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DCAIRSYSTEMS 03-14-2009 11:36 AM

Loud "boom"??
hey, ive just recently become a liscenced gas tech.
I had a call to check a furnace (Lennox High boy, 23 years old)
about a LOUD BANG that would happen. This occured (according to them) "not all the time, every now and then".
Checked the burners for ignition problems, flame spread and ignition FINE.
blower and furnace cycling seemed great. Furnace was still in good shape for an oldie.
I was told a possibility of this BANG could be the ductwork 'popping'.
from what the lady said the BANG that happens is very loud and scary but only seems to happen when the furnace kicks in and sometimes when at the end of its cycle.
I was there for a while turning the furnace on and off, waiting for this BIG BANG so itd be easier for me to locate exactly where its coming from..but didnt happen for me.
could it be the blower motor?
should i worry about the heat exchanger?
Whats my best bet?

anyone that can give me some advice, just in case i go back there?

kenmac 03-14-2009 12:23 PM

could have been dirty crossovers on the burners causing delayed ignition. Could have cleaned itself out with the Bang. Could be cracked exchanger

yuri 03-14-2009 12:46 PM

Sounds like the ductwork bangin/oilcanning as it does it at the end of it's cycle. Those old Lennox units may last 28-30 years but a new high efficiency 92% unit is about 30% more efficient so I would try explain that to her and get a sale. At 23 yrs the gas valve may fail and repairs are expensive. Unless you live in a warm area (few running hours of the unit) a new more efficient unit will pay for itself. Feel free to ask lots of questions here, there is a TON of talent/experience here.

Good Luck and Welcome.:thumbsup:

DCAIRSYSTEMS 03-14-2009 02:33 PM

thanks alot guys.
I just got my G2 and am currently working for a residential hvac company.
Theres alot of responsibility that goes with being the last tech to look at a furnace..ESPECIALLY if anything goes wrong!
i take it very seriously.
So maybe im being a little paranoid..i just want to make sure i cover all the bases..and if i learn from my mistakes.
so yah..expect to hear MANY questions from me..haha..just part of the process of becoming a GOOD gas technician


yuri 03-14-2009 02:43 PM

Take it VERY seriously. Have had to deal with a couple of crazy customers with lots of money who decided to have their lawyer take a run at my company. Fortunately we have deeper pockets than they did. NOT a lot of fun when you have to deal with the Dept of Labour or the gas authority so don't make mistakes. G2 Ontario eh?

DCAIRSYSTEMS 03-14-2009 03:56 PM

haha got it man

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