Single condensate drain line for a Lennox C33 cooling coil and SLP98 FAU

[JKopp]

Condensate water cannot overflow or back up into the fau heat exchanger with this set up. Equipment is set in fau closet with a raised platform for return air. Home has very nice hardwood flooring all around this interior fau closet. With this mechanical switch I don't anticipate water damage from this installation. Without these safety switches a condensate back up on a call for cooling would fill the heat exchanger, overflow the fau vent/trap assembly and make a mess.

John



3/4" Cross tee allows for the installation of a safety switch to break the "Red".


Photo taken from the back of closet looking out at drain assembly and me.


Drawing of this drain set up.

[jimmyed]

Add on txv's? Lennox still in the stone age?

[SBKold]

So you write these manuals for lennox jkopp?

I have to admit they are by far the best instructions ive seen.

[JKopp]

Thanks SBKold, I have a passion for doing illustrations that are correct. So many of them are not correct. Some of my work has made it into Lennox install instructions. The coil condensate drain line drawing, equipment hold down method and equipment elevation extenders fixed and adjustable for the XC series units using 2" ABS fittings to name a few. I also have several HVAC related patents.

We purposely install coils with external TXV valves because we have had to replace a few. Much easier when they are external.

John

[SBKold]

noticed you posted on jimmyeds picture about combining puts positive pressure on fau but I'm curious what happens once water evaporates from the trap?

From the pictures of actual install I can see how your vent placement provides the solution.

However just going by diagram it does not stress the importance of installing the vent never perpendicular to air flow thru trap.

I also cant see the actual lower vent configuration in the install pics.

[JKopp]

One of the issues with our install is the factory FAU trap clean-out is going to be very hard to get to being this is a closet install. Then I am now reviewing Lennox's latest and greatest install instructions and they redesigned the trap clean-out. Maybe to make servicing the thing easier? They and I have both routed the drain line in front of this new horizontal clean-out. It would take installing a 90° fitting to offset the drain line over from in front of the clean-out depending on how much room one has. Looks like I need to rework my drawing.

[Bsmith816]

I myself always run evap coil dain and furnace drain completely separate. Lennox changes their condensate trap every month I think

[George36]

I myself always run evap coil dain and furnace drain completely separate. Lennox changes their condensate trap every month I think

Am considering replacing a 14 year old Keeprite with the SLP98, updraft, side return. Have had an XC14 for the last four years, without trouble. Would be using an iComfort.
The owner/dealer (who only sells Lennox) who came to give a quote on the installation said he would combine the AC condensate drain with the furnace condensate drain, and run them both into the basement floor drain.

When I asked about a trap, he said he didn't use them - because they always clogged. Without a trap there would be no clogs. He has been in the business about 30 years, has done HVAC installs for a nation-wide TV renovation show, and out of the four people who came to quote, he is the one I would prefer to go with, based on his discussion of my needs. His quote was not the least expensive.

But I am puzzled over this trap question. There is now no trap on the AC coil, nor is there a secondary drain, and have had no problems. Is it OK to go with no trap on the furnace drain, too?

[Mike Doran]

you can go with no trap on the ac because it is an updraft blower and will always be positive pressure on the drain but no do not go with out a trap on furnace especially if tying in drains together. if it is a high efficiency furnace should be trapped inside but i would not tie into same line due to positive pressure from blower pushing back into furnace trap run separate line should be ok

[George36]

Thanks! That is very helpful.

[pacnw]

Look in the install manual and it will show a photo of just how to do it.

Be careful, some of Lennox's equipment specifically CANNOT be tied together!!!

[Push It]

Am considering replacing a 14 year old Keeprite with the SLP98, updraft, side return. Have had an XC14 for the last four years, without trouble. Would be using an iComfort.
The owner/dealer (who only sells Lennox) who came to give a quote on the installation said he would combine the AC condensate drain with the furnace condensate drain, and run them both into the basement floor drain.

When I asked about a trap, he said he didn't use them - because they always clogged. Without a trap there would be no clogs. He has been in the business about 30 years, has done HVAC installs for a nation-wide TV renovation show, and out of the four people who came to quote, he is the one I would prefer to go with, based on his discussion of my needs. His quote was not the least expensive.

But I am puzzled over this trap question. There is now no trap on the AC coil, nor is there a secondary drain, and have had no problems. Is it OK to go with no trap on the furnace drain, too?

When adding a cooling coil after a furnace the coil is on the positive side of the fan. If you do not install a trap with a large enough column of water you will be blowing cold and hot air down the drain line. Not sure what percentage it would be but I would prefer to see it not do that.

[Adlerberts-Protege]

Cleaner/primer on the PVC? Tell me it's clear and exists.

[Tkored]

Do they let you use ABS down there for venting?

[George36]

My thanks to everyone for your helpful comments. I did check the Lennox install manual, and re-read the posts and diagrams in this thread. It seems very complex, so as an alternative I contacted a Carrier dealer who sent me the Infinity 98 install manual, plus the Canadian regulations on venting gas appliances, and who has been very helpful in answering all my questions about a new installation. As everyone but me probably knew, the Carrier has an internal trap, and the installer would normally tie it in to the AC drain, but will do separate drains if that is what I want.
Thanks again for your insights.

[pacnw]

My thanks to everyone for your helpful comments. I did check the Lennox install manual, and re-read the posts and diagrams in this thread. It seems very complex, so as an alternative I contacted a Carrier dealer who sent me the Infinity 98 install manual, plus the Canadian regulations on venting gas appliances, and who has been very helpful in answering all my questions about a new installation. As everyone but me probably knew, the Carrier has an internal trap, and the installer would normally tie it in to the AC drain, but will do separate drains if that is what I want.
Thanks again for your insights.

So you would use a Chevrolet manual to work on a Ford?

Why not follow the instructions for the equipment you have. It will work correctly and not be a possible service call/repair issue in the future.

[Adlerberts-Protege]

Do they let you use ABS down there for venting?

Most manufacturer's install instructions state PVC or ABS is fine. Still waiting for an answer on my PVC question though.

I think ABS pipe looks pretty slick on some installs, especially for tankless water heaters.

[suBcools]

Add on txv's? Lennox still in the stone age?

it's nice if the expansion valve ever needs to be replaced though.

Sent from my SPH-L720 using Tapatalk 2

[George36]

Sorry for the confusion. I read the Lennox manual when I was considering a Lennox furnace. Then, when I looked into buying a Carrier, the Carrier dealer sent me the install manual for the Carrier furnace.
Having had two lousy installs, first the Keeprite furnace, then the Lennox AC, I am doing my best to get a good one this time. Before reading this board, I didn't know there was such a thing as a bad install.

[darctangent]

Before reading this board, I didn't know there was such a thing as a bad install.

LOL, comments like that make me laugh.

The truth is that most installs are sub standard by manufacturer's requirements.

You can only learn so much from the install manuals. You aren't equipped to understand them properly, and many topics are not spelled out clearly. I did work for an engineer that had done his own humidifier install. While I was getting paid he asked me what I thought of the way it (the humidifier) was installed, because he was so proud of doing it himself.... it honest to God looked like a little kid had done the work. Everything was done wrong, and I told him so. He replied sheepishly "I followed the install manual perfectly..."


The truth is that he followed the install manual to the best of his ability, and that wasn't that great.