[scirocco70]

Hey everyone.

I have a pair of the furnaces mentioned above. There are two capped pipes under the panel which the technician removes to vacuum out the heat exchanger (I think it's the heat ex?)

Last year, the tech couldn't get all of the pipe caps off, so this year I decided to get them off myself before the tech comes, having the patience and the tools to do so.

Inside these pipes is a lot of corroded metal. It looks (to me) pretty bad in there... on the left side, there is perforation in the curved metal wall, where it looks like no perforation should be.

Please see attached the pics, one very closeup (hard to take pics down that pipe)

My question is: is this a fatal condition for a furnace? Does it need to be replaced? Is the situation dire, or can I wait some time before replacing?

I know the tech will tell me all of this, but I was hoping to get some good, unbiased internet-advice before then.

Thanks!

[hvac1000]

is this a fatal condition for a furnace

Yes if the heat exchanger is bad (need to be tested)


Does it need to be replaced?

If after the heat exchanger is tested it proves defective it probably would be better to replace the furnace BUT depending upon age/warrenty you might be able to replace the heat exchanger under warranty for parts only. You will have to pay labor..

Is the situation dire, or can i wait some time before replacing?

Depends upon the outcome of the testing.

[scirocco70]

Thanks HVAC1000!

That pic with the rusted-through panel, does that not indicate a bad heat exchanger?

How is one tested? My assumption was that if it has a hole in it, it will leak combustion waste into the house airflow..

I'm having the techs out soon, but am looking for as much information as possible up front.

I didn't install these furnaces, though I believe they are not very old. (8 years?)

Thanks again!

[hvac1000]

Looks like the air cond coil has been dripping on the heat exchanger.
Without being there and seeing for sure I cannot say for sure.
The heat exchanger test can be done different ways so ask the service person his method for testing.

heat X's should be under parts warranty. Have the service man check with Lennox. I am sure they have a 10 year warranty and could be 20 or 25 years.

Some service people do not like to change Heat X's so if he says they are not under warranty or it is cheaper to replace the furnace I would call another company for another opinion.

[letmetellu]

I have seen the metal of heat exchangers burned up like this one from a freon leak. When the freon is burned it creates phosgene gas, it is a very corosive gas and will eat holes in heat exchangers especially wrere the flame hits the metal.
If it is the heat exchanger that I am seeing it does need replacing,
It is easier to replace the furnace than it is to replace a heat exchanger so be sure and get some bids before you get anything done, also check out the warranty info on your frunace.

[scirocco70]

Thanks again...

I hope that AC coils dripping on the heat ex are not cause for a not-under-warranty finding... The AC works just fine, all summer long, I would think a freon leak would shortly empty the system. Also, this appears to be affecting both furnaces, and a simultaneous leak seems unlikely.

Some other folks have told me that my furnaces are 12 years old, by serial number (8469L35627 and 8469L35476) and should be under warranty.

How do I go about exercising that warranty? Does it still apply even though I bought the house with the furnaces already in place?

You guys rock!

[letmetellu]

About the freon leak. The leak may be in the room with the furnaces and the freon is drawn into the flame as the pilot burns and uses the air as combustion air.

Go to the brand name web page and you can find out about the warranties.

[hvac1000]

What I saw in the picture did not look to me to be refrigerant/Freon (Dupont trade name) damage. It is possibly the water that comes off the coils for the A/C. If the drain line is plugged,or the coil is dirty the water can overflow the drain pan or drip down onto the heat X. Or see another reason below.

You do not exercise the warranty. A Lennox dealer has to do that if the Lennox dealer thinks it is a warranty situation. If not then a factory rep will have to visit and look over the situation.

If the furnaces are in a high moisture area like a wet or real damp basement that can also do the trick on a heat X.

As letmetellu said you will need to read the warranty at the Lennox site or since these are older units the Lennox dealer or factory will have to find out if the warranty is valid and for how long.

NOTE: I can see in the picture rust drip down from the flue pipe. It have been hitting the transformer and other parts of the burner. Looks like your flue gas has been condensing in the chimney area or water/rain has been going down the chimney or the basement/install area is very damp. Also looks like part or all of the flue/chimney connector has been replaced with new pipe. I wonder if the old pipe had rusted/rotted out. I wonder if the baromatric damper is still installed? Just guessing here since I cannot really inspect from long distance.

The next step is to see the dealer and find out what will happen since I am limited in my knowledge of older Lennox units warranty and warranty requirements. I can tell you the new units have a limited lifetime warranty on the heat X BUT that is only to the original purchaser and you might have to show reciepts where the furnace has had regular service etc. by a HVAC company.

Usually rust/water damage might not be covered depending upon the situation. Post back and let us know how it all turns out.

[scirocco70]

Hey everyone... First off, thanks for the great advice.

Here's the follow-up. The heat exchanger is fine. What I saw (and freaked out about) was the usual thin, flaky rust-stuff that comes down. It just happened to be piled up in a way that looked like the HE was rusted through, and I was scared to poke it for fear of damaging the exchanger even worse.

Once I vacuumed it out, heat-exchanger is pretty darn solid.

The upshot is that:

1) I have identified my local Lennox dealer

2) I have learned that maybe the furnaces (both of them) are not running correctly, hence the condensation in the flue pipes, and the rusty dripping all over everything

3) I have decided that I will have the Lennox dealer out to service them this year, rather than my oil supplier (I buy oil on the open market, no contract), hoping to have them adjusted correctly.



There was one other bit of fun involved... The whole reason this was so bad is that the service guy couldn't get one of the caps off last year. It was stuck. I started with this by taking the cap off myself, before he arrives, so that it gets clean this year.

In doing so, I destroyed a cap. It's a flimsy stamped piece of steel, as you-all surely know. When I went to buy a new one, I found that the price for the kit (two caps and a third one with the bolt in it "inspection port") was $65!

Well, I would have been pleased with $15 (for $5 worth of parts, even all three, at most), and would have been fine with $20 or even $25... but $65??

No way.

So, I fixed the one cap I messed up. Having an anvil, hammers, oxy-acetylene torch and some brazing rod comes in handy. I would have felt seriously ripped off to have to pay that much for a flimsy stamped cap.


Pics related, one of the fixed cap, the other of them installed.

Again, THANKS to everyone here!

;-)

[hvac1000]

Good deal on the cap repair. As a homeowner you can do that kind of stuff but as a service person there would be liability wrote all over it. LOL

I hope the Lennox dealer can get to the bottom of the condensation problem so this problem and others moisture problems will not eventually destroy the furnace.

Post back and tell us what the dealer had to say and what he did to fix the situation.

You might also check the chimny cap on the chimny and if there is not one you might consider adding one. A chimny cap helped to solve a problem I was having on one of my chimneys.

Glad for you that it all seems to be working out for the good for you.

Once again nice job on the clean out caps.

[mikellask]

A question I saw posted earlier in this thread suggested that flue gasses, such as carbon monoxide would be able to leak into the heated air stream, but this is not the case. A very small amount could move into a cracked or perforated heat exchanger until the blower motor starts up. At that point the pressure differential between the higher pressure inside of the heat exchanger and the lower pressure on the flame side will actually pump the household air out of the heat exchanger into the flame side of the heat exchanger, sending air up the chimney. There are other complications that can occur, such as blockages of the chimney (a problem at any time) which might impede the movement of the additional air up the chimney, at which the CO contaminated air will then try to back up out of the flame box where combustion air is drawn in. For those who can't afford a new furnace, furnace cement will withstand the heat of the burner side but it can't be relied upon for a long term solution.

[scirocco70]

Just to update this (I was the original asker) -- these furnaces are old, but the heat exchangers are fine, and actually have no perforations.

If you look at the pics, they look pretty bad. But this was all flaky surface rust, and when I vacuumed it out, everything was fine. Nice and solid.