Hayward ED2 - Page 15

FAULT CODE THUMBNAILS – PAGE F 15
FAULT CODE THUMBNAILS – PAGE F 15
Heater System Solving Guide
Fault Code Thumbnails LO Switch Open within Safety Limit String (ED2)
LO
SWITCH OPEN WITHIN SAFETY LIMIT STRING
ED2
PARTS THAT MAY BE NEEDED
• High Limit Switches • Control Module
• (Water) Pressure Switch • Wiring Harness
• Vent Pressure Switch
NOTE: “lo” is normal when pump is off. Otherwise, “lo” means a
control loop switch is open. Therefore, check for the following:
DIAGNOSTIC SEQUENCE
Possibility 1: Water Pressure Switch Fault
A. To verify that the pump is running, turn the pump OFF and watch to
see that the LO code clears. If LO does not clear, proceed to next step.
B. Check the water pressure switch for faulty wiring and connections:
Ensure wire harness terminals are securely fastened to spade terminals
on water pressure switch. If OK, proceed to next step.
C. Verify the state of water pressure switch contacts: Remove wire leads
from water pressure switch and jumper leads. Then attempt to oper-
ate the heater, measuring continuity across water pressure switch. If
closed, LO code is not caused by water pressure switch fault. If open,
proceed to next step (after removing jumper from wire leads and re-
connecting wire leads to water pressure switch).
D. Ensure that low pump pressure does not exist. Clean filter or clear
blockages. Check position of valves in plumbing system. If OK pro-
ceed to next step.
E. Adjust water pressure switch setting per instructions in IDL Installation
Manual (only if heater is above or below water level). If LO does not
clear, the water pressure switch is defective and must be replaced.
DIAGNOSTIC SEQUENCE (CONTINUED)
Possibility 2: Automatic Temperature Limit Switch Fault
F. Check the (automatic) temperature limit switch for faulty wiring and connections:
Ensure wire harness terminals are securely fastened to spade terminals on the
temp limit switch. If OK, proceed to next step.
G. Verify the state of (automatic) temperature limit switch contacts: Remove wire
leads from (automatic) temp limit switch and jumper the leads. Then attempt to
operate the heater, measuring continuity across (automatic) temp limit switch.
If closed, LO code is not caused by (automatic) temperature limit switch fault.
If open, proceed to next step.
H. OUTDOOR UNITS ONLY: Check for high winds or severe downdrafting and, if
necessary, install High Wind Stack. (For indoor units, skip ahead to next step.)
I. Ensure that flue is not blocked or restricted: Refer to vent sizing requirements.
J. Check for sooted or damaged exchanger. If sooted or damaged, the exchanger
should be cleaned (and may need to be replaced).
Possibility 3: Manual Temperature Limit Switch Fault
K. Repeat steps F through J for manual temperature limit switch.
L. Reset manual temperature limit switch. If switch continues to trip, replace the
manual temperature limit switch.
Possibility 4: High Limit Switch Fault
M. Check the high limit switch for faulty wiring or connections. Ensure wire harness
terminals are securely fastened to spade terminals.
N. Verify state of high limit contacts. Remove wire leads from high limit switches
and jumper leads. Operate heater, and measure continuity across high limit
switches. If closed, LO code is not caused by high limit switch fault. If open, re-
move jumper from leads, reconnect leads to high limit switches, and proceed to
next step.
Possibility 5: Inadequater Water Flow Fault
Q. Verify that water flow rate to heater is above minimum required: 25 GPM.
R. At this point, it must be assumed that a high limit switch is faulty and must be
replaced.
FAULT CODE THUMBNAILS LO SWITCH OPEN WITHIN SAFETY LIMIT STRING (ED2)