Broan automatic make-up air damper with a dedicated HRV?
Cold climate zone 5 – central OH. Mechanical ventilation strategy being considered for the new build is as follows:
– Balanced system featuring an HRV with “dedicated” ventilation ductwork. HRV being considered is the RecoupAerator 200DX equipped with an ECM motor from UltimateAir. Pulls stale air from bathrooms and laundry rooms and provides fresh air to the great room and bedrooms.
– Broan automatic make-up air damper compatible with one of their range hoods to provide for make-up air when the range hood is running; Also linked to Broan bathroom point-source exhaust fans. The Broan system damper is connected to the return side of a central duct system and is synchronized to operate with the range hood and bathroom exhaust fans.
The HVAC system in the home will be the new Carrier Infinity heat pump and gas furnace featuring their Greenspeed technology.
Question … is it overkill to include both the automatic make-up air damper, tied to the central duct return, along with the dedicated ductwork HRV? The bathroom fans wouldn’t run continuously as in a “Exhaust only” strategy, but only operate when the range hood or a bathroom fan is turned on, while the HRV would operate to ventilate the whole house. Would the HRV alone be able to address the use of the range hood and bath fans without the additional make-up air damper?
Appreciate your feedback.
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My house has an HRV, no dedicated makeup air duct, and although the manufacturer (Lifebreath) says it isn't designed to provide makeup air for a range hood, clothes dryer, or other exhausting fans, in fact it does go out of balance when those other fans depressurize the house, as long as the HRV is running. You might check with the mfg of your HRV, but I would expect the same thing to happen. You probably want to keep the range hood capacity reasonable - no "wind tunnel" jobs. There have been other posts on this subject; a search will locate them.
Dick,
Thanks for the feedback. Is your HRV utilizing dedicated ductwork? If it goes out of balance, does it eventually rebalance itself? Intent for the range hood is to keep the CFM's at a reasonable level ... definitely no wind tunnel. The auto damper wouldn't add a lot of cost to the system and it would be tied to the central air handler and it's ductwork ... separate from the HRV. The posts and blogs I've read to date never really spoke to the need for both. That was the main reason for posting.
Milan,
The Broan motorized damper/makeup air duct is only needed for range hoods that are rated at more than 300 or 400 cfm. There is no need to open such a duct for bath exhaust fans, which have lower cfm ratings. Such a makeup air duct incurs an energy penalty.
More information here: Makeup Air for Range Hoods.
Thanks Martin ... then all should be fine with just the HRV with dedicated ductwork, correct? It should be able to handle a lower CFM range hood as well as occasional use of bathroom fans then without that damper ... that's good to know.
Milan,
Right. That's why I advise builders to choose low-cfm range hoods -- to avoid the need for a makeup air system.