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brummydave

which is most efficient for water heating - gas or electric?

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brummydave

Just contemplating...

Which is the most efficient way to heat water? Electrically, say via an immersion heater, or with a gas boiler?

With solar PV on the up, there's extra scope for programming immersion controllers to come on in daylight. But if it's loads more energy guzzling than gas, then maybe the electric's best used for other purposes...

thoughts?

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Onoff

How about pre heating with solar thermal?

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Technician

The USEFUL killowatt hours are greater with electric

than gas.

However the unit cost of electric is higher than gas.

There are tables that give you the useful killowatt

hours and I suggest that you contact Warmfront and

they might be able to help you. I used to have all this

at my finger tips but....that was a long while ago.

Another problem is that, obviously, the rising main

temperature is about 5 deg Cel in winter and rises to 15/16

in summer. Pre-heat with solar may be an option.

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sellers

Pre heat with solar thermal, element linked with solar PV, all good for summer day time.

Woodburning stove for winter linked into the cylinder. Electric shower and undersink instantaneous heater for hot water in desperate times.

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ProDave

If you are planning a new install I would recommend a heat store tank with input coils for solar and a wood burner, as well as an input for a boiler.

But I don't think that is what you were asking is it?

Electrically heating the water will be the most EFFICIENT as 100% of the electrical power used heats the water.

A gas boiler will be less EFFICIENT as it has to heat it's own mass and the hot water used to convey the heat from the boiler to the tank.

But is your question really which will be the CHEAPEST? That's a completely different question. and the answer today, may not still be the same in 5 or 10 years time.

If you have solar PV, build a dump controller to turn on the immersion heater when there is spare unused solar generation. Done properly that will still let you use things like the washing machine, tumble dryer, dishwasher etc, and only turn on the immersion if there is actual spare power at any given moment.

See the Solar PV for my discussion on the Solar PV dump controller that I built.

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Onoff
If you are planning a new install I would recommend a heat store tank with input coils for solar and a wood burner, as well as an input for a boiler.

But I don't think that is what you were asking is it?

Electrically heating the water will be the most EFFICIENT as 100% of the electrical power used heats the water.

A gas boiler will be less EFFICIENT as it has to heat it's own mass and the hot water used to convey the heat from the boiler to the tank.

But is your question really which will be the CHEAPEST? That's a completely different question. and the answer today, may not still be the same in 5 or 10 years time.

If you have solar PV, build a dump controller to turn on the immersion heater when there is spare unused solar generation. Done properly that will still let you use things like the washing machine, tumble dryer, dishwasher etc, and only turn on the immersion if there is actual spare power at any given moment.

See the Solar PV for my discussion on the Solar PV dump controller that I built.

Any chance of the link for your thread on that? I've just trawled through that section but couldn't find it..........Thanks.

Edited by Onoff
bad spellink

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ProDave
Any chance of the link for your thread on that? I've just trawled through that section but couldn't find it..........Thanks.

http://www.talk.electricianforum.co.uk/photovoltaic-panels-pv-solar-panels-green-energy-forum-wind-turbines-renewable-energy/19791-managing-using-your-generated-power-whacky-idea.html

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sellers

Electrically heating the water will be the most EFFICIENT as 100% of the electrical power used heats the water.

A gas boiler will be less EFFICIENT as it has to heat it's own mass and the hot water used to convey the heat from the boiler to the tank.

It could depend how the electricity is generated, theres would be loses in heat, sound and friction at the power station.

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brummydave
If you are planning a new install I would recommend a heat store tank with input coils for solar and a wood burner, as well as an input for a boiler.

But I don't think that is what you were asking is it?

Electrically heating the water will be the most EFFICIENT as 100% of the electrical power used heats the water.

A gas boiler will be less EFFICIENT as it has to heat it's own mass and the hot water used to convey the heat from the boiler to the tank.

But is your question really which will be the CHEAPEST? That's a completely different question. and the answer today, may not still be the same in 5 or 10 years time.

If you have solar PV, build a dump controller to turn on the immersion heater when there is spare unused solar generation. Done properly that will still let you use things like the washing machine, tumble dryer, dishwasher etc, and only turn on the immersion if there is actual spare power at any given moment.

See the Solar PV for my discussion on the Solar PV dump controller that I built.

Spot on Mr Dave. Thank you! I'm very intrigued by a 'dump controller!!' I'm aware that new installs are best served with a multi-fuel supplied water tank and if there's space, solar thermal as well. But in this case, i've no room for thermal panels, and also a megaflo that's only 6 years old and short-sightedly wasn't a dual coil one!

So you're quite correct, the cheapest option is what i'm looking for. As yes electric is more efficient but more expensive than gas.... i'll give warm front a holler too.

Thank yoU!

---------- Post Auto-Merged at 13:48 ---------- Previous post was made at 13:46 ----------

It could depend how the electricity is generated, theres would be loses in heat, sound and friction at the power station.

now that's a good point. pernickity (?) but good.

but in this case i'm talking energy at the house rather than the whole energy cycle.

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Nicky Tesla

I have been told that many new houses are going all electric these days as gas is supposed to be running out.

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brummydave

Wow, what a thread. I've no clue about electronics programming and the like, but feel I've followed most of what you've done ok. I really like the fact that you've taken into account the demand rather than just the generation. Most of the other devices out there seem to be just switch on at a setpoint of generation. Which seems to miss the point!

Currently i've a 3kw immersion in the bottom of the 210l tank. Although I do have a spare 3kva 110v tranny lying around, rather than using it or using an 'immersion heater power halver', i think fitting another immersion in the top part of the tank will be most useful. I'm looking at the marine type 1kw ones. (why they're double the price of a 3kw one is beyond me tho'!!) Maybe i'm being naive. or maybe I should fit a 1kw in the bottom, and the 3kw in the top?

However, the important bit is the controls. Mr Prodave are you likely/able to produce another setup like you've got running? or are you aware of a commercial product that would do the same?

I've been looking at energy monitors too, and there's a couple that seem to know how much is being exported. The 'Wattson' glows green when more is being generated than being used, and the 'geo-solo' has a display like a speedometer with a big tick! I really don't know if these devices could be used to trigger an immersion heater via contactor tho?

it keeps the old grey matter ticking over tho eh?!

---------- Post Auto-Merged at 16:39 ---------- Previous post was made at 16:37 ----------

I have been told that many new houses are going all electric these days as gas is supposed to be running out.

that'll mess up the gas-fired power stations then won't it! Bring on the nuclear!! :)

Edited by brummydave

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ProDave

I have thought about "productionising" my dump controller. I see them selling on ebay for over

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