Reznor UEZ recall?

[lowonfreon]

I'm in the process of uninstalling and reinstalling a Reznor UEZ-55 unit heater for a renovation. This unit was built in 2023 and only lightly used. It appears to be operating normally and the manifold pressure is right within spec, at 3.5" WC.

In the course of this work we noticed a suspicious looking burn mark on the non-access (left) side of the heater. The burn is adjacent to an elbow of the primary heat exchanger. At that spot both the inner and outer wall of the UEZ cabinet are visibly damaged, and feel deformed to the touch. The diameter of the deformation is about half an inch. There isn't enough clearance between the cabinet and the heat exchanger to take a good photo of the heat exchanger, but I do see some discoloration there.

I originally suspected a pinhole leak but I was not able to confirm this using light, compressed air, smoke tests, etc. I have not taken off the manifold and checked with a borescope, and I have not disassembled the cabinet, because this unit is still under warranty.

When I contacted Reznor support about this, the rep was originally very friendly and open. He forwarded my photos to Engineering to ask what was going on. He said he has never seen a bad heat exchanger on a UEZ.

After hearing back from Engineering, the support rep suddenly clammed up. He said there was a known manufacturing issue on this heater and that there should have been a layer of insulation separating the (400F+) heat exchanger from the cabinet. He put me in touch with the Reznor rep at McClintock & Bustad, who wants to refund the purchase price of the heater. (However they want to credit the original installer's account at the supply house for the 2023 purchase price, which doesn't exactly help me get things working again. Discussions are ongoing.)

I observed with a thermal camera that the non-access side of the outer cabinet reaches temperatures of 200-225F after a short test run, with the burned area getting slightly hotter than the rest. This side is rated for 2" minimum clearance to combustibles according to the installation manual. I asked Reznor support if this is safe to continue running with only a 2" clearance, and never heard back. The rep clearly doesn't want to provide any more information, and wants this to be handled through McClintock.

So my questions are:

• For anyone else with access to a UEZ 55, 85, or 110: is there an insulation layer on the inside of the cabinet to shield the chassis from the heat exchanger? Can you post a photo of it?
• If not, how tight is that distance inside the cabinet? On mine I can't even fit my pinky finger in the gap between the cabinet and the heat exchanger, so the cabinet likely absorbs huge amounts of radiant heat from the 400F tube.
• Is there an official acknowledgement of this defect from Reznor (at least a service bulletin sent to distributors, or something)?
• Is this heater safe to operate 2" from combustibles? Safe to operate at a greater distance? Or completely unsafe, because the cabinet is never supposed to handle such high temperatures?

 

[fitter30]

To bad their shut down https://www.usa.gov/company-product-service-complaints
Might try your state attorney general or consumer complaints

 

[Stuart in MN]

At that spot both the inner and outer wall of the UEZ cabinet are visibly damaged, and feel deformed to the touch.

It's a metal enclosure, right? It must have been really hot.
Unfortunately I don't have anything useful to add, other than Reznor heaters are generally high quality.

 

[PCustoms]

Another odd first post...

 

[lowonfreon]

To bad their shut down https://www.usa.gov/company-product-service-complaints
Might try your state attorney general or consumer complaints

At this point I just want to understand what a properly functioning UEZ looks like: is there insulation (or a larger gap), and what is the cabinet temperature on the non-access side?

It's a metal enclosure, right? It must have been really hot.

Looks like steel sheet metal (magnets stick to it), so the deformation was probably just the glossy white finish melting. I can feel a ridge with my finger over the burn mark. It doesn't feel like the metal itself is melted. The deformation is only about 1/2" in diameter; it's not like the whole panel is warped.

Google suggests that the resins in standard (not high temp) spray paint will break down somewhere between 250F-400F. I have no idea what paint Reznor uses on this panel.

 

[fitter30]

Steel melts 2200-2500° so it won't melt. Flue temp 415° -: 525° single wall flue pipe 9" clearance from combustibles. It's over the first year? That's probably why they don't what to pay tontake it apart and put ceramic fiber blanket in it. Would take longer to fix it than hanging a new one.

 

[lowonfreon]

It's over the first year? That's probably why they don't what to pay tontake it apart and put ceramic fiber blanket in it.

Do you know if ceramic fiber blanket is standard on new UEZ builds?

More generally, is that a common way for manufacturers to protect a metal furnace cabinet from a nearby heat exchanger tube with a small (under 1/2") clearance?

I can try MacGyvering something, however I have no clue how it will hold up over time. And since this is in the air plenum, I don't want to use a material that might eventually break down into dust that contaminates the breathing air. If I can confirm what is done on newly manufactured UEZ units, perhaps I can order the same part for this one.

 

[lowonfreon]

Do you know if ceramic fiber blanket is standard on new UEZ builds?

Answering my own question after getting access to a newer (Sept 2025) UEZ-55: yes. There is a thin rectangular thermal barrier between the wall and the primary heat exchanger tubes. It looks like some sort of woven insulating tape. It is not in contact with the heat exchanger.

More generally, is that a common way for manufacturers to protect a metal furnace cabinet from a nearby heat exchanger tube with a small (under 1/2") clearance?

Also on the new UEZ-55: the distance between the heat exchanger tubing and the side wall is ~doubled to about half an inch. I can easily fit my finger in the gap on the newer unit.

Re-measuring the non-service-side wall temperature: it was over 200F on the old unit and 120F on the new unit.



I would take all of this to mean that there are two different versions of the UEZ-55 out there, and the older version should probably have more than 2" clearance to combustibles on the left side.