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WHVS in Washington


Ponyboy
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Just looked at a 3 year old home in Trilogy at Redmond Ridge. Air conditioning was installed 2 years ago and the contractor disabled the Whole House Ventilation System because they say it will void the air conditioner warranty. I think this situation will reduce the air quality inside of this house and the WHVS should be reconnected. I also ran into the same situation in a 1o year old house not to long ago. I checked with my local HVAC code consultant and he feels this is an incorrect installed.

Any input would be appreciated since I will probably have to do some battle next week.

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Hi Brad,

I think that it won't hurt to deactivate the WHVS and close any intake sources when the A/C system is turned on; but, since that amounts to about a week at the most around here, it needs to be on the rest of the time.

ONE TEAM - ONE FIGHT!!!

Mike

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It would be interesting to learn what the a/c mfr. proposes (not only for this house, but all others) as a resolution on how to run the a/c and provide ventilation. Air conditioners are installed all over the country in homes that require ventilation.

Just thinking through . . . what's the ventilation setup on the home? Bathroom ceiling fan running off a timer?

I could see how that setup would cause problems.

Then there's the setup where an intake duct is installed to pull air from the outside, ties in to the return or supply plenum, and feeds in to the home. This setup seems like the right one to ventilate.

Good dilemma to cypher. Curious to see what others have to say.

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Originally posted by Ponyboy

Just looked at a 3 year old home in Trilogy at Redmond Ridge. Air conditioning was installed 2 years ago and the contractor disabled the Whole House Ventilation System because they say it will void the air conditioner warranty.

Oops. Somebody missed Logic 101. Modifying one manufacturer's system won't cause another manufacturer to void its warranty.

I say just fix whatever needs fixing, and disregard the other party's Magical Thinking.

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"...the contractor disabled the Whole House Ventilation System"

Brad, what do you mean by "disabled"? I would expect a 3 year old Trilogy home has a timer near the furnace that controls a fresh air intake damper and one of the exhaust fans (guest bath or laundry). Most of these timers have a simple switch on them that allows them to be turned off (without changing the programming keys). I can see that you might not want or need as much warm "fresh" air drawn into the house while the A/C is on, but disabling the whole thing so it can't be used at other times...well, that's nuts.

Did they nail all the windows and doors shut because opening any of those with the A/C on would also "void the air conditioner warranty"?

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Hi,

I just came from doing a 1-year warranty inspection on a Cam West built home over in Redmond near Trilogy. The WHVS was nothing but a timer hooked up to the furnace with an intake damper tied into the return air. When the timer kicks on, the air handler comes on and the damper opens and allows fresh air into the system. That's it, nothing pulling the old, moisture-laden air out of the house. I guess they figure that they'll put the house under positive pressure and force the old moisture-laden air out of the house.

Kind of dumb if you ask me; I typically find the timer tied to a second floor exhaust fan and the intake damper. In those, the timer kicks in and the damper opens at the same time the ceiling fan comes on at the second floor but the air handler isn't running. The fresh air comes into the home through the return air system to replace what's being sucked out by the ceiling fan on the second floor.

Todays house had some beautiful hardwood floors on the first level that looked like a washboard. The house is well insulated and was cool inside - even in todays heat without AC - but you can feel the stickiness of the humidity inside the home. The interior drywall shows between 12 and 14% moisture content measured with my Protimeter when I typically find it about 9 to 10%; kind of high for drywall around here.

So one would suspect moisture in the crawl, right? Nope, the crawl is dry as a bone and the vapor barrier covers about 95% of the surface. The underside of the floor in the crawl is 9.5% and the air in the crawl is cool and dry. There's no question that the way that the builder set up the WHVS just isn't working very well.

Hope the builder steps up; however, if they go by that NAHB Residential Construction Standard they might not - that requires more than 1/8-inch cupping over 3 inches. It's probably not that bad but it's bad enough that it was all I could focus on when I first walked in the front door.

ONE TEAM - ONE FIGHT!!!

Mike

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Hi

Yeah, here's some other stuff about these systems that will help:

1. The Washington State Energy Code Builder’s Field Guide - Chapter 8 – This chapter of the energy code describes the various types of ventilation systems required in the home and how they are supposed to be configured. http://www.energy.wsu.edu/documents/cod ... 8_2004.pdf

2. The Washington State Energy Code 6th Edition – This is the state law that defines how various energy-saving measures must be incorporated into new construction. The field guide at #1 is based on this code. http://www.energy.wsu.edu/documents/cod ... c_2006.pdf

3. Ventilation System Operating Instructions for a Whole House Ventilation Systems Integrated

with a Forced Air Heating System – This is a handout that explains how this system is supposed to work and provides tips for tweaking performance.

http://www.energy.wsu.edu/documents/bui ... t_9_19.pdf

4. Indoor Air Quality Fact Sheet – Keeping Homes Dry – This handout provides general tips for other lifestyle measures that can be used along with the WHVS to reduce interior humidity.

http://www.energy.wsu.edu/documents/bui ... ms_fct.pdf

ONE TEAM - ONE FIGHT!!!

Mike

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