Our objective is to help educate those that manufacture, design, sell, and install kitchen range hoods and provide a more practical solution to code-required make-up air in cold climates.

Thermolec is headquartered in Montreal, Canada and has been designing and manufacturing electric heating products since 1973. They are an industry leader in supplying heating equipment to manufacturers, distributors, and contractors throughout North America and has customers on all seven continents. They specialize in providing high-quality equipment for the residential, commercial and industrial HVAC industry.

We at Shady Oak are thrilled to be partnered with their local supplier, EP Sales, to offer a compact, relatively low-cost, tempered MUA solution to our Midwest network.

Why is Make-Up Air (MUA) necessary?

The International Residential Code (IRC), and other local codes, require fresh air intake to make up for air that was excessively evacuated by appliances, such as range hoods and bath fans, to prevent back-drafting of combustion devices/appliances in the home.

The two main models are FER and NER (with several sub-models under each):

FER (aka Mini MUA) has a built-in fan and is generally appropriate for making up 600 cfm or less -- Note: it is not a 1:1 ratio between the range hood's maximum cfm rating and the amount of MUA needed - the on-site HVAC specialist can determine, between the local codes and home design/layout, how much MUA is necessary for your specific application. FER models have a maximum temperature rise up to 100ºF.

NER is used for a more robust application to make up between 600-2,500 cfm, in which case the fan is a separate, remote unit (the NER and remote fan are priced together, but they are two separate units). NER models have a maximum temperature rise up to 75ºF.

Both FER and NER units include the following features:

  • Modulated Heat
  • Self-contained Cabinets
  • Duct Temperature Sensor
  • Freeze Protection
  • Current-sensing relay to energize the MUA system when the hood is on
  • Washable Filter

Sizing your MUA Unit

Use steps 1-3 -OR- A. & B. to figure out which Thermolec unit is appropriate for your application:

  1. Choose desired temperature rise (ΔT) which is the difference between the coldest outside air temperature and desired incoming air temp.
  2. Determine how much MUA is needed (ask your HVAC specialist).
  3. Use the following formula to determine required Kw size:
    • ΔT × CFM needed ÷ 3,412 (BTU per Kw) = Kw
    • Example: In an application where the coldest outdoor temp reaches -20ºF and the desired delivery air temperature is 60°F, then ΔT is 80°F. And if 200 cfm of make-up air is needed, then your calculation and result is as follows -
      • 80 × 200 ÷ 3,412 = 4.69 Kw - round UP to the next increment listed on the spec sheet. FER-8-6-240/1 would be appropriate in this case

- OR -

A. Determine how much MUA is needed (ask your HVAC specialist). For example, if 500 cfm of MUA is needed, then round UP to the next available cfm rating which is 600. There are 3 options at this rate: FER-12-10-240/1, FER-12-15-240/1, and FER-12-20-240/1.

B. Make your choice depending on desired maximum ΔT: 50°F, 75°F, or 100°F