What could be causing this

Hey guys. This is a Ducane heating/cooling package unit. The rusting area is where the flue gases are exhausted. That is according to the manufacturers installation. I wrote it up and suggested that it be further evaluated. I mentioned a few potential causes during the inspection. The home owner said its completely normal and refuses to pay for an hvac evaluation. I wanted to hear what you guys had to say so I could at least offer my client some well grounded information.

The customer is right, it’s where the package unit exhausts. But I don’t think this is the original vent. Every one I’ve seen looks like the one below. This setup would hinder airflow and have the effect you see in your picture. This one is also installed crooked - I think it’s a makeshift setup.

Without enough combustion airflow, I would be concerned with improper combustion and localized heat build up in the heat exchangers, which can lead to cracks.

I for one think you’re right.

I agree with what Chad says and every older RTU I have looked at has this near the exhaust.

Chad I’m confused. You started with the customer is right and ended with you think I’m right. The manual shows a cover on it like the one in my pic but I think you are right about it not being the original. But you guys are saying its normal for it to get that rusty?

The customer is right in that is where the furnace section exhausts. IMO I agree it needs further evaluation.

Put steel in a stream of hot, wet, acidic air flow and it will do exactly what’s pictured. Seems counterintuative to have made it that way, but maybe it’s the manufacturer’s version of planned obsolescence?

Oh I was one who said that’s where the exhaust is. So your saying that’s normal for it to happen with the way it’s set up but it shouldn’t be set up that way.

That’s what I think, FWIW.

Heck once it rusts through all the way it will be fine.


That is up to him , But i would inform your client it needs to be looked at. not really normal wear and tear. evaluate or walk , simple enough

Not the first time a design engineer made a screw up and won’t be the last either. Cannot blow acidic exhaust against a piece of metal and not have the problem as seen in the pic just depends on who and how they want it corrected

You would not get away with putting that gas line right over the shield here, so I still would call in an HVAC for that correction.

Thanks for all the input guys. It really helped me put into words what I was thinking.

How about a gas pipefitter:D:D

Oh he should be a GAS PIPE FITTER for sure. I don’t know how things are down there but a HVAC Contractor must have a gas ticket to work on these units.

Two licenses required here one two work on it and one to install gas pipe, that way the State double dips on license fees:roll:

Actually we need three if you include the AC. Here in Ontario you must have a Ozone Depleting Substance Card,Ontario HVAC Certification and Gas Pipe fitter ticket to install the gas line.

Ya guys in Ontario sure speak funny;-):wink:

Just for you Charley!