In the UK, gas boilers for heating Carver Cascade 2 water have been particularly popular among manufacturers of summer cottages in the period from 1983 to the present time. In 1990, the modernized version of Carver Cascade Rapide was released.
It should be noted that such boilers were also installed on their caravans by the Dutch manufacturers Kip and Avento. Rarely, a privately installed Carver boiler can also be found on German trailers.
On the technical side, Carver boilers are fairly simple and reliable. There are several modifications of the boiler: gas (Carver Cascade 2, Carver Cascade Rapide) or gas and electric (Carver Cascade 2GE and Carver Cascade Rapide GE).
- Water tank capacity - 9 liters
- 550 * 236 mm (Carver Cascade 2 GE and Rapide GE)
- 540 * 236 mm (Carver Cascade 2 and Rapid)
- The size of the cutout under the boiler in the wall of the trailer - 240 * 212 mm
- Operating temperature range:
- 50-70 ° C - for a gas burner (adjustable thermostat), 70 ° C - in the Rapid and Rapid GE versions (not adjustable)
- 70 ° C - for electric PETN (not adjustable)
- The rate of cooling water in the tank - 3 ° C per hour
- 12V - for a gas burner
- 220-240V, 50Hz - for electric heating element
- 1200 W - for a gas burner
- 660 W - for electric tena (830 W - for the Rapid GE model)
- Pressure in the gas line:
- Propane - 37 mbar
- Bhutan - 28 mbar
- Water line pressure - 1.4 Bar (20 p.s.i.)
- Water vapor pressure relief valve in excess of 3 bar (for the Rapid and Rapid GE versions - 2.5 bar)
- 96 ° C fuse installed in the ventilation of a gas burner
- 85 ° C thermostat with protective plug (red button) for electric heating element
- 5.64 kg. - empty
- 14.65 kg. - full
For more information on features and installation, see the documentation section.
Principle of operation
The gas burner is controlled by an electrical switch, which is connected by a special wire to the electrical circuit of the gas burner. Also from the switch depart 2 wires to an external power supply 12V. The switch has 2 positions (on / off), as well as 3 LEDs. After pressing the switch to the "on" position, the green LED lights up. The system supplies a spark to the burner using an external voltage of 12V, and also opens the gas supply to the burner using an electromagnetic valve.
If, for some reason (no spark or gas), it is not possible to ignite the gas within 5 seconds, the system automatically shuts off the gas main and stops feeding the spark to the burner. On the switch along with the green LED lights up red. The flame detection factor is the change in potential difference with the flame ignited. The potential difference in early versions of Carver Cascade 2 measures the second (longer) electrode, to which a spark from a transmitting electrode hits upon ignition. In later versions of the Carver Cascade Rapid, this function is assigned to the first electrode (the second electrode is missing).
Attempts to start can be repeated by moving the switch to the "off" position, and then "turn on" again. If the burner starts successfully, the green LED remains on the switch. This means that the burner has started and is heating up. A yellow (far right) LED on the control panel indicates a low voltage (less than 12V) in the external network. In this case, the boiler does not start.
When the maximum heating temperature is reached, the built-in thermostat through the burner solenoid valve shuts off the gas supply, the green LED goes out. When the water cools down, and exactly as when opening the tap and the beginning of its use, the thermostat reacts to a drop in temperature and the process of starting and heating is repeated again.
As you can see, the process of heating water is fully automatic. You only need to turn on the power on the switch once, the gas boiler will perform the rest of the work for you. Updating the water in the boiler is also automatic. When the valve is opened, the electrical switch closes (or the pressure switch depending on the system), the water pump turns on and supplies water from the tank to the lower inlet of the boiler. Cold water pushes hot water out of the top outlet that goes to the faucet.
In the improved version of Carver Cascade Rapid, a different switch body is used, but the functions with control lamps remain the same.
Description of the gas burner device
Gas burner consists of:
- Metal base burner
- Solenoid valve and gas nozzle
- Spark supply electrode
- Ignition-responsive electrode (longer)
- Electrical board and ignition unit
The principle of operation of the thermostat
This type of thermostat uses a bimetallic plate with hysteresis. When the temperature changes, the plate bends in the appropriate direction. But a smooth bend is not enough for electrical contact to work. Therefore, the plate has a spring middle part, which gives, when approaching the moment of operation, additional mechanical energy from the stressed "spring". This leads to a sharp (correct) actuation of the electrical contact. Electrical contactors with hysteresis also have better vibration resistance. If there was no hysteresis, then at a temperature close to the required response temperature, the electrical contact would constantly close and open spontaneously.
This thermostat also has a red adjustment ring, which allows you to mechanically change the bending angle of the plate. This allows you to change the temperature of the thermostat in the range of 50-70 ° C. In a later modification of the Carver Cascade Rapide and Rapid GE thermostat adjustment is absent, and the response temperature is fixed at 70 ° C. The thermostat is installed in a special niche in the metal base of the boiler and heats up as the heating element heats up.
A heating element
The heating element is a round metal rod with a diameter of 12 mm, which is screwed at one end into the heating zone of the gas burner and distributes heat along the entire length of the tank with water. At the other end, the heating element is connected to the back of the tank with a nut, thereby also fulfilling the role of a connecting element of the base of the boiler and the water tank.
Electric heaters are located behind the boiler on Carver Cascade 2 GE and Carver Cascade Rapid GE models. Boilers equipped with heating elements can be easily distinguished by a protruding white plastic box behind the boiler.
It is switched on by a separate switch, usually located in a separate white square case.
The heater has a built-in thermostat for the temperature of the shutdown of the heating element - 70 ° C. In case the thermostat fails, a second thermostat is provided, with a response temperature of 85 ° C and a red knockout plug. The stopper will knock out until the faulty main thermostat is replaced.
Simultaneous switching on of the gas burner and heating element for fast water heating is possible, but after reaching 70 ° C one of the heating devices must be turned off. Thermostats on both devices are set to a shutdown temperature of 70 ° C, but taking into account technical errors, one of the thermostats will work a little earlier, and the other a little later. This will lead to permanent shutdown and turn on one of the heating devices, which will not add to the efficiency of the boiler.
The metal capacity of the boiler for better thermal insulation is covered with a foam housing.
Security and safety elements
When the gas burner is operating, the temperature is controlled by a thermostat. When it fails, the water in the tank will begin to boil. When boiling water in the tank does not apply excessive pressure, which will be relieved by a special pressure valve.
When the water from the boiler boils away, a fuse built into the boiler body above the burner will enter into the case. It is made of steel with a hole in the center, which is filled with low-melting metal (tin).
When the temperature reaches 220 ° C, the tin core melts, opening a through hole in the tank, which will also contribute to a decrease in pressure and temperature inside the tank.
Disassembly of the boiler
1. It is necessary to unscrew the 4 screws on the protective white cover outside the boiler and remove it.
2. Turn off the 2 screws and remove the protective steel plate.
3. Turn off the 2 screws, in the lower right corner, fixing the gas burner unit on the boiler body and remove the burner.
Repairs. Replacement. Spare parts
For the most part, Carver Cascade boilers are very reliable. The most difficult part in the system is a unit with an electronic printed circuit board, a burner, a thermostat and a solenoid valve.
Of frequent problems:
The flame lights up and immediately goes out. Reason: the system does not "feel" the flame, so after 5 seconds it turns off the gas supply by the solenoid valve. The problem is a poor wiring. It is necessary to check and clean the connecting terminals of the wire extending from the electrodes to the coil (ignition unit), as well as check the connections to ground.
Depressurization tank. The connecting part of the tank with the boiler body is the rod. Due to the effects of corrosion, at the junctions of the elements, the metal of the rod may decrease to 0.
A possible repair method is described in the article "Replacing the rod on Carver Cascade 2".
Drain plastic stopper. If it is not unscrewed for a long time, the plaque formed from the constant heating of the water will not allow the plug to unscrew easily and most likely destroy its thread.
Thermostat TENA. Sometimes it can fail.
Protective and decorative outer cover. Made of white plastic. Since the cover is located on the outside of the trailer, it is most susceptible to destruction from external factors.
These and other details you can buy or order in our store Retrailer.
Retrailer uses the special foaming agent Multitec from the Danish manufacturer Unipak to check the sealing of the connections in the gas pipeline of trailers and autocars. Multitec even detects small leaks, determined by the "boiling up" of the compound in places where the connection is not tight.