Space Heaters

[LaurenRose]

My sister and I both live in the Northeast. I've travelled here to spend a few days with her...she has a nice, typical home but she told me something interesting.

In order to save on the heating bill - she sometimes shuts her heat down low when she's ready for bed, goes into her bedroom to relax, shuts the door, to watch TV, read, etc. and turns on the space heater.

I estimate her home is about 1300 sq ft and her bedroom is a typical master suite.

She claims that modern space heaters are very efficient and she saves a good bit of $$.

Anyone else do this?

[Sho]

We do it too, even though we keep heat at 72, my family is quite cold sensitive and like it cosy, so we have total of 6 space heaters in different rooms/spaces ! They don’t run all the time

[rk6]

I have a Delonghi space heater in my basement office. It keeps the office warm enough, cuts down on the gas furnace running in the utility room next door, which is annoying on Zoom calls. Some of the heated air flows upstairs to the 1st floor and reduces the requirement to heat that floor a bit. We have separate systems for 1st and 2nd floors. There's different ways of looking at the efficiency of electric vs gas heating but this is more of a convenience than a savings thing. When deciding whether a space heater is right, you can look at it from either or both of those perspectives.

A mini-split in our bedroom is the "ideal" solution for us, but we just have not gotten around to it.

[valleyrock]

We've switched over from the oil-filled type which looks like a radiator, to the Vornado type which has a fan.

I've found that the oil-filled, convection type must be left on low, at least, in a room with no or very low heat from a home system. The reason is that the walls, furniture must be warmed up if you start from a low temperature. On the other hand, the Vornado circulates warm air immediately and makes a room comfortable fairly quickly after turning it on.

In my home office I have an older 300 watt halogen lamp. These units are inefficient for producing light, but they help heat up the room without adding a space heater.

[LittleMaggieMae]

It depends on the cost of the energy being used.

I live somewhere with relatively inexpensive electricity. Natural gas prices vary from year to year.

When NG prices are higher - it makes some sense to leave the temp for the furnace lower and then "spot heat" for a few hours with a space heater.

It's hard to keep an even temperature across my 80 year old house. My bedrooms are typically colder than the livingroom/dining room (where the thermastat is) so in the winter if I will be spending time in my bedroom (reading in bed) I may use a space heater for a few hours in the evening to make it more comfortable. I don't sleep with the space heater on.

Most of the time for for me, it's not about saving money - it's about comfort. Which, OK, I guess is about saving money - do I turn the house thermastat up to 72 or 74 (from 68) to so I can be "warm" in one room (and heat the whole house) OR do I just spot heat the room I will be spending several hours in.

NOTE: you can not assume that any space heater you purchase will be "energy efficient". You need to do a little bit of research and take into consideration the size of the space you want to heat. The space heater I use in my bedroom and office (bedroom) is too small to change the temperature in my living room for example. I have a second space heater that's sized for the living room - if I need to have a toasty hot room - when the Florida relatives visit during the winter. There is no way I can heat my house to 78 degrees in January. The furnace would run continuously.

[grok87]

We do it too, even though we keep heat at 72, my family is quite cold sensitive and like it cosy, so we have total of 6 space heaters in different rooms/spaces ! They don’t run all the time

+1

[MGBMartin]

Having just moved from a very warm climate to a cold one I’ve been thinking of trying this.
I guess that’s why they are called space heaters because they are intended to heat a space rather than the whole house.

[whomever]

"She claims that modern space heaters are very efficient"

They are 100% efficient. So are the old ones. So is an incandescent bulb, a microwave, or an electric oven.

Any electrical device that pulls 100 watt hours out of the plug and doesn't pump anything out of the room has added exactly 100wh of heat to the room. Old, new, cheap, expensive, whatever.

Things like heat pumps can be - usually are - more than 100% efficient, in the sense they can draw 100wh of electricity and use that to pump more than 100wh of heat into the room.


If you have a resistance baseboard heat, turning it down and heating only one room will be a win (although at a guess, an electric blanket will use a lot less energy by virtue of delivering it right where it is needed).

If you turn down a heat pump and spot heat with a resistance heater ... it's complicated; it might or might not be an energy win.

[adamthesmythe]

All electric space heaters are 100% efficient at converting electricity into heat. Doesn't matter if it's no-brand cheap or the fanciest Dyson.

Some electric space heaters may be more effective at making a person more comfortable, maybe by radiating heat in the right direction or using a fan. This difference is at the margin.

Unless space-heating a rather small area, or if gas is very expensive, it may be difficult to save money using space heaters. Around here we would use a spreadsheet and do a calculation.

[dbr]

"She claims that modern space heaters are very efficient"

They are 100% efficient. So are the old ones. So is an incandescent bulb, a microwave, or an electric oven.

Any electrical device that pulls 100 watt hours out of the plug and doesn't pump anything out of the room has added exactly 100wh of heat to the room. Old, new, cheap, expensive, whatever.

Things like heat pumps can be - usually are - more than 100% efficient, in the sense they can draw 100wh of electricity and use that to pump more than 100wh of heat into the room.


If you have a resistance baseboard heat, turning it down and heating only one room will be a win (although at a guess, an electric blanket will use a lot less energy by virtue of delivering it right where it is needed).

If you turn down a heat pump and spot heat with a resistance heater ... it's complicated; it might or might not be an energy win.

And a heat pump of the mini-split form can be set zone by zone (room by room). In very cold climates one needs more advanced heat pump design such as Mitsubishi hyper heat. The issue is the lowest temperature at which the operation remains reasonably efficient and then what is the lowest temperature below which the unit does not run. Such units can be reasonably used down to 5F but don't actually lock out until -24F. The plain vanilla unit is significantly less efficient below freezing and locks out at 5F. Note less efficient is still a ratio greater than 1.0 as offered by resistance heat.

Usually the motivation for minisplits is air conditioning in homes with hot water or electric baseboard heat. Heating in the shoulder seasons is a further benefit.

Also such equipment is not cheap, meaning thousands to tens of thousands of dollars for an installation. Professional installation is probably recommended but can be done DIY maybe by a person who knows what they are doing.

[knightrider]

Yes space heaters can save you money but most use ALOT of watts. Like 1000+ watts. I now use electric blanket when sitting down at the computer or the couch. Those use only 100 watts and keep me warmer. A few extra wool layers is also needed. As a result I can keep my thermostat at the lowest setting so that pipes won't freeze. Probably save thousands of dollars a year and get the best sleep

[upwind]

Don’t do it for space used as a bedroom. The answer for that is a good winter weight comforter. However, for a 12 x 12 office I have done this last few years. Work from home so house is kept rather cold all day except office space. Not sure if I am really saving much or not but it doesn’t seem to be costing any extra and it’s probably more comfortable than otherwise would be since it is one of the most remote spots in house and doesn’t get heated as well by central system.

In family room we keep a comforter for watching movies during winter.

[Wwwdotcom]

My bedroom is probably 1/8th of my house. Overall, I've found it more comfortable to use a quiet oil filled space heater for my bedroom when I sleep, than keeping the heat pump turned on for the whole house. My approach is not exactly scientific, but I have the heat pump do most of the heating during the warmer parts of the day.

[PeninsulaPerson]

Anyone else do this?

We do, and are very pleased with the attractive electric heater we got from Duraflame that we have in our bedroom. It's silent and warms the room up quickly. Ours would not be good in a larger room, like our living room, for example.

[steadyosmosis]

Anyone else do this?

Yes.

[Patrick584]

For most places heat from natural gas is about 1/ 5 the cost of resistive electric heat. Since this bedroom is not insulated or sealed from the rest of the house, it is significantly more expensive to use the space heater. She could use dampers/valves to reduce heat to parts of her house where it is not needed and this would have a modest impact on heating expense.

[yankees60]

Since it was only me in the house ... I believed in keeping me warm and not the rest of the house where I was not. Therefore, set the thermostat for the house at low (60) and well heated this bedroom I am in right now using space heaters.

However, one 1,500 watt space heater running at high will consume 1.5 kWh per hour. At my rate of about $0.33 / kWh, that would cost me $.50 per hour that it was running. Running it for 10 hours in a day would be $5. Doing that for a 30 day month could be $150.

As I write this my entire house is consuming 640 watts.

This computer with its three monitors is consuming 250 watts while the mini-split in this room set to 67 degrees is consuming 360 watts.

Initially I never considered mini-splits because I looked at them and said that if a tiny space heater can consume 1,500 watts then a mini-split must at least consume double or about 3,000 watts. I was shocked to find out that they were far more efficient than space heaters and only consumed about 1/4 as much -- about 400 watts.

Since I went live with my mini-splits on December 30, 2022, I almost never run a space heater. Only a few times when I've been in the bathroom taking a shower.

Answer to your question is that your space heater can end up costing less heating one room compared to the cost to use oil or gas heating an entire house.

You need to know how much is the maximum wattage draw on the space heater and what is you per kWh cost for electricity.

[Valuethinker]

My sister and I both live in the Northeast. I've travelled here to spend a few days with her...she has a nice, typical home but she told me something interesting.

In order to save on the heating bill - she sometimes shuts her heat down low when she's ready for bed, goes into her bedroom to relax, shuts the door, to watch TV, read, etc. and turns on the space heater.

I estimate her home is about 1300 sq ft and her bedroom is a typical master suite.

She claims that modern space heaters are very efficient and she saves a good bit of $$.

Anyone else do this?

Electricity rates in New York/ New England are quite high I believe. 30c/ kwhr in some places? More than twice US national average (was about 13.5c/ kwhr but may have risen). Natural gas heating should be quite a bit cheaper.

The (Seasonal) Coefficient of Performance of an electric heater is 1.0. 1 kwhr in = 1 kwhr out of heat.

(High efficiency gas furnace about 0.9-0.95. But 1kwhr of energy embodied in natural gas is much much cheaper than 1 kwhr of electricity from your local utility, most places).

A heat pump can have a SCOP of 4.0. 1kwhr in => 4 kwhr of usable heat out. Most times will do at least 3.0. (modern ones, optimised for heating as well as cooling). When it gets very cold, they may run an auxiliary electric bar backup, which has a performance of 1.0 (Ie the same as any baseboard or resistive electric heater).

Recommendation

I don't think it's wrong to try a space heater. Particularly if you have a big house and you use one room in particular, or for nighttime heat (see safety, below).

Complication

There are infra-red panel heaters which look quite good. Because they give off relatively more heat as radiant heat, they feel warmer to a person sitting near them. So they can be energy saving in that you won't need to run them at as high a temperature. I've never actually used one to say if that works.

Warning

Portable electric heaters have been a big cause of household fires and terrible accidents (people will do things like putting one in the bathroom - water and electricity is not a good combination). So use advisedly -- and I would avoid having one on if I am not in the room for any length of time NOR would I leave one on when I am not at home (generally).

[peterw]

In order to save on the heating bill - she sometimes shuts her heat down low when she's ready for bed, goes into her bedroom to relax, shuts the door, to watch TV, read, etc. and turns on the space heater.

Anyone else do this?

Yes, I have a similar-sized condo and have uses a small space heater in my study while at my desk.

I have since discovered that a couple of incandescent lights aimed at me and wearing several layers of clothing do just as good a job of keeping me warm, especially the neck and the hands. With incandescent bulbs, there is no noise associated with a running space heater.

The rest of the house is kept at 66F - 68F during the day.

At night, I lower the thermostat temperature to 64F. I sleep under multiple layers and wear double socks, so there is enough warmth under the covers to get a good night's sleep.

The condo is heated with electricity and the bills for November through April are quite high.

Still, my aim is not so much to save money but to use less energy overall.

[hunoraut]

In main living spaces we use infrared panels mounted to the ceiling. They're almost invisible and are supposed to be efficient because they only heat the 'targets' which are the occupants instead of heating ambient air. I can't really tell. They're scheduled to drop at night.

In rooms we use wall-mounted electric heaters that are also scheduled to drop at night. In effect, we only actively heat where we sleep. Colder is also better for sleeping.

[Valuethinker]

In main living spaces we use infrared panels mounted to the ceiling. They're almost invisible and are supposed to be efficient because they only heat the 'targets' which are the occupants instead of heating ambient air. I can't really tell. They're scheduled to drop at night.

In rooms we use wall-mounted electric heaters that are also scheduled to drop at night. In effect, we only actively heat where we sleep. Colder is also better for sleeping.

I believe that you live in the continental EU?

So compared to Americans:

- your electricity prices are probably on the high end (their average, a little out of date, was 13.5c /kwhr but could easily be USD 0.30+ in New England/NY/ California. European retail prices run sort of USD $0.30/ kwhr in my mind*)

- your domestic natural gas prices should be 2-4x theirs (we'd have to convert BTU to kwhr etc to figure it out)

- if you heat by oil/ LPG (propane)/ even biomass (wood or pellets) your costs will be higher still (albeit because heating oil is not usually taxed, very similar to what a homeowner in New England might pay for their heating oil)

So very limited space heating makes sense v heating the whole house?

(I am working from analogy with the UK. My late aunt, big house in country with oil heat, used to only heat the sitting room and the bedroom with electric fires).

* the big thing in places like Italy is that the power ration. The basic domestic circuit won't run an Air Conditioner and a toaster or kettle at the same time (I think the basic domestic circuit might be 2 kw?). You have to pay for more circuits if you want to do better than that.

Italian and Spanish homes use much less electricity than the EU average*, despite the growing presence of domestic air conditioning (responding to the increased temperatures and heat waves of recent years).

* UK is around 2700 kwhr pa I believe. Figures I saw suggested Spain and Italy were, from memory, around 2000 kwhr pa?

[hunoraut]

- your electricity prices are probably on the high end (their average, a little out of date, was 13.5c /kwhr but could easily be USD 0.30+ in New England/NY/ California. European retail prices run sort of USD $0.30/ kwhr in my mind*)

- your domestic natural gas prices should be 2-4x theirs (we'd have to convert BTU to kwhr etc to figure it out)

So very limited space heating makes sense v heating the whole house?

(I am working from analogy with the UK. My late aunt, big house in country with oil heat, used to only heat the sitting room and the bedroom with electric fires).

Our domestic prices are a bit variable. In the summer the rates are so cheap, most of the cost goes towards infrastructure/network. In the winter, rates go much higher, but recent year the govt provided blanket subsidy to everyone because during the UK-RU war era the prices went absolutely bonkers. (Dutch TTF natural gas prices spiked towards $300, whereas it's about $50 now).

All told my final price is probably around $0.15/kwh

Natural gas service is very rare here. Most people are on electric radiant heating (as primary source) and more and more people are using heat pumps.

If we switch to a larger house we would likely use heat pumps. Don't feel much like adding a box to the outside and inside of the house today. Our house is modestly sized compared to US (and dead on average for local size), so the economics is not that critical yet.

I never understood much the oil heating thing, and controls using 1-5 index instead of actual temperatures!

[JackoC]

For most places heat from natural gas is about 1/ 5 the cost of resistive electric heat. Since this bedroom is not insulated or sealed from the rest of the house, it is significantly more expensive to use the space heater. She could use dampers/valves to reduce heat to parts of her house where it is not needed and this would have a modest impact on heating expense.

Right for my house (100% efficient w/ old, new, cheap or expensive heater, as other said) electric resistance heat costs $0.22/kwh, all in with delivery charge. Nat gas costs $0.95 per therm, all in=$0.032/kwh, but the furnace isn't 100% efficient (heat going out the chimney) so say if 80%, $0.04/kwh, 5.4:1.

The balance is small area heated at 5 times as much v a reduction in cheaper heat everywhere else. The heating requirement is something like linearly proportional to the difference between outside temp and inside setting. Given that linearity it will tend to come out that you need to electric heat less than 1/cost ratio % of the house to come out ahead in $'s, leaving out some details like different insulation in different parts of the house etc. At our 5.4 ratio we'd need to electric heat less than ~18% of the house to come out ahead. But master bedroom, sitting room/study and kitchen/TV room we might both be and have just one of set of e-heaters going are each a little higher % of the house. This might work economically for somebody alone (perhaps w/ limited mobility) in a big house, or where electric is significantly cheaper relative to gas than here.

As it is we use an oil filled electric space heater in the bathroom a few minutes before and during a shower, for comfort not to save money. Also our heating system in recent years doesn't function well on 4th floor, only somewhat after multiple air bleeds and raising pressure setting in basement can result in safety valve lifting sometimes so I don't bother with kids gone. Occasional guests use electric heaters to supplement.

[yankees60]

Warning

Portable electric heaters have been a big cause of household fires and terrible accidents (people will do things like putting one in the bathroom - water and electricity is not a good combination). So use advisedly -- and I would avoid having one on if I am not in the room for any length of time NOR would I leave one on when I am not at home (generally).

When I used them extensively in the past I was always quite careful with them. Always wanting to be in the same room where they are on.

I've safely used them in the bathroom, keeping them away from possibly falling into the bathtub.

[Padlin]

We use one of the oil filled radiator style electrics in the grandkids room when they are here. Good heat for the one room, and safe enough being this style. This way we can leave the bedroom zone for the oil furnace set low, which is how we like it at night. Keeping just the one room in the 70’s has got to be cheaper than heating all the bedrooms that temp.

Might be worth checking out a mini split.

Don’t know where in N.E. you are but with the price of electric here she might not be saving anything. You can use a cheap Kill-a-Watt if you really want to know.

[yankees60]

We use one of the oil filled radiator style electrics in the grandkids room when they are here. Good heat for the one room, and safe enough being this style. This way we can leave the bedroom zone for the oil furnace set low, which is how we like it at night. Keeping just the one room in the 70’s has got to be cheaper than heating all the bedrooms that temp.

Might be worth checking out a mini split.

Don’t know where in N.E. you are but with the price of electric here she might not be saving anything. You can use a cheap Kill-a-Watt if you really want to know.

1) First paragraph is all true.

2) Mini-splits surprisingly use much less electricity than space heaters but require significant upfront investment. That will be mitigated by how generous your state's incentives are for installing them.

3) Since you are ware of Kill-A-Watt have you ever used one while the radiator electric is running to see how many kWh's it averages?

[JackoC]

We use one of the oil filled radiator style electrics in the grandkids room when they are here. Good heat for the one room, and safe enough being this style. This way we can leave the bedroom zone for the oil furnace set low, which is how we like it at night. Keeping just the one room in the 70’s has got to be cheaper than heating all the bedrooms that temp.

Depends on the room's % of the heat requirement relative to 1/cost ratio of electric to gas.

As rough $ example, assume 'set low' is 65. And use our house's costs, $0.22 and $.04/kwh respectively for electric resistance and gas, also our January heat load ~3700 kwh/month at 65 (our usual setting) w/ 24hr outside temp 32F. If thermostat is set to 70 rather than 65 that costs (70-32)/(65-32)-1 15% more, .15*3700kwh/month*$.04/kwh=$22/month. Running a space heater in 10% of the house to produce the same temp increment costs .10*.15*3700*.22=$12/mo. But if the space heater area is more than .04/.22, then electric $increase>$gas savings. At 20% of house our extra electric cost would be $24 (room where our grandkid sleeps when over is around 20% of the house, though his dad's old bedroom is around 10%). The temps drop out of the breakeven equation 1/cost ratio and are given just to show rough real $ numbers (where we can also see it's not a big deal either way). It's ignoring stuff like drafts, more windows etc. in particular rooms. It applies with other combustion fuels depending on the local cost ratio to electricity, but not if house system is a heat pump where you can't assume energy consumption is a linear function of inside/outside temp differential and doesn't depend separately on outside temp.

Space heaters make sense to have around though for various convenience and emergency situations even where they don't save money on an ongoing basis (I have trouble sleeping if the bedroom is 70 so if somebody in another room really needs that, space heater; and our gas furnace was knocked out by flood once at start of heating season and plumbers were overwhelmed, took a few weeks to replace, space heaters in meantime).

[hvaclorax]

"She claims that modern space heaters are very efficient"

They are 100% efficient. So are the old ones. So is an incandescent bulb, a microwave, or an electric oven.

Any electrical device that pulls 100 watt hours out of the plug and doesn't pump anything out of the room has added exactly 100wh of heat to the room. Old, new, cheap, expensive, whatever.

Things like heat pumps can be - usually are - more than 100% efficient, in the sense they can draw 100wh of electricity and use that to pump more than 100wh of heat into the room.


If you have a resistance baseboard heat, turning it down and heating only one room will be a win (although at a guess, an electric blanket will use a lot less energy by virtue of delivering it right where it is needed).

If you turn down a heat pump and spot heat with a resistance heater ... it's complicated; it might or might not be an energy win.

Resistance electric heating in the house is 100% efficient. The generation of electricity at the power station is more like 50-60% efficient. It depends on the fuel used. At the power plant level of generation heat is lost and there is friction loss as well. The power lines aren’t 100% either. Not a free lunch.

[Wwwdotcom]

For most places heat from natural gas is about 1/ 5 the cost of resistive electric heat. Since this bedroom is not insulated or sealed from the rest of the house, it is significantly more expensive to use the space heater. She could use dampers/valves to reduce heat to parts of her house where it is not needed and this would have a modest impact on heating expense.

I'm not sure that even holds true in the places with the lowest natural gas prices in the US. In favorable places, it will probably about 1/3. Here is a nice link that compares a few states in some cold climates. https://www.montana-dakota.com/rates-se ... e8959-246e

[lws]

I do.
I heat only the room that I use.
I occasionally run the gas fired furnace to exercise it.
When visitors come, I run the furnace.