1. Fluctuating or Erratic Hot Water Temperature.
A. Large demand for hot water.







B. Unbalanced Pressures.

Large demands for hot water will cause the
Mixing Valve to operate incorrectly. This Valve was
not designed to compensate for such conditions.
When hot water is removed faster than the
heating source can reheat the water, the
temperature will drop below the setting of the
Valve.

If the pressure differential between the hot and
cold water inlet lines is greater than 30 PSI, a
Balancing or Throttling Valve may be needed on
the cold water line to make up for the heat loss in
the heating source.
2. Hot water backing up in cold water line.
A. City water pressure drops causing hot water
pressure to override cold water pressure.

Install a Check Valve in the cold water line.
3. Water temperature will not adjust to the
desired temperature.
A. Unbalanced Pressures.





B. Heating source inadequate.


If the pressure differential between the hot and
the cold water inlet lines is greater than 30 PSI, a
Balancing or Throttling Valve may be needed on
the cold water line to make up for the heat loss in
the heating source.

The heating source may not produce enough hot
water to maintain the desired temperature.
4. Failure of Thermostat
A. Thermostat exposed to extreme high  
temperatures.




B. Build-up of mineral deposits due to corrosive
water conditions.

C. Electrolysis

Thermostat on heating source may be set too  
high causing water temperatures to exceed 210°
F. Turn thermostat on Heater down. The Mixing
Valve must be located at least 8” to 12” below the
hot water source.

Cleaning the Thermostat frequently and removing
deposits will help prolong life of Thermostat.

Electrically ground the piping system or install
dielectric Unions.
PROBLEM & CAUSE
ANSWER
21 Londonderry Turnpike, Hooksett, NH 03106        www.mixing-valves.com      PH: 800-807-9827        Fax: 603-626-7372        sales@mixing-valves.com
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