Dwyer DFS - Manual

Bulletin T-DFS
The Series DFS Low Limit Freeze Protection Switch protects cooling coils in air
handler systems by preventing frost build up on the coils. By sensing the lowest
temperature along any one foot section of capillary, the DPDT manual or automatic
reset relays signal the building management system as well as cut off the fan. Set
points can be adjusted as low as 34º F (1º C) utilizing the visual set point indicator
and set point screw. The Series DFS includes mounting clips for easy installation.
Installation
The Series DFS Low Limit Temperature Switch can be mounted in any plane;
however, the case of the controller should be mounted at the top of the coil with the
capillary installed in a downwards serpentine fashion across the face of the coil. On
manual reset models, position the switch to allow convenient access to the manual
reset button. Locate the controller case and bellows where the ambient temperature
is always warmer than the set point.
1. Remove cover from switch by loosening the screw on the front of the housing.
2. Mount the switch housing to the duct or other flat surface using the mounting
holes on the rear plate of the switch housing.
3. Install capillary element in a horizontal serpentine pattern across the duct (as
shown in Figure A) on the down stream side of the cooling coil so it is exposed
to areas where low temperature will occur.
4. Use the mounting clips provided or Dwyer Series CC1 clips to fasten the capillary
at sufficient points to prevent damage from air movement or vibration.
5. Adjust set point using the set point adjustment screw as described in the set
point adjustment section.
6. Attach electrical wires through the conduit port in the bottom of the switch
housing according to wiring section of this manual.
7. Re-attach cover and tighten the screw on the front cover to prevent tampering.
Specifications - Installation and Operating Instructions
Series DFS Low Limit Freeze Protection Switch
SPECIFICATIONS
Wetted Material: Vapor-filled copper capillary, tin-plated, 10’ or 20’.
Housing Material: Plated steel case, painted steel cover, plastic set point
window.
Temperature Limit:
Operating: -60 to 160ºF (-51 to 71ºC);
Sensing element: 300ºF (149ºC) max.
Switch Type: DPDT snap acting.
Electrical Ratings:
Inductive: 14 FLA, 84 LRA, 3/4 hp @ 120VAC; 12 FLA, 72 LRA, 2 hp
@ 240 VAC.
Pilot Duty: 720 VA max @ 120 to 600 VAC; 144 VA max @ 24 VAC.
Reset Action: Manual or automatic.
Adjustable Range: 34 to 70ºF (1 to 21ºC).
Deadband: 4.5ºF (2.5ºC), fixed.
Agency Approvals: UL, ULc.
3-5/8
[92.00]
Ø3/32
CAPILLARY
[Ø2.38]
5-33/64
[140.00]
2-41/64
[67.00]
Do not kink or apply excessive force to the capillary element as
it could cause leaks in the capillary. CAUTION
Avoid locations subject to excessive vibration. NOTICE
All wiring should comply with national and local electrical codes. NOTICE
This low limit controller is designed for use only as an operating
control. Where a failure of the controller would result in loss of
property or personal injury, it is the installer’s responsibility to add safety devices
and/or systems that protect against or warn of controller failure.
WARNING
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: [email protected]