Yes, a tankless water heater can be installed in a closet, provided there is adequate ventilation and clearance according to local building codes.
Yes, you can install a tankless water heater in a closet if it meets specific safety and clearance requirements. Proper venting, combustion air supply, and local building codes must be followed to ensure safe operation. This guide covers everything you need to know about closet installations.
Closet Installation Requirements for Tankless Water Heaters
Tankless water heaters can be installed in closets when these conditions are met:
- Proper venting: Must use approved vent materials (stainless steel or PVC for condensing units)
- Combustion air: Requires dedicated outside air supply or sufficient closet volume
- Clearances: Manufacturer-specified spacing from walls and combustible materials
- Access: Minimum service clearance of 24 inches in front
- Drainage: Condensate drain required for condensing models
Venting Solutions for Closet Installations
There are two main venting approaches for closet installations:
| Vent Type | Materials | Best For |
|---|---|---|
| Direct Vent | Stainless steel | Non-condensing units |
| PVC Venting | Schedule 40 PVC | Condensing units |
As noted in our tankless valve kit guide, proper venting is critical for safe operation.
Combustion Air Requirements
Tankless water heaters need adequate combustion air:
- Direct vent models: Pull air from outside through concentric vent or separate intake
- Atmospheric vent models: Need sufficient closet volume (typically 50 cubic feet per 1,000 BTU)
According to Rinnai’s installation manual, their units can be closet-installed when properly vented.
Clearance Requirements
Typical clearance specifications:
- 6 inches from sides
- 12 inches from front
- 24 inches above for vent access
- No storage within 12 inches
Special Considerations for Closet Installations
Condensation Management
Condensing models produce acidic condensate that must be:
- Neutralized with a condensate neutralizer kit
- Piped to an approved drain
Noise Considerations
Tankless units can be noisy during operation. In bedroom closets:
- Consider sound insulation
- Install vibration pads
- Choose quieter models
Alternatives to Closet Installation
If closet installation isn’t feasible, consider:
- Exterior mounting: Many units are designed for outdoor installation
- Garage installation: Often easier to meet venting requirements
- Attic installation: Requires proper drainage and access
For small spaces, compact tankless models may be a better solution.
Professional Installation Recommended
Due to complex venting and gas requirements:
- Always hire a licensed plumber
- Obtain necessary permits
- Schedule final inspection
Proper installation ensures safety and maintains warranty coverage. As one installer noted: “I’ve installed many tankless water heaters in closets and they always pass inspection when done correctly.”
