Heil High Efficiency Furnace Install

[AHI in AR]

Okay boys and girls, today's question relates to the installation of a Heil high efficiency gas furnace. It was located in a well ventilated attic. First of all, since we are in primarily a cooling climate here I don't see a whole lot of high efficiency furnaces. Secondly, the installation instructions are a bit confusing, especially when sitting in a 130? attic. Lastly, I'm under a severe time crunch since these folks thoughtfully informed me that they had to have the report tonight instead of tomorrow as I originally promised when booking the job.

Anyway, the exhaust vent on this thing looks to be AFU. I think they used the condensate trap intended to go on the inlet line and installed it on the exhaust. And then there's the fact that the exhaust slopes the wrong way, and ties into a tee which is oriented improperly. I think the installer confused the inlet and outlet pipe configurations. And he didn't remove the knockout for combustion air.

What do y'all think?

edit: Sorry, forgot to attach pic. It's been a long day.

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[Bill Kibbel]

What do y'all think?

Any way we can see what you saw?

[Neal Lewis]

I think your assessment is pretty accurate.

[Marc]

A little further south I've seen exactly one Hi-Eff furnace in all my life but I get the principle and what I see in your photo seems to be basically what I would expect from a correctly piped unit.

I'm just puzzled by that white thingy in the lower right corner.

Inlet is via the grilled cover that you removed.

Marc

[Hearthman]

Marc, that appears to be the condensate trap for the secondary heat exchanger. Some are mounted inside the cabinet on some units and some external. The installer is supposed to prime it. They can dry out in summer. Nobody puts mineral oil in them but that would prevent them from drying out. The often crack when these units are installed in attics without protection.

HTH

[inspector57]

Looks like the a/c condensate drain is connected directly to the furnace vent condensate which could put combustion fumes back into the interior air stream.

I would like to see the installation diagrams as well as some different angles.

[AHI in AR]

A little further south I've seen exactly one Hi-Eff furnace in all my life but I get the principle and what I see in your photo seems to be basically what I would expect from a correctly piped unit.

I'm just puzzled by that white thingy in the lower right corner.

Inlet is via the grilled cover that you removed.

Marc

The "white thingy" is part of the condensate drain--it's a condensing furnace. And the cover isn't louvered. It's solid. Combustion air should come in through the non-removed knockout to the left of the exhaust. The furnace can be installed horizontally or vertically, and with a left or right side orientation. The appropriate inlet needs to be knocked out. And if installed inside conditioned space or a closed area (this wasn't) you may need a separate pipe to bring combustion air in directly. The exhaust vent should pitch upward. The condensation that occurs in the vent drains out through a rubber hose in the fan housing, and from there it ties into the pvc drain system shared with the evaporator coil.

[Bill Kibbel]

I think they used the condensate trap intended to go on the inlet line and installed it on the exhaust. And then there's the fact that the exhaust slopes the wrong way, and ties into a tee which is oriented improperly. I think the installer confused the inlet and outlet pipe configurations.

There is no need for a drain on the exhaust piping (if it was installed correctly with the proper slope back to the furnace). There is never a need for a trap on the "inlet line". All condensate drains out of the collector box. The only trap should be connected to the collector box.

I have never seen a sanitary tee on a furnace exhaust - I'd remember something that odd.

I don't know if it ever drops below 32F there, but here the exhaust would need to be insulated with Armaflex and freeze protection would have to be installed on the condensate drain system.

[David Meiland]

Couple of questions here.

Is the A/C condensate line tied into the furnace exhaust? Not quite clear in the pic but it looks like there's perhaps a trap that connects to the bottom of that larger tee. If so, the furnace exhaust would have to keep the trap full in order to prevent a small (?) amount of exhaust gas from being pushed into the airflow at the A/C coil when the furnace was running. Perhaps there's enough condensate to reliably do that, I dunno.

And, is it legit to leave off the intake pipe when installed in an open attic? I've never seen a two-pipe furnace with one pipe. They always have two pipes here, no matter where installed.

[AHI in AR]

I think they used the condensate trap intended to go on the inlet line and installed it on the exhaust. And then there's the fact that the exhaust slopes the wrong way, and ties into a tee which is oriented improperly. I think the installer confused the inlet and outlet pipe configurations.

There is never a need for a trap on the "inlet line". All condensate drains out of the collector box. The only trap should be connected to the collector box.

I have never seen a sanitary tee on a furnace exhaust - I'd remember something that odd.

I found a similar unit's installation instructions online. The trap is listed by the MFR as an "optional combustion air inlet trap" and the tee goes ahead of the trap. Definitely not on the exhaust.

[Brandon Whitmore]

And, is it legit to leave off the intake pipe when installed in an open attic? I've never seen a two-pipe furnace with one pipe. They always have two pipes here, no matter where installed.

The intake pipe isn't required.

The exhaust/ condensate set up in the OP is all jacked up.

[Eric B]

Around here that installation would be flat out wrong and void the manufacturer's warranty.