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Aprilaire Humdifier questions

Posted by veesubotee (My Page) on
Sun, Jan 27, 13 at 14:40

I'm considering installing an Aprilaire humidifier, model 700. With regard to the OD temperature sensor, how long is the attached wires/cable? Is there a limit on length? Can the cable be lengthened with additional wire/cable. If so, what type (gauge/shielding) is required.

My plenum (installation site) sits on top of a cased coil. My thinking is, that in the rare case where water would overflow, it would fall on the A coil, pass through, then drop into the condensation tray (same side as humidifier.

I have ruled out a bypass unit, as my furnace is modulating and spends a lot of time at low fire (airflow).

Comments please.


Follow-Up Postings:

RE: Aprilaire Humdifier questions

The humidifer has it's own drain, it's not going to overflow into the furnance.

The outdoor sensor is a thermistor ( a resistor that vaires resistance with respect to temperature ). I would guess that it uses thermostat wire. Series Installation Instructions 04.10.pdf

RE: Aprilaire Humdifier questions

Thanks, I have a copy of that PDF. I had never noticed that the water panel w/associated hardware was entirely outside of the plenum, so notwithstanding some PROs arguing in favor of a bypass unit to avoid water flooding electronics, there appears to be little possibility of that happening.

My biggest concern regarding the sensor deals with gauge of wire and shielding requirement. Length (resistance) might also come into play. Aprilaire's contact email line if very subject oriented. Will take a look at Alpineair's site.



RE: Aprilaire Humdifier questions

They are measuring the resistance in the thermistor. My guess they are using the 24 volt power. As I said, it probably uses 18 gauge thermostat wire. You don't need any shielding with low voltage wiring.

RE: Aprilaire Humdifier questions

"As I said, it probably uses 18 gauge thermostat wire. You don't need any shielding with low voltage wiring."

I'm not disagreeing with you, but just concerned. My A/C unit has an outdoor temperature sensor installed. The installation sheet states that the wires be separate from the thermostat bundle.


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