HVAC Guys - Air Handler Condensate Drains

Ron

Ron

Dum Spiro Spero
Moderator
Joined
Apr 16, 2005
Location
Sharon, SC
House has 2 split units.
1 AH in the basement and 1 in the attic, both heat pumps outside.
Pretty typical setup.

After an incident a few years ago where the downstairs drain got clogged and "flooded" (not really flooded but made a mess is a better way of saying it) the basement I have added annual maintenance to the list to disconnect the drains on both and blow the lines out with compressed air.

Did this yesterday.
Both units buildup a tremendous amount of "gunk" of some mold variety. Seems like a design flaw to me as the drain is level with the bottom of the pan and had a threaded output that a pvc fitting threads into. So essentially the unit stands in water to a depth equal to the wall thickness of a 3/4 pvc connector. WHich raises as series of questions

1) is this normal
2) anything that will cut down on this buildup of crap
3) both units have p traps where the drain exits the unit. Since this is a (very) low pressure flow doesnt this p-trap just serve to cause stagnation? would I be better to eliminate it
4) In both cases I can screw the line out because of the p trap so I end up cutting it every year. If I dont glue it it weeps, if I do..its a time losing battle before the whole pipe shooting match has to be replaced. Any tips or tricks here?

Anything else I should know?
 
Ron said:
House has 2 split units.
1 AH in the basement and 1 in the attic, both heat pumps outside.
Pretty typical setup.

After an incident a few years ago where the downstairs drain got clogged and "flooded" (not really flooded but made a mess is a better way of saying it) the basement I have added annual maintenance to the list to disconnect the drains on both and blow the lines out with compressed air.

Did this yesterday.
Both units buildup a tremendous amount of "gunk" of some mold variety. Seems like a design flaw to me as the drain is level with the bottom of the pan and had a threaded output that a pvc fitting threads into. So essentially the unit stands in water to a depth equal to the wall thickness of a 3/4 pvc connector. WHich raises as series of questions

1) is this normal
2) anything that will cut down on this buildup of crap
3) both units have p traps where the drain exits the unit. Since this is a (very) low pressure flow doesnt this p-trap just serve to cause stagnation? would I be better to eliminate it
4) In both cases I can screw the line out because of the p trap so I end up cutting it every year. If I dont glue it it weeps, if I do..its a time losing battle before the whole pipe shooting match has to be replaced. Any tips or tricks here?

Anything else I should know?
Click to expand...


Mine is like that. It is suspended from the floor joists in the basement. The pan on ours is just high enough to walk under if I crouch down, but is CONSTANTLY covered in condensation to the point that walking underneath it gives you a nasty little "shower". The drain also has a p-trap that gets dunked up, so I occasionally pull out my mini wet dry vac that has a hose about the same OD as the drain. About twice a season I clean it out. Pan still gets condensation, but it improves greatly if I vac it out. System "seems" to work better after vacuuming it as well. Might just be imaginary, however.
 
Ron said:
House has 2 split units.
1 AH in the basement and 1 in the attic, both heat pumps outside.
Pretty typical setup.

After an incident a few years ago where the downstairs drain got clogged and "flooded" (not really flooded but made a mess is a better way of saying it) the basement I have added annual maintenance to the list to disconnect the drains on both and blow the lines out with compressed air.

Did this yesterday.
Both units buildup a tremendous amount of "gunk" of some mold variety. Seems like a design flaw to me as the drain is level with the bottom of the pan and had a threaded output that a pvc fitting threads into. So essentially the unit stands in water to a depth equal to the wall thickness of a 3/4 pvc connector. WHich raises as series of questions

1) is this normal
2) anything that will cut down on this buildup of crap
3) both units have p traps where the drain exits the unit. Since this is a (very) low pressure flow doesnt this p-trap just serve to cause stagnation? would I be better to eliminate it
4) In both cases I can screw the line out because of the p trap so I end up cutting it every year. If I dont glue it it weeps, if I do..its a time losing battle before the whole pipe shooting match has to be replaced. Any tips or tricks here?

Anything else I should know?
Click to expand...

1) yes it’s normal. Cleaning your drain line is a yearly thing.

2) they sell condensate tablets and other items that you can put in your drain pan to help it not build up so much gunk.

3) if the fan is after the coil it’s pulling air from the coil area then you have to have a p trap. Otherwise what can happen is the suction of the air will keep the water from draining until the fan turns off. If the fan is before the coil/ blows through the coil then yes you can eliminate the trap. With a heat pump/air handler set up the fan is normally after the coil and will need a trap.

4) next time you pipe it in add a union before and after the trap then You can unscrew the union and remove the trap. Also you can unscrew the union and the threaded piece as one if you need to clean it also.
 
Also you can add a float switch to the auxiliary drain whole and break your y thermostat wire through it just Incase it was to ever back up it would shut down before flooding the area.
 
There SHOULD be a primary and secondary drain. The primary SHOULD be in the unit itself

Primary is connected to P-trap. P-trap stops the plenum from sucking air in...so No, you can't eliminate it. But you CAN get a clear trap with dual cleanouts

ptrap.JPG



This is actually the unit in my office....see the gunk?

ptrap2.JPG


We had the same issue of flooding

Difference is, we have a Aux float switch in the SECONDARY (which SHOULD be the visible pan) that shuts the unit off when water builds up.

Typically, if you have your unit serviced every year, and at LEAST inspected, this can be caught. But hell, how many people even think to change their FILTERS once a month?!?!
 
You need a p trap from the unit. You don’t need a p trap from the plastic pan under the unit.

The gunk is normal. Don’t let it build up too much and get into your air plenum, it’s where legionnaire’s disease originates.

As far as having a lot of the condensate in your pan, you may could slope the pan some to get it to drain a little faster.
 
There SHOULD be a primary and secondary drain. The primary SHOULD be in the unit itself
^

This was my first thought, all my units have a primary and secondary is in the pan. But I dont have a heat pump and I'm not a HVAC guy. I did stay in a holiday inn though.

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Make sure you check the distal end of the drain too. Had ceiling damage when the air gap into the vent stack was clogged and drained onto the Sheetrock
 
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