Turning on the Garment Steamer one day, it tripped the earth leakage circuit breaker (ELCB), cutting off the electricity to the whole apartment. The steamer is Novita brand and the model is SS23. It was about 14 months old and the warranty has just expired.
What could be wrong?
Immediately, a corroded heater unit came to mind. Water or moisture could have found its way to the heating element, thus causing the short circuiting of the line to the earth and the tripping of the ELCB.However, after opening up the unit for inspection and testing, it was found that boiler unit was covered up completely with calcium scales inside and outside of the heater unit but the heater unit was found to be in good condition. The moistures soaked up in the calcium scaling could have caused the ELCB to trip.
Opening Up
The unit is attached to lower carriage by about 8 screws. After releasing the 8 screws and opening up, one can see the plastic boiler unit and the heater unit. The boiler unit is held onto the upper case by 4 white screws and the heater unit is held onto the boiler unit by 6 black screws. A silicone gasket at the rim of the heater unit and the ring bracket provides the water sealing.
In this particular unit, one could see that the base of the boiler is covered by whitish calcium scales. It may be formed by steams releasing through the gasket under the steam pressure. The scales may have been built up on the base of the heater unit over the one year period.
Insulation Testing Before Dismantling and Cleaning
It is good to use a multi-ohm meter to test the insulation resistance of the heater element after clearing and cleaning up all the terminals using industrial thinner or spirits or other suitable solvents. One should get some reading of more than 200 K-ohm before proceeding to strip the boiler unit. Should one get a reading lower than 100K-ohms, it is likely that heater unit could be bad and may require replacement.In this particular steamer, the heater unit was found to be in good condition except for the calcium scaling at the base which had lowered the insulation resistance.
Removing the Boiler Unit
To clean up the calcium scale and cake completely, one would have to remove the 4 white screws of the boiler unit and all the wirings attached to the thermostat and the heater unit. Note down where and how each wiring is attached and connected to before dismantling the wirings.Unscrewing the plastic nuts on the top cover to remove the whole boiler unit. After that, unplug the silicon hose. After that, unscrewing the 6 black screws on the heater bracket that holds the heater unit to boiler shell will remove the heater unit completely. Please take care not to damage the silicone gasket which can be re-used.
In this particular steamer, the dome shaped heater unit and its base were completely covered with calcium scale and cake.
Reasons for Calcium Cake and Scale forming
The use of ordinary tap water which contains a lot of minerals especially rich in calcium might have cause the built-up of the calcium scales and cakes.If the water remained in the boiler unit is allowed to dry without draining out after use, calcium scale and/or cake will start to form. This is true when the calcium concentration in the water exceeded the soluble limit. Further, the evaporation of water, turning water into steam will leave concentrated calcium elements behind in the boiler unit to form the scale. This calcium scaling or caking is a common problem in all boiler units.
How to Prevent Calcium Scaling and Caking
Always use soft water that has little or no mineral. If one has air conditioning unit in the apartment, the condensate water will be an ideal soft water for such usage after filtering. Using PUB's Newater is another source; besides, there are other drinking water that has been filtered to get rid of most minerals especially calcium carbonate and related calcium products. Should ordinary tap water be used, always drain the water completely after use and never leave any water behind to form the scales and cakes.Cleaning the Heater Unit and the Boiler Shell
The boiler shell is made of plastic. There was no de-scaling required except for removing the calcium cake formed at the shell.The heat unit on the other hand will require a complete wash down using damped cloth soaked in vinegar, then brush over with an used tooth brush and thereafter, flush in the running water.
Avoid using shape and hard object such as a knife to remove the scales except when clearing away the scales at the rim of the heater unit for proper seating and sealing of the silicon gasket.
As running water will be used for cleaning, it may be necessary to masking tape the heat terminals to prevent water seeping into and damage the insulation of the heater.
Assembly
1. Reverse the dismantling procedures except for:- Applying silicone grease onto the silicone gasket and “polishing” the base of the boiler with silicone grease to prevent future scaling taking place;
- Heating and drying up the heater and the boiler units with a hair dryer, making sure there is no water at the wiring terminals
Starting Up After Repair
Some water moistures or molecules may have found its way into the heater unit if the insulation resistance is less than one mega-ohm.These moisture will have to be “purged” out; otherwise, it may trip the ELCB again when the unit is turned on for testing.
To “purge” the moisture, use an adaptor without the earthing connection or otherwise, remove the earthing cable temporarily to prevent ELCB from tripping.
Exercise caution not to touch any metal part of the steamer in the absence of the earthing cable as these metal parts may be alive without the earth wire connection.
Fill the steamer with some water, then switch on the steamer. Let the steamer run for at least 5 to 10 minutes; thereafter, measure the insulation resistance of the heater unit again using the ohm meter. One should get insulation resistance of more than 1 Mega ohm between the heater element and earth; otherwise, repeat the process.
While draining out any water left in the boiler, make sure to take necessary precaution as the water in the boiler may be very hot.
Schematic Wiring Diagram
