305
Thermo G
3 Description of assemblies and components
3.5
Gas pressure regulator
Gas is supplied by means of the vehicle’s gas supply sy-
stem, in which the gas pressure regulator is incorporated.
The gas pressure regulator regulates the storage pres-
sure (max. 220 / min. 5 bar) downward in 3 steps to the
required operating pressure. In the regulator at a pressure
below atmospheric pressure the required quantity of gas
is released by a diaphragm valve.
The gas pressure regulator has two solenoid valves (see
Fig. below).
Solenoid 1 (MV1) opens the gas supply from the storage
tank to the gas pressure regulator (high pressure branch).
Solenoid 2 (MV2) opens the gas supply from the gas pres-
sure regulator to the heater (low pressure branch).
Both solenoid valves are controlled by the control device.
Thus, the gas pressure regulator is integrated into the
control concept of the heater.
.
3.5.1 Heating of the gas pressure regulator
As the expansion of the compressed gas causes conside-
rable cooling, the gas pressure regulator must be warmed
up. This is accomplished by its integration into the cool
water circuit.
By means of T-pieces the gas pressure regulator is
connected with the water outlet and the water inlet at the
heater.
Heated water is branched off at the water outlet and flows
through the gas regulator. Then it re-enters the heater
through the water inlet.
The gas regulator further has an electrical preheating
(ERH). The heating cartridge is connected to a dedicated
output on the control unit.
The ERH is activated at (water) temperatures below -20°C
by the control unit. It is switched off again at a water
temperature above -10°C. In addition, the initial cycle time
from regularly 15 seconds increases to 40 seconds in
water temperatures below -20°C.
3.6
Circulating pump
The externally arranged circulating pump ensures coolant
transport within the vehicle and/or heater circulation
system.
Depending on the application, the circulating pump is swit-
ched on via the control unit or directly via the vehicle
electrical system and operated during the entire heater
operation duration.
Further information on installation and operation of the
circulating pump contain the Thermo G Installation
instructions.
All service information regarding your Valeo circulating
pump(s) can be found under www.valeo-thermalbus.com/
eu_en/Products/Pumps.
High pressure
solenoid valve
(MV1)
Low pressure
solenoid valve
(MV2)
Gas outlet
Gas inlet
Water outlet
Water inlet
Screw for fixation
of the heating cartridge
