Operating instructions

ZONE VALVES (2-WAY PRIORITY)
Figure 19 is a connections diagram for a priority zone system using Honeywell V8043F motorized valves.
An R8285B relay is used which is equipped with its own transformer and a set of SPDT contacts.
The Maxi-Therm control is connected to terminal R and G on the R8285B so that when the Maxi-Therm
control calls for heat, the relay coil is energized. One side of the transformer is connected to the common
contact. The normally closed contact is connected to all space heating thermostats. The normally open contact
is connected directly to the Maxi-Therm zone valve motor.
As long as the Maxi-Therm is not calling for heat, power is supplied to all space heating thermostats and a
call from any space heating thermostat will energize that zone’s zone valve and bring on the boiler. As soon as
the Maxi-Therm calls for heat, however, the normally closed contacts, which supply all power to the space
heating thermostats, open. This de-energizes the heating zones and closes any open space heating zone
valves. At the same time, the normally open contacts in the R8285B become made which energizes the Maxi-
Therm zone valve. The Maxi-Therm zone valve opens and its endswitch brings on the boiler.
If four or fewer zones (including the Maxi-Therm zone) are present, the transformer in the R8285B may be
used instead of an external transformer. Use terminals R and C with C being the “common” side of the 24-volt
wiring.
ONE VALVE (3-WAY PRIORITY)
Figure 20 is a connection diagram for a Honeywell 3-way zone valve. As long as the Maxi-Therm is not
calling for heat, a call from the space heating thermostat will start the boiler and water will circulate to the space
heating zone through the normally open port of the zone valve (see the piping section for more information on
this). If the Maxi-Therm thermostat calls for heat, however, the zone valve motor is energized and all boiler
water is redirected through the Maxi-Therm coil regardless of the status of the space-heating thermostat.
MANIFOLD WIRING
Wiring for manifolded Maxi-Therms is identical to wiring for a single Maxi-Therm except for the presence of
more than one tank aquastat. If the Maxi-Therms are piped together as shown in the Piping Section, only one
thermostat should be needed and it can be installed in the thermostat location on any Maxi-Therm.
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Figure 18: Zone Valve Wiring (2-Way, Non Priority)