Water heater buying guide
There is a dizzying array of water heaters on the market today. They run on a variety of fuels—from propane to oil, electricity, and on-site solar energy. Use this guide to learn about two of the cleanest types: heat pump water heaters and solar hot water systems.
Heat pump water heaters
Heat pump water heaters use electricity to pull heat from the surrounding air and transfer it to water enclosed in a tank. These systems use the same technology found in air-source or ground-source heat pumps, which transfer heat from one location to another and condition the space around them.
Consider these factors prior to purchase:
- Location: To maximize energy savings, install units in a space where the temperature stays above 50 degrees. Heat pump water heaters are better suited to basements because of their cooling effect and noise, about as loud as a dehumidifier.
- Size: Select the smallest-sized water heater to meet your household’s needs. To correctly size your system, look at the First-Hour Rating (FHR) on the Energy Guide label. It represents the number of gallons of hot water the heater can supply per hour (starting with a tank full of hot water). Talk to a contractor, manufacturer, or retailer to determine what FHR and size is appropriate for you.
- Spacing: Provide at least 750 cubic feet of space around the unit (the size of a 10-square-foot room), and follow the manufacturer’s recommended clearances from walls and ceilings for proper circulation.
- Condensation drain: Drainage must be accounted for, as a heat pump water heater produces condensate that must be pumped outside or passively drained into a sink, washing machine drain, or floor drain.
- Installation and maintenance: It’s best to hire a licensed plumber who has attended installation training from the product’s manufacturer. Once the system has been installed, maintenance is relatively straightforward, requiring regular cleaning of air filters.
Solar hot water heaters
Solar water heating systems rely on solar energy (i.e., free fuel from the sun) to generate heat. Roof-top solar collectors heat water that is then transferred (either actively or passively) to a storage tank. During Vermont’s summer months, solar hot water systems can meet almost 100% of a household’s hot water needs. In the winter months this percentage drops, requiring a back-up system for cloudy days or when usage is high.
- Location: Solar hot water systems feature components located throughout the house. They include roof-top solar collectors, water pipes (typically roof-to-basement), a storage tank, and often a backup unit.
- Size: The size of your roof-top collector must align with your storage tank, and vice versa. Work with a contractor to determine system requirements and sizing based on your roof’s orientation, your household’s hot water needs, and the average available sunlight where you live.
- Installation and maintenance: Proper installation of a solar hot water system and its components is essential. To qualify for our rebates, your system must be installed by one of the State’s preferred providers, who can evaluate the suitability of your home for solar hot water. The maintenance required will depend on your system. An active system that pumps water from the collectors to the tank in your basement requires more maintenance than a passive system that allows heated water to rise from where it’s collected to where it’s stored.