Cutting Holes in furnace cabinet

Andy_6

I was wondering what you guys know or think about the practice of cutting holes in the back of forced air furnace cabinets to look for cracks in the heat exchanger. It seems to me that this would void the UL listing on the furnace. Am I not thinking clearly about this, or should I be bringing this to the attention of the local authorities. In my area there are dozens of furnaces that were cut up in this manner.

MikeB34

No no no no no no no no no

You cannot cut an opening in the cabinet unless it is in an approved location. There are other ways to check. I have never had to do that in 15 years.

John Levey

NOT a good idea!

Andy,

Mike's right, there are much better ways to check! Many technicians test the integrity of the heat exchanger with a draft gauge, it's totally non-invasive & better than a smoke bomb!

Andy_6

I thought that this was a bad idea also. However I called LENNOX and was told that they do not see any problem with doing this to one of there furnaces. They also said that the UL listing is still good just as long as the insulation is put back and the same kind of glue is used to hold the insulation to patch. I think I will stay away from this method.

[Deleted User]

heat x

In selling our home we had a home inspection by the buyers. The inspector punch a hole in the back of the furnace to test. Upset me greatly, I explained he didn't own the furnace or I didn't hire him and you punch a hole in the back of my furnace! And just patches it with foil tape. He tells me to "chill, we do it this way all the time". He was just a home inspector, not a tech. Good thing they bought the house, now we have real heat. Hot water!

jim lockard

not much

I agree with the above there are better ways and I do not think you would see much. What about pulling the blower fan and sticking your head in and looking up, or spray salt water into the return with the fan running and watch the flame change color or pass your torch under the draft hood and look for color change, draft gauges work too. Maybe just sit down in front of the furnace and watch the fire. You can do a lot to check the furnace other then chop holes in the case.

Greg Swob

Try a

borescope instead of cutting holes. You can only see so far with mirrors and sometimes trying to be a contortionist to get the mirror, flashlight and your eyes ligned up is tough. I would think the labor saved over patching holes and taking risks of cutting into a sensitive area would outweigh costs of a bore scope - haven't found one on Ebay to date, but have seen them around $280 & up. Also, furnacesafetyconsultants.com supposedly has a book with fairly complete list of major brands of furnaces with their most prone areas of fracture or burnout in the HX. Don't have this book, but have heard it is a timesaver. My own experience: Lennox 'G' models from the 70's & 80's (must be hundreds in our tiny town) - look to the upper far rear of the HX, especially middle or right HX chambers. Place mirror into draft hood area and shine your light so as to look to the far rear; also often just above the burners about 8" - sometimes it looks like the HX 'skin' is flaking off in peels, hiding a burnout spot. Carrier/Bryant/Payne (various horizontal models from the 80's & early 90's) - right above the pilot flame at the HX weld - found lots of these cracked all in the same spot during this fall pre season service checks alone. Greg

Andy_6

I have the books from furnace safty consultants and agree with the fact that there is better ways to check than cutting holes in the cabinets. In my area a number of companys are in my opion needlessly chopping holes in the furnaces. They are cut right where the books show the most common places for cracks. The way I found out about it was fromm a mad customer that wanted a clean and check done and had a what another company called a safety inspection done in which they cut a 1 foot square hole in the back of the furnace. No cracks back there just a big hole. The customer kicked them out of his house before they did any more safety inspecting. I am just trying to get as much information as I can to support NOT CUTTING holes in the cabinets. So far I have not found UL testing labs to be concerned or any manufactures!