Why are radiators so complicated?!
November 17, 2010 2:55 PM   Subscribe

Brrr! It's getting cold, and I'm getting tied up trying to research heaters... Hope me, AskMe!

I live in Granada, in Spain and we're 800m above sea level, which means the winters are cold - below freezing at night, and 10-15 oC during the day. The flat has no heating, and is built to remain cool in the Summer, so it's really cold in the Winter.

I'm looking at getting enough heaters to heat a large lounge (24m2) and a couple of smaller bedrooms (10-12m2) but I'm getting confused between radiators, heaters, oil-filled heaters and the like and what the differences are.

Why, for instance, can I get a 1500W deLonghi oil-filled radiator for 89€, but this 1500W wall-mounted oil-filled radiator is almost 5 times as expensive? Is it just the fancy digital timer, or is it somehow 5 times better at heating my rooms? And how about this dry technology 1500W radiator? Why is that 100€ cheaper than the oil-filled one?

And how many watts do I need to heat my spaces anyhow - are the oil-filled radiators cheaper to run or as efficient at heating? Is 1500W of dry radiator equivalent to 1500W of oil-filled?

Gah! Anyone know this stuff? Throw me a line!
posted by benzo8 to Home & Garden (12 answers total) 2 users marked this as a favorite
Well, I love me some passive heaters... That's how we keep the used rooms in our house livable during the winter months. And we used to use oil-filled radiators all the time. They were cheap to run and did a pretty good job of taking the chill off the rooms.

That is, until the one day I came home from work early because I wasn't feeling well, and walked in to find there was a tiny fire starting under the oil-filled radiator in our living room. It apparently had just started. I'm not entirely sure about how or why, but the oil was leaking out very slowly, and was on fire, and dripping little drops of fire onto the carpet beneath the heater unit. Thank goodness I was home early -- I have no idea what the result would have been if that had been allowed to continue for the remaining 3 hours of the work day.

That incident kind of set us against oil-filled radiators in general. We looked around for other passive room heaters, and found this style, called a "micathermic heater". Now, what that really is, I have no idea. But we've got 4 of units of this style in our house now, and they work as well as the oil-filled ones, cost about the same to run, and don't have any oil in them to leak out while on fire.

Some units can be wall-mounted. Others are only free-standing.

As to your other questions, I don't really have any solid information.
posted by hippybear at 3:17 PM on November 17, 2010

IMHO the reason oil filled radiators have become popular is largely due to safety. The oil disperses the heat of the heating element over a larger area so that there are no hotspots that could catch something on fire, like with a traditional exposed-element heater. It also gives them a bit of thermal mass so that they stay hot/warm as the heating element cycles on and off, whereas with a traditional electric heater when it cycles off you instantly feel it get cold. From a thermodynamics standpoint, 1500W of heat is 1500W of heat; the only thing that matters is how well that heat is diffused/circulated into the environment. Personally, from my experience, the oil filled electric radiators are only good for enclosed spaces like a bedroom where you can keep the door shut. I wouldn't try to use one for a large room or a space that can't be isolated.

I think the first thing I would focus on is making the place less leaky. Plug-in electric heating devices are really going to fight to maintain comfort if the place leaks like a sieve. You can get plastic shrink wrap kits that let you seal a drafty window with a hair dryer, and it can be taken down easily when spring comes. If any of the outside doors don't have seals around the edges, you can buy kits from the hardware store that screw into the frame and provide a seal.
posted by Rhomboid at 3:28 PM on November 17, 2010

Yeah, I should mention that we have blankets hung across the doors to keep the heat in the rooms rather than leaking out into the halls and stuff.

Passive heat is great, but not if the heat can just flow anywhere it pleases. You have to capture it.
posted by hippybear at 3:30 PM on November 17, 2010

All the radiators you are describing are resistant-heat only. No matter what type you choose, they use 1500W of electricity for 1500W of heating (or whatever wattage). A more efficient option is to use a reverse-cycle type heating system, possibly using a ground loop. A local HVAC company can discuss costs and the pay-back on them, usually more efficient is more expensive in the short term, but will save you electricity in the long.

This site discusses a couple of other options
posted by defcom1 at 3:36 PM on November 17, 2010

Oil-filled radiators take a long time to heat up and cool down. If you put one in your bedroom, for example, power it on at least an hour before you go to bed, and shut the door.

And I agree with everyone else's advice to only use space heaters in enclosed rooms, and to seal the rooms as much as you can, for example with plastic wrap on the windows. Insulated curtains could help too.
posted by Pruitt-Igoe at 3:42 PM on November 17, 2010

We got this last year for our super-cold apartment and it is awesome. The remote-control is great, so you can adjust temperature while on the couch or in bed or whatever. It doesn't get very hot to the touch, which makes it less of a fire hazard. Also the fan and oscilation make the room heat quickly.
posted by radioamy at 3:46 PM on November 17, 2010

The 10-12 m^2 rooms are a perfect size for plug-in space heaters, but I'm not sure how well they're going to work in your lounge.
posted by Pruitt-Igoe at 3:48 PM on November 17, 2010

Thanks for the answers to far... I assume when you guys refer to "passive heat", that's as opposed to active heat like a fan heater or similar, or am I misunderstanding the use of the word "passive" here? Also, do I take it from defcom1's answer that Watt for Watt, the heater that's 5-times more expensive than the other is just overpriced and won't heat 5-times better?
posted by benzo8 at 4:08 PM on November 17, 2010

Yes, when I say "passive heat" I'm meaning that the heating unit doesn't have a fan, but rather relies on natural air circulation to eventually heat the entire room.
posted by hippybear at 4:28 PM on November 17, 2010

All electric heaters are 100% efficient, whether oil-filled or not, fan or not, expensive or cheap. You pay for 1500 watts of electricity, you get 1500 watts of heat. Period. What makes one 1500-watt heater more expensive than another is styling and features.
posted by exphysicist345 at 5:35 PM on November 17, 2010

We've done as well as we can to insulate and define the lounge space. I'm thinking now we'll track down a couple of passive oil-filled radiators on wheels and a couple of active heaters - perhaps like the ceramic tower ones mentioned upthread - and mix and match to see what works best where. We can always buy in-socket timers rather than spend an extra fortune on radiators with such programming built-in.

Thanks for all the answers - I think I understand better now what radiators are all about!
posted by benzo8 at 1:50 AM on November 18, 2010

The big difference between a plug in, portable heater (whether oil filled, fanned, ceramic or whatever) and a wired direct wall mount (not being able to read Spanish I'm assuming the unit you linked to is wired direct) if the direct wire models are rated for unattended use where portable units rarely are (and in fact usually advise unplugging when not supervised). That's why they are often so much more expensive. The testing, engineering and quality control needed for an unattended rating adds to the price.
posted by Mitheral at 7:43 AM on November 18, 2010

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