EZ Plate™ Storage Water Heater
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PV500-64 12/14
5.2 High Water Temperature Limit Control
The appliance is equipped with an adjustable temperature limit control and a non-adjustable high temperature limit
control. These controls are located inside the control cabinet and are accessed by removing the bottom cover.
The adjustable limit control is an auto reset type and should be adjusted at least 10 degrees above the set point of
the Operating Thermostat.
The high limit is an auto reset type with a fixed set point, but is optionally available as a manual reset type. If the high
limit is a manual reset type, it cannot be reset until the water temperature has dropped below its reset point.
5.3 Electronic Low Water Cut-Off (Optional)
The optional low water cut-off remains energized and allows the water heater to operate as long as the water level is
above the electrode position in the storage tank. When the water level falls below the electrode position for more
than three seconds, the low water cut-off de-energizes and turns off the pump, which stops heat from being added to
the storage tank.
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DESCRIPTION OF OPERATION
The EZ PLATE storage water heater can provide potable water up to 175ºF, using boiler water as the energy source.
The supplied boiler water temperature must be within the range of 125ºF to a maximum of 180ºF and must be at
least 5ºF above the potable water temperature desired from the water heater storage tank outlet.
The water heater storage tank and heat engine (heat exchanger and associated components) are assembled on
separate skids then, factory plumbed together in the typical side by side configuration. If necessary, the storage tank
and heat engine can be relocated by the customer using field-supplied piping. A larger field-supplied pump may be
necessary when increasing the distance between the heat engine and the tank.
6.1 Sequence of Operation
1. When there is demand for hot water consumption, hot water exits from the top of the storage tank and is replaced
by cold water entering the bottom of the tank. When enough cold water enters the storage tank to lower the
stored hot water temperature below the set-point entered into the programmable electronic operating control
thermostat, the control circuit closes creating a call-for-heat, which energizes the circulating pump (and boiler
water control valve, if supplied).
2. When the circulating pump is energized (and boiler water control valve, if supplied), the pump circulates domestic
water from the storage tank through one side of the heat exchanger plates. Boiler water flowing on the other side
of the heat exchanger plate heats the domestic water before it returns to the storage tank.
3. When the stored water temperature increases above the set-point entered into the programmable electronic
operating control thermostat, the control circuit opens and the circulating pump (and boiler water control valve, if
supplied) is de-energized.
4. When the circulating pump is de-energized, the pump stops running and no more heated water flows from the
heat exchanger to the storage tank.
5. If, for any reason, the water temperature in the storage tank raises above the set-point entered into the
programmable electronic operating control thermostat, the circulating pump (and boiler water control valve, if
supplied) will be de-energized by the adjustable limit control or the fixed high limit.
