Tips and Techniques

HRVs and ERVs

HRVs and ERVs

  • Supply fresh air to places where people spend the most amount of time and exhaust air from places where moisture and odors are generated
  • Balanced ventilation systems are designed to operate slowly and steadily. To evauate a bathroom quickly, a customer will want the option of additional exhaust.
  • Use rigid duct wherever possible for the best performance.
  • The Panasonic ERV is perfect for use in master bedrooms, home offices, hobby rooms, and any other room where small amounts of fresh air is beneficial. It can be mounted horizontally or vertically on a side wall. 


  • Great for single point or spot ventilation
  • Use timers or speed controls for continuous or intermittent whole house ventilation
  • Use rigid duct wherever possible for the best performance.
  • Think in straight lines - every elbow reduces CFM.
  • Use a short piece of flex duct at the fan or HRV connection to break vibration noise in the duct
  • Support flex duct with strapping to avoid dips.
  • Insulate any ducts in un-conditioned space to avoid condensation and energy loss
  • Seall all joints, seams, and connections with mastic. Avoid using duct tape on anything except duct.
  • Two 45 degree elbows allow better airflow than one 90 degree elbow.
  • Run duct in inside walls if possible. Make duct runs continuous. Wall cavities are NOT ducts.
  • Run duct all the way to the outside of the building. Attics, basements, and crawl spaces are NOT outside of the building.
  • Fans with short duct runs perform better - locate ventilation equipment to achieve shorter runs and better performance.



  • With +/-8' ceilings and less than 15 equivalent feet of duct, multiply the square footage of the room by 1.10 and install the next size fan size available.
  • ​EXAMPLE: 80 square foot bathroom x 1.10 = 88 square feet, so look for a 90 or 110 CFM fan. If the ceiling is higher or vaulted, or the ductwork is longer, increase your selection by one size.


  • Great for ventilating either a single point or multiple points.
  • Can be used for range hood ventilation - taking much of the noise out of the kitchens.
  • Can be used to boost dryers with long runs.
  • Can be used to circulate heat and AC for overall balance. 
  • Can be used for sub-slab or crawl space ventilation.
  • Use timers or speed controls for continuous or intermittent whole house ventilation.


  • Ventilation without adequate make-up air can create negative pressure in a room or house.
  • A 30" door with a .5" gap only allows 25 CFM of makeup air. A 30" door with a 1" gap allows 50 CFM of make up air.
  • Consider installing a Pressure Balancing pathway to relieve pressure.


  • Seal all seams and joints by applying mastic with a brush.
  • Use mastic along with mesh tape to bridge the gap and strengthen the seal.
  • Use Butyl Tape as an alternative to seal seams.


  • Single component foam is moisture cured. Use a spritzer during very cold, dry weather to induce curing.
  • Keep the can of foam attached to the gun between uses to eliminate waste.
  • Cleaner should be used infrequently.
  • Put an electrical nut filled with petroleum jelly on the tip of your foam gun. This will protect the tip from damage and keep it sealed from moisture penetration. Be sure to pull the spring out of the wire nut to avoid damaging the gun.


  • Temperature is CRITICAL. Materials may be stored below 70 degrees F but the core temperature must be brought to a minimum of 70 degrees prior to application.
  • EFI is unique in that we offer a "warm room" to house foam that our customers intend to use same day. Ask for "warm" foam the next time you pick up!
  • Closed cell foams can be used to air seal and as a vapor barrier because they are less vapor permeable than open cell foams. 
  • Kits should be used within two weeks once factory seals are broken.
  • With larger kits, hoses can be transferred to subsequent kits up to 5 times.


  • Use wide V-Seal on bottom sils, the top of windows, and sash sides. Use narrow V-Seal on meeting rails.


  • Photoelectric sensors detect smoldering, slow moving fires while Ionization sensors detect faster moving fires with flames. Consider buying combination units that ensure maximum safety.
  • Check with local code officials to make sure you are in compliance with local regulations.


  • If you're not sure what the flow rate is for an existing showerhead, you can estimate the Gallons Per Minute by filling a one gallon bucket and timing it with a stopwatch. If the bucket fills in about 20 seconds, you have a 3.0 GPM showerhead.


  • Not all dimming switches are compatible with dimming CFLs. Buy a small quantity of dimming CFLs and try them in your application before re-lamping a large area.
  • Not all CFLs are outdoor/wet rated. Check the specifications for an outdoor rating and a minimum start temperature that makes sense for your region. 

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