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- CommentAuthordilangar
- CommentTimeSep 22nd 2012
Good morning,
Where in a rather large new build house with an annex. Are question is per kilowatt an hour what more efficient for hot water oil or electric? -
- CommentAuthordilangar
- CommentTimeSep 22nd 2012
Just realised!! The boilers are thermecon bfo190 and bfo80/95 verses two mega flow one 300 litre and I guess the other slightly smaller. My maths wasn't partically good at school
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CommentAuthorSteamyTea
- CommentTimeSep 22nd 2012
Are you after the efficiency on site (electric as all the energy goes into the water) real efficiency that includes losses from your boiler, the power station, thermal losses etc.
Or are you after the CO2 per kWh as that will depend on when you use electricity and how good your oil boiler is and where the fuel is sourced (bio-diesel percentage). -
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- CommentAuthorWillInAberdeen
- CommentTimeSep 22nd 2012 edited
air source heat pump is cheaper and greener than oil or electric.
Edit: if you already have oil installed, its cheaper and greener than electric. -
- CommentAuthortony
- CommentTimeSep 22nd 2012
ground source even more efficient than that and water source competes too.
Do you really mean which is cheapest? -
- CommentAuthorCWatters
- CommentTimeSep 22nd 2012 edited
Posted By: dilangarJust realised!! The boilers are thermecon bfo190 and bfo80/95 verses two mega flow one 300 litre
If your choice is between an existing thermecon Oil boiler and an existing megaflo with electric immersion coil then the oil boiler should be a lot cheaper to use. Possible exception would be if the electric is on E7 or some other discount tariff. Even then need to do the sums.
http://www.nottenergy.com/energy_cost_comparison/ -
- CommentAuthorwoodgnome
- CommentTimeJan 23rd 2013 edited
Sorry to resurrect an old thread. The roof on my new build isn't orientated for any panels on the roof, so if i can't ground mount some, (trees and hedges might be in the way for this,) i am considering either E7 or oil for DHW, to run alongside a GSHP and underfloor.
What's the thoughts on E7 versus oil for DHW?, Looking for the cheapest option.
The tables in the link above don't show E7.
Thanks -
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CommentAuthorSteamyTea
- CommentTimeJan 23rd 2013
E7 may cost more by the kWh, but has less seasonal price fluctuation, takes up little space on site and can be used for 'other things'. You may or may not have noticed that when we have a price increase in gas and electricity that th erise in electricity is generally less than gas, this is because gas prices are currently linked to oil prices (though they have not come down in the last few weeks but probably will). Long term (over 20 years), the price of electricity will probably be linked to the price of nuclear and wind, with only a small part based on gas and oil prices, unless we sort out CCS on coal fired, then about 30% more than today's coal generation prices.
May be worth looking at the installation costs of an E7 system versus and ASHP versus an Oil Burner.
Your water type may effect the maintenance, I am in a soft water are and my E7 system is now about 26 years old, but when I lived in a very hard water area it lasted less than 10 years.
Also think about how much water you use, halve that and you almost halve the running costs. -
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- CommentAuthorCWatters
- CommentTimeJan 23rd 2013
If you use E7 wouldn't that increase the rate you pay for electricity running the GSHP in the daytime? -
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CommentAuthorSteamyTea
- CommentTimeJan 23rd 2013
Yes, why usage patterns are important. Last year my mean price all in was 10p/kWh, which is cheaper than standard electricity at 12p. -
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- CommentAuthorwoodgnome
- CommentTimeJan 23rd 2013 edited
As Steamy has mentioned in another post, ( E7 and combined solar for DHW) E7 might not be the best option for DHW unless you use most of the water in mornings. I think most of my DHW will be used in the evenings for bathing the kids etc, and they will soon be at school all day, so not much requirement in the day, so although i wasn't considering oil initially for DHW, it might be the way to go.
But then, if i had E7 my GSHP would be cheaper to run during E7...... -
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CommentAuthorSteamyTea
- CommentTimeJan 23rd 2013 edited
Posted By: woodgnomeunless you use most of the water in mornings.
E7 is fine for using water any time of day because you know that there is a consistent supply of energy every night.
Solar is the issue here as if your store is already at maximum temperature when the sun comes up, you are not going to be able to pump any more energy into it. So no point in having the ST system unless you are going to discharge the hot water at dawn (as long as Dawn don't mind).
One way around it is to pre heat the header/feed tank with solar and then let the E7 top up if needed. More plumbing and tanks though. -
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- CommentAuthorRobinB
- CommentTimeJan 23rd 2013
How about solar and a instant hot water heater to bring it up to temp if, as and when needed. E.g. nikhoward's 12kw on "offers and wants" Would that zap any legionella? -
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CommentAuthorSteamyTea
- CommentTimeJan 23rd 2013
Starts to get complicated now, and complication is just another work for cash.
Not as complicated as an oil burner though. -
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- CommentAuthorSeret
- CommentTimeJan 23rd 2013
Posted By: SteamyTea
E7 is fine for using water any time of day because you know that there is a consistent supply of energy every night.
Depends. If you use water both morning and night (showers in the morning, bathing kids at night) then you'd need to be sure your tank was big enough to last a whole day. -
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CommentAuthorSteamyTea
- CommentTimeJan 23rd 2013
Yes, or the temperature is higher.
Pretty easy to work the amount and temperature needed for a typical day, not so easy to work out the amount of solar on a typical day.
Not that I am saying that it is not a valid way to heat water (solar that is), just that it is not the most reliable for the money. -
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