Oil heaters - effectiveness / difference between brands / good value

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timmmay

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#251553 30-Jun-2019 21:14

Short question: do the more expensive oil heaters do a better job than the cheaper ones? Consumer seems to think they do.

Longer question:

We mostly use heat pumps to heat our home, but when we're sleeping and in an office that doesn't get much heat from the heat pumps we use oil heaters. The house is well insulated, double glazed, well ventilated.

The oil heaters in the bedrooms are 4 fin / 1000W heaters I got from The Warehouse for about $25 each about 10 years ago. They work great. On about 1/3 they keep bedrooms about the right temperature in winter, given the heat pumps have already warmed the whole house. Their surface temperature is about 95 degrees.

In my home office I appreciate quiet heating. I use a fan heater to warm it up (during my free hour of power) then an oil heater to keep it warm while I'm working. The 1000W heaters weren't keeping it warm enough during the recent cold days, so I went up to 2400W. I figure power in = heat out so I buy the cheapest one that isn't too ugly. I do understand that the heat goes straight up, and that a fan to distribute the heat makes them much more effective, but I don't want a fan on all the time.

So far I'm fairly disappointed by the relatively low priced oil heaters I purchased:

The Goldair 2400W ($70 or so from Briscoes) came with a manual timer that ticked every two seconds. It went back immediately.
The K-Mart 2400W ($60) is silent, but when I hold my hand over it the heat coming off it feels less than the heat off the old 1000W oil heaters. It warms the room ok, not great. It's 11 fin instead of 4 fin but the power to fin ratio is about the same. I find even with the thermostat on max it cuts off heating earlier than I would expect, maybe to prevent the surface getting too hot. The surface temperature is about 95 degrees near the top and about 75 degrees near the bottom, give or take ten degrees. This is the consumer lowest rated oil heater, and the cheapest.

Consumer says the $60 K-Mart heater is slow to warm the room, but the $350 DeLonghi warms the room more quickly. It says both keep the room warm quite well. The DeLonghi has quite a different design from the cheaper oil heaters, they're more boxy whereas the cheaper ones are more finned.

Q: Does the brand / design of an oil heater really make any difference?

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#2267519 30-Jun-2019 21:29

They can differ because of the amount of surface area exposed will result in a different amount of convection. They are testing how effective they are at getting a whole room to temperature.

I have also found that my cheap one will get so hot that its internal thermostat will cut in and out even when the outside one that you adjust is set to max and should be on all the time. Its too much power for its small surface area so it gets too hot and it has to protect itself.

Richard rich.ms

timmmay

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#2267524 30-Jun-2019 21:51

Has anyone owned both cheap and expensive oil heaters who can comment on the difference in effectiveness? The expensive ones cost 3X more than the cheap ones.

Batman

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#2267612 1-Jul-2019 07:30

i have.

I have used delonghi and unbranded ones. that was a long time ago.

if my memory is correct, the delonghi ones heated itself up faster and heated the room faster.

but i can't remember if the room was the same warmth given enough time, for the cheaper ones - i think it was.

i think it's just the speed on heat onset that's the difference.

can you please buy one of each and re confirm :)

nakedmolerat

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#2267617 1-Jul-2019 07:41

i am a big fan of micathermic heater. i use them in bedrooms as i don't like constant humming noise in bed. we use firewood as main heating.

i recently bought oil heater from the warehouse which i find it works well at heating but just cannot get the temperature right. i left it in the lounge instead.

alasta

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#2267629 1-Jul-2019 08:27

I have had a Sunbeam oil column heater for the last seven years, and prior to that I owned a couple of Goldair ones which only lasted a couple of years each before dying or leaking.

So in my view there is a noticeable difference in reliability from buying a better quality brand but I can't say I ever noticed any difference in heating effectiveness.

It's probably worth also considering the environmental impact of buying a poor quality oil heater with a short lifespan.

dfnt

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#2267637 1-Jul-2019 08:44

Not an oil heater, but we got one of these https://atlantic.nz/product/tatou-panel-heater-1000-watt/ for our daughters room, from birth to current

It's amazingly effective, expensive but worth it imo

Sustainability Trust in Wellington stock them as well

tehgerbil

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#2267660 1-Jul-2019 09:32

I had a good chat with the heating team at Mitre10.

According to him you're really paying for the adjustable thermostat accuracy. The very high end ones have climate control, the cheaper ones can be +-7 degC the expensive ones are +-~2 degrees C.

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mdf

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#2267662 1-Jul-2019 09:43

We've currently got a couple of the smaller (4 fin?) Delonghi Dragon oil column from Briscoes to keep the chill off some bedrooms at night. Seem to give off heaps of heat even on the middle setting, including out as well as up. Build quality is good.

Compared to other fin style ones we've had previously, the flatter style (I think) means that there aren't edges that are super heated.

We use these with heatermate external thermostats and that seems to work really well to keep the rooms a constant temperature.

We don't use them to heat rooms from cold so not sure about that. From previous experience, fans to circulate the air do work fastest.

mdf

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#2267663 1-Jul-2019 09:43

Holy triple post Batman!

timmmay

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#2267666 1-Jul-2019 09:48

I'm going to return the K-Mart oil heater. I pre-heated my office using a fan heater to 20 degrees, then turned the k-mart oil heater onto full. In 45 minutes it managed to get the temperature to 21 degrees - fairly pathetic. I'll look at either a decent brand, use the fan heater, or bring in the oil heater from another room and replace that with a panel heater.

Aredwood

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#2267669 1-Jul-2019 10:14

richms:
They can differ because of the amount of surface area exposed will result in a different amount of convection. They are testing how effective they are at getting a whole room to temperature.

I have also found that my cheap one will get so hot that its internal thermostat will cut in and out even when the outside one that you adjust is set to max and should be on all the time. Its too much power for its small surface area so it gets too hot and it has to protect itself.

Agree. The smaller ones definitely have an internal thermostat. It is usually wired in series with the smaller element. So such heaters only draw 2400W of power during their initial heat up. Then there power usage (and heat output) then drops back to 1400W or so. The heater needs to have at least 10 fins to be able to actually output 2400W continuously.

Any reason why you cant get a convection heater instead? (metal box with heating inside that are directly exposed to the air) As since you dont have the thermal mass of the oil, they start outputting heat pretty much instantly when you turn them on.

Batman

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#2267698 1-Jul-2019 11:07

i really loved the convection heaters, they work really fast. but all the ones i've had broke. but that could just be me. also had one oil heater catch fire so i think it's just the luck of the draw

sir1963

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#2267724 1-Jul-2019 11:59

There are only 2 things that impact oil heaters ability to warm a room.

The size of the heating element (2000W will give off more heat than a 1000W)

The ability of the heater to give off the heat, ie surface area.

HOWEVER

If you have a low surface area, the oil heater will simply become hotter so it can shed the energy being put in.

THIS is a problem because it is an exposed surface I think they are allowed to get to something like 60°C max.

So a heater with a small surface area with a big element will switch on and off to keep the oil/surface within safe margins, this means on average it will probably output the same heat as a heater of same size but a smaller element.

The external thermostats are there to measure the room temperature (to varying degrees of accuracy), so when the room gets to say 20°C it turns off the element . Good thermostats will have a small differential (ie difference in temp between when the turn on and off, 2° is good, 7° is not)

The MAXIMUM efficiency of a basic heater is 100%, i.e. energy output (heat) = energy input.

Heatpumps on the other hand can have efficiencies of 3:1 up to 6:1 , ie for every watt of energy you put into them they can transfer 3->6 watts of heat from outside to inside (and vice versa). They also have fans and are mounted high on the wall so they can suck the warm air near the roof , warming some more, and blow it downwards to wards the floor keeping the lower parts of a room warmer.

The differences between an expensive oil heater and a cheap one will come down to

Surface area to dissipate the heat , thickness of the metal used (will last longer), quality of the heating element (last longer), however they are ALL considered inefficient when compared to other heating options (Gas, heat pump, wood fire, central heating, )

timmmay

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#2267739 1-Jul-2019 12:51

K-mart oil heater went back. It wasn't very good. Sure, if you leave it on for a few hours it might do something, otherwise don't bother.

I think I'll ditch the idea of an oil heater for now, and just keep using my fan heater. If I see any heater that's reasonably quiet with a fan I might get that instead. Larger fans tend to be quieter for the same volume of air, so I wonder if there's anything like that around.

Batman

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#2267743 1-Jul-2019 12:57

Take a look at convection heaters they are quiet and fast.

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