GAS Connections

Installation (Gas Line)

Pipe Sized For Length Of Run In Equivalent Feet

Table 1.

GAS LINE INSTALLATIONS

1/2 in.

3/4 in.

1 in.

1¼ in.

1½ in.

2 in.

Model

Nat

Before installing the gas line, be sure to

200

20'

30'

80'

125'

250'

450'

600'

check which gas the heater has been

designed to burn. This is important

250

10'

20'

50'

70'

150'

250'

500'

600'

because different types of gas require

300

10'

30'

50'

100'

200'

350'

400'

600'

different gas pipe sizes. The rating plate

400

10'

20'

60'

100'

150'

200'

450'

400'

on the heater will indicate which gas the

heater is designed to burn. Table 1., shows which

REGULATED MANIFOLD PRESSURE TEST

size pipe is required for the distance from the gas

1. Attach the manometer to the heater jacket.

meter to the heater. The table is for natural gas at a

2. Shut off the main gas valve.

specific gravity of .65 and propane at a specific

3. Remove 1/8 in. NPT plug on the outlet side of the

gravity of 1.5.

valve and screw in the fitting from the manometer kit.

When sizing gas lines, calculate three (3) additional

4. Connect the manometer hose to the fitting.

5. Turn on the heater.

feet of straight pipe for every elbow used.

6. The manometer must read 4 in. WC for natural gas

When installing the gas line, avoid getting dirt,

or 11 in. WC for propane, while operating.

7. For adjustment, remove the Regulator Adjustment

grease or other foreign material in the pipe as this

Cap and using a screwdriver turn the screw clock-

may cause damage to the gas valve, which may

wise to increase - counterclockwise to decrease gas

result in heater failure.

pressure.

The gas meter should be checked to make sure that

Regulator Adjustment Cap

it will supply enough gas to the heater and any other

1/8" NPT Plug

appliances that may be used on the same meter.

(Inlet Press)

The gas line from the meter will usually be of a

larger size than the gas valve supplied with the

heater. Therefore a reduction of the connecting gas

pipe will be necessary. Make this reduction as close

to the heater as possible.

OFF

The heater and any other gas appliances must be

1/8" NPT Plug

Figure 10.

(Manifold Press)

disconnected from the gas supply piping system

during any pressure testing on that system, (greater

CAUTION

that ½ PSIG).

The use of Flexible Connectors (FLEX) is NOT

The heater and its gas connection must be leak

recommended as they cause high gas pressure drops.

tested before placing the heater in operation. Do not

use flame to test the gas line. Use soapy water or

another nonflammable method.

A manual main shut-off valve must be installed

MINIMAX NT STANDARD GAS PRESSURE REQUIREMENTS*

externally to the heater.

Natural

Propane

Maximum inlet gas pressure

10 in. WC

14 in. WC

Minimum inlet gas pressure

**5 in. WC

12 in. WC

WARNING

Normal manifold pressure

4 in. WC

11 in. WC

Do not install the gas line union inside the heater

*All Readings are taken with the heater fired. Any adjustments

cabinet. This will void your warranty.

or readings made with heater off will give incorrect readings.

** 6 in. WC for 400 model

P/N 472032

Rev. A 1-2-02