Pressurized Water System Installations; Water-To-Water Heat Transfer System - Central Boiler CL 4030 Owner's Manual

Pressurized Water System Installations

Water-to-Water Heat Transfer System

To keep the existing system pressurized, a plate
exchanger or tube & shell water-to-water heat exchanger
installed in the return line of the existing system may be
used (see Fig. 28 and 29). The water from the existing
system passes through the heat exchanger when the
thermostat calls for heat. The water from the outdoor
furnace circulates through the other side of the heat
exchanger continuously.
It may be necessary to lower the water temperature at
which the burner in the existing boiler starts to a setting
that prevents the burner in the existing boiler from
cycling on when the outdoor furnace is heating the
building. Another option is to install a thermostatically
controlled interlock switch that prevents the burner
in the existing boiler from operating when the water
temperature in the outdoor furnace is above 150˚F.
Water-to-water heat exchangers will produce transfer
temperatures approximately 20ºF less than the outdoor
furnace water temperature; therefore if the outdoor
furnace water temperature is 185°F, it will produce
approximately 165°F of water temperature transfer.
The temperature controller on the outdoor furnace
may be adjusted to allow the outdoor furnace to reach
water temperatures up to 195ºF. Each system will vary
in water temperature transfer depending upon the heat
load of the existing heating system.
Fig. 29
24
The addition of a wraparound pump with a water-to-
water heat exchanger (see Fig. 29) may increase heat
transfer by allowing circulation continuously through
the existing boiler and heat exchanger. This will maintain
the maximum temperature in the heat exchanger for
heat transfer to the existing boiler. Note the water flows
in opposite directions through the heat exchanger.
With this type of installation, the exchange temperature
may be more than 165°F and may eliminate the need
for additional baseboard heaters, panel radiators or heat
exchangers.
When installing water-to-water heat exchangers, be
sure to flush any rust particles or sediments out of the
existing boiler and install a Y-strainer as illustrated in
Fig. 29. Also be sure to add Corrosion Inhibitor Plus™
(p/n 1650).
A Taco 007 or 014 pump can be used as a wraparound
pump when a plate exchanger is installed. A Taco 009
or 014 pump should be used when a shell and tube heat
exchanger (i.e., p/n 148, 151 or 177) is installed.
NOTE: See the Hydronic Component Selection
Guide (p/n 2482) for more detailed information.
Plate Exchanger
Section 1 - Furnace Installation