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Brian Horton
Brian Horton,
Category: HVAC
Satisfied Customers: 3
Experience:  Service Technician II at Hobart Corporation
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Installed a honeywell true steam humidifier hm609, have a

Customer Question

installed a honeywell true steam humidifier hm609, have a carrier thermidistat TP-PRH. thought i wired correctly but it doesn't shut off. I connected the HUM on thermidstat control to GT on humidifier and C on thermidistat to C on humidifier, put jumper between HUM and HUM on humidifier. Produces plenty of steam but does not shut off when humidity setpoint is reached
Submitted: 1 year ago.
Category: HVAC
Expert:  Brian Horton replied 1 year ago.

Have you tried removing the jumper? That could be causing it to bypass the thermidistat.

Customer: replied 1 year ago.
it turns off the humidifier but when i raise the setpoint on the thermidistat above the actual humidity in the house the humidifer does not turn on without the jumper in place
Customer: replied 1 year ago.
still running with jumper in, set point at 30%, fan on AUTO, not calling for heat, actual humidity is 40% and humidifier is still producing steam
Expert:  Brian Horton replied 1 year ago.

I would almost bet its a wiring problem with the t-stat. Let me look into it.

Customer: replied 1 year ago.
fan is set to ON, turned temperature up on t-stat, HEAT is on, humidity set point at 46%, actual humidity is 38%, t-stat screen now says humidify, so i assume it is calling for humidifier to turn on
Customer: replied 1 year ago.
i have 24V at HUM terminal on t-stat control when screen says 'humidify' when i turn set point below actual humidity the 'humidfy' does not display and i no longer have 24v at HUM on t-stat control
Customer: replied 1 year ago.
the wiring diagram that came with humidifier shows the connection i need but i don't know what terminals to use from the t-stat....humidifier has two terminals labeled HUM, t-stat only has one terminal labeled HUM, i don't know what other terminal on t-stat to use to connect to the remaining HUM terminal on humidifier.....the honeywell prestige IAQ t-stat shows two U1 terminals connected to the two HUM terminals on the humidifier....i don't know what equates to the U1 terminals on the TP-PRH t-stat...i assume one of them is HUM and i thought the other one might be C but that didn't work so i am wondering if i should use D1
Customer: replied 1 year ago.
i would like the humidifier to turn on whenever the actual humidity drops below the setpoint, right now i have it connected so it turns on only when the heat is on and the actual humidity is below the setpoint....so it is HUM on humidifier to HUM on tstat and other HUM on humidifer to G on tstat
Expert:  Brian Horton replied 1 year ago.

I would try D1 for sure. That may stand for dehumidifier 1 , As you stated you have 24v at Hum terminal on the tstat when it is calling for the humidifier and when you turn the setting down the 24v goes away as it should. That part is correct. Let me see if i can get a wiring diagram for that unit.

Expert:  Brian Horton replied 1 year ago.

Do you have the Optional airflow switch installed?

Expert:  Brian Horton replied 1 year ago.

Can you send me a picture of your tstat terminals to***@******.*** That would help a lot. We will get this fixed one way or the other.

Customer: replied 1 year ago.
no optional airflow switch installed. .jpg below of terminals in tstat
Expert:  Brian Horton replied 1 year ago.

Did you ever try D1? Try putting the other HUM wire on C . Not G.

Customer: replied 1 year ago.
I tried putting the other wire to C instead of G last night and it did not work at all

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