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I have two Pet Peeves as a inspector of split system A/C systems that I find quite common in my area. They may not pertain to other areas of the country especially the north and the east (as in Yankee country)[;)]

The first is improper installed A-coil condensate drains on a upflow 80% or a horizontal installed 80% furnace within the attic. Yes I know some areas don't install furnaces in the attic but its quite common in my area. Contractors often will install a 1-1/2" indirect P-trap to a plumbing vent stack and discharge the 3/4" condensate line from the A-coil into this P-trap.

I write it up as being wrong what say you

My second Pet Peeve is installing wood on the supply air side of a furnace A-coil I write it up as wrong do you???????

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What I've seen with attic installations is the 1 1/2" coming up through the attic floor. The p-trap is concealed elsewhere so I don't know where it drains to.

I've never seen a wooden supply plenum, if that's what you're referring to. I'd write it up if I did on account of the hot air drying out the wood in the winter. Dry wood always burns well. Good for a campfire, not good in a house.

Marc

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What I've seen with attic installations is the 1 1/2" coming up through the attic floor. The p-trap is concealed elsewhere so I don't know where it drains to.

What they connect to in the attic is a bathroom vent stack with a Tee fitting and then just put a P-trap for a indirect drain connection for the 3/4" drain line

I've never seen a wooden supply plenum, if that's what you're referring to. I'd write it up if I did on account of the hot air drying out the wood in the winter. Dry wood always burns well. Good for a campfire, not good in a house.

Its not really a true supply plenum its on a downflow furnace with a slab foundation. There is a metal plenum beneath the slab that the supply air trunk lines connect to. The metal plenum is flush with the top of the slab.

The A-coil box should be resting on the concrete but there are some contractors that will build a small box 2X4's or 2X6's resting on the concrete and then place the A-coil on the wood. The wood is not a concern in the heat mode because of the distance from the furnace the problem is in the cooling mode. Moist air from the A-coil making contact with the wood creates mold spores and distributes through the duct system.

That is my story and I am sticking to it

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Never seen such a thing.

Marc

Are you saying you have never seen a slab foundation with a downflow furnace and A-coil...

I've seen those many times.

...or you have never seen one with wood between the coil box and the foundation

Haven't seen it.

Marc

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I have only passed through your State but with all the water I would guess slab foundations would not be very popular down near the coast or where there was a high water table

We do have a high water table in many areas here but that doesn't seem to discourage slab foundations, just sandy or silty soils. In those areas, houses are supported by pilings.

Marc

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. . . Contractors often will install a 1-1/2" indirect P-trap to a plumbing vent stack and discharge the 3/4" condensate line from the A-coil into this P-trap.

I write it up as being wrong what say you

I've never seen it done that way. How does the trap stay wet throughout the non-cooling season? If there were a trap primer installed, I probably wouldn't have a problem with it. If the trap were free to dry out, then I'd have a big problem with it.

My second Pet Peeve is installing wood on the supply air side of a furnace A-coil I write it up as wrong do you???????

I've never seen it done. We use metal here.

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It does not stay dry in the heating season that is why I call it out. If it had a primer that might work until the primer line froze. The only way I don't call it out is if the furnace is 90% or above, the drains from the furnace is most usually warm enough to keep the trap from freezing between cycles. With the temps we have in this state I don't like any water in the attic that is not heavily insulated.

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It does not stay dry in the heating season that is why I call it out. If it had a primer that might work until the primer line froze. The only way I don't call it out is if the furnace is 90% or above, the drains from the furnace is most usually warm enough to keep the trap from freezing between cycles. With the temps we have in this state I don't like any water in the attic that is not heavily insulated.

Even with a drain from the furnace, you might go for weeks in the spring and fall where neither the furnace nor the AC were to run. That trap could easily dry out in that time.

The freezing is an issue even without a trap. The water can freeze right inside the condensate line.

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Even with a drain from the furnace, you might go for weeks in the spring and fall where neither the furnace nor the AC were to run. That trap could easily dry out in that time.

In Okla we don't go weeks at one time without operating either heat or A/C we have a wide range of temp in the spring and fall. Operate the A/C during the day and the furnace at night its kinda crazy with our weather

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