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LAARS Rheos RHCV - Install and Operating Manual User Manual

Page 21

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Rheos Boiler and Water Heater

Page 21

SECTION 5.

Electrical Connections

WARNING

The appliance must be electrically grounded in

accordance with the requirements of the authority

having jurisdiction or, in the absence of such

requirements, with the latest edition of the National

Electrical Code, ANSI/NFPA 70, in the U.S. and

with latest edition of CSA C22.1 Canadian Electrical

Code, Part 1, in Canada. Do not rely on the gas

or water piping to ground the metal parts of the

boiler. Plastic pipe or dielectric unions may isolate

the boiler electrically. Service and maintenance

personnel, who work on or around the boiler, may

be standing on wet floors and could be electrocuted

by an ungrounded boiler. Electrocution can result in

severe injury or death.

Single pole switches, including those of safety

controls and protective devices must not be wired in a

grounded line.

All electrical connections are made in the field

wiring box that is located inside the appliance.

NOTE: All internal electrical components have been

prewired. No attempt should be made to connect

electrical wires to any other location except the wiring

box.

Wiring connections are shown in Figures 18

through 33.

5.1 Main Power

Connect a properly sized and fused, 120-volt

supply to the main power switch (hot leg is connected

directly to switch). Neutral leg is connected directly to

the white wire. Ground wire can be connected to the

grounding screw in the box or on the switch.

5.2 Pump Connections

The pump time delay relay will call the pump

to be energized upon a call for heat, and will keep the

pump energized for a delay period after the call for

heat has ended. The delay period is adjustable from

0.1 to 10 minutes.

Pump-mounted Rheos units have pumps that are

wired at the factory to the pump time delay through a

relay. Wiring to a separate 230V single phase circuit,

per the wiring diagrams in Figures 18 through 33 is

necessary.

Rheos units without the factory-mounted pump

also have the pump time delay relay. A 120V single

phase pump, which is no larger than 1hP, or 230V

single phase pump no higher than 3/4hP, can be wired

directly to pump time delay relay, as shown in the

unit’s wiring diagram (120V hot connection on the

pump to terminal 2 on the pump delay relay, and 120V

neutral to the 120V neutral circuit of the unit.)

If the pump is 3-phase, higher voltage than 120V,

or higher horsepower than 1hP, the pump’s starter

or a separate relay can be connected to the unit’s

pump time delay relay, and the pump can be driven

indirectly.

Contact the factory if there are questions about

connecting a pump to the Rheos’ pump time delay

relay.

5.3 Temperature Control — Boiler

Connect boiler T-T wires to isolated contacts on

zone valves, circulator relays, sequencing controls

(multiple appliance applications) or other temperature

controlled devices. The Rheos boiler temperature

control measures temperature on the boiler inlet. Set

the temperature control such that the setpoint plus

the boiler temperature rise equals the desired boiler

outlet temperature. Also set the manual reset high limit

20°F above the outlet temperature to avoid nuisance

lockouts.

Example, Imperial units: If the desired outlet

temperature is 180°F, and the boiler temperature rise is

25°F, then set the boiler temperature at 155°F (180°F

– 25°F). Lastly, set the manual reset high limit to

200°F (180°F + 20°F).

Example, Metric units: If the desired outlet

temperature is 82°C, and the boiler temperature rise is

14°C, then set the boiler temperature at 68°C (82°C-

14°C). Lastly, set the manual reset high limit to 93°C

(82°C+11°C).

5.4 Temperature Control — Water Heater

5.4.1 Remote Water Heater

Temperature Control

The Rheos water heater can be used with a field-

supplied tank aquastat, sequencing control, or other

temperature control device, which will call the unit for

heat when the temperature goes below the controller’s

setpoint. For the most efficient setting, set the tank

temperature at the lowest possible setting for adequate

hot water in the application.

Caution

If the tank temperature control is set too high, a

potential for hot water scalding may exist.

After a setting has been chosen for the tank

temperature control, set the heater temperature control

10°F (6°C) higher. The heater’s temperature control

senses the inlet water temperature to the heater. The

heater’s manual reset high limit senses heater outlet

temperature, and should be set 20°F (11°C) above the

outlet temperature to avoid nuisance lockouts.

Example, Imperial units: If the tank temperature

is set to 140°F, set the heater’s temperature control to

150°F (140°F+10°F). Further, if the temperature rise

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