I’ll try to get a photo up later when my internet cooperates. I was looking at a 43 year old furnace which I am at least recommending some routine maintenance and a complete evaluation on for several reasons. It’s a low efficiency, open draft hood, rusty antique. There were several water lines/stains from moisture leaking out of the A/C pan and running down around the furnace.
One set of rusty water stains was at the back of one of the burners inside the heat exchanger. My question to the furnace gurus is, would these stains be considered confirmation of cracks in the heat exchanger since water made it through to the interior of the burn chamber?
When you create heat you create moisture. If the burners are set incorrectly and you are getting a cooler flame condensation can accumulate causing the staining. Not sure about the cracked heat exchanger though. I learned this from a heating tech about a month ago: He lets the furnace run for about ten minutes and the heat exchangers are red hot. He turns the burners to pilot and lets the fan run. He lites a piece of newspaper and puts it out so he has smoke. Run it along the burners and look for signs of the smoke coming back instead of going into the chamber. I would not use this as difinitive but another clue there is an issue. I also use a carbon monoxide detector and a mirror. I will never ever ever tell them yes or no as it should be confirmed but I will say it is suspected.
Based on my limited information from your post, I would recommend “evaluation by a licensed HVAC contractor to evaluate, repair or replace the heating system. Due to age and normal wear and tear and projected life expectancy, the unit may need to be replaced at any time.” and state any visible rust, and if/how the unit operated. Nuff said.
Yes, let’s try to avert that scene. My internet has been on the fritz for days now.
Actually, I see that my subject line was poorly chosen. This is not a request for what I should put in my report or tell my client, this unit is so old a cracked heat exchanger is a foregone conclusion whether I would say it or not. I just wanted to see what the opinions of inspectors and HVAC guys would be if they came across this. Cracked or not cracked? Could it be another viable piece of evidence?
In the photo, I think it’s pretty clear the water did not form as a product of combustion. It traveled down only one or two spots and stayed wet for a while allowing it to rust in the pattern it leaked. The moisture then leaked out the front of the exchanger(2nd photo). There were also stains all around the outside of the unit which came from the A/C.
My assumption would be the seams at the top of the exchanger would be watertight, but perhaps they could allow a condensate leak to trickle down.
XXXXXXXX XXXXXXX Furnace (1969)
*- Design life expectancy of the HVAC is 15 - 20 years. *
*- Recommend annual service and evaluations on all HVAC equipment to maintain. Recommend service of the HVAC at this time if annual service has not been performed. *
*- Service records are not visible or apparent at time of Inspection. Recommend obtaining service records from the homeowner. *
***- Due to the age of the HVAC equipment, replacement needs should be anticipated ***[FONT=Arial][size=2]***and estimated.at this time. ** *
This will cause a bit of thread drift, but is replacement always the recommendation of HVAC contractors after 20 or so years? I know they are in the business of selling equipment but I regularly see older than 20 year units with up to date bi-annual service cards stuck on the return vent.
I’ll let the HVAC expert suggest replacement, that recommendation has already been made, but I just hoped to discuss it a little. I like to know what makes things fail and the evidence we can find regarding it.
Lets make it simple until a crack is actually observed by someone one can only assume it is cracked. Take a single pane of glass hot on one side cold on the other side condensate forms on the warm side and there is no crack in the glass just condensate
Normally during the A/C cycle, with a furnace that old there would have been a standing pilot light which in essence if left operating during the cooling season the heat from the pilot light would have been enough to dry any condensate during the off cycle. As a Tech I always recommended to leave the pilot burning during the heat season but most home owners would not do it thinking it would increase the gas consumption. Kinda like when people don’t use their turn signal lights when turning as it increases fuel consumption to use the lights:(