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!


14 Answers

Hydronic Heating System Hydraulic Buffer Tank vs Hydraulic Seperator

This question might be more appropriate in a plumbing forum but I have had such great and thoughtful responses in the GBA forums I look to here first. This is also a hydronic heating mainstream topic which should be appropriate for GBA.

Asked By Roger Smith | Feb 26 17
11 Answers

HVAC ducting - Climate Zone 7a

The house is 40 year old bungalow with heated basement. It has an older 80% efficiency forced air natural gas furnace with an input BTU/hr 88,000 and output BTU/hr 71,000 with 1400 CFM.

The living room is 268 sqft and is ~24% of the total volume of the main floor, which is open plan so it is connected to the dining room (268 srft) and kitchen (137 sqft), each being ~12% of tot vol, respectively. The living room is at grade level with 9.3' high ceilings, compared to the rest of the main floor that has 8' height ceilings and is ~2' above grade.

Asked By user-6759891 | Mar 19 17
4 Answers

ERV and flex duct

We're planning to install a Renewaire EV90P ERV with dedicated ductwork in our new 1900 sq ft home. It's going to be a budgetary strain to install hard pipe for all the entire system. So I'm hoping we can get away with a rigid duct for a trunk (running parallel to floor trusses) and then 6 inch flex duct going out to the exhaust and supply registers (through the webs of the floor trusses) - this is what the HVAC contractor is recommending, but I'm concerned about this small unit being able to handle the additional resistance to air flow from the flex duct.

Asked By William Costello | Mar 22 17
1 Answer

Air handler or fan coil for low load home?

Hello,

I am building a 2,000 sq.ft. townhouse in Oakland, CA. I plan to use a Sanden heat pump hot water heater to provide both domestic hot water and space heating. I am seeking guidance on how best to distribute the heat to the basement, first floor, second floor, and attic loft. Due to budgetary constraints, I am looking for the most economical heating distribution system. While a hydronic distribution system would be nice, I assume forced air is going to be my best bet - let me know if you disagree!

Asked By Gregory Sherman | Mar 22 17
17 Answers

Ultra-Aire XT105H vs. Honeywell DR90A2000

I've seen much praise of the highly efficient (most efficient?) UA XT105H whole-home dehumidifier in my research. It certainly seems like a winner. As with many things, though, having the best often comes at a price and the XT105H seems to be no exception to that rule. See below for the specs:

http://s7d2.scene7.com/is/content/Watscocom/Gemaire/article_142249153705...

Asked By Lance Peters | Mar 1 17
10 Answers

Air King Introducing most efficient fan?

I was mulling around on the Energy Star website and came across a listing for an Air King in-line fan. Curious, I checked out their website and also found they have a new line of DC motor exhaust fans coming to market.

According to a page on the 2017 AHR Expo website, these new Air King D4S and D4D fans will be the most efficient exhaust fans on the market:

http://ahr17.mapyourshow.com/7_0/exhibitor/exhibitor-details.cfm?ExhID=1...

Asked By Lance Peters | Mar 21 17
35 Answers

Inexpensive, efficient HRV?

I just saw the posts about the Panasonic Intelli Balance 100 ERV. Does anybody make a similar HRV? Something with a price point under $1,000, good efficiency and at least 50+cfm airflow? A unit like that would make me reconsider an exhaust-only system.

The closest I've found are the Braun HRV160 ECM units.

--John

Asked By John Ranson | Mar 12 17
10 Answers

ERV vs. HRV Efficiency - Humidity Loss Considered?

I've been looking into Heat/Energy Recovery Ventilation and comparing specifications of different models. As we know, HRVs transfer heat and ERVs transfer both heat and humidity to incoming air from outgoing air in cold/dry conditions, and do the reverse in hot/humid conditions.

I was looking at the specs and I couldn't really figure out how the latent recovery of an ERV was being accounted for when compared to the efficiency of an HRV. Perhaps the specs indicate this and I'm just not getting it?

Asked By Lance Peters | Mar 15 17
6 Answers

Maximum CFM for range hood without makeup air

In a tightly sealed house, what's the maximum CFM that you could consider in a range hood without supplying makeup air. I know that the IRC allows up to 400cfm without makeup air, but is that actually advisable? Any personal experiences about 200-400cfm fans in tightly sealed houses?

I'm considering putting in a fan that goes up to 350cfm, and opening a window if I need to run it at full speed.

-John

Asked By John Ranson | Mar 18 17
11 Answers

Electric vs. Propane Direct Vent Water Heater

Hi All,

My water heater is nearing the end of its lifespan and I am trying to decide the best option for replacement. My main criteria is lowest energy cost. Secondary criteria are installation cost and overall efficiency/greenhouse gas emissions.

Right now, I am limiting my search to storage units (no on-demand).

The unit I have right now is a direct vent propane heater. I pay about $4/gallon for propane (well over 4X the wholesale price ! Don't get me started about the unjust economics of residential propane). My electric rate is about $0.20/kWH.

Asked By Pierre Donner | Mar 18 17
Register for a free account and join the conversation


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