DriSteem STS Manuel page 4

S T S / LT S , D I w a t e r, s e r v i c e i n s t r u c t i o n s
Cool down humidifier
Before performing any maintenance, allow the tank to cool
down. Insulated and uninsulated tanks will have hot surfaces.
Note: Fresh make‑up water is used to speed up cooling. Do
not close the manual water supply before cooling down
the humidifier; otherwise the tank could stay hot for
several hours.
1. Close the manual shut‑off valve on the inlet steam supply
(STS humidifiers) or the inlet hot liquid supply (LTS
humidifiers).
2. Drain the tank:
Models with a standard drain valve:
a. Manually open the drain valve. The fill valve will open
after enough water has drained out of the tank.
b. Let the fill water run until the tank is cooled; then shut
off the field installed manual supply water shut‑off
valve.
c. Let the tank drain; then manually close the drain valve.
For models with end-of-season drain option (must have
Vapor‑logic3 controller), use the keypad to perform the
cool down procedure. Refer to the Vapor-logic3 Installation
and Operation Manual for more information:
a. Select Manual Drain in the control modes screen.
b Allow approximately half the water to drain out of the
tank.
c. Select Auto in the control modes screen; the fill valve
opens and the humidifier cools down.
d. When the fill valve closes, select Manual Drain in
the control modes screen and allow the tank to drain
completely dry. The humidifier should be cool enough
to work on.
Shut down humidifier
Follow the procedure below before performing service or
maintenance procedures, (after the tank has cooled down and
drained):
1. Use the Vapor‑logic3 controller keypad to change the
control mode to Standby.
2. Shut off all electrical power to the humidifier using
the field‑installed fused disconnect, and lock all power
disconnect switches in the OFF position.
3. Close the field‑installed manual water supply shut‑off
valve.
4. Close the manual inlet steam supply (on STS) or inlet hot
liquid supply (on LTS) shut‑off valve.
Page 4 • DRI-STEEM STS/LTS, DI Water, Service Kit Manual
Inspection and maintenance
Annually (also recommended when maintenance is performed)
1. All safety devices in the control circuit should be cycled on
and off to verify they are functioning. These include:
• High limit switch
• Airflow proving switch
2. Inspect tank and gaskets for leaks.
3. Verify that the float valve is closing off. If the float valve
will not shut off, there may be particulate on the valve seat,
or the stopper may be worn and need replacing.
As long as mineral‑free water is used in the humidifier, no
cleaning or flushing should be necessary.
Off-season maintenance
1. Perform a complete inspection of the following:
• Heat exchanger
• Float valve
• Humidifier tank and gaskets
2. After inspection, leave the humidifier empty until
humidification is required.
After the humidification season, DRI‑STEEM recommends a
complete inspection and cleaning of the heat exchanger and
water chamber. After cleaning, the unit should remain empty
until humidification is required.
On units with Teflon coated heat exchangers, do not use
a sharp object when cleaning. Cuts or scratches on the heat
exchanger will impair its ability to shed scale during operation
and could cause the Teflon to separate from the metal surface.
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