RESIDENTIAL GAS AND ELECTRIC WATER HEATER
SERVICE HANDBOOK
Residential Gas - continued
Electrical Testing– continued
Millivolt dropout test through copper magnet winding and ECO (Emergency Cut Off) Procedure: Move meter probe to upper ECO solder joint and ground
If … | … then |
reading of at least 10 MV is not present | replace the control valve. |
reading of more than 10 MV is present but, | replace the control valve. |
gas to the pilot shuts off each time knob is |
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released |
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Safety drop out test – the safety gas shutoff should interrupt gas through the valve when MV current drops to
Procedures:
Meter still connected to upper ECO solder joint and ground.
Turn Top Knob to “off” position
Millivolt output will decrease as thermocouple cools
| TO GROUND |
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|
If… | … then |
internal safety does not activate between 1 | replace the control valve. |
and 3 MV (you will hear a “click” inside the |
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valve) |
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*internal safety does activate between 1 and | valve is within tolerance and will interrupt gas |
3 MV | flow if pilot looses heat or ECO opens. |
*Note: A “click” sound should be heard from the valve as the main gas interrupter snaps up to the “closed” position.
Condensation
Flue gas products contain moisture. If these flue gas products are cooled to their “dew point”, they become visible moisture – condensation.
Flue gas may become cooled by:
•Cold supply air temperatures
•Cool surfaces – generally, if tank water temperatures drop below 110°F, the flue pipe surface and/or bottom tank head will be cool enough to cause condensation.
•Increased combustion efficiency – higher thermal efficiency means that an increased amount of heat is transferring from the flue gas into the water. If you transfer (approximately) 87.5%, or more, the moisture in the flue gas will condense.
A.O. Smith Water Products Company | 13 | Training Department | |
©2002 | Ashland City, Tennessee | ||
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