Whats up w/ the drain line trap?

 

Static pressure?

This is not a drain line/trap issue.
The trap and drain line is made from 1" ID clear vinyl tubing. I made it from that in order to be able to see that water does get trapped and flows out of the drain pan as it should. The trick is to get all of the condensate water from the evaporator coil to make it all the way to the drain pan. I've seen many questions like this online and the fix is to replace the evaporator coil and given the cost most replace the entire system inside and outside. Replacement cost is around $5K and not an option for me. Also, please know that my AC guy checked the freon and it is at the proper charge. He said the issue is poor design by Trane who has changed the unit to a dual "A" shaped coil design. I disagree with that because the unit didn't do this when it was new. If it were possible to angel the coil up about an inch, I suspect the issue would be resolved however that is not an option without breaking something. Very frustrating. As stated before, the coil has been cleaned many times however the only cleaner that I have yet to try is Nu-Calgon 4171-75-Rinse Evaporator Cleaner. I read somewhere that the product has "Sheeting Action" that will make the condensate adhere to the coil as it travels downward all the way to the catch pan. I ordered some and will clean again when it arrives but I suspect it will be no different from what I used already.

 

Static pressure?

 

From my experience the unit is low on refrigerant. I have seen it many times. The coil has a hot spot in it where because of the temperature change the surface tension changes and when the water hits that point it bead up and drops off. My guess is your guy never checked the super heat and just went off pressures. It is not a lot low so pressure look good but SH will be high, thus the hotspot.

 

Thanks for your reply.
My AC guy says he did check super-heat along with refrigerant and all is spot on. He said they have had this issue with many Trane customers for years and found the only way to stop it is to replace the coil and even then there's no guarantee it won't start happening again in 6 months or even 3 years down the road. He said they have went over this issue many times with the manufacturer and replacement is the best they can come up with. I think I could extend the catch pan out by 3 or 4 inches to catch the condensate but I'm afraid it will affect the overall performance of the unit. There just has to be a way around this. Opinions welcome.

 

Trane used to have a green air handler from back in the late 70's early 80's that in downflow this was a known issue to the point they built a set a louvers that let the air past but diverted the water back into the coil.

So what number is spot on for SH. Did he take a return air wet bulb temp?

I suppose that it is possible that if water has dropped off there long enough that mineral deposits may have collected there and that is causing it. I don't know I hope I am wrong but it sounds to me like replacing a coil is much more profitable than fixing the problem especially since it didn't do it until the last several years if I understood correctly.

If I am correct it is a surface tension issue with the coil. If this is what it is there are some spray on coil coatings to prevent other coil issues but it may make the surface tension the same again across the coil.

 

I'm not sure what number is SH and I'm not sure if he took a return air wet bulb temp.
Also not sure I want to deal with him anymore. The next time I call him just to discuss he's going to want to bill me.
What sort of spray on coatings are you thinking about?

 

SH is short for super heat. You need the wet bulb reading on a fixed metering device to calculate the proper SH. If it is a TXV then SH is a range it should fall in and SC (Sub Cooling) is the number that is needed.

It is a special coating to prevent bio build ups, etc. The stuff I have is old from when dirty sock syndrome first raised it's ugly head. You could send the coil to be coated or do this spray if the issue was not very bad. The thing about the spray is it is designed to maintain heat transfer and once coated the underside of the coil should once again have the same surface tension assuming that is the problem. The stuff I got was cheaper then having the coil dipped but not much.

 

Thanks for the reply but you talking over my head. Is there some sort of spray coating that you are thinking about that I can buy and apply myself without removing the coil?

 

No!

 

You didn't upset me, that was just the simple answer and I was short on time. It has been so long since I used it it may not even be available anymore and was only available through HVAC distributors which normally don't sell to home owners.

If I were to look at it I would try adding some refrigerant especially since I thought you said you can see a line where drops form. Adding the refrigerant is probably the cheapest easiest thing to try.