Install Instructions

INSTALLATION INSTRUCTIONS
95-6994EF-03
VS820 and VS821 MILLIVOLTAGE
COMBINATION GAS CONTROLS
APPLICATION
The VS820 and VS821 are used on gas fired, standing
pilot appliances with 750 mV self-powered control
systems. The gas controls include a manual gas valve,
safety shutoff, single millivoltage automatic operator
and pressure regulator.
Refer to Table 1 for capacity ratings and Table 2 for
pressure regulators and temperature ratings. Separate
models are available for natural and LP gas.
Power for the gas control and the control system is
provided by a 750 mV Powerpile generator.
Table 1. VS820 and VS821 Pipe Size and Capacity Ratings.
a
Capacity is based on 1000Btuh/ft
3
, 0.64 sp gr natural gas at 1 in. wc pressure drop [37.3 MH/m
3
, 0.64 sp gr natural
gas at 0.25 kPa pressure drop]. Use conversion factors in Table 3 to convert for other gases.
b
Reducer fittings must be obtained locally.
Table 2. Pressure Regulator and Temperature Ratings.
Table 3. Gas Capacity Conversion Factors.
INSTALLATION
When installing this product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a
hazardous condition.
2. Check the ratings given in these instructions and
on the product to make sure the product is
suitable for your application.
3. Make sure installer is a trained, experienced
service technician.
Model
Inlet x Outlet Reducer Fittings
b
Pipe Size
Capacity
a
Size
Capacity
cfh m
3
/hr cfh m
3
/hr
VS821 1/2 x 3/8 110 3.1 — — —
VS820 1/2 x 1/2 225 6.4 — — —
1/2 x 3/4 250 7.1 3/4 x 1/2 225 6.4
1/2 x 3/8 110 3.1
3/4 x 3/4 335 9.5 3/4 x 1/2 250 7.1
3/4 x 1/2 225 6.4
Model
Pressure
Type Regulator Model
Temperature Rating
°F °C
VS820A,H Standard V5306A 32 to 175 0 to 79
VS821A
VS820C, VS821C Step V5307A
VS820M Standard V5306A -40 to 175 -40 to 79
VS820P Step V5307B
Type of Gas Specific Gravity
Multiply Listed
Capacity By
Manufactured 0.60 0.516
Mixed 0.70 0.765
Propane 1.53 1.62