new blower sucking condensate from pan

[grodan1]

I'm still new and don't have all the info you probably will demand,nevertheless,my question is why is the blower sucking condensate from pan and not letting it get to drain.Cust had new furnace installed and kept old a-coil.Downflow with a-coil on top of blower.Had to set blower speed to med-low and slant coil and pan forward to let gravity help flow to condensate hose before it finally kept leeking.At first I made a loop in condensate hose to make a trap and it did'nt work.My thought was blower was oversized,but boss said no.Last furnace caused no leakage and is the only thing changed in this trailer home.After setting blower speed to med-low leaks stopped and pressures were fine along with good temp split on supply/return.

[trane]

Electric furnace?

[dorrmann]

I'm sure that this is probably not the case, but did you remember to prime the trap before running it?

[grodan1]

electric furnace and trap was primed.Soon as you put blower door on you can just see the water get sucked out like moses parting the water.

[trane]

To big a furnace or to little a coil. Most I have came across the coil is not enclosed but sits on top of the furnace in the closet which would eliminate the neg pressure possibility unless the return in the door is to small. Most of these coils come with a trap for the hose and if its full I would say check your cfm on the fan or tell your boss to fix it.

[dorrmann]

Did you mean that you can see the water getting sucked out of the trap? If so, that means it's not a big enough trap.

[robnjr]

Sounds like the "airbrush" effect caused by Bernoulli's principle....air flowing across something can cause a partial vacuum: that's how an airbrush draws paint up the dip-tube (and an airfoil gets lift)....I would think one of two things is needed: less airflow, or a larger drain pipe diameter (large enough to overcome the vacuum).

[tinknocker service tech]

robnjr
Member

thank you i never heard of that and will remember it if i come acroos anything like this

[grodan1]

thanks for the responses.I did reduce fan speed and it solved it.

[cweezer]

Since when do you put an evaporator on top of a downflow?
especially an electric furnace.

[Mr Bill]

I don't think I have ever seen a down flow application with a coil on top.

[trane]

All the trailer homes and double wides with electric furnaces have coils on the top around here. Most coils are just sitting on the top in the open and you drape a foam filter right on the coil. You get what you pay for.

[go_redskins]

Re: coil on top for down flow application

Since an electric furnace is often used with a heat pump, the coil is on top for down flow applications. Otherwise you would not be able to run the heat pump and electric strip simultaneously.

[Mr Bill]

Yea I guess, but in Texas most downflow especially moble homes the coil in setting in the bottom