How expensive are electric heaters to run?

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MonkeyDavid
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How expensive are electric heaters to run?

Post by MonkeyDavid » Sun Jan 10, 2010 6:02 pm

I've been wondering for some time about the running cost of an electric heater in a greenhouse. I currently have a paraffin heater which cost about £7ish a week to run & is usually sufficient except in extreme cold when the temps drop too low for my liking & it also becomes almost impossible to buy any as everywhere sells out. i Know all about the pro's & con's regarding how good they are & water vapour etc but what about ££££? I've worked out if i had a 1kw heater running for 24 hours a day in 1 week it'd cost about £19. Obviously it wouldn't be on 24/7 but what would it cost in the real world? ( i only need frost protection) eg, how long does it switch on compared to off in this cold spell?

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Dave Brown
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Re: How expensive are electric heaters to run?

Post by Dave Brown » Sun Jan 10, 2010 9:55 pm

David, that is an impossible question to answer :lol:

Requirements are

What size :?:
What insulation :?:
What Outside temperature :?:

My polytunnel is.... on frost setting controlled to +1.4C

Size: 3.5m x 2.1m x 2.1m

Insulation: Insulated by big bubble, bubble wrap (whole surface) and 2.5cm thick polystyrene sheet on bottom 90cm of sides.

14W extractor fan sucking 103 cu/m per hour from ridge to floor
Heat blown across floor by 30W 16" oscillating fan
Both of these run 24 x 7 while the greenhouse is closed down.

Outside Temperature @-1.5C

1Kw heater was coming on about 30sec in 3 mins...... 1/6 th of the time. which would equate to 4kw/h per day or 28Kw/h per week.

Fans = 44w x 24 x 7 = 7.3kw/h per week

At an ave temp of -1.5C heating system is 35.3Kw/h

However, I have twin rate electricity and 7 hours of the night is under 50% of day rate.

so for me at an average temp of -1.5C works out at £4.63 per week.

HOWEVER,

Your greenhouse exposure/ insulation etc will be different :roll:
Best regards
Dave
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Roll on summer.....
http://www.hardytropicals.co.uk

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MonkeyDavid
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Location: Telford, Shropshire

Re: How expensive are electric heaters to run?

Post by MonkeyDavid » Sun Jan 10, 2010 10:22 pm

Granted Dave, everybody's cicumstances will be different & i know there are a lot of variables, but i thought a few people giving their experience would give a ball park figure, your figures give me something to work with, Although someone who has recently switched to electric would be ideal. Basically i need to prove to the other half that it isn't going to cost too much more than paraffin icon_scratch too much of a pain in so many ways to use but she only thinks of cost :ahhh!:

mushtaq86

Re: How expensive are electric heaters to run?

Post by mushtaq86 » Sun Jan 10, 2010 10:51 pm

Ill tell you when my elecy bill comes. :lol: :lol: :lol:

vivi
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Re: How expensive are electric heaters to run?

Post by vivi » Mon Jan 11, 2010 1:26 pm

I have a Dimplex Coldwatcher 500w and an old tube like heater in my homemede greenhouse.One side is brick and insulated with polystyrene sheets,the rest is made up of double glazed doors and a polycarbonate roof,there are a few gaps here and there.Last year while away on holiday we left the heaters on for 2 weeks and had some minus 7s in that time and i worked out it cost no more than £15 for the fortnight.My other half say's its a hell of a lot cheaper than having to replace all the plants,and even reminds me to turn the heaters on if frost is forecast.!Hope this helps :)

musa_monkey

Re: How expensive are electric heaters to run?

Post by musa_monkey » Mon Jan 11, 2010 8:21 pm

I have an 8 x 6 greenhouse lined with bubblewrap.
The heater is a 2kw fan heater set to the 1kw setting.
I installed it just over 2 weeks ago and its running 24/7 with the thermostat set to maintain 3°c so its seen the worst of the weather here.

I just checked the consumption over that period and its 23.58KwH
If your wondering how i know this the heater was plugged into a power consumption monitor to record the power used over that duration.

23.58KWH works out at £2.64 or about £1.32 a week.
I am staggered that it is so low. Paraffin was costiing me over double that figure so i am well pleased that i moved to the fan heater. icon_thumright

gardenofeden

Re: How expensive are electric heaters to run?

Post by gardenofeden » Tue Jan 12, 2010 6:08 pm

I heat a large 18 foot by 8.5 foot, large bubble wrap, to a minimum of 5°C. There is not much difference between my summer and winter electricity bills. In the summer, we run an immersion heater to heat our water for the house, probably on 3 1/2 hours a day, 3 kW, not in winter (back boiler). So about 10.5 kwh per day, whatever that costs you (very similar to musa_monkey's 11.79 kwh). This is in an average winter though, current winter is probably double that for me!

metalhammer

Re: How expensive are electric heaters to run?

Post by metalhammer » Mon Jan 18, 2010 10:52 am

Check out Two Wests & Elliott catalogue,they give a rough rule of thumb to what how much kilowatts you'll need for a given size.Double glazing it will reduce your heating bill by around 40%,but use the double-skinned large bubble plastic.Also,for every 5c you raise the temperature,you'll double yor heating bills.Poly tunnels are harder to keep warm than a glasshouse.





metalhammer.

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