Dunkirk ARTESIAN 220 Installation And Operating Instructions Manual page 29

Domestic Water Piping for Distant Fixtures
in some cases, the furthest fixture may be quite distant from the water heater. In such an
installation, there will be a slight delay before hot water reaches these distant fixtures. Even if all
the fixtures are relatively close to the water heater, the building owner may want hot water at all
fixtures as soon as they are opened. Figure 12 illustrates a solution to this problem. In it, a pipe is
run from the furthest fixture on each branch back to the return of the water heater. A small bronze
circulator is mounted in this line and is wired to run continuously. A check valve in this line permits
flow towards the water heater inlet only.
When no fixtures are drawing water, the bronze circulator moves hot water from the water heater
to the end of the branch just below the last fixture, then back to the inlet of the water heater via the
return pipe. When a fixture is opened, hot water is already out in the branch very close to the
fixture and hot water immediately appears. The check valve prevents cold water in the water
heater's inlet pipe from passing around the tank and heading directly to the fixture. Because hot
water is always circulated in the hot water branch, the entire branch should be insulated to
prevent excessive heat loss.
Manifold Domestic Water Piping
Figure 13 illustrates the recommended method of piping the domestic waterside of several tanks
together. All water heaters are piped in a "reverse-return" manner just like the boiler piping. This
balances the pressure drop through each coil, resulting in an even flow rate through each coil.
Each coil must have its own temperature and pressure valve. It is recommended that each tank
be equipped with its own isolation valves, unions and drains so that one tank may be removed
from the system.
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