Oil-filled radiator element upgrade

[Carolina]

I have an 80's oil-filled heater at home and although it's almost in mint condition on the outside, it's the heating element that's giving me trouble, it's on its way out as it's only using about 700W out of the 1500W the heater is rated at, because of this, the oil and fins never hit a temperature high enough to make the thermostat kick in, so it's constantly drawing power rather than clicking on and off.

I was thinking I could bring it back to life, BUT (there's always a but), I only have a 15 amp heating element @ home, it works and from the looks of it will fit my heater... question is, what could go wrong?! I know I'll have to redo the wiring and front panel, I'd be replacing all the inner wiring for 2.5mm² silicone insulated rated for 180ºC, all wire terminals, the 10A switches and thermostat for a pair that can handle 20A, and of course the cable and plug end for something a bit better that can handle the higher current... but specifically talking about the oil, is there a chance pressure inside the heater could increase due to the new heating element doing it's thing but faster? could it make the oil hit boiling point before the thermostat kicks in? as we all know, boiling oil is often bad, except if you're cooking.
Diathermic oil isn't hard for me to get, just have to take a few steps down to the basement ^^ I used it for some other heaters already but the can says nothing about the temperatures it can handle, even so, the heater still has oil inside but I was thinking I should flush it out when replacing the heating element.

Maybe I'm just overthinking it and the thermostat will prevent the oil from heating up too much. Maybe not, I've repaired heaters before but never thought about the what ifs and possible modifications.
Oh, and by the way, the heater has 10 fins, not sure if that matters. Input ~240V, wall sockets can handle 16A.

In a side note, I've been seeing a lot of these things (and some alternate models) where I live, they pull as much as they can from the wall to the point the wires get hot, then too hot, then the plug contacts get hot, the socket melts... and boom. I rather NOT get one of these things.

 

[Avo Mk8]

The idea of 'modifying' an oil convection heater by replacing its 1.5kW element with a 3.6kW element sounds dangerous to me, especially not knowing what safety cutout arrangements there are (in addition to the thermostat).
Mending it with the correct part is one thing, pimping it like that is mad!

 

[Carolina]

The idea of 'modifying' an oil convection heater by replacing its 1.5kW element with a 3.6kW element sounds dangerous to me, especially not knowing what safety cutout arrangements there are (in addition to the thermostat).
Mending it with the correct part is one thing, pimping it like that is mad!

Hi there. It's certainly dangerous.
From what I've been seeing inside there's no thermal fuse, or any safety features at all, it's an older design. The thermostat isn't even on the heating element but at the front panel right next to the switch.

I've been eyeing some similar heaters and they top at 2400W, to comply with energy saving and safety regulations that didn't exist in the 80's, they're all similar in size (10 fins) but there's no mention at all about what kind of oil there's inside.

 

[littlespark]

there's no mention at all about what kind of oil there's inside.

That’s possibly because they’re not designed to be user- refilled.

Many household appliances are disposable now. The cost of repair is so high, it’s cheaper buying new.

 

[Carolina]

That’s possibly because they’re not designed to be user- refilled.

Many household appliances are disposable now. The cost of repair is so high, it’s cheaper buying new.

Which is a shame because I could go and get a 1500W heating element for around $15 -it's still on my plans if the one I have is beyond overkill- instead of spending over $80 on a new heater. Maybe that's what I'll do in the end rather than using the 15 amp heating element.

I volunteer at a recycling centre and it's amazing the stuff people simply ---- into the garbage because of an issue that's often really simple and cheap to fix, last year while driving I spotted some people throwing away some appliances and there was a similar heater between all the stuff and when I was picking it up a lady told me oh don't bother, these things aren't working anymore, picked it up anyway and also a microwave oven, some cool nightstand lamps, a record player and an old vacuum cleaner. All of them had wiring faults except for the heater that had a busted thermostat, everything's in working order after a quick fix and I'm thinking of donating the stuff to a charity so people in need could make use of them.

 

[Carolina]

Ok, I feel this needs to be properly closed.
Before starting, to any other DIY enthusiasts out there that someday could find this thread -and I can't stress this enough- DO NOT TRY THIS AT HOME without taking all the necessary precautions, improperly handling components of electrical appliances can result in injuries or death.

Everything here was done in a controlled environment away from people and flammable materials, the appliance being in this case a heater was wired to a dedicated circuit properly wired and earthed according to -due to lack of local- IEC standards. A proper fire extinguisher rated for oil/grease and eletrical fires is also necessary when dealing with such things.

I've doing some testing, replaced the faulty heating element with the 15 amp one and also added a rod thermostat given it was compatible, and as I had planned all of the old wires were replaced with new modern 2.5mm² silicone insulated ones that can withstand both high current and temperature, the existing twin rocker switch was upgraded to a single 20A model, and the neon works this time, about the front panel thermostat... I did installed a new one to avoid bypassing it but it never kicks in given the rod takes care of the temperature control.

So, the rod thermostat can be calibrated so I began testing with the lowest setting, 60ºC, upon placing the heater in a controlled environment I monitored voltage and current draw, it took the heater 9 minutes to hit this temperature and trigger the thermostat.
Using a handheld infrared thermometer I measured the surface temperature, really close to 60 at the bottom (58.6) and 53.1 at the top of the fins, the heat seems to be evenly distributed as the delta between the first and last fin was .7 degrees.

Setting the thermostat to 85ºC did not alter the heat-up time from a cold start but it -obviously- increased surface temperature to 83.7 bottom 80.2 top evenly distributed.

Going up to 95ºC caused unbalance between the bottom and top temps so I assume the oil was simply heating up too quickly and became saturated, it also caused the thermostat to trip after 5 minutes even though the top temperature of the fins was still below the 60 degrees mark.

I let the heater cool down for 2 hours or more between each test so residual heat wouldn't spoil my results or alter the current readings during startup. After I found the sweetspot for the thermostat I let it constantly run for as much as possible while still measuring everything, once the oil was hot the heating element wouldn't kick in after at least 30 minutes.

I also did the brownout test by wiring a 100W incandescent bulb in parallel with the heater to observe how much would it dim upon startup, there was a slight dim that only lasted fractions of a second and was no different than the one caused by smaller heaters or other high consumption appliances.

Still inspecting for possible leaks or strange behaviours but I believe it ended up working pretty decently and was even able to cause a noticeable temperature difference down in my basement that's pretty big. The front panel is made out of metal with a small piece of hard plastic that's about 5cm away from the hot surfaces so it doesn't melt, both the switch and secondary thermostat are able to withstand high temperatures as well.

That is all.

TL;DR= No fire