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Questions about bathroom vents and heat recovery ventilation

 
Posts: 33
Location: Glasgow, KY zone 6b
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I have a 1920 sq ft energy star certified berm house. My energy advisor told me when he performed the blower door test that I may need an hrv or erv but I should wait and see if we needed it first. It's not uncommon for humidity in Kentucky to reach 90+%, while my gauge in the house reads around 80%. It rarely drops below 55% in the house through the winter. We don't have any mold or mildew issues but the house is only 4 years old and I've seen light fixtures in the bathrooms are starting to rust. And sometimes it just feels damp.

•Would an erv or hrv lower humidity in here even with high levels outside?
•How do I determine whether I need one or not?
•Do I just need a whole house dehumidifier?

On to the next part. A few days ago on a cold day, I changed a light bulb in one of my bathroom vents and was shocked at how cold it was next to the fan and could actually feel a draft. I knew they couldn't be very tight but it was disheartening to find them to be this severe.

•Are there any efficient alternatives?
•Or is there any way to modify these to stop my dollars from flying through the ceiling?


 
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
59
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Jared Blankenship :I can offer you a 3rd option That should perform better for you in Kentucky than It can here in upstate New York ! Investigate Air to water
domestic Heat pumps ! They will both lower your air temperature and your humidity within your Home while making hot water from electricity, and do the job
3-4 Xs more efficiently than any other Electric Water heater !

You may qualify for installation credits at the fed, state, and local levels, and also your utility company !


Now about that pesky lighted exhaust fan ! Most exhaust fans have a damper to close of the vent pipe at its end somewhere ether on the side of your house,
where the type of damper is often less substantial than a Clothes driers flap valve. Often if the local codes call for the bathroom fan to be vented through the
Roof, in those cases the vent pipe may only extend into the attic space and never pierce your roof at all, a long cold snap can cause moist air vented into this
space to form as frost on the roofing nails sticking down into your attic and when the warms you have 'rain' in your attic space that soaks your insulation! This
will eventually announce itself as stains around the nail heads holding up your ceiling sheetrock !

I have seen this 3 Xs, once in most of the housing for military families !

Also possible is the contractor who has had problems with the damper/flapper valve and has eliminated that part from the installation in order to avoid call backs
when that part fails ! Also lumped into this category is the electrician that wired it up and left a mess that was not fixed by the Insulation crew (or made worse-
by them)

Now depending on what was available on the market, when your bathroom fan was installed, it is very likely that insulation was banned by code from contact with
that appliance in order to keep that fan or its light from overheating- potentially causing a fire !

It is actually difficult to find Bathroom Fan/light appliance that can be covered in insulation, the amount of wasted heat energy coming off of incandescent or
compact florescent is the problem, A L.E.D. type light solves this problem but does not address the possibility of the fan motor not getting enough air circulation
to prevent overheating, or the fact that the Building Codes have not been updated to allow better/safer units !

Here is one thing you could do about it, Check on the damper/flapper valve and the tightness of all fittings, Instal a big box, 2' by 2' by2' over top of the fan light,
add a smoke fire detector hard wired into your whole house fire protection system ( this requires running a new Electric cable I think )then insulate over
the top of that Box !

Damn that came out more negative than I intended, its not difficult if you are well prepared and are willing to do it by stages !

For the Good of the craft ! Big AL

 
Jared Blankenship
Posts: 33
Location: Glasgow, KY zone 6b
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Thanks Big Al for the fast reply! I thought about the heat pump water heater when I built the house 4 years ago but I didn't think it would pay off for me. I have a geothermal unit with desuperheater so all my water heater does now in the warm months is keep it hot. That pushed the payoff time way back in my situation.

About the fans. I installed those and just ran a flex pipe to dump them through the soffit. I saw later(I couldn't have seen it before) on a diy show that doing this can cause the hot moist air to be drawn right into the attic and cause ice, mold, and rotting of the roof sheeting. So I've checked it from time to time and have seen no evidence so far of any moisture.

But now that you mention the flap in the vent, I have had some moisture stains to creep out around the fan housing in the Sheetrock. They only appeared and got worse in cold weather, never anything in warm weather. Do you think by not having a flap in the vent it would be making that problem worse? Or could something else be causing it?
 
Jared Blankenship
Posts: 33
Location: Glasgow, KY zone 6b
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I forgot to mention that I didn't read anywhere whether they were safe for insulation contact so they were covered directly in blown in fiberglass insulation. I think they had a pretty large sheet metal housing around the motor.
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Jared B. : Interesting, So you have insulated around Your ventilation unit which should have eliminated the Cold air draft !

I have been the installer called back to a previous job where the furnaces duct work was sealed at the joints with plain Grey Duct tape and came back to find
the adhesive had failed and the cloth body of the tape was hanging like ribbons from the ducts, Very Embarrassing !

Since then I have used the Silvery Duct tape with a backing paper that must be pealed off be for installation ! I friend uses a sealing foam product that only
time will tell if it holds up !

Plan to take the time during real cold weather to spend some time in your attic after a several day cold snap, and just see about what is actually happening up
there !

A word about those UV heat guns that are handy for measuring The surface temperature of objects ! Actually using this in your bathroom will give you ideas of
what to check when you get up in the attic But As they are only capable of measuring surface temps and you will be trying to find surface temps of the cold side
of insulation I would have to play with the idea of what your readings are actually telling you !

I am actually sending you a couple of links to you-tube videos from a site I trust, the people at Cold Climate Research Center ccrc.organ arm of the Univ.
Alaska at Fairbanks! You and I know Cold, They know COLD

The first one deals with Whole House Stack Effect, and increases your understanding of how your house breaths ! Link Below :


https://www.youtube.com/watch?v=54XRm25Ykqc&list=PL67021C206D70C449

A second one not as obvious, and this one deals with sealing off all crawl spaces, and further deals with the problem of Moisture accumulation at the Rim Joists and
mud sill of your home if you have tried to insulate this area with Fiberglass or Rockwool ! Link below :


https://www.youtube.com/watch?v=iLce_UzT7JI&list=PL67021C206D70C449&index=4

If your house is very well sealed you should also find out about your local areas potential for Radon gas, ccrc.orghas us full information on this subject too!

A final thought, use a little care when retrieving information from U-Tube sites/channels ,there is a lot of steaming crap out there !

For the Good of the Craft ! Big AL



 
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The issue I have had with bathroom vent fans is when the wind blows the built in damper flaps with the wind. In the cold of winter it sucks a lot of heat out when it does this. I made a rudimentary cover made from a plastic lid with adhesive velcro and a stick taped to it for retrieval. UGLY, but it works. I have seen a site that has baffles for situations like this and also for chimney dampers. I have never tried any of their stuff but have been tempted. I think it's called batticdoor. I have no affiliation with them.
 
pollinator
Posts: 684
Location: Richmond, Utah
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Jared, it sounds like you need to seal the drywall to the fan housing. Fiberglass doesn't stop air from blowing through it(you may want to cover this as well), so you must seal the drywall really well or moist warm air will escape and condense in the attic during cold weather.
 
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