SmartPlate Application Guide for Boiler Interface
SP-1010
Technical Application Guide
TAG-0026_0B
01/08/2016 AERCO International, Inc.
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100 Oritani Dr.
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Blauvelt, New York 10913
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Phone: 800-526-0288
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1. General
The SmartPlate is an instantaneous water heater that satisfies diversified domestic hot water
demands and maintains accurate temperature control under varying loads without requiring
domestic water storage. These objectives are achieved using digital controls with feed-forward
sensing and a fast-acting electronic control valve.
The SmartPlate’s control valve accurately regulates the primary energy source (boiler water) in
the proper proportion to satisfy the secondary (domestic water) load requirements. The
SmartPlate transfers energy between the boiler water and domestic water using either a single-
wall brazed plate heat exchanger or a double-wall plate-and-frame heat exchanger. Because
these plate heat exchangers are so efficient, they are capable of functioning effectively with as
little as a 5°F approach. This allows for a lower boiler water supply temperature, which will
increase condensing boiler system efficiency.
The availability of boiler water at the proper flow and at a reasonably stable temperature (±10°F)
is key factor to the success of this design. The specifying engineer must consider what type of
hydronic heating system and boilers the SmartPlate will interface with in order to optimize
system performance and maximize boiler efficiency. Keep in mind that the boiler supply
temperature to the SmartPlate must be at least 5°F above the desired domestic hot water
setting; hence the boilers supply temperature cannot be reset below that point.
2. Purpose
The intent of this guide is to enable the specifying engineer applying SmartPlate to ensure
acceptable temperature control at the heater and minimize boiler cycling, thus avoiding
associated loss in system efficiency and physical wear and tear on the boiler.
3. System Categories
Most hydronic heating systems fit into one of two general application categories:
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Large volume systems with sufficient thermal mass and year-round loads to dampen out
the peaks and valleys associated with domestic water heating loads.
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Small volume systems with insufficient thermal mass and/or seasonal loads that do not
dampen out the peaks and valleys associated with domestic water heating loads.
Systems in the second category can induce excessive boiler cycling while working to meet the
domestic hot water demand. A properly designed system should not allow any single boiler to
cycle more than 2-1/2 times per hour when domestic water heating is the only load - much less
during the heating season.
3.1 Large Volume Systems
To minimize boiler cycling, sufficient thermal mass must exist in the piping between the boiler &
SmartPlate, in each individual boiler, or in both. Sufficient boiler water flow at specified
temperature must be provided for the SmartPlate to meet variable potable water load demand.
The location of the SmartPlate heater relative to the boiler is also important ― the required
thermal mass must be between the boiler and the SmartPlate.
Large conventional boilers can contain anywhere from a few hundred to a few thousand gallons
of water. In this scenario, the boiler and piping water volumes alone are typically (but not
always) sufficient to ensure minimal boiler cycling and smooth operation of the SmartPlate.
When this is the case, the SmartPlate should be installed as shown in Figures 1 and 2.
