Heat Pump Water Heater Sound Mitigation Strategies

As more homes move to heat pump water heaters (HPWHs), we hear from clients that some homeowners are still skeptical about making the shift. Their concerns aren’t always performance based, but rather they are concerned about noise levels. Water heater unit selection and design strategies can have a significant impact in reducing noise transmission.

The sound associated with HPWHs varies by make and model, but most are rated between 45db and 55db, similar to the noise level of many dishwashers or clothes dryers. If the HPWH is making noise at higher levels or if the unit is making rattling or high-pitched noises, the unit should be inspected for improper function. NEEA-rated water heaters have sound ratings, which can be helpful when selecting a water heater. To find the sound rating of NEEA-rated water heaters:

  • Look for HPWHs rated either Tier 4 or Tier 5 for the quietest water heater options

You’ll notice on the Qualified Products List that split system HPWHs, like Harvest Thermal or SANCO2, don’t list an indoor rating. These units can have the outdoor unit ground-mounted outside and located away from the occupant’s favored rooms, while the silent hot water storage tank with no moving parts can be located indoors and as close as possible to the hot water fixtures.

In general, regardless of which HPWH is specified for a project, there are some best practices that can help alleviate noise perceived by the occupants.

  • Install the unit in a garage or large utility room or closet that is acoustically isolated from the rest of the house. Don’t install units along bedroom walls or on the backside of bedroom walls.

  • Make sure the unit is installed on the ground level. Use R-10 rigid foam base (25 psi closed cell) on slab-on-grade construction. Additionally consider using a sound/vibration isolation base for installations on raised floors.

  • Use PEX piping between the unit and other non-flexible piping. Flexible PEX piping can help isolate sound transmitting into rigid pipe and other structural fasteners.

  • Use flexible seismic strapping or use sound/vibration isolation fasteners where the metal seismic strapping is attached to the structure.

  • If using duct kits, install flexible (R-6) ducts for all, or a portion of, the duct intake and exhaust and use sound isolation fittings at the duct terminations.

Original source: Rheem marketing material

For sound sensitive homeowners and occupants, consider using sound transmission class (STC) reduction construction techniques both at the sound source and at the receiver (occupant) favored spaces, in addition to the recommendations above.

A combination of these strategies can be applied to create a solution addressing noise concerns, without having to compromise on the energy efficiency benefits that come with installing a heat pump water heater in your project.

HarborWalk Plaza Awarded LEED Silver

We’re delighted to announce that HarborWalk Plaza in Morro Bay has been awarded LEED Silver certification! The boutique hotel and retail project is the first commercial LEED-certified project in Morro Bay.

Co-Owners Cherisse Hansson and Travis Leage noted, “With our deep roots in this community and our commitment to caring for the environment for future generations, LEED certification was a natural fit for our project. We are thrilled to achieve this milestone.”

Specific achievements for HarborWalk Plaza include:

·      Low-flow plumbing fixtures, drought-tolerant plants and rainwater catchment reduce water use by 45%.

·      Efficient heat pump mechanical systems, LED lighting, excellent insulation, high-performance windows and strategic overhangs reduce energy and increase thermal comfort. With the addition of solar panels on the roof, total energy use has been reduced by 55%.

·      Light-colored roof and paving materials reduce the heat-island effect for the project, helping keep the site cool and aligned with natural conditions.

·      Indoor health for occupants is improved with low-emitting finishes, individual thermal controls and excellent daylighting in guest rooms and public spaces.

Financial Savings through LEED and Commissioning

In addition to providing LEED certification services, our team worked with Larry Myrick to provide fundamental and enhanced commissioning of energy systems, which turned out to be particularly impactful. During commissioning, we observed that the anticipated energy savings from the PV system were not being achieved; through troubleshooting, we helped identify an oversight in the utility connection. Based on the feedback, the grid-tied connections were reset, and the owners are now seeing the savings as anticipated.

Congratulations to the entire HarborWalk Plaza Team!

·      Owner-Builder: TLC Family Enterprises

·      LEED Certification: In Balance Green Consulting

·      Architect: Chris Parker

·      Mechanical Engineer: BMA Mechanical +

·      Electrical Engineer: JMPE Electrical Engineering

·      Stormwater: Ahsirt Engineering

Girls Build Summer Academy - Lessons in Insulation

In collaboration with 3C-REN, we were delighted to be invited to present again at the annual Girls Build Summer Academy here in San Luis Obispo.  Organized by Cal Poly Construction Management, and funded in part by local industry members, the five-day camp hosts young women from all over southern California. 

The week’s activities run the gamut from “Tool training” to plumbing and electrical projects to planning, designing and building playhouses that will be donated to local families through Habitat for Humanity.

In Balance was offered a chance to speak about energy efficiency and the role of different insulation types in achieving a project’s goals. We know…. exciting stuff! Luckily, the camp organizers were up for a hands-on approach to the material, so after a couple of slides (ok thirteen), the campers got to dig into loose-fill cellulose, cut denim batts and try their hands at applying house wrap around pesky penetrations.

A big shout-out to Mike Horgan of Cairn Collaborative Design Build for providing supplies and construction wisdom, both in abundance!

Energy Code & CALGreen Blogs at 3C-REN

Looking for more helpful tips for compliance with the Title 24 Energy Code or CALGreen? As part of our partnership with the Tri-Counties Regional Energy Network (3C-REN), our Code Coach team writes a monthly blog posted on the 3C-REN website. Recent topics include:

Certified Energy Analyst (CEA), Who They Are and Where to Find Them provides information about the Title 24 energy standards professional accreditation program – a brief history, training required, scope of work and how to find one.

Are Water Submeters Required for an ADU? originated from a local jurisdiction requesting clarity on a CALGreen submeter requirement and if it would apply to a new ADU.

Checking for Compliance with Title 24 Commissioning Requirements highlights key processes and documents to keep you on track for commissioning.

Other recent topics include Global Warming Potential for Refrigerants, Title 24 forms for window replacements, HERS requirements for kitchen exhaust, and why there are two sets of climate zones overlapping in California. Check out the full library at 3C-REN.org.