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7 Answers

What is minisplit short cycling? Turndown?

I understand that a "somewhat" oversized mini split will generally run at a more efficient rate, as opposed to an undersized mini split, which will run full-out, and therefore be less efficient. It sounds as if the problems with oversized mini splits would be 1) wasted money on oversize equipment, and 2) decreased dehumidification, due to the equipment not running enough. Am I about right, so far?

Asked By Ben Rush | Jun 25 17
0 Answers

My double stud wall assembly

We are in Minnesota (Zone 6a). 2200 sq/ft single level, slab on grade.

Finalizing my 10" double stud wall assembly details and want to get your suggestions and recommendations for improving the assembly without increasing significantly increasing costs.

-Certainteed Membrane 1-10 perm
-Dense pack cellulose
-1/2" plywood
-Tyvek 58 perm
-furring strips on the (north and east sides of the house)
-LP smartside lap, b&b, & shakes (north and east sides of the house)
-No furring strips, just vinyl siding (south and west sides of the house)

Asked By Scott K | Jul 22 17
26 Answers

Unvented cathedral ceiling interim remodel

I have a roof problem on a small section of 4/12 above the bathrooms. It is only about 15 feet by 10 feet of insulated ceiling. Background information.... We are in Enumclaw, WA, which is zone 4C, I believe.

My home was built in the early 80's as a Justus Homes kit. All of the ceilings are unvented cathedral construction as follows:
2x6 tongue and groove on the interiors
15 pound felt
2x6 on edge at 24 inch spacing

Asked By User-6883899 | Jul 11 17
10 Answers

Insulation question and new construction.... thoughts?

New construction, we are doing a non-vented attic to keep our HVAC ductwork in a conditioned space with foam on the roof deck. Come to find out, we can put foam in all the walls vs using bibs for the same price which surprised me. This will make for a tight house and this brings the question in my mind "what type of mechanical ventilation"? House needs to breath and have a good exchange of air.

House is a 2 story and about 2700 sq ft. 2 HVAC units will be installed. Biggest concern is a good ventilation system..

Asked By Thomas Roberts | Jul 20 17
0 Answers

Naive question on LEED certification


Asked By Brian Gray | Jul 21 17
3 Answers

portable dehumidifiers

Are there any that are as efficient as Santa Fe? And durable/reliable too? I need something that extracts about 40 pints a day.

Asked By charles CAMPBELL | Jul 21 17
2 Answers

Humidity and negative pressure

A customers home (zone 4 non-marine) has condensation problems (summertime) on a particular HVAC duct. Upon inspection the %RH was at 60%. There is a whole house dehumidifier hooked in with the HVAC System (Fan runs at low speed continuously) Bathroom exhaust fans are backflowing and letting in a significant amount of heat, and when opening the front door one can feel the hot air entering the house. There is no ductwork in the attic, it is all in the basement.

Asked By Jeff Classen | Jul 20 17
0 Answers

HVAC question


We are building an energy efficient 2700 sq foot ranch, open concept. We live in Wisconsin and leave the windows closed year round due to allergies. So, the AC or Heat is normally running.

It has been suggested that I get an HRV. It has also been suggested that I get a whole house air purifier. Do I need both? Or maybe just and HRV and 4' media filter?

For the HRV, I have seen Lifebreath or Zehnder? Either one better, or other brands to consider?

My builder is not familiar with these specific types of products.

Thanks in advance for any help!


Asked By jabehling | Jul 21 17
2 Answers

What Mil vapor barrier will stop radon too?

I am going to install new plastic over the gravel in my crawl space. My primary goal is to reduce humidity. I was reading about radon and I might as well put down a plastic that will block both.

How thick of plastic do I need to stop humidity and radon?

Asked By 99IdoDIY | Jul 21 17
3 Answers

Venting for multiple appliances

Hey GBA,

I wanted to reach out to the community for a thought experiment.

The home I am building will have the following :

High efficiency Gas furnace
High efficiency Gas water heater
Central vacuum

All of these require exterior intakes and exhausts.

The house is a row house, so the majority of the side walls are attached to another house. Thus, this only leaves one spot where I can place the multitude of vent pipes. (which is pretty much a small alcove at the rear between the two houses) see attached image.

Asked By Jamie B | Jul 21 17
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