To modify a dehumidifier

[Toddfather]

Hey Guys,
I work mostly residential hvac service. With that said, I have a dehumidifier at home that I run during the summer months in my basement. Problem is, at times, although very few times, the evap freezes. Of course I know why it's doing that, but I'd like to hot rod it a little so it could run at a slightly lower ambient.

It's not a problem for me to add a couple access fittings, vacuum, drier, recharge, etc. however: Not having any experience with creative servicing, would it be as simple as adjusting the charge to run a little warmer evaporator to keep it from freezing, or does it get more involved than that? Please trust that I have enough knowledge to know why it's freezing.

Toddfather

[sedgy]

hi tod , well if its short of gas . add some , is the filter blocked , wash it , is the evap blocked , clean it ,
if you cover a portion of the condencer, to get the evap psi higher, do so,

[chemi-cool]

Or.... you can add high pressure control to keep the condensing temp a bit higher, but first as sedgy suggested, clean it throughly.

[Gary]

Increase the airflow, controlling fan speed by evaporator air off temp.

[Toddfather]

Sedgy,Chemi,&Gary,
Thanks for the quick reply! I probably should have included in the original post that the dehumidifier is working perfectly fine. There are no leaks, evap and cond are squeaky clean. I was considering playing with the airflow but came to the conclusion that, on this unit, it would be a waste of time because of the way the air comes on and off the coils.

The evap sees the air first, and, all of the air off the evaporator becomes air on the condenser coil. By restricting the airflow of either coil also restricts the air across the other coil. It would be simple to adjust the air flow and subsequently the heat load and/or head pressure if the same air didn't fall across both coils.

I realize there would be a number of ways to tweek the units preformance but, I was hoping I could make it a little less sensitive to low ambient without going to extremes.

Aside from myself being a little foolish about the tweek, do you have any other suggestions. If so, they would be greatly appreciated.



Toddfather

[Brian_UK]

Please trust that I have enough knowledge to know why it's freezingModification of the defrost controller perhaps might reduce your freeze ups.

[Gary]

The key is the temp of the air between the coils. The colder this temp the more moisture is removed, but too cold freezes the coil. You can adjust this temp by adjusting the airflow. Experiment with this by partially blocking the intake air and you will see what I mean. Increasing the airflow increases the temp and vice versa.