Best Method for Bringing in Makeup Air
So we have a 600 CFM vent hood going into a “pretty good” house, new construction climate 6b.
I’ve read the pros and cons of using a vent hood and due to our cooking habits we feel the vent hood is a necessary evil although I’ve been pushing for something in the 400 cfm range my wife found one to meet her style requirements that is 600 cfm and doesn’t come with a smaller exhaust.
The hood can be bought with an interlinked make up air damper which we were going to procure.
My HVAC guy wants to run the make-up air directly into the return line of the furnace.
My thoughts were to run it directly into my mechanical room, have it get partially pre-warmed in the mechanical room, then run up to the kitchen (directly above) through holes drilled in the subfloor then out through some grills in the cabinet toe kick.
I’m concerned about running directly into the furnace return line because whenever the blower kicks in there is going to be a negative pressure pulling cold air from outside past the damper. I know the seals on those motorized butterfly dampers are not great and it doesn’t seem like a smart idea to have them be pulled on all the time because I’m sure the seals will wear out quicker and they will surely leak more with the suction.
Using my method there is no suction on the damper until there is a net negative pressure in the home i.e. when the vent hood is turned on. In that case the damper will be open which is what I want.
I think I might need to make it an active system so when the vent hood turns on there a damper opens and a fan kicks on to pull in the required air flow.
Does anybody see any problems with my plan to bring the air into the mechanical room? How do people “normally” bring in makeup air to the house?
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