Crown Boiler Mega-Stor Operations Instructions download pdf (Page 22)

CIRCULATOR ZONE WIRING (PRIORITY)

Figure 8.2 is a connections diagram for priority circulator zoning. This system is similar to non-priority circulator zoning except

that a Honeywell R8285B relay is used in place of the R845A on the Mega-Stor zone. This relay is equipped with its own 24 volt

transformer and D.P.D.T. contacts. The Mega-Stor control is connected to terminals R and G so that when the Mega-Stor control

calls for heat the relay is energized.

One set of contacts on the R8285B is used to switch line voltage. On this set of contacts the common is connected to an un-

switched “hot”. The normally closed contact is connected to terminal #1 on each of the space heating zone’s R845A’s. The nor-

mally open contact is connected to the Mega-Stor zone circulator.

The normally closed contact on the other set of R8285B contacts is not used. The common and normally open contacts are con-

nected in parallel with terminals #5 and #6 on the space heating zone R845As.

As long as the Mega-Stor zone does not call for heat, the R845As for the heating zones have 110 VAC across their 1 and 2 termi-

nals and the heating zones will function as described in the non-priority circulator zone section. As soon as the Mega-Stor calls for

heat, however, the normally closed terminals in the R8285B open, de-energizing the heating zones and energizing the Mega-Stor

circulator.

The other set of contacts in the R8285B (connected across the boiler thermostat connections) become “made” which brings on the

boiler.

ZONE VALVES (NON PRIORITY)

Figure 8.3 is a connections diagram for a zone system using Honeywell V8043F motorized zone valves. The motor on these

valves is connected between TH and TR. TH/TR is provided for the electrician’s convenience as a binding post and is connected

to nothing inside the valve. The “endswitch” terminals are connected to a set of switch contacts inside the valve which become

made when the

valve is open.

A call for heat from any thermostat or the Mega-Stor aquastat results in the application of 24 volts across the motor in that zone’s

zone valve. This drives open the zone valve. When the valve has opened, the endswitch in that zone valve makes and brings on

the boiler.

ZONE VALVES (2-WAY PRIORITY)

Figure 8.4 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 S.P.D.T. contacts.

The Mega-Stor control is connected to terminals R and G on the R8285B so that when the Mega-Stor 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 Mega-Stor zone valve motor.

As long as the Mega-Stor 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 Mega-stor 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 Mega-Stor zone valve. The Mega-Stor zone valve opens and its endswitch brings on the boiler.

If four or fewer zones (including the Mega-Stor zone) are present, the transformer in the R8285B may be used instead of an exter-

nal transformer. Use terminals R and C with C being the “common” side of the 24 volt wiring.

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Crown Boiler Mega-Stor Operations Instructions Page 22