Looks to me like plumbers and HVAC people are stealing ideas from the Proctology gang! ;-)

"Looks to me like plumbers and HVAC people are stealing ideas from the Proctology gang! ;-)"

Everybody seems to be saying that! I'm going to be afraid to whip that thing out sometimes.
"What are you going to do with that thing?" :) :0

Smoke bombs used in the HVAC/R trade are a lot cheaper!

They are also more impressive to the customer and allow him/her the ability to see an actual leak which makes you more creditable.

Of course the rip off contractors will just use it to show the customer normal rust and discoloration in the heat exchangers and scare them into buying new systems.

While still contracting, I have never found a cracked heat exchanger using smoke bombs if I was called in for a second opinion.

I know some of you are going to say smoke bombs are not practical these days because most systems use induced draft and the burners are inshot style at the top of the primary heat exchanger.

That is not entirely correct as you can suspend the smoke bomb near the openings that the inshot burners occupy and jumper the combustion exhaust fan to suck the smoke through. You and I both know that under that scenario the smoke will never make it through the heat exchanger into the house air ducts.

Systems using top mounted inshot burners are most likely to develop cracks where the greatest heat differential takes place which is right at the top of the heat exchanger which can be easily seen looking straight on.

Even if you had a cracked heat exchanger in a furnace using induced draft, if the smoke can't make it into the house air ducts, it ain't gonna hurt anyone.

Just another toy for those that won't or can't do the basics.

Fairyprincess

Daddo, ahh don't listen to FP, he's just an old fashioned guy who can't accept the new technology. He gave up the trade when the horse died the pulled his service vehicle around! :-)

There are many techniques to checking a heat exchanger and the smoke is one of them. The smoke however won't show a crack that isn't open and though it may not bother you that a crack exists but doesn't leak into the home, it is still there, and should overheating occur due to a stuck valve or a failed motor happen- I've seen a harmless crack split right open and lengthen as it does. Not something I would want in my home should I have a family I love dearly, to find I could have prevented such a thing from happening. What would you say? "Well, you have a crack in your heat exchanger, but don't worry about it?" "Yes- it's under warranty, but let's wait next year and see if it get's worse". Don't want you working for me! :)

Mr. Havac:

My horse did not die!

I sold him to the glue factory when I found out I could get more manure for my gardens and lawn by having unscrupulous contractors of all trades come to my house and give me quotes (Of course I hid the wagon in the lean-to shed next to my leaning barn with the rat infested silo so they wouldn't know I was a technician.).

Daddo:

As long as the heat exchangers have negative pressure, even a sudden crack, or separation in the heat exchangers WILL NOT endanger the occupants.

Efficiency will be reduced and depending on how the combustion air flow proving switches are programmed to operate, the furnace should go into lockdown.

In the newer HI-EFF furnaces I would be much more worried about gas supply connection and exhaust pipe leaks into the house than I would cracked heat exchangers.

Naturally aspirated systems are much more dangerous in the event of cracked heat exchangers in only a few circumstances.

If the leak is on the upflow side of the house air supply, you will get the vacuum effect of the air flow sucking some of the exhaust out of the heat exchanger.

Since furnaces in general are designed to have a strong positive pressure in the house air chamber, any heat exchanger crack is much more likely to push house air INTO the heat exchanger and OUT the chimney.

On older naturally aspirated furnaces a cracked heat exchanger is more likely to extinguish the pilot light of knock down the flame near the flame sensor thereby causing the furnace to function erratically enough to call in a repair person.

I agree that cracked heat exchangers should be changed out and have personally shut down and red tagged bad heat exchangers, but there are way too many contractors and techs that scare people into new units or major repairs when they are not needed.

When I have found bad heat exchangers I point out the obvious cracks and DO NOT GET INTO THE DETAIL I GIVE HERE only because my liability insurance would have disappeared if I told customers they could carry on for a while depending on the type of heat exchanger crack or hole they had.

I hate to see one more high tech tool that is going to be exploited to take advantage of the innocents.

Fairyprincess

"I hate to see one more high tech tool that is going to be exploited to take advantage of the innocents.

Fairyprincess"

You sound as if everyone out there is a ripp off. Those types will rip people off anyway.
So no one should buy or possess a tool to aide them in finding a problem that otherwise could go unchecked? If they came up with a tool that would absolutely test a furnace for leaks and be 100% sure- no one should buy one because they might mess with the settings to make it read falsely? How many ways can I think of to make "smoke bombs" make it seem like there is a crack or hole? I don't think "anyone" should use that tool either. Hey- let's don't use anything! We'll guess at it! Unless guessing can be rigged to seem a rip off.
Air ventury affects happen in furnaces where there is turbulence and even in a positive atmosphere a negative pressure can be present around the curves of the exchanger and co can be pulled into the home at that point.
Your baseing all the argument on those that try and rip folks off- those people are out there and it does happen, but how in the world should we neglect all availible resourses at our disposal based on what they do?
Sorry to hear about your horse. You know- all contractors are not crooked. At least 10% of them.

Hey, personally I think that tool could come in handy just as an aid in checking the condition of a heat exchanger during routine maint or after service, especially in a unit that is starting to log some miles on it. Its a pretty decent way to impress the customer and you can let them take a look and maybe try to give him a guestimate as to how much longer he might expect the unit to be around before he has to start thinking about a replacememnt. I know if I were a layman I would be impressed with something like that.
FP could use one to lift a ceiling tile and peek into the ladies room!!!!!

Mr. Havac:

You are so behind the times.

A mutual old friend of ours called Bountyhunter, who used to be a P.I. for almost five years tells
me the "see snake" is so "1960's" technology for surveillance.

Nowadays you can get a wireless camera that will replace any hinge pin on any door in the world
with heat sensing capabilities.

The heat sensor only activates the camera when something is in its programed vicinity to save on
battery power.

It can transmit up to 200 feet using coded burst technology which was only available to the CIA
in the "1950's" but which has become so inexpensive that anyone who knows where to buy one
can afford it.

A "repeating transmitter" within that 200 foot range can then send it as far as necessary using sub
frequencies that have no monitored traffic to anywhere in the world.

Bountyhunter is long out of the P.I. field but he still keeps up with what's out there. He even uses
satellite technology to monitor the condition of his lawn and garden without having to pay for the
service that so many farmers use.

"Lifting ceiling tiles"; how amateurish and so "1920's".

Fairyprincess

Yeah but its the thrill of getting caught and getting chased for 20 blocks but a bunch of overweight women who feel their large bottoms have just been violated. :-) So whats the name of the site where your collection of pics are posted? LOL
There is also a certain contributor to this forum who could insert that cam daddo bought where the sun don't shine and give himself a brain scan!:-0 No names,,,,

Bought one the other day. $206 at grainger. so far I've only used it to look at the dust under my fridge but it will come in handy.

Fairy Princess,

You stated, "As long as the heat exchangers have negative pressure, even a sudden crack, or separation in the heat exchangers WILL NOT endanger the occupants. "

There are always exeptions to the rule. This winter I was dispatched to a home with a 90+ Goodman GMNP series gas furnace with a crack at the top of the primary heat exchanger. The mother had collapsed down the stairs and her daughter called 911. The paramedics found elevated levels of carbon monoxide in the home. A negative pressure inside the burner chamber did little from preventing airflow from pulling co and other gases into the house.

Even on natural draft furnaces co can be pulled from the heat exchanger. Before I started carrying a video camera I once watch the flame being pulled off a burner light over and sucked into a crack when the blower came on. This continued to happen a few more times before I shut the furnace down.

The American Gas Association (AGA) developed a 3 step inspection process for heat exchangers.

1. Visual inspection

2. Flame disturbance test

3. Injection of the heat exchanger chambers with 14.3 percent methane mixture with the remainder nitrogen mixture and testing the exterior with a combustible gas detector.

With furnaces becoming more compact making a visual inspection more difficult than with a mere flashlight and mirror any tool that can assist in doing a more thorough inspection should be embraced.