Rinnai CX199iN Vent Gasket Fault Analysis

RickDelta

Hello HeatingHelp.com community! : )

This analysis suggests a possible manufacturing defect on the CX199iN tankless water heaters.

Fault presentation: (new units after just 48hr of run time)

Water dripping from the bottom heat exchanger "tub" from the center located power resistor mounted there. This water pools inside the bottom of the cabinet and drips out near/around the condensate drain port.

The origin of the leak cannot be seen as it is leaking from the back side of the "tub". You need to remove the entire heat exchanger assembly to see it.

The leak is from the exhaust duct attached to this tub ….. a screw down clamped frame and rubber gasket.

Rinnai Tek support stated this is a known problem and has shipped out a new gasket to effect repairs.

But, ….. the problem is not the gasket! : (

The rubber gasket is a "J" shaped vent gasket.

The reason for the leak is that the formed over metal stamping in the tub is of different depths!

The "J" short leg can't wrap around the deeper depth/width on one side and seat properly.

Installing an new "J" gasket does not resolve this!

The gasket bunches up/ puckers where it can't seat around this stamped ledge.

(see pic ….. its hard to see in pic)

Suggested resolution:

Redesign the shape of this gasket to an "T" or "L" profile to negate the ledge width differences and possible application of a bead of high temperature Permatex gasket sealer.

Note:

This "fail to seal" gasket issue is introduced at the time of factory assembly. Of the 7 new units we just installed …….. 2 have failed "out-of-the-box".

This gasket is made of a very soft rubber and any physical challenge to it's seating design profile results in an incompetent seal.

I suspect all our other units we have will exhibit early seal failure.

The water "leak" is from the generated condensate from the combustion flue gases. My concern is if its leaking water ….. is it also leaking cabonmonixide as well? : (

Read:

https://www.rinnai.us/support/recalls

gas3.jpg

UPDATE:

After I installed replacement gasket from Rinnai Tec Support ….. leak was worst than before! : (

Below:

Look at the warping of the screwed down gray duct. This causes uneven pressure or no pressure to the seal within ….. aiding to the leaking.