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4 Answers

ERVs and formaldehyde

In the Allison Bailes interview with Dr. Iain Walker
the emerging concerns about formaldehyde transfer (or non-transfer) are discussed at the end. As stated in the interview, it's hard for the purchaser to know the exact extent of the issue with particular units, but Dr. Walker does describe the 2 methods of exchanging moisture, wheel and membrane with the latter being preferred.

Asked By Greg Wilson | Jul 8 14
2 Answers

Minisplit efficiency - multiple single zone vs single multi-zone

Hello all,

Asked By Brian Gray | Jul 2 14
1 Answer

Deciding between conventional heat pump and minisplits

I'm working with homeowners who are considering an HVAC upgrade for their new house, approximately 2,000 sq.ft. It's vintage 1970's, but we'll be doing a number of air-sealing and insulation upgrades. Eventually we'll have an HVAC design professional come check the place out, and make recommendations, but for the moment we're considering what options are out there. Currently, the house has the original forced air ductwork, with a new heat pump put in last year by previous owner. It's a Lennox XP14-042, with matching new air handler and resistance heat.

Asked By Andy Chappell-Dick | Jul 8 14
5 Answers

Advice on passive air inlets with bath fan exhaust ventilation?

Background: new construction, climate zone 6 (03846), 12" double stud walls w cellulose, heating/cooling is single Mitsubishi 12k btu heat pump, 2 story, very open floor plan downstairs (and up). Blower door test done before insulation/sheetrock and came in at 0.67 ACH at 50 Pascal.

Asked By Brian Post | Jul 3 14
4 Answers

Anyone have experience with Aeroseal duct sealing?

I'm considering developing a magazine article on Aeroseal duct sealing. This is a process where registers and diffusers are sealed with plastic and a vinyl based sealant is blown into the ducts. The sealant collects around leaks until they are ultimately closed off. The big advantage is it can seal ducts that are inaccessible for conventional sealing methods.

Here's more:

Patrick McCombe
Fine Homebuilding Magazine

Asked By Patrick McCombe | Feb 26 14
6 Answers

2nd story addition heating

We're working on an addition to a 740sf 1940s home in Portland, OR - addition includes +300sf on main level and new 2nd floor (1300sf). The existing furnace is brand new high efficiency gas, but not enough capacity for the addition. The owners do not want to replace it since it is so new. We are in the process of value engineering to bring costs down, but need to evaluate how to heat the new 2nd floor. Cost is an issue, but could possibly persuade them on a good investment.
Insulation: R-49 flat ceilings/R-30 vaulted attic storage space, R-23 walls.

Asked By Miyeko Endy | Jun 26 14
2 Answers

How to prevent check valve malfunction in a hydro-air system?

I have a propane water heater with a loop to the air handler. Potable water goes through the coil. I noticed that my water heater would run twice an hour even though there was no demand. I guess I should have cleaned the back yard up before June. Anyway, I found the coil was not so apparently there was a convection loop happening. I closed the valve and all is well. My plumber says that since I have potable water running through the coil, I will always have this problem. Is that right? Should i stick some type of solenoid valve in the loop?

Asked By Walter Gayeski | Jun 25 14
16 Answers

Mechanical Ventilation in a Tight, Permeable House

Ok, I am going to thoroughly expose my lack of knowledge with this question (no claims to any expertise on my part), but I'm hoping that some of the experts here can comment on something I am thinking about.

Asked By Stephen Youngquist | Apr 16 14
1 Answer

I live in a two story townhome with 2,000 sq. ft. and one heating system

I live in a two story townhome with 2,000 sq. ft. and one heating system. The temperatures are always uneven from one floor to another. Should it take two separate HVAC systems to even out temps? Looking for suggestions.The present system is 80% natural gas furnace and builder AC.

Asked By James Brown | Jun 21 14
11 Answers

TwinFresh Comfo 32 CFM Power 5 in. Single-Room Energy Recovery Ventilator

I just took ownership of the first HRV to be sold at Home Depot. I love it.

Price $475

Extra stuff I learned about it:

1. The 16cfm mode (perfect for a 2 person bedroom) is only 0.3 sones at 4 watts. Almost inaudible.

2. Low speed is 8cfm (the one person setting) is 0.1 sones which is TOTALLY inaudible.

3. It can cycle on humidity if desired. That is, it will come on when the humidity reaches 40%RH (low), 50% (medium), or 60% (high). When the humidity drops below the setpoint, it shuts off.

Asked By Kevin Dickson, MSME | Jun 6 14
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