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10 Answers

ERV + dehumidifier ducting in a minisplit house

I'm working on a 2400sf house (CZ4, but very nearly 3) where the owners have selected minisplits - one ductless 1st floor, one ducted w/ very short runs for each of 2nd & 3rd. So there will be no major duct lines throughout the house for heatning and AC. They've also chosen to go the ERV and Dehumidifier route, this being the humid southeast.

Asked By Chris B | Jul 28 16
4 Answers

Zone 6 Dew point

2"x6" wall
Roxul Comfort Batt R 23 in cavity
OSB Exterior
R-Tech 1/2" R 1.93 foil facer facing OSB, poly facer facing out, tape all seams
Owens Corning Fomular 150 2" R 10
Stucco

In your opinion is this an acceptable wall structure for Zone 6, or do you need to add an interior or exterior vapor retarder. The R-Tech product has a water vapor transmission <1 (perms) and Absorption <1 (% vol)

Asked By David Dunn | Jul 29 16
2 Answers

Need Help With our Duct Work Decision

I contacted a reputable contractor to come do a duct test and take a look at our attic insulation. The ducts are very leaky and most of them are the old grey kind and some are not in the best shape. One even was missing all the inner plastic and all you could see was the metal ribbing and fiberglass. The house is around 2050sqft and the blower door showed about 2600 cfm at 50. The aduiter showed me all the areas I need to seal up from the inside and took picture of the worst areas in the attic like the chimney and bathroom soffits.

Asked By Blake Lasslett | Jul 29 16
3 Answers

Separation of concrete slab and foundation

We removed carpeting in a condo that we own. We noticed by the sliding glass doors a crack in the slab. The slab has a layer of rigid insulation on the perimeter which seems to have seperated from the cinder block foundation. The cinder block wall does not appear to be bowing looking at it from the outside. Is this a big concern or is there a way to fix the problem without ripping everything up?

Asked By Joel Silverman | Jul 29 16
2 Answers

Double Wall Opening detail

Hello,

I am embarking on my first energy efficient home in Maine for my own residence. Walking away from the Code Built norm finds me scratching my head a bit.

Double walls at 14", 2X6 and inner 2X4. Stem walls and footing with an insulated and thermally broken floating slab system.

Sill pan recommendations for the door breaks where they will contact directly with the concrete stem wall? I will be using an EPDM sill gasket/10 mil poly/tremco sealant sandwich under all the sill plates and I assume under the thresholds of the many doors.

Asked By David Chapman | Jul 29 16
14 Answers

Open-cell foam contacting a water heater flue

I have open cell foam being put into my attic. My hot water heater is in the garage below, but where the flue goes through the rafters, is it OK for the open cell foam to contact around the flue? If not, how much of a gap is left around it? I guess they would have to just cut that gap after foaming since the foam isnt going to just cooperate....

Asked By John Sexton | Jul 27 16
3 Answers

Good source for minisplit turndown ratios and turndown vs. HSPF / SEER?

Hi,

I was going to ask this on this thread:

But realized it was a separate question.

Asked By Keith H | Jul 28 16
3 Answers

ERV as a bathroom vent fan?

My wife and I are purchasing a new house. House is in NJ and was built in 1987. Stick framing, average to slightly above average construction quality, average energy efficiency as far as we can tell.

For whatever reason, none of the bathrooms have vent fans. Putting fans in is likely to be one of the first projects I do.

Simple question - is an ERV appropriate to use as bathroom ventilation in a not-so-tight house? Our priorities are as follows:

#1 remove moisture to reduce mirror steaming and mold potential
#2 energy efficiency in terms of not wasting heated/cooled air

Asked By Matt Culik | Jul 28 16
5 Answers

Reducing humidity without AC

I live in NJ. Typical summer weather here is highs in the mid-80s/low-90s, lows in the 70s, and very humid.

Our house has a "natural" overnight temperature of about 73. What I mean by this is that if I set the AC to 74 before we go to bed, it cycles on/off until about 3AM, at which point everything has cooled off enough outside that no more AC is required to hold 74.

While this is nice from an electricity use perspective, no AC means the interior air gets stuffy and the humidity starts to creep up.

What is the most energy efficient way to address this?

Asked By Matt Culik | Jul 28 16
11 Answers

Minisplit retrofit in Climate Zone 2

I'm trying to figure out how to use a minisplit system on a retrofit project. I got a quote from an HVAC company (recommended by the equipment rep), but some of their opinions don't make sense...which brings me here today.

The HVAC company proposed 4 zones with a 3 Ton compressor outside:
1 ducted 9k unit in attic, serving Guest Bath, Guest Bed, and Office
1 ducted 9k unit in attic serving Master Bed and Bath
1 9k ductless serving kitchen
1 9k ductless serving living

Asked By Green Heron | Jul 26 16
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