This spring i will move into my SIP house i have been working on for about 5 years. it is 3500 sq ft 2 level slab on grade radiant heat total SIP including roof. i live in wyoming, so while i have installed the duct system for central air, i am hoping to avoid it. i have a HRV that runs at low all the time. the house has a rumford fireplace, a gas dryer, and a 400 cfm range hood. the radiant floor and all the hot water needs are supplied by renni (sp?) instanteous water heaters.
last winter when i used the fireplace i had to open a window to avoid smoke in the house. i am sure it is a pressure issue, and i am concerned with the range hood and dryer and the potential for CO as well as back drafting. i have been thinking about how to supply make up air, but still have not found any scrap of information that relates to my type of construciton.
i know the hrv is a balanced unit, so no real help there, i know that opening a window will work, but is not a real pretty solution, and i have not seen anywhere that a passive system ie. hole in the wall, works.
i know there are some real smart guys out there who can help, and i really need your advice.
thanks in advance
steve
Replies
When the vent fan runs an electrically operated vent could be made to open , or possibly modify the HRV flow to compensate.
Do the water heaters have external combustion air?
The clothes dryer could also have a vent installs that opens when the dryer is running.
The fireplace should have had a external combustion air duct installed, maybe a retrofit is possible.
the water heaters do use external combustion air. as the house is already wired and rocked, additional wiring will be a problem. i suppose i could use an ir switch. i was wondering about using the ductwork already in place to provide a passive intake.
my thought is to put a T in the intake air for the hrv and plumb it directly into the cold air return plenum for the A/C (there is no ac unit, just a plenum between the ceiling joists). i would then cut a hole where the return air for the A/C would have been installed and allow negative pressure to supply my makeup air. this air would not be conditioned in any way however?
any thoughts?
I'd add a separate air intake for your idea. Otherwise the HRV may pull in air from the house rather than outside like it should. Also you may want to have a damper on the vent so that you can adjust the air flow, especially when operating the fireplace.
I have a dampered fresh air intake that I designed and built in my house - all published here on Breaktime.
Here's the link - http://forums.finehomebuilding.com/breaktime/construction-techniques/how-set-dampered-fresh-air-intake
It works great.
Jeff
Very interesting
Jeff,
I missed this when you originally posted it. Thanks for the link. I'll be remodeling and adding a good size sucker in the kitchen. And I hope to have my house sealed well, tho perhaps not as well as a sips house can get.
I'm interested in your reactions to the comment by Clewless regarding the location for the make-up air. He said that commercial units provide air along the front edge of the hood. Wouldn't the system then simply be self serving? The goal is to remove the air/smoke/odors from the cooktop so doesn't the makeup air have to be located in a position to "push" those nasty airs into the hood? I like the thought of hiding the makeup air duct behind the microwave... where exactly is that in your kitchen in relation to the cooktop? Can you post a photo?
I will probably fabricate my own SS hood so I could incorporate something for makeup air into it. If you or anyone has any good links/references I'd sure appreciate seeing them.
I am also,
Jeff
See photo below - microwave to left of hood recessed in wall - makeup air duct/grille in back of recess.
Jeff
Thank you. That's a nice looking kitchen.