Community: Mechanicals

Q & A Instructions

[Click map to enlarge]

drawing of climate zone map.gif

Advice can depend on climate — Please specify your climate zone in your question.

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!

Ask a Question >

1 Answer

Minisplit Design for Whole House

Hello, first of all thank you GBA for all of your articles, I have read many and found them to very helpful and interesting.

I am renovating my house (in Tampa, FL) and installing a new AC system, I will be installing minisplits most likely DIY, but will also talk with installers. I want to see what GBA users recommendations are for how I should design my system.

Asked By Jimmy Black | Sep 29 16
3 Answers

Can a ductless mini-split heat pump be installed for a walk-in cooler?

I have a contractor that installed a Fujitsu AOU12RLS3/ASU12RLS3 in a walk-in cooler for a restaurant. They claimed that it was more efficient than a traditional cooling system. Is this an acceptable installation for this system?

Asked By Kristin McAlpine | Sep 29 16
6 Answers

Please help me pick the best option for HVAC replacement

We moved into this 20 year old house here in Nashville, TN in June and have been doing various projects to bring the home up to and above current building best practices. We have put open cell foam in the attic (average ~8 inches with rafters covered) and have encapsulated and foamed the crawl with 1.5 in of closed cell and 12 mil vapor barrier. We replaced the upstairs HVAC with a new 5 ton Trane xr17 and S9v2 furnace.

Asked By John Sexton | Sep 8 16
3 Answers

Do I have an issue?

The weather is my part of Zone 3 is still pretty hot (90s during the day with a cooling trend into the upper 80s). I noticed that my two year old air-source heat pump is struggling a bit to keep things comfortable. The thermostat upstairs is set for 77 degrees but the temperature is hovering around 81.

I also observed some wetness under my outdoor unit as well as some similar signs of water in the pan under the air handler. What do you guys think? Am I low on refrigerant? What might cause that?

Asked By Steve Knapp | Sep 26 16
3 Answers

Is HPWH reliability still an issue?

I'm seeing a lot of negative feedback on the reliability of heat-pump water heaters. Are they much more prone to problems than straight resistance heaters? If you had to choose a 50-gallon domestic model, what would you choose?

Asked By Charles Campbell | Sep 23 16
2 Answers

Temperature adjustment / offset on Mitsubishi minisplit

I installed my MSZ-FH12NA two months ago and the unit is performing very well and I am not experiencing the short-cycling issue that others have, but the unit seems to consistently cool (haven't used heating mode yet) past the set temp on the remote by 4-5 degrees. (If I want it to cool to 70, I have to set the remote at ~74.) Does anyone know if there is a way to offset/adjust the remote control temperature to accurately reflect the actual room temperature?

Asked By Adam Emter | Sep 22 16
7 Answers

Crawl space ventilation

Hello,

I am building a raised floor wood construction home in the Monterey Peninsula, CA. The current plan to keep the crawl space dry and ventilated is to put a rat guard, seal off the space, and add a 75+ cfm fan that will have tubing that will draw & supply air from exterior locations. The footprint of the crawl space is about 3700 SF. The height varies from 1.5' - 2'.

My questions are:
Is this a good plan?
What would be good exhaust and supply locations?
Can you recommend a reasonably priced fan for this application?

Much thanks,
Barbara

Asked By Barbara French | Sep 22 16
2 Answers

Is a reflective surface necessary under radiant floor heating?

I have a situation in a house with a full basement where there is radiant heat in the floor joists of the first floor, accessible from the basement.
There are unfaced fiberglass batts in between the joists under the radiant piping. My business partner thinks we should replace the fiberglass with foil faced foam, but I think it's not necessary.
My partner's rationale is that there needs to be a reflective surface and there is none now.

Asked By Josh Engle | Sep 22 16
18 Answers

Why does my house SUCK?

It appears that most are concerned with proper ventilation considering the tightly built homes of today. I have a very severe flooring problem that I believe to be caused by negative pressure within my home and would like an opportunity to discuss with people more knowledgeable than myself. Allow me to explain a bit about the construction of my home, myself and my problem.

Asked By Cole Sumner | Sep 18 16
4 Answers

Mini split duct problem

Hi,

I am adding two new rooms onto my house; one room is a 13x26 with one octagon window and the other is 7x10 with no windows. The two rooms are located next to each other and would be considered "renovated attic space".

I had 3 HVAC bids provided and the cheapest one was over $5,500 so I decided to DIY the project.

Asked By M C | Sep 20 16
Register for a free account and join the conversation


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