EcoRenovator - View Single Post - Alternative to bath vent fan? an idea or two.

MN Renovator · 04-06-11, 02:49 PM

I'll chime in on this since this is what I did this winter. In the winter I used the shower to humidify the house, I would run the furnace blower so the air would be distributed throughout the house. The master bedroom is connected to the master bathroom so I close the door to the hallway, open the one to the bedroom and keep the bedroom door shut. There is a furnace return in the master bedroom not too far from the bathroom door, although its near the floor it seems to help. In the winter, I start the furnace and hop in the shower, after 5-15 mins(usually 10, but before work its 5, on a leisurely day or sore muscles 15 mins). I have the furnace run for 30 mins minimum, so there is 15 mins of house circulation going on. If the house could use the heat and I'll be leaving the house, I'll let it run for an hour before setting the thermostat back to its normal temperature.

This works great when its below freezing out and the furnace will run for over 2 hours in a day but if it doesn't there isn't enough infiltration in the house(I have no ventilator), there is too much humidity. I've already got an issue where with the bathroom fan being on and the days being within 20 degrees of the furnace setpoint(furnace not running) where I can't keep the dew point above the point where any infiltration could cause insulation condensation. ...so I don't do it unless I need the humidity in the house.

I also recover all of the heat from the shower water by not draining the shower until the water is room temperature, also adds humidity to the house in the process.

In the summer you really don't want to exhaust the humidity into the house unless your air conditioner runs long enough to get rid of that humidity along with the extra humidity from any infiltration. The better insulated you have it the less your air conditioner will run and you might be battling a comfort psychrometrics issue. I try to keep my humidity below 30% as much as I can but once I get more insulation and correct any remaining infiltration issues in my house, I think I'll find it difficult to keep the humidity low because the air conditioner won't run enough.

Every house is a little different but outside of the coldest winter months or on the highest cooling demand days you might be adding too much humidity to the house.

A dehumidifier takes too much time and uses too much energy to get rid of the huge bulk load of humidity that taking a shower quickly adds to the air. I'd rather let the humidity escape and recondition the infiltration, I actually think it would be cheaper.

The two ideas I like best are AC_Hackers solution of having a bathroom window above the shower, assuming its waterproof and double-pane for efficiency. The other idea is the one where you enclose the shower area, that way a very small cubic foot area has condensed water vapor and in that small area, only so much humidity can be created. In that case one you open the shower door/curtain, the amount escaping will be minimal, probably to the point where you won't need to ventilate the bathroom.

I can't say anything about the smell issue, I usually don't use a fan and if my roommate doesn't like it, he just uses the other bathroom. ...as do I, but he usually uses the fan but it doesn't seem to help much and I doubt an ionizer or UV light would much either, but I suppose its worth a shot.

04-06-11, 02:49 PM	#7
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	I'll chime in on this since this is what I did this winter. In the winter I used the shower to humidify the house, I would run the furnace blower so the air would be distributed throughout the house. The master bedroom is connected to the master bathroom so I close the door to the hallway, open the one to the bedroom and keep the bedroom door shut. There is a furnace return in the master bedroom not too far from the bathroom door, although its near the floor it seems to help. In the winter, I start the furnace and hop in the shower, after 5-15 mins(usually 10, but before work its 5, on a leisurely day or sore muscles 15 mins). I have the furnace run for 30 mins minimum, so there is 15 mins of house circulation going on. If the house could use the heat and I'll be leaving the house, I'll let it run for an hour before setting the thermostat back to its normal temperature. This works great when its below freezing out and the furnace will run for over 2 hours in a day but if it doesn't there isn't enough infiltration in the house(I have no ventilator), there is too much humidity. I've already got an issue where with the bathroom fan being on and the days being within 20 degrees of the furnace setpoint(furnace not running) where I can't keep the dew point above the point where any infiltration could cause insulation condensation. ...so I don't do it unless I need the humidity in the house. I also recover all of the heat from the shower water by not draining the shower until the water is room temperature, also adds humidity to the house in the process. In the summer you really don't want to exhaust the humidity into the house unless your air conditioner runs long enough to get rid of that humidity along with the extra humidity from any infiltration. The better insulated you have it the less your air conditioner will run and you might be battling a comfort psychrometrics issue. I try to keep my humidity below 30% as much as I can but once I get more insulation and correct any remaining infiltration issues in my house, I think I'll find it difficult to keep the humidity low because the air conditioner won't run enough. Every house is a little different but outside of the coldest winter months or on the highest cooling demand days you might be adding too much humidity to the house. A dehumidifier takes too much time and uses too much energy to get rid of the huge bulk load of humidity that taking a shower quickly adds to the air. I'd rather let the humidity escape and recondition the infiltration, I actually think it would be cheaper. The two ideas I like best are AC_Hackers solution of having a bathroom window above the shower, assuming its waterproof and double-pane for efficiency. The other idea is the one where you enclose the shower area, that way a very small cubic foot area has condensed water vapor and in that small area, only so much humidity can be created. In that case one you open the shower door/curtain, the amount escaping will be minimal, probably to the point where you won't need to ventilate the bathroom. I can't say anything about the smell issue, I usually don't use a fan and if my roommate doesn't like it, he just uses the other bathroom. ...as do I, but he usually uses the fan but it doesn't seem to help much and I doubt an ionizer or UV light would much either, but I suppose its worth a shot.