Size of condensor coil

[allwet]

If I am having a humidity problem in my home, will sizing the condensor coil by .5 ton larger than the compressor help or hinder the dehumidification capabilities of the system? This would be used in conjunction with a variable speed furnace.

 

[ChasBean1]

Allwet, could you clarify your intention a little? Do you mean .5 ton larger than the evaporator? Or install a smaller compressor so that it runs more frequently? Pls. detail a little more. Tx, CB

 

[RJVAN]

I'm not sure how condenser size would affect humidity. I would speculate that either
1)the evaporator is too small, and can't keep up with the moisture (in which case the A/C woud be running constantly. Of course if the system is low on refrigerant, that would cause the same effect. or
2)it's too big and cools the air before it can remove the moisture (in which case the A/C is frequently switching off and on. or
3) The evap coil temperature is too low, and the coils are frosting up, and can't pass the air flow.

 

[Steviehvac]

my hunch is you should focus your effort on the indoor unit..if you have variable speed you could try some sequencing strategies...example: on start up or a call for 1st stage cool run the fan on low speed, let a call for second stage bring on another fan speed (probably high speed)...lower air flow means lower evaporator temps (enhanced dehumidification..evap temps should be in the mid 40's F) and will allow the compressor to continue to run (as opposed to short cycling)..

good luck

 

[imac]

The other replies to your question are right on. The key to your problem is likely the evaporator coil. You need to reduce the temperature of the evap coil so that it will de-humidify as well (but not so much that it freezes!). Be sure the air handler is delivering the proper amount of air over the coil - too much air will raise the evap temperature and reduce its ability to de-humidify. Have a look at the blower performance chart for your furnace/air handler - it will tell you how much cfm the blower is capable of delivering. Too much air also loads the compressor decreasing its longevity.

The installer of your A/C system may have selected an inappropriate blower speed hoping that the extra air flow would help to cool the extremeties of your home. This is wrong-headed. If you have trouble cooling remote areas of the building, you have an air distribution problem that needs a different solution. Check the V/S motor controller to be sure it is set to deliver air at 400 cfm per ton. Sometimes with V/S motors you can easily select 350 cfm per ton by simply moving a couple of DIP switches - this may be an option for you as well.

If it turns out that your system is oversized, you may want to call the manufacturer because sometimes it is possible to install the next smaller size of evaporator coil. For example, you might be able to run a 3.0 ton condenser with at 2.5 ton evaporator coil. This might reduce capacity enough so that dehumidification is improved. Of course, this will cost you a fair chunk of change, so I suggest that you first check your air handler carefully.

I hope this helps.