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-   -   90% Furnace, AC Drain, & Secondary drain pan. Hook all together? (http://www.diychatroom.com/f17/90-furnace-ac-drain-secondary-drain-pan-hook-all-together-31974/)

hartkem 11-16-2008 09:16 AM

90% Furnace, AC Drain, & Secondary drain pan. Hook all together?
 
I have a 90% furnace, a/c coil and secondary drain pan. Can I hook all of these together and then run one line to the drain? More than likely only one will ever be producing water at one time.

MT Stringer 11-16-2008 09:37 AM

My house was built in 1983. The drain from the AC unit was plumbed into the vent pipe off the toilet. I've had to cut into the wall (living room side) to replace the "pee" trap because it plugged up. I had no idea it was even there until the water started showing up at the baseboard. I add drain cleaner occasionally. Hopefully that will help.
Mike

DRFREON 11-16-2008 01:29 PM

TO HARTKEM,

No, you cannot join together the Condensing Gas Furnace (that's what it is) to ANY other drain. You can pipe the overflow pan and the Evaporator coil drain together, ONLY after the TRAP (downstream). As an option, as long as you're sure the overflow pan is 100% sealed, pipe the furnace drain into the pan with a 1" air gap. Be sure to support it.

Dr FREON

beenthere 11-16-2008 05:26 PM

A/C drain and pan drain when piped together, requires a float, or wet switch to be installed.

Some manufacturers do allow both the furnace and A/C drain to be piped together.
But its a bad idea.

kennzz05 11-16-2008 06:04 PM

suprized noone mentioned this but since this is in an attic install ill mention it dont know how cold it gets where you are but if youre in northern ca. where it gets significantly below freezeing you need to think about insulating the furnace drain or useing heat tape so you dont have issues with it freezeing. also most times the drainpan is piped seperatly and run out somewhere conspicious so that if you see it dripping you know the main a/c drain is clogged,and i agree you should also put a float switch that will shut off the equipment if the secondary pan clogs. dont know your codes locally but if your not required to use a trap on the a/c dont use one, its just asking for a place to have a clog. your systen is under positive pressure and dosent need a trap...ken:)

hartkem 11-16-2008 06:54 PM

I am in southern california so It will never get much below 40 in the attic.

Since my install is in the attic I was planning on running a 1/2" drain pipe down to under the house(crawspace) and use a sadle to tap into one of my galvanized drain pipes. I have heard of people using sewer vent pipes but I believe that is not legal or a good Idea. I don't have a problem running three dedicated drain lines but I don't want to tap into the sewer line any more than once. It would be nice just to let them drain under the house without being hooked into the sewer line.

kennzz05 11-16-2008 07:09 PM

most a/c drain outside somewhere, personally i wouldn't go thru the trouble to tap into the drain line plus than you will need a trap to keep out sewer gas dont drain under the house it will create dampness and can also breed mosquitoes but like i said if you go the drain outside route run a seperate line for the drainpan and just stub it out an eave so that it will be obvious if its got water coming out there, the main a/c drain is clogged. another option is to install a condensate pump and pump it outside, run the drainline with the freonlines (lots of people use the a/c water to water plants as its considered distilled)

bluefitness 11-16-2008 08:32 PM

Do not pipe the overflow drain and main evap drain together. Here is why:

If the main drain clogs, the secondary drain will catch the water. It will then try to drain through a pipe that caused the problem in the first place. It just doesn't make sense, and it wouldn't pass code in my area.

You have two options. The first option is to run a dedicated overflow and condensate line. You can run the overflow drain through the soffit and over a window. If you see it dripping, you know you have a leak. Your primary drain line should be run to the outside. The majority of the time it is run down with the refrigerant lines. Your second option is to install float switches. You will need to install one on your primary drain and install a pan float switch. You can then cap off the overflow pan. There will be no need to run a line for it. This will protect you from all leaks excluding a leak in your overflow pan.

Edit: my post is referencing the evap and pan drain lines only. Also, you mention using 1/2" lines. Your evap and overflow lines should be 3/4" pvc.

hartkem 11-17-2008 07:58 AM

Thanks for your suggestions. At this moment I will run the overflow pan to a soffit so I can see if its leaking. I will run the a/c drain outside where the condenser will be. Where should I run the condensing furnace drain? The manual says it isn't good for plants. Where do most people run it?

Marvin Gardens 11-17-2008 08:55 AM

In my neck of the woods they have to be separate lines but can use the same pump if you have to have a pump. They can join near the bottom into the pump but it has to be after the p-traps. Both lines have to have an opening at the top to prevent vapor lock.

kennzz05 11-17-2008 11:13 AM

Quote:

Originally Posted by hartkem (Post 186206)
Thanks for your suggestions. At this moment I will run the overflow pan to a soffit so I can see if its leaking. I will run the a/c drain outside where the condenser will be. Where should I run the condensing furnace drain? The manual says it isn't good for plants. Where do most people run it?


if youre sure your not going to have freezeing issues with the pipe run it outside theamount of water is much less than the a/c produces and just dont water plants with it during heating season pipe it with the a/c drain

DRFREON 11-17-2008 02:32 PM

You cannot run an evaporator or heat pump drain with out a trap.... let's see who knows the three reasons why.....

beenthere 11-17-2008 02:42 PM

Quote:

Originally Posted by kennzz05 (Post 186320)
if youre sure your not going to have freezeing issues with the pipe run it outside theamount of water is much less than the a/c produces and just dont water plants with it during heating season pipe it with the a/c drain

Not unusual to get 5 or more gallons a day of condensate from a condensing furnace.

kennzz05 11-17-2008 02:42 PM

Quote:

Originally Posted by DRFREON (Post 186404)
You cannot run an evaporator or heat pump drain with out a trap.... let's see who knows the three reasons why.....


i call b/s its has been done for many years and is code legal in wssc wash dc area as of 3 yrs ago on a h/p yes i agree as it is under neg pressure and wont drain otherwise on a positive pressure system its just a clog waiting to happen

kennzz05 11-17-2008 03:22 PM

Quote:

Originally Posted by beenthere (Post 186411)
Not unusual to get 5 or more gallons a day of condensate from a condensing furnace.

i suppose that amount would vary greatly depending on if its 1 pipe or 2 a 2 pipe i wouldnt think unless you live on the water as when it gets colder the humidity drops acccordingly and he is in ca. so its pretty dry there


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