This 2000W oil column heater has a small and large heater element. Power settings I, II & III presumably use either the small element (I), the large element (II) or both elements together (III). The 30mA threshold RCD (I think these may be known as GFI in the U.S.) on the switchboard is being tripped when you switch from setting II to III. Have removed the control panel and all wiring from the from the chassis of the heater. Have not been able to find any earth leakage by doing a continuity test between the electrical contacts of the element and chassis. I'm in the southern hemisphere and it's perhaps significant that this heater has not being used since last winter (around 6 months ago) although there is no excessive build-up of dust inside. It went for around 10 minutes initially before the first RCD trip. Other components on this heater include thermostat, timer, LED's (x2), non-upright safety cut-out switch plus another as yet unidentified. No earth leakage detected at 3-pin plug before taking apart. Heater also trips RCD in another building which suggests the RCD is not at fault. Perhaps the earth leakage only occurs under greater load than what my meter is testing at. Any thoughts on what to test for next in this situation? Thanks.

themuffinman, March 2010

i have a delonghi dragon 3 that is overheating & the plug goes red hot. it went that hot it burnt the socket on the wall from white to brown

john mcdonald, March 2014

I bought a DeLonghi oil filled heater earlier this year. Was ok for 2 months then blew main fuse after being on for about 10 minutes. Now trips main switch as soon as it is turned on. Can't find purchase receipt! Is it possible to get it repaired?

amh, May 2010

I have the same problem - different brands of oil filled heaters. The one that pops the RCD circuit breaker is fairly old. With a multimeter on 20M ohm range from power pins to earth it measured 7M ohms one way, and -2 ohms with meter leads reversed (yes negative reading). Put meter on millivolt range, the element is generating 50mV from power pins to earth. I think the element is corroded inside and the voltage is from a battery electrolyte effect. There may be moisture in the oil.

Checked 2 other heaters that don't pop RCDs - 1 has 20mV, the other zero. This last one has no earth leakage resistance on a low voltage ohm meter.

True earth leakage should be measured with a "Megga" tester which puts 500V at 1mA into the appliance.

I might have to throw out 2 of our heaters.

Craigy, April 2010

I am having exactly the same problem with a Delonghi dragon 2 oil heater.

Is there a design problem here?

Joe, April 2010

Would also add that the TRD2000T was only around 3-4 years old. Have another DeLonghi oil column heater type 31/1.5 which has done good service over about 15 years I think (with the switch replaced 10 years ago). That one is still working fine.

themuffinman, March 2010

I took the switch apart that controls the I, II & III power settings, cleaned and re-assembled. Still tripping after being on for a few minutes - seems to happen once a certain temperature is reached. Bypassed the thermostat but this did not help either. Using extreme care I finally wired the mains plug up directly to both element terminals (matching original phase & neutral connections) and earthed the chassis. After switching on it still tripped the RCD after a couple of minutes, meaning the earth leakage is around the element itself somewhere. There was shellac (or similar) around the element terminals at the point where they enter the chassis. This had become brittle and started to break away in places. Limited access to this area. Given that the element seemed fine inside, I suspect this cracking shellac was the cause of the problem. Decided to trash the heater but not before draining the 4 litres of clean light weight oil (to keep as a useful multi-purpose oil). It was good to at least locate the source of the problem.

themuffinman, March 2010