22
Pumps must use a separate power supply and run
the power through a field-supplied contactor. Use
appropriately-sized wire as defined by NEC, CSA and/
or local codes. All primary wiring should be 125% of
minimum rating.
If any of the original wire as supplied with the heater
must be replaced, it must be replaced with 105°C wire
or its equivalent.
All high voltage wiring connections to the XTherm
heater are made inside the rear wiring box as shown
in Fig. 28. There are two factory-supplied pump inter-
lock relays in the rear wiring box to provide an enable
signal via dry contact (5A max) for the Boiler Pump,
Electrical Power Connections
Installations must follow these codes:
• National Electrical Code and any other national,
state, provincial or local codes or regulations hav-
ing jurisdiction.
• Safety wiring must be NEC Class 1.
• Heater must be electrically grounded as required
by the NEC.
• In Canada, CSA C22. 1 C.E.C. Part 1.
The XTherm heaters are wired for a 240 VAC, sin-
gle-phase 60 Hz power supply. Consult the wiring
diagram shipped with the heater. Before starting the
heater, check to ensure proper voltage to the heater
and pump.
• Natural Gas – 1,000 BTU/ft
3
, 0.60 specific gravity at 0.5 in. WC
pressure drop
• Propane Gas – 2,500 BTU/ft
3
, 1.53 specific gravity at 0.6 in. WC
pressure drop
Table J: Maximum Equivalent Pipe Length
NOTE: Manifold pressures should be ±0.2 in. WC.
Table K: Manifold Gas Pressure Settings
Model
No.
2-1/2 NPT 3 NPT 4 NPT
N P N P N P
2505 55 135 160 400 600 --
3005 40 85 120 250 500 --
3505 30 45 80 200 400 600
4005 25 35 65 160 300 400
CAUTION: For proper operation, no more than
a 30% drop in gas supply pressure from no-load
to full-load conditions is acceptable. Under no
circumstances should the pressure be outside the
listed operational range.
Model
No.
Manifold Gas Pressure
(High Fire Values) (in. WC)
Natural Gas Propane Gas
2505 -4.0 -6.7
3005 -6.5 -8.5
3505 -6.1 -9.1
4005 -4.5 -8.2
Gas Supply Pressure
A minimum of 4.0 in. WC and a maximum of 10.5 in.
WC upstream gas pressure is required under load and
no-load conditions for natural gas. A minimum of 4.0
in. WC and a maximum of 13.0 in. WC is required for
propane gas. The gas pressure regulator(s) supplied
on the heater is for low-pressure service. If upstream
pressure exceeds these values, an intermediate gas
pressure regulator, of the lockup type, must be
installed.
When connecting additional gas utilization equipment
to the gas piping system, the existing piping must be
checked to determine if it has adequate capacity for
the combined load.
The gas valve pressure regulator on the heater is
nominally preset as noted in Table K.
During normal operation, carbon dioxide should
be 9.7% ± 0.5% at full fire for natural gas and
11.2% ± 0.5% for propane gas. Carbon monoxide
should be less than 100 ppm at all firing rates, mea-
sured at test port, on flue outlet adapter.
Table L: Expected Amp Draw
Model
Boiler
Amp Draw
Boiler Pump Amp Draw
Injection
Pump
Amp Draw
H7-2505 12 8.2 7
H7-3005 15 8.2 8.2
H7-3505 17 8.2 8.2
H7-4005 20 16 8.2
Amp draw at 240V/1PH
Model
Heater
Amp Draw
Heater Pump Amp
Draw
Injection
Pump
Amp Draw
Soft Med/Hard
WH7-2505 12 8.2 8.2 7
WH7-3005 15 8.2 16 8.2
WH7-3505 17 8.2 16 8.2
WH7-4005 20 16 16 8.2
Amp draw at 240V/1PH
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