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HVAC humidity discrepancy

Posted by BillBCatCity (My Page) on
Sun, Sep 15, 13 at 16:10

Folks, got a new Lennox SEER 21 really great HVAC in May. We live in the Palm Springs, CA (desert) area. The salesman who said he had been in installation for decades said we could expect lower humidity in the house as a result of the new system. It's a 2-ton system replacing a 4-ton builder's grade that was 12 years old. I asked why the smaller unit and they said they use SoCal Edison's standards when they evaluate (actually, they just input data they collect into a Web page) and units are more efficient these days.There is a small trickle coming off outside. The system is two stage and spends time in both.

The humidity right now outside is 19% and the house is 61% and it's been like that all summer (slightly muggy indoors).

Any ideas on whether this big a difference is expected or if something isn't working well or if i need to turn on the de-humid cycle (i think i tried that and it had barely any effect). i think they also sell an add-on de-humid device for the HVAC but not sure of that.

i do remember reading that a de-humid cycle can result is a lower house temp because the humidity setting now becomes the setpoint rather than temp. That can result in a lot more energy use.

Any help/experience/knowledge is appreciated.

thanx. bb

Follow-Up Postings:

RE: HVAC humidity discrepancy

Your condition seems strange. On the east coast we suffer from having high outdoor humidity and run the AC to help lower it below 50%.

Do you trust your humidity gauge? It is hard to believe you have more than a 40 point difference between indoor and outdoor humidity. I have never seen a condition like this.

Your house must be very tight and you are doing something to create a lot of humidity. Are you doing a lot of cooking and taking many showers?

Perhaps the coil is not draining properly and the bulk of the condensate is going back into the conditioned air. Have the installer check the condensate drain. You should see a steady flow of condensate.

RE: HVAC humidity discrepancy

No, it's not normal.

Size of your home?

Provide complete model numbers of outside condenser, inside air handler or furnace, evap coil model number, thermostat.

You need to recheck humidity with a different hygrometer.

I would call the installing dealer out to check system.

If dehumidify on demand is set up and you actually do have high humidity, then system would be running constantly. The question remains what is causing the high humidity? Can't be due to outside weather for your location/climate.


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