Can the humidifier's housing for a Honeywell model HE265 By-Pass Humidifier be installed on the return air duct, or must the housing for this model always be installed on the hot-air supply duct just above the furnace unit?

Here is a link on humidifiers http://www.iallergy.com/humidifier_answers.html.

Open the waterline tap valve or may have to clean small orifice that is in line where 1/4" line meets humidifier. Need to shut water off and in screw nut holding copoet line to humidifier

no because you have not clovered the hole supply of the hole run

Humidifiers are installed in the return air unless they are a forced (uses a fan) type of humidifier.

The sail switch is in the cold air return it is wired in with the humidastat when your furnace goes on the air movement pushs the sail down inside the duct work that makes a contact the lets the 24volts to the humidastat. If the humidastat calls for moisture it turns on the humidifier but only when the blower on the furnace is on So in short it detects air movement

Evaporative should be in the return plenum and steam in the supply plenum.

Neither, even if the solenoid or humidistat stick, it should always drain properly. Is the unit mounted on the cold air return duct or the supply plenum? If it's mounted on the supply plenum, the water panel might be getting blown forward and spilling the water. High efficient furnaces also can leak water on the floor if its drain is restricted. If hum. is mounted on return duct make sure drain is clear by blowing through it. On Honeywell hum's I've seen the rubber hose from the solenoid valve to the distributor tray leak too, check the rubber 1/4" hose.

thanks for your question,
you have to install the bypass humidifier on the supply side of your heating system, (hot side) and run a bypass pipe from the return side, (cold side), it does matter which side it goes on, you do not want water vapor going directly into your furnace, as this can damage it and shorten the life of it, your humidistat is installed on the return side of your duct work, this will allow proper operation of the unit as the humidistat senses the moisture in the air and brings on and shuts down the humidifier as needed. hope that helped to answer your question, please let us know what you think, again thanks, mr.grzz

sounds like to me you have a condensation pump attached to your hvac system. this can be used to pump water produced during the cooling of your house when in the a/c mode. if you have a typical bypass humidifier, you will have excess water running past the water panel and it must be sent to a drain of some kind. I would imagine the pump is being used to get your bypass water to the drain. another scenario may be that you have a 90% condensing furnace. if your exhaust pipe for the furnace is made out of pcv pipe, it is a condensing gas furnace. it will produce water when it is running. the water if from the combustion gases being condensed in the secondary heat exchanger. this is normal. some condensing gas furnaces will draw combustion air from inside the house and some will have a second pvc pipe that is used to pulll combustion air from the outside of the house. either way, it is not dehumidifying your house. the humidifier should be able to keep up if it is runnng properly. you should have water running out the bottom drain of the humidifier any time the fan on your furnace is running and the humidistat is calling for humidity. if this is not happening, it is not wired properly.

THE MOTOR ONLY TURNS THE SPONGE DRUM AT MAYBE 10X'S PER MINUTE. THIS IS A BY-PASS TYPE HUMIDIFIER THAT RELIES ON YOU FURNACE BLOWER MOTOR TO SUPPLY AIR ACCROSS THE SPONGE MEDIA. NOTICE THE 5"-7" ROUND HOLE MUST BE DUCTED TO THE PLENUM OR RETURN AIR. (IF MOUNTED ON THE PLENUM, THE HOLE HAS TO BE DUCTED TO THE RETURN AIR, AND VISA-VERSA.) CAUTION!!!IF YOU HAVE CENTRAL AIR? A "DAMPER" MUST BE INSTALLED AND KEPT CLOSED THROUGH-OUT THE "COOLING SEASON". SERIOUS DAMAGE TO YOUR COMPRESSOR CAN RESULT FROM TOO COLD OF AIR ... CIRCULATING AND "BY-PASSING YOUR EVAPORATOR COIL".