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Using Immersion heater on night rate instead of gas?
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JimLad
Posts: 950 Forumite



Hi Green Team!
My gas price just dropped on to variable rate and with no prospects of things getting cheaper any time soon i was wondering....
I am on octopus Go where electricity is 5p for a period at night...Would it be cheaper / the same price to heat my hot water during this period using the immersion heater in my hot water tank vs using my gas boiler in the day (3.9p). Ive read online that gas boilers are usually only around 80% efficient and this can drop as low as 50% if they are not doing heating at the same time (condensing mode). THis is vs an immersion heater which is in theory close to 100% efficient.
There is also the environmental argument too of using electricity which can be lower carbon (especially at night) vs gas.
Any thoughts?
My gas price just dropped on to variable rate and with no prospects of things getting cheaper any time soon i was wondering....
I am on octopus Go where electricity is 5p for a period at night...Would it be cheaper / the same price to heat my hot water during this period using the immersion heater in my hot water tank vs using my gas boiler in the day (3.9p). Ive read online that gas boilers are usually only around 80% efficient and this can drop as low as 50% if they are not doing heating at the same time (condensing mode). THis is vs an immersion heater which is in theory close to 100% efficient.
There is also the environmental argument too of using electricity which can be lower carbon (especially at night) vs gas.
Any thoughts?
Mortgage Free 22/03/17
MissWillow is my OH!
MissWillow is my OH!
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Comments
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The 50% typically refers to combi boilers, but if you've got a HW tank I guess you've got a conventional boiler? If so, the price is pretty close between 5p electricity on Go and 4p gas.I'm in a similar position and have stuck with gas but that's mostly because I don't have a timer on my immersion heater and the £20 one would cost is far more than I could possibly save!N. Hampshire, he/him. Octopus Intelligent Go elec & Tracker gas / Vodafone BB / iD mobile. Ripple Kirk Hill member.
2.72kWp PV facing SSW installed Jan 2012. 11 x 247w panels, 3.6kw inverter. 34 MWh generated, long-term average 2.6 Os.Not exactly back from my break, but dipping in and out of the forum.Ofgem cap table, Ofgem cap explainer. Economy 7 cap explainer. Gas vs E7 vs peak elec heating costs, Best kettle!1 -
QrizB said:The 50% typically refers to combi boilers, but if you've got a HW tank I guess you've got a conventional boiler? If so, the price is pretty close between 5p electricity on Go and 4p gas.I'm in a similar position and have stuck with gas but that's mostly because I don't have a timer on my immersion heater and the £20 one would cost is far more than I could possibly save!
Luckily i have an iboost which diverts excess solar in the day time. It also has a timer functionMortgage Free 22/03/17
MissWillow is my OH!0 -
Hi JimLad and welcome to the Madhouse, as others have often mused. It's great you are considering making a change as many of us on here are already in the process of transitioning away from FF's with some even having completed the move. With a PV array and iboost already installed it would seem you're already along the road. It's great taking small steps at a time especially where the cost differences are so minor making the decision all the easier to make.One thing often neglected with gas costs is that there is also the hidden cost of electricity in powering the circulating pump and fan in the gas flue. Maybe not massive but that 250 Watts or so when coupled to a heatpump would possibly return 1 kW of heat!Enjoy the journey, however quickly or otherwise you take it.East coast, lat 51.97. 8.26kw SSE, 23° pitch + 0.59kw WSW vertical. Nissan Leaf plus Zappi charger and 2 x ASHP's. Givenergy 8.2 & 9.5 kWh batts, 2 x 3 kW ac inverters. Indra V2H . CoCharger Host, Interest in Ripple Energy & Abundance.3
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I guess the situation may change at the next price rise though8kw system spread over 6 roofs , surrounded by trees and in a valley.1
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Coastalwatch said:Hi JimLad and welcome to the Madhouse, as others have often mused. It's great you are considering making a change as many of us on here are already in the process of transitioning away from FF's with some even having completed the move. With a PV array and iboost already installed it would seem you're already along the road. It's great taking small steps at a time especially where the cost differences are so minor making the decision all the easier to make.One thing often neglected with gas costs is that there is also the hidden cost of electricity in powering the circulating pump and fan in the gas flue. Maybe not massive but that 250 Watts or so when coupled to a heatpump would possibly return 1 kW of heat!Enjoy the journey, however quickly or otherwise you take it.
I also have an e-golf which i charge at night on GO.
I think im just going to have to switch the gas hot water off and turn on the immersion and see how it performs. I can keep an eye on costs on my online dashboard as i have a smart meter. As you say it would be really nice to burn less FF.arty688 said:I guess the situation may change at the next price rise thoughMortgage Free 22/03/17
MissWillow is my OH!3 -
Coastalwatch said:One thing often neglected with gas costs is that there is also the hidden cost of electricity in powering the circulating pump and fan in the gas flue. Maybe not massive but that 250 Watts or so when coupled to a heatpump would possibly return 1 kW of heat!NE Derbyshire.4kWp S Facing 17.5deg slope (dormer roof).24kWh of Pylontech batteries with Lux controller BEV : Hyundai Ioniq55
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EricMears said:
Another point worth considering is that heating by immersion heater is close to 100% efficient but a gas boiler is less so (exact losses vary for different boilers).7 -
Interesting thread as I am in a similar position: iboost, car, GO etc.As I type I've already put 2.55kWh into the tank today so a useful contribution. I've one of the early iboost (8633kWhs) so no timer function so in the same position as QrizB.3
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silverwhistle said:Interesting thread as I am in a similar position: iboost, car, GO etc.As I type I've already put 2.55kWh into the tank today so a useful contribution. I've one of the early iboost (8633kWhs) so no timer function so in the same position as QrizB.
Are you sure about the timer function? I didnt think mine did but if you hold A for 5 seconds and release and then press A to scroll though you might get to a boost timer?Mortgage Free 22/03/17
MissWillow is my OH!0
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