cracked heat exchangers

[vapor hvac/r]

i took a heat exchanger class the guy said to pull the blower and spray the heat exchanger with high concentrated dish soap then pull the burners to check if any soap went thru. i tryed it a few times but never found a crack he also said a tracer gas will work. does anyone have any good tips

[Juleous]

Is that a serious suggestion? Inspection with a scope or mirror, Smoke test, I have also closed all supply registers and watched the flame change. Lots of ways to check best is to remove the blower take a light shine it on the outside of heat exchanger and look for light through the burner inlets. This works on open clam shell style type found in older furnaces. RTU units just pull the top off or open up the inspection panel they are a lot easier than furnaces. Goodman I would remove the limit and slide my scope in you could see the rings cracking off or cracks in the exchanger, if it's really tough then you pull it out but only if your sure and you have to check it. I could go on and on with ways to check different furnaces you just figure out what works best for you.

[Paul Bee]

Juluous just about covered it. A carbon monoxide detector really helps too. Go to www.tpi-thevalueleader.com and look at the HXG-2 and HETKIT this is the tracer gas method you mentioned in your post.

[amd]

A carbon monoxide detector really helps too.

How?

The combustion side of induced draft furnaces operates under a slight vacuum.

I doubt that a co meter can detect bad heat exchangers, unless there's a crack which allows the air stream to blow combustion byproducts out the inlets. (where the burners are)

[Paul Bee]

There are still a lot of natural draft furnaces out there. Also you can check the flue gasses on a gaspack to see if the flame is burning clean. Maybe thats why the guy giving the class suggested the soap trick and tracer gas test kit.

[bja105]

i took a heat exchanger class the guy said to pull the blower and spray the heat exchanger with high concentrated dish soap then pull the burners to check if any soap went thru. :

Not concentrated soap, I use water with a few drops of soap. It works, just need to practice. I sell a lot this way. The water washes the soot and rust out of the cracks and leaves a dark wet spot.

[Mr Chesapeake]

A good combustion analyzer will help determine if a heat exchanger is bad. Have found quite a few that way.

[Diceman]

Their all cracked anyways, why bother.

[coolestacman]

water is the best soak down the outside of the heat exchanger and look for wet spots inside

[jdavis72]

At Comfortech 2009 this year, there was a small company selling this UV dye and flightlight kit for checking HX. You took a screw out somewhere, and with a long metal tube, sprayed the dye all over the outside of the HX. Then you took the UV light and looked inside it, or vice versa. Anybody tried something like this in the real world? It looked impressive, but I had my doubts on the tube type HX's.

[coolestacman]

i have been doing this for 15 years and water has never failed and it is free

[vapor hvac/r]

the guys name is ellis from heat exchanger experts the book that comes free when you take the class tells you where to find the stress point in the heat exchanger for alot of differnt furnaces he sells a mirror that is long and comes with a pvc case to keep the glass safe. the class is alot of money but the company paid for it also his class his hard to take cuz you got to wait untill he comes to your city im from chicago and we had to wait to take the class.

[wildtech]

I primarily do rtus my way is a well charged battery and cordless drill, I have carbon monoxide anyalizer but I don't trust it good or bad until I see it with my eyes. Yes I sound crazy but every rtu that I p.m I try to pull apart if easily possible, Yorks are easy, carriers, tranes. If its not easily possible then I used the anyalizer. Heck last week I had a really close buddy say that his co2 detector was goin off, I went over there did a co test then proceded to rip the oil furnace apart (resi). I don't like takin chances and jepordizing safety

[wildtech]

I primarily do rtus my way is a well charged battery and cordless drill, I have carbon monoxide anyalizer but I don't trust a heat-x good or bad until I see it with my eyes. Yes I sound crazy but every rtu that I p.m I try to pull apart if easily possible, Yorks are easy, carriers, tranes. If its not easily possible then I use the anyalizer. But then even if I have a doubt I pull apart. Heck last week I had a really close buddy say that his co2 detector was goin off, I went over there did a co test then proceded to rip the oil furnace apart (resi). Everything was ok justa bad co detector the darn thing was goin off outside. I don't like takin chances and jepordizing safety

[Twilly]

Twilli still uses Bon Jovi Twilli's pet hamster. Bon Jovi wears a little helmet cam and Twilli can sit on a stool and watch the monitor with the customer.

[mattm]

Or you can see them clear as day without special tricks.

[derhas]

if water is used, add a wetting agent which reduces waters surface tension to allow it to fall through a crack easier.

[derhas]

for an extra step of security; if you use water, it would be a good idea to add a little amount of wetting agent to the water as it will reduce its surface tension and allow easier crack penetration quickly

[richvacr]

what is the real deal with cracked heat exchangers?

the blower makes positive pressure on the exterior of the hx the external pressure is greater then the internal hx pressure so flue gasses can not enter the the conditioned i.e. breathing air. except for the period of the fan delay.

And the great prevalence of draft induced the hx is under further negative pressure - there are a few combustion blowers out there also gravity. If they have gravity it probably should be replaced for that reason alone or at least customer told that they should plan on it, unless they are 94yo with a furnace from 1952.

So with draft induced and positive pressure on the hx what are in consequences of cracks revealed by extraordinary measures - beyond visual - flashlight works well.

The way I see it, excluding a mound of rust, if visually it is ok and age is not an issue it is ok. A mound of rust a closer inspection or if there are problems.

If the crack is enough to cause ignition problems that is serious. If the crack is enough that a enough flue gasses are entering the airstream yes. But a small opening found by removing the rust & soot (well there is another problem) and condeming the unit is to me questionable.

[TheSearcherMan]

what is the real deal with cracked heat exchangers?

the blower makes positive pressure on the exterior of the hx the external pressure is greater then the internal hx pressure so flue gasses can not enter the the conditioned i.e. breathing air. except for the period of the fan delay.

And the great prevalence of draft induced the hx is under further negative pressure - there are a few combustion blowers out there also gravity. If they have gravity it probably should be replaced for that reason alone or at least customer told that they should plan on it, unless they are 94yo with a furnace from 1952.

So with draft induced and positive pressure on the hx what are in consequences of cracks revealed by extraordinary measures - beyond visual - flashlight works well.

The way I see it, excluding a mound of rust, if visually it is ok and age is not an issue it is ok. A mound of rust a closer inspection or if there are problems.

If the crack is enough to cause ignition problems that is serious. If the crack is enough that a enough flue gasses are entering the airstream yes. But a small opening found by removing the rust & soot (well there is another problem) and condeming the unit is to me questionable.

MONEY! ITS ALL ABOUT THE CABBAGE