10
Gas Pipework Installation
The installation must conform to all standards and regulations.
The gas supply pipework and gas stop valve to be installed
near the unit must be dimensioned so as to assure the gas
pressure is sufficient at the unit inlet when operating at full
load.
The pipework must be self supporting and the final connection
to the burner must be made by flexible pipe. Provide a dust
protection (filter) upstream of the unit connection. Look for gas
pipe leaks using "Typo", "1000 bulles" or a similar product.
Soapy water must not be used.
Caution: Never use an open flame to check for gas leaks.
Required gas pressure at the unit inlet connection are
given in Table 4.
Caution: The gas pipework must not exert any stress on
the burner gas connection.
The heating system must be isolated by a gas stop valve from
the gas supply pipe during the pressure test as soon as it is
higher than 0.035 bar. Applying a pressure higher than 0.035
bar at the unit valve gas could damage it.
Operating Principles of the Gas Heating Module
The heating function of the YK* units is controlled by the heat-
ing module ignition burner. The burner, of the forced air type,
has two capacity stages controlled by the UCP electronic con-
troller which optimizes the air conditioner operation.
A normal call for heat is initiated by the UCP, using the tem-
perature detected at the zone sensor. The UCP module inter-
nal relays K5 and K6 energize, which in turn energize the heat
relay (H), the combustion fan motor (CFM), and the ignition
control module (IGN).
The relay K5 switches CFM into high speed. After approxi-
mately 1 minute K5 switches back and the CFM changes into
low speed. If the low pressure fan switch (LPGS), and the high
limit cutout (TC01) are closed, ignition is allowed. The ignition
control module pre-heats the ignition probe (IP) during ap-
proximately 36 seconds. After this pre-heating stage the gas
valve is energized for approximately 8 seconds to ignite the
burner. If the burner fails to ignite, the control module tries
again twice before self-locking out. When the gas ignites suc-
cessfully, the IP probe is de-energized and maintains a flame
detection function.
If the zone temperature remains below the first stage heating
setpoint for 90 seconds after the heating cycle has started, the
UCP energizes again the K5 relay. The burner fan then
switches into high speed and the heating capacity is raised to
maximum.
When the temperature of the zone has reached the setpoint,
the UCP de-engerizes the relays K5, K6, H and IGN; the
burner then stops.
If the indoor fan is set to auto operation, it will stop 90 seconds
after the burner has stopped in order to recover as much heat
as possible from the exchanger.
To reset the ignition controller which has tripped on safety, it is
necessary to cycle power to the unit.
Note: The supply static pressure should be checked and
should be no less than 200 Pa.
In addition to the safety features of the ignition controller, the
burner includes the following safeties:
- detection of a gas supply minimal pressure by the automatic
reset pressure switch LPGS.
- detection of an abnormal temperature of the supply air (Ther-
mostat TC01).
- detection of an overheating problem due to a lack of air circu-
lation through the heat exchanger (Thermostat TC02).
Table 2 - State of LEDs on Gas-Fired Heating Module
Diagnostics
Green LED
Red LED
1. Powered without heating demand
Off
Off
2. Heating demand without fault
Flashing
Off
3.No flame detection on ignition or
Off
Flashing
signal detected and then lost
4. Gas unit incorrectly wired or flame
On
Flashing
signal detected on a heating demand
5. Internal fault
Off
On
Putting the Gas-Fired Heating Module into Operation
(Reserved for the qualified gas technician)
This type of burner can only
be put into operation by an approved techician who has
read the following procedure beforehand, or preferably has
undergone the training course on Trane gas burners.
Before performing ignition tests it is first necessary to perform
the following operations:
- Check a gate valve is present
- Check an expansion valve is present. This valve must be
adapted to the type of gas used:
* G 20 : 20 mb
* G 25 : 25 mb
* G 31 : 37 or 50 mb
Note: To operate with propane gas, the burner is fitted with
a limiter (supplied by Trane).
- Vent the gas line
- Check the gas pipe is leak-tight upstream of the gas unit (see
drawing). Use Typol or a foaming product ("1000 bulles"
aerosol or similar). Do not use soapy water.
- Check the pressure upstream of the gas unit ( the pressure
connection is located on the minimum gas pressure cut-
out). This cut-out must be set to 15 mbar. This operation
must be carried out while the burner is not operating.
- Check the power supply voltage is present at the T2-2 trans-
former output.
- 115 volts for power supply of the IGN module (L1 - L2 and S1
- S2).
* 230 volts for power supply of the burner fan motor.
