Viessmann 7968315 User manual

Brand: Viessmann

Model: 7968315

Type: User manual

Viessmann 7968315 is a low gas pressure switch designed to protect your heating system by shutting down the burner when gas pressure drops below a safe level. Suitable for use with Vitocrossal CM2 boilers, this device enhances safety and prevents potential damage caused by low gas pressure. Its adjustable setpoint allows customization based on specific system requirements. Installation requires professional expertise, and the device should be integrated with the boiler's gas supply line.

Installation Instructions

6179 770 - 01 10/2021

Auxilliary Low Gas Pressure Switch

Part No. 7968315 CM2 186

Part No. 7968316 CM2 246 to 620 (TX)

Please file in Service Binder

Refer to the applicable boiler Installation

Instructions.

Ensure that main power to the equipment being serviced

is off.

Ensure that the main fuel supply valve to the boiler is

closed.

Take precautions to avoid accidental activation of power

or fuel during service work.

Do not perform service work on any component part

without ensuring safe operation of the heating system.

When replacing parts, use original Viessmann or

Viessmann approved replacement parts.

Safety and Installation Requirements

Please ensure that these instructions are read and

understood before starting any service work. Failure to

comply with these instructions may cause product/property

damage, severe personal injury and/or loss of life.

Working on the equipment

The installation, adjustment, service and maintenance of

this product must be performed by a licensed professional

heating contractor who is qualified and experienced in

the installation, service, and maintenance of hot water

boilers. There are no user serviceable parts on the boiler,

burner or control.

Codes

Refer to current CAN/CSA B149.1 and .2 or National

Fuel Gas Code ANSI Z223.1/NFPA 54, as well as

local codes for gas piping requirements and sizing.

Pipe size to the boiler must be determined based on:

- pipe length

- number of fittings

- type of gas

- maximum input requirements of all gas appliances

in the residence.

Design piping layout in such a way that piping does not

interfere with serviceable components.

All electrical wiring is to be done in accordance with the

latest edition of CSA C22.1 Part 1 and/or local codes. In

the U.S. use the National Electrical Code ANSI/NFPA 70.

CAUTION

Low gas pressure can cause the heating system to shut

down.

IMPORTANT

Low pressure switches are suitable for making and/or

breaking a circuit when the medium pressure changes

relative to the setpoint. The setpoint can be set in the

field by an adjustable dial with an integrated scale.

Installation Steps

IMPORTANT

for use by heating contractor

for use with:

Vitocrossal CM2 boilers

6179 770 - 01

CM2 Low Gas Pressure Switch Installation

Installation - CM2 186 to 620 TX

Installation steps

1. Disconnect boiler power supply.

2. If the boiler has already been installed, shut off main

gas supply to the boiler and disconnect gas supply

piping.

3. Supply and install gas piping components as required

(see illustration on page 5).

4. Route supplied cable beneath the top rail 1 as shown.

Secure using plug-in cable retainers as shown.

5. Remove jumper from terminals 26 and 27 and make

electrical connections as shown between the boiler

and the low gas pressure switch as required..

6. Set the low gas pressure switch to 4.5” wc.

7. Open gas supply to the burner.

Note: The setting must be higher then the GW1

pressure switch (4” w.c.) located on the gas

valve. If a 4” w.c. setting is required then the

GW1 pressure switch must be set below 4”w.c.

8. Using an approved gas leak detector, check gas line

and low gas pressure switch.

9. Reconnect power to the boiler.

Note: Venting is not required, subject to the authority

have jusisdition. The switch has a built-in vent limiter.

Legend

1 Low gas pressure cable (supplied)

CM2 Boiler

connection

Low pressure

gas switch

connection

Cable color

26 (G) Green (GN)

26 (L) COM Black (BK)

26 (N) N White (WT)

27 (L) NO Red (RD)

Legend

A DIN rail (junction box)

B Auxiliary low gas pressure switch (Dungs)

6179 770 - 01

CM2 Low Gas Pressure Switch Installation

Operation

Legend

A Nipple (supplied with boiler)

B Elbow (supplied with boiler)

C Reducing tee (kit part)

D Short nipple kit (field supplied)

E Manual gas shutoff valve (supplied with boiler)

F Ground joint union (recommended) (field supplied)

G Reducing bushing kit (only for 7968316)

H Short nipple (kit part)

I Low gas pressure switch*

* the switch can be installed in the gas line anywhere

near the boiler.

Operation

When sufficient gas pressure is available, the low gas

pressure switch contact terminals 3(COM) and 2(NO)

will close. The burner control is then energized and the

system will operate normally.

When sufficient gas pressure is no longer available, the

low gas pressure switch contact terminals 3(COM) and

2(NO) will open. The burner control will stop operating

and generate a fault C1 at the boiler control (the indicator

light on the pressure switch will be illuminated).

To restart the boiler, press the low gas pressure switch

reset button (only once) and reset the boiler control fault.

If the fault persists, verify the gas supply pressure. There

should be a minimum operating pressure of 4.5” w.c., if

not contact your local gas company.

Gas Piping Components

Note: Typical gas piping shown.

6179 770 - 01 Technical information subject to change without notice. Printed on environmentally friendly

(recycled and recyclable) paper.

CM2 Low Gas Pressure Switch Installation

Viessmann 7968315 User manual

Viessmann 7968315 User manual

Viessmann 7968315 User manual

Related papers

Other documents