Combination systems help

[barlyhop]

Up in da nort here eh we have a lot of condo's with combination heating/AC systems. The units are completely sealed except for access to the filter and condensing coil. I have found that the average life expectancy of these units is relatively short, 10-12 years or so. The heat exchangers tend to crack at that point.

I am looking for advice on the best way to inspect these units and what equipment might be beneficial to do this. It seems that the temp differential between supply and return are one sign of early failure but are there other symptoms? Why do these units fail much earlier than a split system? I have found most units to be Armstrong or Goodman. Also, most of these if not all are located in a closet or just framed into the room with no intake air available from within the confined space, I never see vented openings to the interior for intake combustion air, since the units are exposed to the exterior I assume that intake air is drawn from the outdoors. Installation guide would be nice to review, etc.

Thanks

Randy

[Terence McCann]

Up in da nort here eh we have a lot of condo's with combination heating/AC systems. The units are completely sealed except for access to the filter and condensing coil. I have found that the average life expectancy of these units is relatively short, 10-12 years or so. The heat exchangers tend to crack at that point.

I am looking for advice on the best way to inspect these units and what equipment might be beneficial to do this. It seems that the temp differential between supply and return are one sign of early failure but are there other symptoms? Why do these units fail much earlier than a split system? I have found most units to be Armstrong or Goodman.

Two reasons for the short life, Armstrong and Goodman.

Also, most of these if not all are located in a closet or just framed into the room with no intake air available from within the confined space, I never see vented openings to the interior for intake combustion air, since the units are exposed to the exterior I assume that intake air is drawn from the outdoors. Installation guide would be nice to review, etc.

Thanks

Randy

These units draw combustion air from the outside.

I see a lot of old Janitrols in this neck of the woods (they aren't much better).

With regards to the manual, if you have model numbers you can try to Google it or write to the manufacture for the information.

[kurt]

You've already made the most informative observations; they're Armstrong and Goodman, and they're about 10-12 years old when they kick.

In the age of globalization, when parts can come from anywhere, and are assembled somewhere else, there can be little to no quality control of individual components.

I just make sure they're installed to the mfg's. spec's as well as possible, I verify that they heat and cool, that they exhaust satisfactorily, and I note the age. I tell folks they're cheap junk, they can run fine for 20 years, or fail tomorrow, and to understand that they could fail at anytime after I walk out the door.

I used to get a lot more techie about them, but it's pretty cut and dried nowadays.

[plummen]

do you have a picture of one of these units?

only issues i generally find with goodman furnaces are igniters and occasional noisy inducer motor.

ive found lots of trane heat exchangers cracked on the other hand,usually late 80s-early 90s 80% stuff.i was finding cracks in trane equipt back in the early-mid 90s

[Terence McCann]

Jim, look for a private PM.

[Marc]

I am looking for advice on the best way to inspect these units and what equipment might be beneficial to do this. It seems that the temp differential between supply and return are one sign of early failure but are there other symptoms? Why do these units fail much earlier than a split system?

Inspect these units as you would inspect any other self contained system. Temperature differentials on a self contained system in cooling mode should be approximately in the 18 to 25 degree range. Some brands may have a shorter average life span than other brands. Smaller self contained systems often do not have a filter dryer installed within them. This often results in early failure of the refrigerant circuit i.e. clogged capillary tubes, high head pressures and reduced temperature differentials.

Just my opinion, is all.

Marc

[Terence McCann]

Smaller self contained systems often do not have a filter dryer installed within them. This often results in early failure of the refrigerant circuit i.e. clogged capillary tubes, high head pressures and reduced temperature differentials.

Nonsense.

A filter dryer is more of an insurance policy for shotty service after the fact. Actually, when you do things correctly, a filter dryer isn't needed.

[Marc]

Originally posted by Terence McCann

Nonsense.

A filter dryer is more of an insurance policy for shotty service after the fact. Actually, when you do things correctly, a filter dryer isn't needed.

Ok Terrance. Filter dryers are not needed? Good service eliminates the need for a filter dryer?

Tell me...how do you service the refrigerant circuits on a small self contained system like a window unit?

Marc

[Terence McCann]

Originally posted by Terence McCann

Nonsense.

A filter dryer is more of an insurance policy for shotty service after the fact. Actually, when you do things correctly, a filter dryer isn't needed.

Tell me...how do you service the refrigerant circuits on a small self contained system like a window unit?

Marc

You throw them away and buy a new one.

[Marc]

Right! So shouldn't they have a filter dryer installed? You can replace the dryer but you can't practically clean out or replace the capillary tubes. They're too small.

Marc