Zoning Hydronic Systems

Zone Control Divides the Space to be Heated

1. Each with its own heating needs and control systems

2. There are several reasons for using zone systemsA. To Provide different temperature levels in living and sleeping areasB. To provide uniform temperature in buildings which might be difficult to control with a single thermostat

C. To match heating output to load differences caused by variations in exposure to sun and other variables

D. One advantage of hydronic heating systems

E. The heating need may be determined by difference in heat loss or by occupancy

3. Hydronic zones may be zoned by either of two means

A. Zone Valves

B. Individual circulators

4. Both systems control the flow of heated water to the affected zone

5. Zone valve setups use one central circulator

6. While individual circulator systems use a separate circulator pump for each zone

Multiple Circulator Systems

1. Each circulator pump is controlled by a separate thermostat through a relay

2. Some Aqua stat relays have special terminal designated for a zone control

3. You would use switching relays for zone two and each additional zone

Zone Control 1. Methods of providing zone control

A. Zone controls B. Zone circulators

2. Zone valvesA. A separates zone valve is installed in the line going to or returning from each zoneB. Each zone valve is controlled by its own thermostat

Lever for manual valve operation

Zone valve motor

Valve cover

C. End switches in each zone valve control the central circulator and the burner

1. All end switches are wired parallel

2. The circulator and burner are powered when any zone is calling

3. Zone circulators

A. There is a circulator for each zone

B. Flow valves in the piping for each zone to prevent flow in the zones where the circulator is not running

C. A relay for each zone switches that zones circulator and the burner

1. On a call for heat from a zone thermostat the relay turns on the

power to the zone circulator and the burner

D. The relay includes a transformer to power the zone thermostat circuit

1. It has two contacts; one is for line voltage to switch the circulator, and the other is rated for line or low voltage to switch the burner

E. Valve Construction

1. A low voltage motor

2. A auxiliary switch ( end switch )

3. A valve housing and seat

4. A valve stem and ball

5. The power head can be replaced without breaking the water

line connections

F. Valve operation

1. When the valve is powered the motor drives and swings the ball off the valve seat

2. The end switch makes just before the valve reaches full open

3. When power to the motor is cut off the return spring closes the

valve

Adding Zones to a System

1. Components needed to add valve controlled zones

A. A new valve

B. A new thermostat

2. Make sure that the system has enough boiler capacity to handle the added heating load

3. Is there enough low voltage power to carry the new valve?

A. The transformer for the new circuit may be separated or it may be incorporated in the aqua stat controller

B. Check source to be sure it puts out enough VA to handle the new total load

4. Components needed to add circulator controlled zones

A. A new thermostat

B. A new circulator pump

C. A new relay to switch the circulator on and off

1. Low voltage power for the thermostat poses no problem because the new circulator relay has its own

transformer