Gas Furnace Sequence of Operation w/ Justin Skinner

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 22 November 2016

⏱️ 44 minutes

🔗️ Recording | iTunes | RSS

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Summary

In this episode, Bryan talks to Justin Skinner about the standard gas furnace sequence of operation.

Regardless of the furnace type, it all begins with a heat call on W...

Then, the furnace checks the safeties to make sure ignition is possible and safe. If all systems are a go, the inducer motor comes on and clears a path for the exhaust. The furnace then proves that the path for the flue is clear, and a pressure switch closes upon sensing a pressure differential. The miracle of ignition comes next. There are a few different types of ignition, including hot-surface, intermittent spark, and standing pilot. Once the furnace opens the burner, it has to prove the flame.

Proving flame is somewhat similar to proving the flue path. A flame sensing rod creates a potential, and it determines if a flame is present by picking up microamps of current to ground. We're merely scratching the surface here, but the bottom line is that the furnace does a lot of checking and proving throughout the startup procedure.

Above all else, remember to check the fault code if the sequence of operation fails to complete. The absolute WORST thing you can do is restart the furnace, take the door off, or turn the furnace off. You lose a major troubleshooting clue.

Join Bryan and Justin as they talk about these furnace sequence topics:

Low Voltage Wiring
Boilers
Forced and Natural Draft
Flame rectification
Cleaning Flame Sensors
Gas Pool Heat
Silicon Nitride and Silicon Carbide
Hot Surface and Intermittent Pilot

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Transcript

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0:00.0	This episode of HVAC School is sponsored by HVAC-HAC.
0:10.0	HACS.com.
0:11.0	HVAC HACS reminds you, don't be a hack.
0:15.0	And Brian Orr reminds you that if you are a manufacturer or you are a tool distributor or anybody who wants to get in front of air conditioning
0:24.4	technicians and businesses you can also sponsor the H.E.C. school. We're looking for
0:29.7	people to partner with us to help us keep producing good quality content. So if you're interested in that you can
0:34.6	always email me Brian, B rYa n at H VACR school.com. The man who still cringes every time he sees equipment flying with a crane.
0:53.6	Brian Orr.
0:55.5	Thank you for that, Joel.
0:57.1	And I don't think of myself as a fearful person,
1:00.1	but anytime I see a RTU or a condenser flying through the air, I just constantly am thinking like the worst is going to happen.
1:07.5	I know I've done it hundreds of times, but it still bothers me.
1:11.5	And it sits right up there in my list of fears along with parking
1:15.7	garages. I don't know if anybody's with me on this but I despise parking garages I
1:19.7	did a job one time on a skyscraper in Tampa where we were installing some Marver units on the outside of a co-locate for a cell tower.
1:28.0	And that parking garage was just such a nightmare with my big diesel truck that it just made me
1:34.5	Scared of them from now on. So anytime it doesn't matter what I'm driving when I go into a parking garage
1:38.8	I just have extreme anxiety attacks. But that's probably just my weakness of character.
1:43.7	Today on the podcast I have Justin Skinner and Justin is a boiler tech from Virginia
1:49.8	and he primarily works on commercial and industrial boilers but he was kind enough to come on the podcast and talk me through
1:56.4	Furnace sequence of operation. I have worked on a lot of 80% furnaces, but I don't do a lot of furnace work day and day out so I figured it'd be better to have somebody else on with me while we go over sequence of operation.
2:08.0	Still pretty simple stuff, but for those of you who don't work on furnaces every single day it's a good little brush up to prepare for the cold winter that is coming and has already come for some of you.
	...

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