Rapid Engineering UHAT 150 Installation, Operation & Service Manual Download

Page: 41 / 72

SECTION 11: O

PERATION AND

AINTENANCE

33 of 59

11.2.2 Start-Up the Gas Valve (All Gases)
11.2.2.1 Check Burner Gas Pressure (Single
Stage)

1. Remove the plug in the outlet (burner) pressure

test point and connect a pressure tap and a
manometer. Page 31, Figure 13.

2. With the burner firing, measure the pressure on

the manometer. To adjust the burner pressure,
remove the regulator cover from the valve and
turn the regulator adjustment screw to set the
required burner pressure as stated in the

Technical Data Table for the correct gas and

model on Page 56, Section 1 6.3 and Page 58,
Section 16.6.

11.2.2.2 Check Burner Gas Pressure (Two Stage)

1. Remove the plug in the gas valve outlet pres-

sure test point and connect a pressure tap and
a manometer. See Page 31, Figure 14.

2. With the unit operating in high fire or low fire,

measure the outlet pressure on the manometer.
Measure burner pressure in both operating
modes. To adjust the burner pressure, remove
plastic cover from regulators and adjust High
and/or Low regulators as needed. Required
burner pressures are indicated in the Technical
Data Table for the correct gas and model on
Page 56, Section 16.3 and P age 58, Section
16.6.

3. To set the high fire rate, adjust the high fire

adjustment on the gas valve. To set the low fire
rate (with the unit running in low fire), adjust the
low fire adjustment on the gas valve.

11.2.2.3 Check Burner Gas Pressure
(Modulating)

1. Loosen screw in outlet pressure tap shown on

Page 32, Figure 15 and connect manometer.
Gas pressure is NOT measured at Honeywell
single stage gas valve.

2. With burner firing, measure pressure on

manometer. To measure high fire burner
pressure, disconnect modulating thermostat
signal and apply 10 VDC to modulating input
connections (polarity sensitive). To adjust high
fire burner pressure, remove regulator cover
from Honeywell single stage gas valve and turn
regulator adjustment screw to set required
burner pressure as stated in the Technical Data

Table for the correct gas and model on Page

56, Section 16.3 and P age 58, Section 16.6.

3. To measure low fire burner pressure disconnect

10 VDC signal to modulating valve.

NOTE:

Low fire burner pressure is set at factory and

not field adjustable. (modulating)

NOTE:

If the correct burner pressure cannot be

reached, then check the inlet pressure to the valve
with the burner firing. See Technical Data Table on
Page 56, Section 1 6.3 and Page 58, Section 16.6
for inlet pressure requirement.

Do not continue to adjust the regulator if the
pressure is not changing.

If the inlet pressure is too low to allow correct burner
pressure setting, then the gas inlet pressure must be
corrected before completing the start-up.

11.2.2.4 Check Gas Rate (Single and Two Stage)

1. After burner pressure adjustment, allow the

heater to operate for at least 15 minutes and
then re-check settings. Adjust pressure setting
if necessary.

2. Check gas flow rate at gas meter.

NOTE

: For two stage valve (High/Low

operation) check gas flow in both operating
modes.

3. Turn off heater and electrical supply.

4. Remove the manometer and refit all covers to

the valve and tighten the screw of the outlet
pressure tap.

11.2.2.5 Check Gas Rate (Modulating)

1. After burner pressure adjustment, allow heater