HVAC design, Manuals J, S, T, & D, Duct leakage, Air flow, ENERGY STAR new home requirements, and more. Since heating & cooling are such a big part of home energy use, understanding HVAC is critical.

Members: 171
Latest Activity: Nov 13

Discussion Forum

Furnace with ECM: How to Model 5 Replies

Suppose you have a forced-air natural gas furnace.  At the end of its life, you are considering replacing it with an ENERGY STAR model.  In the cold northern states, that means 95 AFUE with an…Continue

Tags: blower, PSC, fan, ECM, gas

Started by Barbara Smith. Last reply by Ryan Schmidt Nov 13.

Exposed AC and ducts. How would you like to tackle this??

Some of the things homeowners,…Continue

Started by Hal Skinner Sep 7.

ENERGY STAR Furnaces & Failure of DOE Standard 7 Replies

Any speculation on why DOE was not able to make its new minimum federal standard for furnaces stick?…Continue

Tags: effectiveness, cost, market, share, ECM

Started by Barbara Smith. Last reply by Bob Blanchette Aug 15.

Conditioned air in the attic? Not us.

i have read in this group where someone suggested conditioned air in the attic.  This being done to make the cooling and heating equipment and duct more effective.  Please excuse me if that is NOT…Continue

Started by Hal Skinner Aug 14.

Are Zoned Heating/Cooling Systems a Good or Bad Idea? 24 Replies

For starters, I live in Atlanta, Ga and I am not an HVAC pro so this is a serious question that I would like answered for one of my clients.  I understand the premise of a zoned system and on the…Continue

Started by Jon LaMonte. Last reply by John Proctor Jul 5.

How to Read Load Calculation Reports 37 Replies

Hello to everyone again -- This is an update on a building I'm working on for a NG furnace.  It's been about a month (a very busy month) since I last posted questions and I have been to the building…Continue

Started by Kari Sauder. Last reply by Bob Blanchette May 5.

Needed: High Efficiency NG HVAC for a 2,100 sf single story building 15 Replies

I've been asked by the owner of a theatrical company about heat for her building.  It is a single story, 36' x 57' building (almost 2,100 sf) with only a little bathroom partitioned off in one…Continue

Started by Kari Sauder. Last reply by Kari Sauder Apr 24.

raised ranch heating, can't balance it 17 Replies

I need some input on an HVAC balancing question --- I have a raised ranch home with a finished basement and an open stairwell connecting the two floors.  It's an early '90's build originally equipped…Continue

Started by Kari Sauder. Last reply by Eric Kjelshus Nov 8, 2013.

Looking for a good load calculation software 15 Replies

Hey all, My company is going to be installing a few ductless heat pumps very soon and I'm going to need a load calculation software. Any suggestions?Thanks, AndrewContinue

Started by Andrew Vidal. Last reply by Perry Ning Sep 23, 2013.

Where to find EER and SEER if it is not on the label 4 Replies

That's allJudiContinue

Started by Judi Lyall. Last reply by Bob Blanchette Dec 29, 2012.

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Comment by John Nicholas on September 26, 2013 at 3:18pm

For ES 3.0 you have to verify the contractor is certified.  If he is certified he knows he has to take that measurement.  I would discuss the requirement with him and find out why he doesn't want you drilling in the cabinet.  I know you do not want to hit a piece of the coil.  The recommended practice is to use the same holes the certified HVAC companies tech used for rater measurements.

My next step is who hired you and is paying you.  They can decide not to go ES 3.0 - talk to the contractor - or depending on the paper work, refuse to pay him until he properly completes the process.  I hope it doesn't go that far.

Comment by Steven Lewis on September 26, 2013 at 3:12pm

I just go through the filter.  if it is not metal or electronic.  Leave the filter in place and poke a hole with your probe in a corner.  If you want to know the pressure drop across the filter place the probe just under the filter and compare to the number above the filter.

Comment by Bruce A. Bailey on September 26, 2013 at 2:30pm

I want to test static pressure for Energy Star version 3 in a split heat pump with the air handler in an interior closet so it does not have any return air duct the filter is in the slot at the bottom of the air handler. The inspection form requires 2 inputs a supply side static pressure (I took it in the riser plenum attached to the Air handler.) and a return side static pressure that is supposed to be between the filter (slid in the bottom of the Air handler) and the blower fan. The contractor says he doesn't think he needs to take the return side static pressure because there are not any return air ducts but he will not allow me to drill a hole in the cabinet between the filter slot and the blower. What do you suggest I do to get an accurate number?

Thank you in advance for any help you can offer.

Comment by Steven Lewis on December 17, 2011 at 11:55am

You  havent given  enough information to make an educated guess.  How dusty was the house before?  Is it in all rooms or just a few.  is it dust or fibers from the cloth materials in the home.  If you can sweep your hand across a surface and the materiall rolls up it is fibers and is probably not coming from the duct work

Take a camera and shoot some pictures down the duct or runs and that will show you if something is in the duct system as well.  What type and efficency  filter is the homowner using?  You might check the returns and see if there are any openings to the outside of the envelope . 

when you gave "more air" how did you do that?

Comment by Judi Lyall on December 17, 2011 at 6:42am

Good morning,

   I have a client that complained that certain rooms were either cold or hot. She had 45% leakage. We gave her more air, tightened the ducts and now she called and said that the home is now getting very dusty. What is the cause and what to do next. It has gone through the summer with the air blowing thru it, I would think the the dust in the ducts are already blown out

hanks for your reply

Comment by Al Tibbs on February 3, 2011 at 11:20pm
When will the ICC Codes prevent the installation of air handlers and ductwork in unconditioned attics. This practice is the biggest obstacle to achieveing the best results when retrofitting.
Comment by John Nicholas on December 31, 2010 at 10:02am

I went out to get the mail this morning and saw my neighbor's roof.  The attached image shows what I am thinking is ice, frost on the roof.  It is obviously circular around the flue from the furnace. The flue from the DHW is separate and not in the image.  It was frosty this morning and overcast. At 8:30 most roofs have frost. By the time I noticed this and took the shot, the frost on the other roofs is gone.

Is this excessive condensation from moisture in the flue gases and does that mean the furnace has a problem?



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