Joe Lstiburek’s perfect ventilation system
I was reading an interview between Allison Bailes and Joe Lstiburek from July 22, 2013 called “The Ventilation Debate Continues” and in the article Ms. Bailes says:
“What about combo systems where someone’s using a balanced system for part of the ventilation and an exhaust for the remainder to meet the requirements. I’ve seen this in some Habitat houses where they’re trying to do balanced with the Whisper Comfort, Panasonic’s ERV, and it doesn’t quite get them to the 62.2 level so they put controls on the bath fan. So you see the Whisper Comfort, which is balanced but it doesn’t have distribution according to your definition, do you think that would count for distribution?
JL I’m assuming they’re going to have some kind of forced air as well, right?
ab3 Right.
JL So the mixing also provides distribution, right? They’ve got it all so they’re going to get the lower rate. That’s a phenomenal approach. So you basically put in that system and you provide a timer on an AirCycler to mix the air, that mixing gives you mixing and distribution. You get it all, and you’re going to get it at the lowest rate. To me, that’s the least expensive way to get everything. I think that’s a phenomenal system.”
I was wondering if this system applies to a whole house ventilation solution, or just for a bath fan? Are there any other components needed for a whole house approach?
Also, do you need to have a furnace and forced air ductwork for this system to work or can it be a stand alone system?
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Replies
Scott,
First of all, I can't pretend I can answer for Joe Lstiburek. All I can do it guess what he meant.
Q. "I was wondering if this system applies to a whole house ventilation solution, or just for a bath fan?"
A. It sounds to me as if Joe Lstiburek was talking about whole-house ventilation.
Q. "Are there any other components needed for a whole house approach?"
A. In the scenario under discussion, Lstiburek's approach requires (a) a Panasonic Whisper Comfort ERV, (b) a high-quality bathroom exhaust fan, (c) a control -- presumably a timer -- on the bathroom exhaust fan, (d) a forced-air heating system, and (e) an AirCycler control to turn on the air handler blower periodically to mix the air in the house. That's five components.
Q. "Do you need to have a furnace and forced air ductwork for this system to work?"
A. Yes. The forced-air ductwork, the air handler fan, and the AirCycler control are necessary to mix the air in the house to improve distribution.
Q. "Or can it be a stand alone system?"
A. I don't understand this part of your question. If you install all 5 components, it is a stand-alone whole-house ventilation system.
Martin, I meant a stand-alone system from the point of view that the Aircycler unit could be installed in the ducting used for the ERV rather than having to use the ducting from a forced air furnace (If a house has no furnace or furnace ducts then the 5 components used in the proposed system could be the entire ventilation system).
Scott,
No, that wouldn't work. Joe Lstiburek was proposing using an AirCycler control to energize the air handler fan. (That's the way AirCycler controls are used.) When the air handler fan is energized, you get good mixing of house air -- so if there is fresh air in one room, the air will be mixed and provided to all rooms with a supply air register. If you try to use an AirCycler to control an ERV, all you end up achieving is control of the ERV -- which is delivering the fresh air to a limited number of rooms.
The forced air ductwork and the air handler fan are the components that provide mixing of the indoor air. (And by the way, if you do this, make sure that your furnace has an ECM blower, or you'll get sky-high electricity bills.)
Hi Scott -
The air flow of energy recovery ventilators (tens of cubic feet per minute) is considerably less than that of a whole-house air handler (hundreds of cubic feet per minute). Ventilation systems are about how much outside air is coming in or being replaced and may have very little whole-house mixing capability, central forced-air system air handlers have the capacity to mix whole house volumes.
Peter