Fan Coil Unit design question 1

[Hannes]

I have been looking at condensate pan design in fan coil units (FCU). How prevalent is the practice of using only a minimal sized condensate pan on coils installed on an angle?

I have worked with only a small sampling of FCU's for residential condo's and they seem to have the condensate pan only at the coil's lower corner, apparently feeling that the surface tension of the water will stop drips (doesn't work well if the coils have excessive dust, debris or if something goes wrong).

Is the use of minimal sized condensate pans normal?
What companies design the FCU's with a full pan?

Thanks.

 

[tikitime]

I do mostly commercial hvac design but I'm not aware of any differences for FCU's for residential applications versus commercial. So maybe I can be of some help.

All of the major manufacturer's I have dealt with (Trane, Carrier, etc.) have a drain pan the width of the coil located beneath the coil. The drain pan is sloped toward the pipe connection. Then we always call out for a secondary drain pan to be installed below the FCU with a float valve to shut off the fan in case water is detected. This secondary pan is a little wider and longer than the FCU. Of course, you have to decide if the piece of mind is worth the extra cost.

 

[KenRad]

Hannes,

I too have wondered about the wisdom of relying on the water to travel along the coil and not drop down before it gets to the pan. But I can say that I've used Trane rooftop units and fan coil units that have this design, and one definite advantage is that you can remove two screws, and the pan easily slides out of the unit for cleaning (I wish my A-coil at home was that easy). I haven't had any water problems in these units yet; the oldest one is about 4 years old.

---KenRad

 

[lilliput1]

I was going to say - consider printing an instruction sheet with pictures on fan coil filter maintenance, cleaning coils & pans with vacuum. Indicate property damage potential if regular maintenance is not done. Make maintaining unit part of the responsibility of the Owner.

But then don't they always jack up conduminum maintenance cost? If so do the worl you are paid to do before ruining tenant's property!

 

[ChasBean1]

I like csaskie's post. Making the drip pan smaller than the coil invites trouble. Might be okay in the factory test but what about after a few gum wrappers are dropped down there in the classroom? Sort of an extreme analogy, but to us HVAC enthusiasts it's like putting hinges on the wings of an airplane to get better access to the motor. Or removing your vacuum cleaner bag so you won't have to go through the trouble of changing it...

 

[SolutionsProvider]

The condensate pan is an issue but more important is the fin amount per inch and the flow of air. If you don't have those right the drain pan woill not see the water it will become airborne. If you provide me with the model and serial number of this unit I could run a selection and see if your ok.