Carrier Blues - DF

Dan Foley

Black Flag was servicing a commercial building with four Carrier packaged units. He was reading 30-40 PPM CO in the building and they were complaing of combustion odors. I wonder why?!! All four had split heat exchangers - two of which had holes you could put your fist through. These tubulular style heat exchangers always seem to split right down the welds. It's no fun working outside when it is 25* and the wind is whipping around at 15 mph. -DF

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Joe Kuhl

Carrier blues

Yeah but on the bright side,,,, look how much easier Carrier has made it to change out their heat exchangers now compared to the models from 20 years ago. I know,,, little consolation there. I would definately check out the temperature rise across these heat exchangers after the changeout. This is very premature.

David_5

heat exchangers

I think this a problem with all tubular heat exchangers, not just Carriers. Now is the time to sell them on preventive maintainance. The problem exsisted months ago when it was warmer and easier to replace.

David

Wethead7

Heatexchangers

Carrier says that is cuased by overfiring. I do not think so. We have found unit with that problem only one year old. We will not install carrier for this reason. We think this is a design deffect. We have always used a manometer to set gas pressure, and a combustion anl. to check anything we install. The preventive maintance might have cuaght it, but I am not comfortable with Carrier gas PACT units around any place.

Mike

Unknown

Dan, it has been

my experience when I see this kind of damage that some sort of VOC's are present. That in addition to some high moisture retention which is not unusual with roof top units as they have trouble sometimes with creating sufficient Delta T at all times to insure proper venting to the outdoors.

It is also critical that gas input be very accurate as over temperature along with the other things I mentioned can cause this. The newer design on warm air systems contributes to thermal stress on metals above and beyond what they can stand. The pictures really show me that at the point of connection high levels of condensation are taking place with in the unit. I am sure it was not designed to do that.

I have a ritual of stopping at several HVAC shops on a regualr basis and they allow me to pick through there dumpsters. It is amazing what you learn looking at old equipment that has been removed. The reddish tint to the corrosion tells me that some flourinated hydrocarbons may be present somewhere in the environment of that unit.

What does that building house? Just curious to know.

One of the places I frequent is a Carrier dealer. I do not see many Carrier products in his dumpster most of them are someone elses that they have replaced with Carrier. I am not saying that Carrier may not have a problem I just do not see many in the junk.

The other thing I see is the result of most units being combination electric air and gas heat. The reaction of metals to the very moist summer load and the condensing that takes place adds to the deterioration of the gas heat excahnger. I would prefer an isolation fo the two from one another.

jim lockard

carrier x changer

Have seen this before on Carrier heat exchangers (roof top package units) always feel was a Carrier fault.
Looks like that return duct could use some insulation on the outside. I personally do not like just sound insulation on the inside. Hate to have my customers breathing it.

Dan Foley

Carrier

Tim,

These units heat/cool a supply house. Two of the units serve office areas, one serves the counter, and one serves a parts storage area. The main warehouse is heated with unit heaters.

I could not determine a source of contaminants. We will adjust the firing rate and delta T after we replace the HE's. I will post photos of the others as we change them out. -DF

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John Mills_3

Typical Carrier...

We don't do much light commercial but even we have changed ...packaged heat exchangers. More than 5 years old and you better look carefully at them unfortunately.

I think the design of packaged units in general causes this. In split system, we wouldn't think of putting a coil in the return for fear of ruining our heat exchanger. In gas packs, I think they all are. So you have steamy outside air getting into the heat exchanger through the combustion air opening and cold supply air blowing over it. Nobody has explained why this is done --- to make a short lived product for more replacement?