Infrared panel heater - efficient alternative to hot water bottle?

ArbitraryRandom

I agree with the above - but don't discount the importance of getting up regularly when working from home (and getting a hot drink to stay hydrated will mean boiling the kettle anyway ). 

Being warm and saving cash where you can is important - but you don't want to be building up other problems down the line. 

QrizB

QrizB said:

SamDude said:

I'm looking at whether a freestanding 180/300/500w infrared panel heater would be a cost efficient way to keep a person warm when we're not using the gas central heating during evenings/weekends, compared to a hot water bottle every hour or compared to putting the gas central heating on for the whole house for an hour at a time?

The hot water bottle is the cheapest option to run.

A heated throw or seat cushion will be cheaper than the IR panel.

I did some calculations on this a year or two ago. I'll get them out and update them.

OK, let's compare:

1. 2-litre hot water bottle, refilled hourly to 50C using hot water from the kettle.
2. 2-litre hot water bottle, re-heated from 30C to 50C hourly in the microwave.
3. The same hot water bottle, but emptied and refilled with gas-heated tapwater hourly.
4. Electricaly heated seat pad like the one I'm currently sitting on (see details here).
5. Electric heated throw, 90 watts (example).
   
6. 180-watt IR panel heater (example).

What is this going to cost?

1. If your incoming mains water is at 10C, filling the HW bottle anew with 50C water will take 93 watt-hours of energy (via omnicalculator). A kettle is 90%+ efficient (assuming you don't overfill it), so let's say it uses 100 watt-hours of electricity to heat the water. At the current capped SVR of 27.35p/kWh, 100 watt-hours of electricity will cost 2.7 pence. doing that once an hour, your cost is 2.7 pence per hour.
   
2. Heating 2 litres of water from 30C to 50C will use 47 watt-hours of energy. According to this study, microwave ovens are typically only 72% efficient at converting electrical energy into heat, so putting 47 watt-hours into our hot water bottle will need 65 watt-hours of electricity. At the SVR, 65 watt-hours will cost 1.8 pence per hour.
   
3. This is just like case 1, but using gas. A gas boiler oprating at a microwave-like 72% efficiency (ie. a pretty ropey one) will burn 129 watt-hours of gas to provide that much useful heat. At the current capped SVR of 6.89p/kWh, 129 watt-hours will cost 0.9 pence per hour.
   
4. My electric heat pad draws about 20 watts, but the mains adapter gets slightly warm so let's call it 30 watts. At the SVR, that will cost 0.8 pence per hour.
5. The 90-watt throw, at the SVR, will cost 2.5 pence per hour.
6. The 180-watt IR heater, at the SVR, will cost 4.9 pence per hour.
   

Suggestions for Mrs SamDude:

• 2.7p per hour, for the current approach, isn't terrible. If it works for her, she can carry on doing it. Doubly so if the hourly kettle-boiling is also used to make her tea/coffee/cocoa.
  
• Re-heating the HW bottle in the microwave (assuming you have a microwave already) would save 1/3 of the energy cost and avoid any problems with boiling too much water.
• Using gas-heated hot water from the tap, rather than the kettle, would save another 1/3 compared to using the kettle. This assumes you have gas CH; it might also work if you have E7 electric-heated water, but that will depend on the tariff.
• An electrically-heated seat pad has a similar running cost to a gas-heated HW bottle.
• An electrically-heated throw has a similar running cost to an electrically-heated HW bottle.
• An IR panel heater will cost at least twice as much as any othe roption, but might provide broader quality-of-life improvements that are worthwhile.
  

Personally, I'm going to continue sitting on this heat pad!

ArbitraryRandom

QrizB said:

2-litre hot water bottle, re-heated from 30C to 50C hourly in the microwave.

I'm assuming you mean the water from the bottle reheated, but just to be absolutely clear - you shouldn't microwave a hot water bottle unless the manufacturer has said it's safe to do so.

Rubber and PVC are not safe, silicone can be (and obviously 'heat bags' are designed to be). 

QrizB

elsien said:

With apologies for jumping on board, is anyone able to recommend a heated foot pad or similar?

@Grumpy_chap endorses his "Fellowes Climate Control Footrest", but it's not cheap:

https://forums.moneysavingexpert.com/discussion/comment/78872749/#Comment_78872749

If that's not wht you're looking for, how about a heated pet pad (example)? Fairly cheap, intended for the floor, should be fine with socks?

SAC2334

Personally I prefer the very similar Halogen heaters 400/800/1200 with  three bars  .These are ideal for heating the person rather than the whole house . One bar costs me around 6.4 p an hour if my daily tracker rate is on 16 p a kwh
.If you sit reasonably close to them I measured the temp around 21 c . Lots of different makes all doing the same thing ,and they have a safety feature which shuts them off if tipped over. Available in many shops at around £20. No need to go to Amazon 

Brie

Lidl and Aldi tend to have "people heaters" this time of year.  We had a heated back pad with a bit that went over the shoulders.  Simple on/off switch.  I think I saw one recently for under £20.  No idea what they cost to run.

Another alternative is a microwavable wheat pillow.  I got 3 from Wilko for £5 each a couple of years back and they are nice and quick to heat and drop down your jumper or wrap round your an@elsien

@elsienI did try to convince my cat that sleeping on my feet was a good thing but she disagreed.  She was also rather expensive to maintain as well. 

matelodave

A heated throw/electric blanket. Easy to use, cheap to run and it keeps all of you warm. Like this - https://www.argos.co.uk/product/3201174?clickPR=plp:17:16 They are usually around 100 watts

My wife has one as she's a chilly mortal and it keeps her warm and cozy without having the heating flogging away all day.

Swipe

elsien said:

With apologies for jumping on board, is anyone able to recommend a heated foot pad or similar?

I can keep my top half warm no problem, but I’m getting chilblains on my feet already even with a couple of layers of thick socks on. Primarily due to sitting at my home desk without moving around enough. I don’t wear slippers because they irritate me immensely.

Not sure if these are suitable or will irritate you but I have a couple of these, one for the kitchen and one for the living room. Best money I ever spent. If my feet are warm my whole body is warm even at 16C

https://www.argos.co.uk/product/3443592

elsien

Thanks, but they’re just like big slippers. And I can’t be doing with furry slippers. 

Scot_39

Are the heated throws really that much better than regular unhet ones ?

I guess it depends - on how hot you want to be vs the room - but even a basic one - I would think should allow a couple of degrees difference on the thermostat for many - without the additional expense - purchase and running.

@elsien

There are some heat and heat and vibration pads / heated slipper devices - bought one of those double slipper ones one year for an elderly aunt (70s) - who struggled with feet - despite room being c20C+ - felt a bit hot for us as visitors.  Cannot remember brand - but was a known brand from high st store - was c£40 in 00's.

There's all sorts of options - pads and full / partial covers - but if you don't like slippers you'll probably just want a pad - theirs a few examples for pads too

https://www.amazon.co.uk/heated-foot-warmers/s?k=heated+foot+warmers

I find simply double layering legs when on computer at desk ((cotton - not thermal - leggings under trousers) with leggings or a simple unhet throw when on sofa - makes a big difference. 

 

I did once invest in heated socks for outdoor use in far N Canada - when working there - but probably a bit extreme for outdoors in most of UK in most winters - let alone indoors - but if you really don't like enclosing your feet and struggling...

https://www.amazon.co.uk/s?k=heated+socks&ref=rsl_sug_1_2