Community: Mechanicals

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, the usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration: Under the box labeled “More explanation,” look for the words “File attachments.” Click that, and you should be able to attach a photo.

Thanks for joining the conversation!


0 Answers

Average lighting, appliance and plug loads for PV sizing?

In doing some energy modelling for a future single-family net zero residence (in Canada), I am running into the problem of trying to guesstimate what the total lighting, appliance and plug loads will be. Because it can be different with every specific family, I'm wondering if anybody has any links or resources they can provide that offer average values for these loads that one can use. I will calculate the heating, cooling and hot water loads separately, but am hoping somebody has some suggestions for those remainders.

Asked By Burke Stoller | May 23 17
6 Answers

Can I combine floor and wall heating in a solar passive house to avoid overheating?

I have consulted many "experts" on highly insulated houses, most of them recommend to use ductless heat pumps to heat the house. But I am a radiant heat addict...
Apparently the problem with radiant floor and passive solar is that when the sun comes out, the southern side of the house is too hot because the concrete slab has heated during the night and is warm and when the sun comes out it can bring it to a much higher temperature.

Asked By Micheline Freyssonnet | May 22 17
2 Answers

The shoulder season with mini splits- Do I select heating or cooling or shut it off completely?

I Recently hired a contractor to install a Mitsu MSZFH15NA indoor unit with MUZFH15NA outdoor unit to be the sole source of heat and AC for a 1970 single floor ranch, 900 sq. ft, open concept with cathedral ceilings about 12 feet tall, in the Cape Cod, Mass area..

Previously, a pellet stove was the source of heating and a window ac unit for cooling. Both which worked well in terms of comfort and efficiency when paying the electric utility at months end.

Asked By James Someone | May 20 17
23 Answers

Ductless minisplit - completed Manual J

Hello

Asked By Jeremy Archer | May 1 17
4 Answers

Heat Loss and Manual J - PHPP and/or HRAI Manuals?

After looking into having heat loss/gain analysis done on my new house build I'm not surprised to see the costs coming in at $500 and up.

I am a Mechanical Technologist and have no problem with technical topics and math. As such, I have a hard time justifying paying other people when I can educate myself and learn how something is done. I generally prefer doing things myself anyway, that way I not only fully understand what's going on, I also know the job is done right.

Asked By Lance Peters | May 16 17
4 Answers

Air exchanger ducting strategy

We are in Minnesota (Zone 6a). The home is an "L" shaped, 2200 sq/ft single level, slab on grade. Our floor plan is attached. We will be using a mini split for primary heating and cooling and electric baseboard to satisfy the code.

Asked By Scott K | May 15 17
17 Answers

Georgia Power's PV policy

We are under Georgia Power which does not allow net metering. Instead, I think we currently get reimbursed 4.2 cents/kwh for what our PV system produces, which is about 1/3 of what GA Power charges us for their power. Complicating matters is that during the summer, when our west-facing array is producing significant output, we are on GA Power's "Nights & Weekends" program which charges 20 cents/kwh on afternoons and 5 cents/kwh at all other times.

Asked By charles CAMPBELL | May 12 17
18 Answers

Is a single head minisplit practical?

This is a mostly accurate plan of dear, old Mom's house.
2265 ft²; zone 4 marine; target ACH50 = 1.5; 5000 HDD; 22°F design temp;
2x6 walls w/2 stud corners, 24" o.c., 1½" horizontal cross-hatched walls (similar to "Mooney"), 7" of dense pack cellulose; front wall faces north; awesome PV potential on south facing roof.

Asked By Mark Walker | Apr 27 17
6 Answers

Ducted mini split sweating

Hello, I'm in zone 2A and recently had a 2 zone ducted Midea minisplit installed. The system is running well except for some sweating issues on hot/humid days.

I have 4 registers where airflow must go through a 14x5.5" joist space, 6" flex duct is joined to the end of custom made metal boxes insulated with R4 on the inside, R6 flex duct is joined via a metal collar on the end of the box, the end is insulation only (no metal).

Asked By Jimmy Black | May 9 17
10 Answers

School me on whole-house dehumidification ... the good, the bad and the ugly?

Looking for some input on whole house dehumidifiers. We are going to be building a 2 story 3,000 sq ft house, the attic space will be conditioned and we'll be running two HVAC units. Ideally when we are done, we can be at around 900 sq ft per ton on the HVAC equipment. We are in Pensacola, FL which is technically Zone 2. Having lived in South Florida for 20 years which is Zone 1, our area feels pretty much the same. We have extreme levels of humidity.

Asked By Thomas Roberts | May 7 17
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!