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13 Answers

Rigid foam minimum for 2x8 stud wall

Zone 5 - helping with a wall design. They are using 2x8s for studs to fit in R-30 mineral wool. I am suggesting rigid foam, EPS or XPS, but I have only read that 2x6 wall needs R-7.5 But, this is a 2x8 wall, and I don't think R30 is traditional. So Will 2" of XPS or EPS be sufficient? Don't really want to have to go with two sheets and achieve 2.5" of rigid foam if 2" is sufficient with R30 mineral wool on the interior.

Is there any way to make 2" work? Such as a smart membrane installed before drywall?

Asked By Nicholas C | Dec 9 16
7 Answers

Tiny home heat pump (Mitsubishi or Fujitsu) for a mostly empty house

I am in the process of renovating a 1-level 470 sq ft basement walkout condo in Kittery, ME. It has two floors above it. I've consulted a contractor, and don't agree with their suggestion for a mini split. So, I've started doing research!

Asked By Kate Harris | Dec 9 16
10 Answers

Does anyone have experience with the Rheem Prestige heat-pump water heater?

I was excited about using the Sanden CO2 HPWH, but communication with the company was very hit or miss. The local installer they referred me to was very responsive and helpful with technical information. He gave me a quote for $5,900 installed. This was for a 43 gallon tank (the 83 gallon tank, oddly enough, would've been $6,100 installed). Because of the poor communication, and the cost, we had to move on.

Asked By Eric Whetzel | Dec 8 16
3 Answers

What capacity rating should be used for sizing ductless heat pump?

The easily obtainable heating capacity information for ductless heat pumps are generally listed as Btu/h at 47 degrees and Btu/h at 17 degrees. These don't appear to line up with the expanded capacity charts which can (sometimes) be found with some digging on manufacturers websites. Let's look at the Fujitsue ASU9RLS3:

It's capacity is readily reported as:
7,0000 Btu/h @ 17 degrees
12,000 Btu/h @ 47 degrees

However, if I look up the expanded heating capacity chart, it reports the Total Capacity as (assuming 70 degrees indoor temperature):

Asked By James Reider | Dec 9 16
2 Answers

Ventilating heat pump water heater

I have to replace my 28 year old ventilating heat pump water heater (leak in tank) and can't find anything to fit the bill. My unit doubles as an air to air heat exchanger. When the water heater cycles on, air is ducted from the bathroom & kitchen, across the coil in the heat pump, and outside. Fresh, replacement air is allowed into the house through small openings in outside walls in bedroom closets. None of the heat pump water heaters I've found allow for ducting in although some can be adapted for ducting outside.

Asked By Grey Doffin | Dec 9 16
2 Answers

How to seal floors dyed with India ink?

Hi All! Does anyone have specific experience using India Ink on hardwood floors?

I am in need of specific information on how to seal the floors once they are stained. I've asked around a few woodworking/DIY sites and while people offer idea's, it doesn't seem like anyone can give me an answer on a tried and true product and means of application. What product and what means of application can be used to seal India ink on hardwood floors? All suggestions, completed project examples and even failed attempts helpful!

Asked By Sarah Hoffman | Dec 9 16
5 Answers

Lunos e2 ductless HRV system vs. ducted system

I am building a net zero house, 2000 SF, 2 stories. Can you tell me the pros and cons of the Lunos e2 ductless HRV system vs. a ducted system? The rep told me that 3 pairs of the Lunos e2 would be about right.

Asked By Courtney McCracken | Dec 8 16
7 Answers

Converting a 1830 House to a Super Insulated House

I am diving into the insulation in my 1830 Farm House, 1500 sqft, which is located in upstate NY. I am looking to retro the house into a tightly insulated house that will ultimately heat off of electric heat or heat pump mini splits. I just had 10kw Solar system to create the electricity for the heat. The solar system was designed to cover 110% of our projected electrical consumption with a mini split system running. My goal is an 1830 super insulated house.

Asked By Larry Broderick | Dec 7 16
8 Answers

Double interior rock wool

Working on plans for my next home. After lots of research on here and others I am considering the following wall assembly. From the exterior... wood siding, tar paper, 1/2" plywood with taped joints, 2x4 ,16 on center wall stud with roxul, uniterupted layer of 1 1/2" comfort board, layer of a variable perm vapor barrier (taped seams and such), then a layer of 2x3 installed 2 ft. on center as battens for electrical with shallow boxes , second layer of comfort board fit between the battens, drywall finish. I am in zone 5 in northern ct.

Asked By scott mangold | Dec 8 16
6 Answers

Optimum air gap for skylight

Context: a 14x7x6' tinyhouse with 4"-thick polyiso insulation on all surfaces except the windows, which, for reasons that aren't relevant here, must be on the roof.

Several hours of research shows that the optimum air gap for a typical double-glazed window ranges between 13-30mm depending on whom you ask. Charts show that U-value tends to bottom out at around 13mm and slowly climbs up from there. From this research I've gleaned hints that the glazing material and the angle the window is mounted at are factors, but I've been unable to find out how they matter, so I turn to the Community.

Asked By Geva edhrven | Dec 8 16
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