So I just had my first real negative pressure experience in that cabin. Over the summer the electrician connected our dual speed bathroom fan. They always are running on low and either have a switch or motion sensor to kick them to high. Ours is the motion sensor type which stay on for about 15 minutes after leaving the room. Started a fire while it was running on high and smoke just absolutely poured into the Great Room. Quickly opened the patio door and issue resolved, but holy cow!
First negative pressure experience...
- Thread starter NickW
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See if you can add an inlet valve that opens when underpressure is present in the bathroom (and make sure you keep the door closed)?
That way fresh air is let into the bathroom when the fan is running, which should alleviate the issue with the stove.
That way fresh air is let into the bathroom when the fan is running, which should alleviate the issue with the stove.
Interesting thought @stoveliker.
The current building theory being used around here (and assuming elsewhere) is "controlled breathing" for new houses. Back when the first "airtight" houses were being built they developed mold issues inside the walls within a few years due to inadequate air exchange. Now the same and better technology is used for air sealing but accommodations are made for controlled air exchange by use of an HRV or variable speed bathroom fan with a scuttle/make-up air vent on the furnace. I'd be curious to know if the inlet valve (which would have to go through 16" of insulation into an attic crawl space) would nullify the intended effect of the make-up air...?
It doesn't seem to be much of an issue on the constant low speed. This wouldn't be an issue if the fireplace drew better through the outside air intake. It just doesn't. I have to keep the doors cracked a long time to keep it burning. Smoke the glass on the sides all the time. I'll double check mc next weekend when my moisture meter comes up with the missus. I found it interesting that tech support at SBI told me that room air was better than outside air, but that whole conversation should probably be a whole new thread. @begreen would like a report on the Stratford II.
I'll probably wait for some colder temps and to run it a bit more this season before doing so. I do remember being a bit frustrated at times last winter with it. Hoping my 12" long splits will help (if they are ready) so I can load N/S. E/W sucks even with N/S runners under...
The current building theory being used around here (and assuming elsewhere) is "controlled breathing" for new houses. Back when the first "airtight" houses were being built they developed mold issues inside the walls within a few years due to inadequate air exchange. Now the same and better technology is used for air sealing but accommodations are made for controlled air exchange by use of an HRV or variable speed bathroom fan with a scuttle/make-up air vent on the furnace. I'd be curious to know if the inlet valve (which would have to go through 16" of insulation into an attic crawl space) would nullify the intended effect of the make-up air...?
It doesn't seem to be much of an issue on the constant low speed. This wouldn't be an issue if the fireplace drew better through the outside air intake. It just doesn't. I have to keep the doors cracked a long time to keep it burning. Smoke the glass on the sides all the time. I'll double check mc next weekend when my moisture meter comes up with the missus. I found it interesting that tech support at SBI told me that room air was better than outside air, but that whole conversation should probably be a whole new thread. @begreen would like a report on the Stratford II.
I'll probably wait for some colder temps and to run it a bit more this season before doing so. I do remember being a bit frustrated at times last winter with it. Hoping my 12" long splits will help (if they are ready) so I can load N/S. E/W sucks even with N/S runners under...
Yes. I open a window in the bathroom when using the fan. (And I close the door to the bathroom so the cold (or in summer humid warm) air won't affect the house much. I open the door once the fan goes off and I close the window, so I only have one bathroom air exchange to re-condition.
The point about the hrv is that if it is farther away from the bathroom that the stove is, the stove will still see an underpressure, because of the impedance of the airflow from the far hrv past the stove to the fan.
So, adding "make up air" at the location of the fan will alleviate the problem at the stove.
The point about the hrv is that if it is farther away from the bathroom that the stove is, the stove will still see an underpressure, because of the impedance of the airflow from the far hrv past the stove to the fan.
So, adding "make up air" at the location of the fan will alleviate the problem at the stove.
I don't get a back draft very often, but when I do it's because of the clothes dryer, I bet yours will do the same.
I also use room air for my stove, free ventilation of stale air is the way I look at it.
I'm not a fan of HRV's, they are often placed in the basement with flex hoses run to the bathrooms and kitchen. Those hoses allow far to many places for moist air to condense and grow mold.
I also use room air for my stove, free ventilation of stale air is the way I look at it.
I'm not a fan of HRV's, they are often placed in the basement with flex hoses run to the bathrooms and kitchen. Those hoses allow far to many places for moist air to condense and grow mold.
Gotcha. No window in my bathroom, central location. Theoretically once the fireplace doors are closed they shouldn't be fighting each other as the fireplace is fed by outside air. For now I will just pay attention to if the bathroom fan is on high when starting or reloading the fireplace and crack a window or door if necessary.
brenndatomu
Minister of Fire
Bath and kitchen vent fans, dryer, central vac system, even a radon fan can all cause a negative pressure on the house...especially if 2 running at the same time (might explain "randomness"?)
We don't have it happen often, but very very occasionally...never have been able to put 2 n 2 together as to why. Never enough to set off the CO alarm, but just a lil smell (and slighty raised numbers on the CO alarm/monitor...probably just the perfect storm of wind direction, state of the fire, and household systems that are running...
We don't have it happen often, but very very occasionally...never have been able to put 2 n 2 together as to why. Never enough to set off the CO alarm, but just a lil smell (and slighty raised numbers on the CO alarm/monitor...probably just the perfect storm of wind direction, state of the fire, and household systems that are running...
My setup is prone to negative draft, and if starting cold, I always have to check draft. I use hair dryer to get it going then start.
brenndatomu
Minister of Fire
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