To test the thermocouple, disconnect the thermocouple lead to the ECO. Insert a multi-meter probe into the thermocouple lead and attach or hold the other lead to the metal gas valve (DC common). Light the pilot flame and hold button, meter reading should be 24 mVDC or more. If the reading is 24 mVDC or more the thermocouple is good. To test the electromagnet, re-connect the thermocouple lead to the ECO, light pilot and hold button while taking a reading between the ECO leads and the metal gas valve (DC common). The reading should drop to 19 mVDC or less. If it does not, replace the electromagnet.
BURNERS DO NOT IGNITE WHEN HOT WATER IS TURNED ON
1. Pilot is not on.
Light the pilot. See lighting instructions.
2.Gas valve button not positioned on Burner Position
Be sure once the pilot flame is on, that after a 15 to 20 second wait, the main burner button ( 
) is pushed all the way in.
3.Cold incoming water connection made to wrong side of heater
Make sure cold water inlet connection is on the right side of heater when you are facing the heater.
4.Water flow rate at hot water tap is too low. Note: The AquaStar models 125B”S” require 0.5 gallon per minute flow to activate the burners. This is a flow which would fill a quart jar in 30 seconds.
5.Cold water inlet filter on heater is dirty.
Remove filter and clean. This screen filter is located at the inlet side of the brass water valve (fig. 11, #34). Check and clean faucet aerators too.
6. Crossover in household plumbing
The AquaStar burner activates when there is sufficient water pressure drop in the AquaStar water valve assembly — ie. when a hot water faucet is opened. If there is a crossover in the plumbing, the necessary pressure drop in the AquaStar will be insufficient, or totally eliminated. A plumbing crossover can be caused by a bad washer at a single lever faucet or incorrect plumbing or a mixing valve in the line, etc. which permits hot and cold water to mix in the plumbing. The crossover will create a back pressure in the system preventing the pressure drop in the Aquastar — i.e. cold water is entering the water heater from both sides and the burners will not come on. To confirm there is no crossover in the plumbing, shut off the cold water supply to the AquaStar. Open your hot water taps. There should not be any water flowing. If there is water flowing, there is a crossover in the plumbing. This is a plumbing problem, not an Aquastar problem. Please contact your plumber.
7.Water valve parts may be dirty or components damaged.
Water valve and component parts must be totally free of dirt. First check that the venturi is free of dirt particles. In hard water areas, mineral deposits can eventually (3 to 5 years in hard water areas) corrode the water valve parts to a point where they will need replacing.
Any sign of moisture or corrosion at the joint of the water valve and the gas valve is a sign that the water valve assembly components need to be replaced immediately.
Note: Water valve for model 125B”S” is part # 8707002393 for both LP and NG models. (Contact service person to clean water valve or replace if corrosion is present).
PILOT LIGHT GOES OUT DURING OR IMMEDIATELY AFTER HOT WATER HAS BEEN USED
1. Gas pressure too low
Very low gas pressure may be caused by low delivered gas pressure, a jammed gas regulator or undersized gas lines. If the gas lines are undersized, there may still be the specified static gas line pressure. However when the water valve opens,and gas enters the burners, the pressure could drop sharply, causing the pilot flame to go out.
Have a gas technician confirm the gas pressure both static and at maximum Btu output. Specifications for your heater are on page 2.
2. Pilot may be dirty or weak
See Page 13 for instructions on pilot maintenance.
3.Burners are not shutting down immediately when hot water is turned off
Note: If burners don’t shut down immediately when the hot water is turned off, the heater will overheat and the ECO will shut-off the gas. Rebuild the water valve assembly using the repair kit from CEC (part #8 703 406 204).
WATER IS TOO HOT
1. Water flow rate is too low. Increase the flow rate.
2. Not enough cold water mixing at faucet
Contact your plumber to adjust mixing valves on faucets.
3.The heater’s fixed degree rise is too high for user The calibration nut for the thermostat assembly at the gas valve can be adjusted upward to lower the temperature rise. A seal of paint coats two adjusting nuts there, the thin up- per one is a lock nut while the lower one is the adjuster. Loosen the lock nut one first. Tighten the adjuster nut in- crementally upward and check water temperature, stop when
satisfactory. Then tighten down the lock nut. Caution:
Never back the adjuster nut downward to the last thread unless the thermostat is being replaced. This is a gas seal.
WATER IS NOT HOT ENOUGH
1.Water flow rate is too high. Decrease the flow rate.
2.Btu input is too low due to insufficient gas pressure It is extremely important for a tankless instantaneous water heater to have the right size gas line to obtain the correct gas pressure
