With winter coming up, I have two options for home heating.
Central unit
- I can use the central unit and close/open vents throughout the house to heat up only the individual rooms I want. This would heat up rooms very quickly. However, to make this work, the living room with the thermostat will also need to be heated so that the thermostat reads the proper temperature. The living room is by far the largest space at about 2.5 times the size of the largest room.
Oil-filled radiator
- I can use an oil-filled radiator to heat up an individual room. This would be much slower, but I wouldn’t have to heat up the entire living room. However, the oil-filled heater might not be as efficient as the central unit. I don’t know. I plan to rarely heat up the living, no more than once per month.
Edit: The central heating unit is actually a heating kit made up of a few coils that is added to the central a/c.
Edit 2: Where I live, it might freeze once per year over night for a few hours.
Which would be more efficient on the electrical bill, and would t be considerable or negligible?
If you’re in an area that doesn’t freeze you can keep the house cold and heat one room with an electric oil filled radiator very inexpensively.
If you’re in a place that freezes you need to keep the house warm enough to avoid freezing the water pipes.
Otherwise have fun, heat one room and bundle up everywhere else.
Get a cheap thermometer to place in the room you’re going to heat and look how much it is off the thermostat and regulate accordingly.
Leaving one room cold while others are significantly warmer might raise the risk of mold, because the warm air might cool in the cold room and condensate on the walls and windows, creating conditions for mold growth.
I look that every room is at least about 16°C as an absolute minimum in winter.
I’m not familiar with mobile oil radiators, but it sounds kind of dangerous to me.
They are actually one of the safer plug in type heaters.
I thought they burn oil or something, but they just use oil instead of water in a closed system.
Sometimes I’m dumb. The CO buildup from my version of oil radiator would be deadly.
When my wife first mentioned she was using one, I had the same initial reaction lol
Right it’s just an electric resistive heater in a radiator shape filled with an oil to circulate heat.
- no combustion
- no hot surfaces
- more consistent heat
- generally more engineered for continuous use than other space heaters
- generally have tip sensors (depending on country)
When my ex wanted a space heater, I insisted that this be the only type, for safety. And of course not allowed to use a power strip or extension cord with it
Good idea! Thanks for the info and suggestion.
What type of central unit do you have?
It’s a central a/c unit with a heating kit added to it.
It’s probably better to use a space heater where and when you need the heat. That central heating kit is basically the same thing, but it’s using more electricity providing heat to the entire home, including the rooms you aren’t using. Just set the thermostat to a minimum temperature to keep the pipes from freezing.
I’m curious to an actual, scientific answer, but I do something similar, and here’s my anecdotal results:
I’ve got one of those electric fireplaces (fancy 1500w space heater basically) in my den, and I usually spend a lot of time in here (it doubles as my WFH office). I’ll turn the central thermostat down about 5 degrees and just run the fireplace while I’m working in there. When I’m done, I’ll bump the main thermostat back up.
My furnace is gas, and the price keeps rising every year, but doing this over the last 3 years, my gas bill has stayed relatively flat even though the price has skyrocketed. I think it averages me an extra $20 at most on the electric bill which is less than the gas would have cost.
Granted, I live by myself, so I don’t have to worry about other people in other rooms getting chilly lol.
I actually did some googling and there are some okay-ish articles debating this topic. All of them said “it depends”, which isn’t really helpful.
It got me thinking, though… how much savings would you need to make it worth it to you? ($20 savings? $100 savings? $500 savings?)
The oil heater is going to cost ~$50 to purchase if you don’t already have one. That means you’ll at least need to save $50 just to break even. So over the winter, your electric bill will need to drop by $50 plus whatever the dollar amount you need in order for it to be “worth the trouble” for you.
If an extra $50 over the winter in savings ($100 total) is worth it to you, I think you have a high chance of an oil room heater getting you that savings over your central heating. I’m doubtful how much more you’d be able to save beyond that. (I didn’t do the math on it, but based on the articles I read, the oil heater is going to be cheaper in general.)
Another thing to consider: The oil heater is likely to be a lot more convenient to use than the central air option and having to close all the other vents in your house though.
Just an FYI, closing up vents in an hvac can actually cause problems. It puts more strain on the fan unit, which can cause it to burn up quicker. The unit is designed to move a certain amount of air, if you restrict that air, pressure builds up in the system.
A couple closed over an entire system is fine, but closing all but one room would definitely cause problems.
I have been closing 3 out of 5. Is that too much?
How cold does it get where you live and which sides are the room and living room on compared to the coldest wind?
If the room you use is on the north side and the cold wind comes from the north, that electric heater is going to get a workout and you lose the advantage of the house having a heat mass that can even out the need to hwat the one room.
If the room is on the south side away from the wind the rest of the house would be a bit of a buffer, making heating only that room less of an energy simk. The number of windows and other ways to lose heat will matter too. If the living room has a lot of windows and other ways to leak heat then not heating it could be an advantage.
If it gets to freezing where you are at I would suggest a combined solution if possible. Set the central heat to a temp a bit above freezing to keep the pipes from bursting (around 55 F) and shut the ducts to rooms you don’t care about. The difference in temp to the outside temp is what uses the most energy, and closing that difference has a huge difference on energy costs. Then use the space heater in the room you do care about to reach the temp you want.
This will result in the central unit doing a lot less work than it would to bring the whole house up to temp, but the portable unit wouldn’t need to heat the the room and the interior walls nearly as much becuae it would be heating the difference between the central unit at the desired temp. This will probably be the most comfortable/consistent arrangement and likely close in cost to just doing the room by itself.
It might freeze once per year…maybe. My area is surrounded by trees, so I think wind hitting the house is negligible.
In that case, I still recommend turning on the main thermostat but setting it very low so it only kicks on during extremely low temps as this can help with comfort without much cost at all. The space heater would then do the job in the room you care about to save costs.
One other thing that I haven’t seen mentioned elsewhere and I forgot myself is humidity. While a heater isn’t going to change the humidity like an air conditioner that is cooling does, the fan in the unit can even out the humidity in the house and humidity can have a big impact on how the temp feels. Depending on the size of the room and how much air gets circulated, your presence could have a significant impact on the humidity levels.
I would recommend that whether you run the central at a low temp or not, running the fan for a bit once in a while would be a huge benefit to the home. You don’t even need to turn on the heat for that, just the blower. This will help to reduce any damage from condensation throughout the house, and you don’t need to open your room to get the benefit. Within the room you are using it might be a good idea to check the humidity levels and look up what the best humidity is for the temp you are aiming for. While that might mean getting a humidifier or dehumidifier if the room is way off, that will most likely be a lot less expensive than the heating cost and you might even find a slightly lower temp comfortable and save more than you spent on adjusting the humidity.
Great suggestions! I will definitely do them. For now, I’m guessing that I’ll prolly set the central heater at ~62*F. That will make sure it kicks on when it gets too cold and will also move the air about the house. Once I try this out, I can see if I’d like it to be set at a different temperature.
Most all forms of heating are near 100% efficient, since it’s the waste heat you want. Unless the central heating is using a heat pump instead. Does your central heating use gas heating? If so, using it will probably be cheaper. If it uses resistive heating, the individual unit might be cheaper. But if it uses a heat pump, it might be cheaper to use central again. There are a lot of variables it’s hard to know.
It uses a heating kit that is added to the a/c unit.
Okay, that’s resistive heating. So it’ll be the same efficiency as a oil heater or any space heater. So heating less space with it will save money.
Electric radiator is 100% efficient.
If your central heating works by heating coils with electricity then it’s 100% efficient as well. If you heat all the rooms to the same temperature it makes no difference which one you use. If you use radiators but leave some rooms cooler than others then that’s going to cost less money.
If your central heating works by burning oil / gas then that’s probably going to produce heat for cheaper than electric radiators are. Same applies if it works by heat-pump. Those are 200 - 300% efficient.
i recommend you avoid polluting the air in an enclosed space. So no oil burning inside the room. The central heating would be a much better option in my opinion
Alternatively, weak (1 to 5 kwh) electric heaters with good placement can heat rather large rooms without wasting nearly as much power
They said oil filled radiator, not oil burning. I expect it’s a very efficient electric heater like these:
If they are trying to keep one room warm and don’t care about freezing the rest of the house those are very efficient.
I was thinking of one of those radiators that burn oil, and you have to fill them up before use. Thank you for clarifying!
ps. the link appears to not work for me? Maybe they have a region block?
This is the same layout as the device I was referring to:
Oh that’s an odd approach, it’s just an electric heater with extra steps
Basically yes.
It adds some efficiency because once you have a radiator full of hot oil in the radiator it tends to release the heat for a long while after the electric is shut-off.
Most electric space heaters send a plume of hot air arcing upwards.
You end up with a nice heat storage device to radiate warmth at the level you want to use it for longer than a normal resistive space heater using the same energy.
ahh, that is handy! But I guess that’s only suitable for some types of spaces
It has its uses.
Like most bespoke items they’re good at some things, not everything.It’s nice if you’re trying to keep an indoor living space warm for a longer period, like overnight.
They typically have a thermostat setting on it to maintain the temperature.
It doesn’t make the same noise as a blowing space heater, as there’s usually not a fan. I’ve heard creaks and such from them.
As noted, the radiative effect can last for a few hours depending on energy loss in the space.
It has its uses.
Like most bespoke items they’re good at some things, not everything.It’s nice if you’re trying to keep an indoor living space warm for a longer period, like overnight.
They typically have a thermostat setting on it to maintain the temperature.
It doesn’t make the same noise as a blowing space heater, as there’s usually not a fan. I’ve heard creaks and such from them.
As noted, the radiative effect can last for a few hours depending on energy loss in the space.
I agree that burning oil would be a terrible idea. In this case, the oil would be in an enclosed radiator that is designed to function as an indoor heater. Thanks for looking out tho!
That is actually pretty cool! In that case, the slowness shouldn’t be a big issue. As soon as you’ve got a comfortable temperature you only need to maintain it
Tp calculate needs way more info that. U would need to know the effective efficiency of the central heating system. The houses per room insulation effect and inter room insulating effect. The heat output of each device. Ambient temperature. Then u could do some thermodynamic analysis to determine which is more expensive. Alternatively u just measure both taking care to compare the getting to temp and maintaining temp separately.
I believe u thermostats are a standard wiring so u can probably wire up a relay and a raspberry pi with a wireless thermostat.
upgrade your house insulation, get a heat pump on the central furnace, and heat the whole house. People have better things todo than closing vents or moving heaters., your central furnace needs most of the vents open to work right.
