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0 Answers

Beware the dual-hose portable AC / heat pump

For years I've wondered if a dual-hose portable heat pump/air conditioner could be a poor man's ductless minisplit heat pump. The advantage, as my logic went, was that I didn't have to drill any holes or charge any refrigerant.


I bought a 14kbtu portable heat pump (Edgestar AP14001HS Portable Air Conditioner) ($400-$700)

I did some primitive temperature and airflow measurements.

I was impressed by the overall quality and the 11.2 EER, but what I found was very disturbing.

In Mechanicals | Asked By Kevin Dickson, MSME | Sep 12 14
11 Answers

I need help choosing the correct minisplit and heat pump for my studio

I have two proposals to install a single unit mini-split with an outdoor condenser for my studio building. The building has a 24 x 32' foot print. The walls are 10' high, with a cathedral ceiling that is 16' high at the ridge. Walls are 2 x 6 (at least) with fiberglass batts. Roof rafters are 2 x10" (I think) with fiberglass batts between, and then either 1 or 2" rigid foam insulation skimming it (under the sheetrock). Building is tight. Floor also has fiberglass and rigid foam board between the 2 x 12" joists.

In Mechanicals | Asked By DANIEL GOTTSEGEN | Sep 10 14
6 Answers

Chemical smell in a new construction crawl space

Hi folks, great site.

I have a crawlspace in a new house that smells of chemicals. The dirt floor is sealed with a vapor barrier and the walls have Spray Foam Insulation. The space is pretty airtight.

My ERV was installed incorrectly (another story) and sometimes the smell from the crawlspace comes up into the house. Makes my eyes burn, and it gives me a headache. Hopefully that will be fixed this week!

Should I be able to smell the foam 2 months after it has been installed?

In Green products and materials | Asked By Brett Michaels | Sep 1 14
30 Answers

When roofs do rot, which side does the rot start on? worth using copper-borate treatment as preventative?

When roofs do rot with closed cell foam underneath, which side does the rot start on?

Is it worth using a copper-borate treatment as preventative?

Zone 6. There will be 4" 2lb closed cell foam on the underside of the sheathing. tar-paper on top. Attic space will be living space. not expecting to have any rot issues but....I'm thinking a belt-suspenders approach here. considering spraying whichever side is prone to rot in this situation with a copper borate solution as a preventative.

thank you.

In General questions | Asked By eric Mikkelsen | Sep 8 14
2 Answers

Improved air sealing brings other challenges

In Kansas 9 Jurisdictions allow an Energy Rating Index analysis as an alternative compliance path for meeting the 2012 IRC chapter 11. Other builders use the HERS index for marketing purposes. Use of air sealing recommendations and increased quality of installation have seen air change rates move down from 5-6 ACH pre-implementation to 3 ACH or less in a growing number of audited homes. Early antidotal results are showing problems with supply only strategies. The 6" pipe to the return is causing summer humidity problems in some cases.

In GBA Pro help | Asked By Bruce Chyka | Sep 10 14
4 Answers

Necessary layers for a wood-framed insulated metal building

I have recently framed up my new wood shop. Initially, I was going to do cedar siding and metal roof, but now have decided to wrap the whole building in metal (black metal at that) for ease of install and durability...and black metal just looks darn good. The building is now covered in tyvek on sides (on 1/2" osb) and underlayment on the roof (on 5/8" plywood). Should I take down the tyvek (which was intended to go with wood siding) and use some other material before i put on the metal siding? Should i install horizontal batten strips to help the building "breath"?

In Energy efficiency and durability | Asked By Zane Morgan | Sep 11 14
3 Answers

Double insulated rim joist?

Is spray foam on the rim joist beneficial/necessary if there is already an inch of xps on the exterior of the sheathing? The plan is to use dense packed cellulose in the walls above and below. The framing is 2x6 and this is a doubled 2x10 rim joist. (Zone 4).

In General questions | Asked By mike mcguirk | Sep 11 14
3 Answers

How do I adhere and waterproof a metal roofjack to a previously foamed flat roof?

I am putting in a exhaust fan in the bathroom and need to vent it out the roof.

In General questions | Asked By pat sullivan | Sep 10 14
14 Answers

Best location for fresh air intake for ERV/HRV

I can't have the fresh air intake on the wall since it would be quite difficult to drill thru the walls of my ICF home. I do not like the idea of going thru the roof since I do not want risk drawing asphalt shingle gases into my home. One option I am closely looking at is having it on the external soffit pointing down but I see at least one ERV manufacturer advising against it (I wonder why). Does any one see a problem with this approach?


In GBA Pro help | Asked By Venkat Y | Sep 8 14
9 Answers

Our roof is 1/3 hipped slate, and 2/3 is flat-sloped with a conventional roofing material, coated white

Our roof is 1/3 hipped slate, and 2/3 is flat-sloped with a conventional roofing material, coated white.

The underside of the entire roof was coated with spray foam a few years ago. The house was built in 1930, and the attic joists have a layer of rock-wool in them.

We'd like to get additional R-value, but don't want to screw up the expensive foam coating. Thanks for your time & attention.

In General questions | Asked By Woody Stemms | Sep 11 14
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