder of the cold water system. The valve shall be provided with access on the same floor level as the water heater served.
Three failures this rule addresses: a shutoff so far away it is unusable, a shutoff that also kills the building's cold water, and a shutoff in a crawl space under a first-floor heater.
IPC 503.2 Water circulation: the method of connecting a circulating water heater to the tank must provide proper circulation through the heater, and the pipe or tubes for appliances drawing from the heater or storage tank must comply with the code for material and installation.
IPC 501.3 Drain valves: a drain valve for emptying must be installed at the bottom of each tank-type water heater and hot water storage tank. The inlet is not less than 3/4-inch nominal iron pipe size and the outlet has male garden hose threads.
Water heater as a space heater — IPC 501.2
Where a combination potable water heating and space heating system requires water for space heating at temperatures greater than 140 degrees F, a temperature-actuated mixing valve conforming to ASSE 1017 must limit the water supplied to the potable hot water distribution system to 140 degrees F or less. The potability of the water must be maintained throughout the system, and the system requirements otherwise follow the International Mechanical Code.
IPC 501.6 sets the companion limit for tankless heaters: water from tankless water heaters shall be not greater than 140 degrees F where intended for domestic uses. That does not supersede the 120-degree protective shower valve requirement of IPC 412.3.
Keep the two numbers apart: 140 F is the ceiling on what the heater or the system may deliver into the distribution piping; 120 F is the ceiling at a shower or tub valve outlet; 110 F defines the top of tempered water for public hand washing and bidets.
Hot water supply — IPC 607
Chapter 6 completes the picture, and its rules are scored under Water Heaters as often as under Water Supply:
- 607.1: in residential occupancies hot water must be supplied to fixtures and equipment used for bathing, washing, culinary purposes, cleansing, laundry or building maintenance. In nonresidential occupancies, hot water is required for culinary purposes, cleansing, laundry and building maintenance, and hot or tempered water for bathing and washing.
- 607.1.1: a water heater thermostat control may serve as the temperature-limiting means for maximum delivery temperature only where the heater complies with ASSE 1082 or ASSE 1085.
- 607.1.2: tempered water is controlled by an ASSE 1070 device set to not greater than 110 F, an ASSE 1017 thermostatic mixing valve, or an ASSE 1082 or ASSE 1084 water heater — and none of that supersedes the 412.3 shower valve.
- 607.2: the developed length of hot or tempered water piping from the source to the fixtures shall not exceed 50 feet. Recirculating system piping and heat-traced piping count as sources of hot water, which is how large buildings comply.
- 607.2.1.1: pump controls circulating water between a heater and a storage tank must limit pump operation to not greater than 5 minutes after the end of the heating cycle.
- 607.2.1.2: a demand recirculation system's pump control must start on a user signal, presence sensing or flow sensing, and must limit the temperature of water entering the cold water piping to 104 F.
- 607.2.2: where a temperature-actuated mixing valve is used with a recirculating pump, the hot or tempered water return line must be routed to the cold water inlet pipe of the water heater and to the cold water inlet or hot water return connection of the mixing valve.
- 607.4: fittings, faucets and diverters must be installed and adjusted so hot water flow corresponds to the left-hand side of the fitting — except ASSE 1016 or ASME A112.18.1 shower and tub/shower mixing valves, where the flow corresponds to the markings on the device.
- 607.5: piping to the inlet of a water heater and piping conveying heated water must be insulated per the International Energy Conservation Code.
Insulation of unfired tanks
IPC 505.1: unfired hot water storage tanks shall be insulated to R-12.5.
A quick field checklist for a replacement
- Third-party certified heater, working pressure marked and readable from outside (501.5, 501.7).
- Cold water branch valve near the heater, serving only the heater, accessible on the same floor (503.1).
- Drain valve at the bottom, 3/4-inch inlet, hose-thread outlet (501.3).
- 30 by 30 inch level working space at the control side (502.5).
- If in an attic: 30-inch-high, 22-inch-wide passageway, 20 feet maximum, 24-inch continuous flooring, 20-by-30-inch opening (502.3).
- Not in a plenum room if fuel-fired (502.2).
- Relief valve, discharge piping, pan and thermal expansion control per Sections 504 and 607.3 — the next two sections of this guide.
What is the minimum height and width of the passageway to a water heater installed in an attic?
Where must the cold water shutoff valve for a water heater be located under IPC 503.1?
A combination potable water heating and space heating system requires water above 140 degrees F for space heating. What does IPC 501.2 require?
Under IPC 607.2, what is the maximum developed length of hot or tempered water piping from the source of hot water to the fixtures served?