How to Inspect HVAC Systems

[Leon Slack]

Just starting course. I also started the Nachi TV course. So far, it seems very educational

[Dale R. Tolly]

Hello there! Just beginning the HVAC course for the first time. Thank youfor such great courses

Dale Tolly

[Guy White]

done

[Joe Funderburk, CMI]

More info from the 2009 IRC on gas appliance connectors:

Limited to 6' in length.

Shutoff valve is required upstream of the connector.

Cannot pass through the cabinet of an appliance (furnace) even if protected by a bushing.

Cannot be joined to another connecter (only 1 connector for each appliance).

Appliance connectors are CSST and require bonding per G2411.1 (NEC 310.1)

[Joe Funderburk, CMI]

"Most jurisdictions do not permit flexible gas pipes going through walls, floors or ceilings. They cannot be concealed. They are limited in length. And the shut-off valve cannot be in a different room than the appliance unless it is clearly labeled."

None of the above is a limitation on CSST per the IRC, the IFGC or by CSST manufacturers.

[Joe Funderburk, CMI]

Course language: "Galvanized Steel
Black steel is commonly used inside a residential property to carry the natural gas. Galvanized steel is not used [emphasis added] because the zinc coating might flake and clog the line or the appliance. Try not to get confused easily by the appearance of the pipes. A gas pipe may appear to be a water supply pipe, and vice versa. If copper is permitted, both the water and the gas piping may be copper. Special identification of the lines in your jurisdiction may be required or recommended."

Statement above is incorrect in jurisdictions that go by the IRC

"2009 IRC G2414.4.2 (403.4.2) Steel. Steel and wrought-iron pipe shall
be at least of standard weight (Schedule 40) and shall comply with one of the following:

1. ASME B 36.10, 10M;
2. ASTM A 53/A 53M; or
3. ASTM A 106.

Code Commentary: Steel pipe must be Schedule 40 or heavier, must comply with one of the listed standards and can be black iron or galvanized. Contrary to popular belief, natural gas does not adversely react with the zinc coating on galvanized pipe."

[Joe Funderburk, CMI]

"Drip Leg

The drip leg (or dirt leg) should be installed at the heating system. Look for the drip leg at the bottom of the vertical pipe that leads to the gas heating system. The debris that floats in the gas will drop into the drip or dirt leg before entering the vulnerable components of the heating system, such as the gas valve."


Better term in most cases is "sediment trap". A shut-off valve should be installed upstream of the sediment trap so that it can be removed and cleaned during system maintenance.

[Joe Funderburk, CMI]

Course quote: "All Air from Outdoors If all combustion air is taken from the outdoor air, then one opening should be within 12 inches of the top and one within 12 inches of the bottom of the space. The openings are permitted to connect to spaces directly communicating with the outdoor air, such as a ventilated crawlspace or ventilated attic space. Each opening should have a free area of at least 1 square inch per 4,000 BTU/per hour (550 mm2/kW) of total input rating of all appliances in the space when using vertical ducts (2,000 BTU/per hour if using horizontal ducts)."

2009 IRC G2407.6.2 (304.6.2) One-permanent-opening method.
One permanent opening, commencing within 12 inches (305 mm)
of the top of the enclosure, shall be provided. The appliance
shall have clearances of at least 1 inch (25 mm) from the sides
and back and 6 inches (152 mm) from the front of the appliance.
The opening shall directly communicate with the outdoors
or through a vertical or horizontal duct to the outdoors, or
spaces that freely communicate with the outdoors (see Figure
G2407.6.2) and shall have a minimum free area of 1 square
inch per 3,000 Btu/h (734 mm2/kW) of the total input rating of
all appliances located in the enclosure and not less than the sum
of the areas of all vent connectors in the space.

Code Commentary: Research has shown that for modern appliances, a
single opening to the outdoors will perform as well as
the traditional two-opening method. The one-opening
method described in this section depends on a reduced
pressure being created in the enclosure by the
draft created by the venting system. This reduced
pressure causes combustion air to enter the enclosure
through the single opening. The opening must be
properly sized considering both sizing criteria: the
square-inch-area-per-Btu/h ratio and the area minimum
based on the sum of the areas of all vent connectors
in the enclosure. This method allows for fewer
openings, fewer ducts and fewer objections by the
owners/occupants.

[Paul R. Bernier]

Boy howdy! Lookin forward to gettin down and doin it, yea! Here I go!
All of the courses proir to this one have been informative and challenging so far! THX Paul Bernier Soledad,Ca

[Jeffrey M. Cohen]

Taking the course now as well, havent had any problems with the slides loading.

[Andrew Bieber]

Hey,
I am starting the course right noww as well, Ill let you know how well it was.

Andrew Bieber

[Christopher Engelman]

Just starting the course today and looking forward to see how it compares to others that I have taken.

Chris

[Michael H. Easter]

Just beginning course,I'm sure it will be as informative and useful as the other courses I have taken.

[Juan C. Jimenez]

This is a great course but I feel like I have read that "furnaces can be divided into two broad categories, gravity warm air systems or forced warm air systems" about 25 times. I keep thinking I am reading the same page but I am not. Great course though.

To Joe Funderburk I agree that "sediment trap" is a more accurate term but it is not a choice on the NACHI exam. I kept getting it wrong because I knew it was a sediment trap and I did not know it was called a drip leg until i asked another inspector.

[Ben J. Gromicko]

Great suggestions, everyone.
Thank you.