Paloma PH2-20R OFN Engineering Handbook page 150

Section 1.0 - System Description
A manifold system consists of the manifold controller referenced by
this instruction, and a bank or 3 to 6 tankless water heaters. The
tankless heaters are installed in a parallel manifold system where
each unit is independently fed with cold water from a common water
Figure 1.0
REMOTE
CONTROL
CONTROL
CABLES
HOT WATER
Section 1.1 - Basic Operation
This section covers the basic operation of the Manifold System by
the end user from turning on the system, temperature adjustment,
and trouble shooting. This section assumes the system has been
installed and is operating normally.
The system is designed to operate with multiple tankless water heat-
ers (units), each of which is fi red sequentially depending upon the
demand or water fl ow rate. Over time the starting unit will rotate to
spread the total operational time out evenly over all the units.
As the hot water demand increase the system will detect this and
bring online additional units to meet the increased demand. As the
hot water demand decreases the system will reduce the number of
operating units. As the water fl ow stops, or units are shut down for
reduced demands, the system will go into a stand by ready to fi re
mode for a few minutes. It is normal for the fans to run after the wa-
ter demand has stopped and the burners have shut off.
The system will sacrifi ce water fl ow rate to maintain water tempera-
ture. If the water fl ow rate exceeds the systems capability the sys-
tem will automatically restrict water fl ow to keep it at the thermostat
setting. When this occurs there might be a slight or noticeable drop
in the hot water pressure at the plumbing fi xtures. This is normal, if
it occurs frequently the system may be undersized for the demand.
- 150 -
Typical Manifold System
TANKLESS
WATER HEATER
UNIT #1
Manifold System Operation
main and each feeds a hot water main. See Figure 1.0. This system
will not operate if the tankless water heaters are installed in series,
one feeding another. All tankless water heaters on this system must
be of the same type, do not mix types or capacities.
TANKLESS
WATER HEATER
UNIT #2
To turn on the system, stop any hot water fl ow, and press the Power
Button on the Remote Control Thermostat. See Figure 1.1. A Green
indicator in the power button will light, and the display will show the
current temperature setting.
Figure 1.1 - Press Power Button
4
TANKLESS
WATER HEATER
UNIT #3+
GAS
COLD WATER