why switch from gas to electric water heater?

lilac_dawn

Well we are not planning on opening the thing up anyway, as any damages we will have to pay for.
I will try to do the sums with the calculations previously, but it is really the cost of the standing loss that I am concerned about.

espresso

lilac_dawn wrote: »

Well we are not planning on opening the thing up anyway, as any damages we will have to pay for.
I will try to do the sums with the calculations previously, but it is really the cost of the standing loss that I am concerned about.

You have not said how much you are charged per kWh unit but the standing loss is very small at approx 1.5 kWh over 24 hours. This is how much electricity is used to replace the heat lost and maintain the full tank of 150 litres at 65 degrees.

e.g. If you pay €0.10 per kWh, it would cost you €0.15 per day to keep the tank full of water.

Obviously the total cost would depend on how much water is actually drawn from the hot water storage tank, which then needs to be replaced by cold water and heated up to temperature again.

Why don't you read your meter, switch it on and then read it again after one week. A simple calculation will show you how much extra electricity is being used to have hot water available on demand 24/7.

Richie-from-the-Boro

lilac_dawn wrote: »

Well we are not planning on opening the thing up anyway, as any damages we will have to pay for.
I will try to do the sums with the calculations previously, but it is really the cost of the standing loss that I am concerned about.

I have no doubt that the thermal loss measured data figures for your precise cylinder exist .. .. you would have to find them. Good quality foam insulated cylinders will lose heat at different rates [surface area] depending on size. A 90 litre would have a standing heat loss of about 0.8 kWh per 24hrs, a 90 litre would have a standing heat loss of about 0.8 kWh per 24hrs and a 250 litre would have a standing heat loss of about 2.10 kWh per 24hrs.

Figures are 'ish' !

matelodave

There's no need to guess or give dodgy info - it's written down in black & white in the specification for the cylinder which the OP has identified.

There are several 150l versions of the cylinder, with different mountings and slightly different heating elements which affect the amount of time it takes to heat them from 15 to 65 degrees. They range from 4 hours 46 mins to 5 hours 38 mins so a reasonable average would be 5 hours. They either have a 1650w element or an 1800w element so 5 x 1650 = 8.25kw or 9 kw for the 1800 version. The heat losses again, depend on the specific cylinder and vary between 1.37kw/day to 1.75kw a day so the average is 1.5 kw a day

So without a lot of effort you can add 8.25 to 1.5 and get 9.75kw as the amount of electricity it will use in 24 hours from switch on with a stone cold tank and it will take 5 hours to fully heat it.

Assuming you leave it on continuously then you'll lose 1.5 kw a day plus the cost of heating however much water you use, say 50 litres which is about a third of a tank = 8.25/3 = 2.75kw so your daily consumption will be around 4.5 kw - more if you use more than 50 litres a day. It will take about 1 hour 40 minutes to heat that 50 litres.

Before anyone takes me to task on precise figures these are rough average estimates - If the OP identifies the exact tank that they've got then they can do the sums themselves, however it would still be an estimate unless they were precise about the amount of water that they draw off and the exact voltage being delivered to the tank as that would have an effect on the heating output of the element (not enough to worry about though)

Cardew

Richie-from-the-Boro wrote: »

I have no doubt that the thermal loss measured data figures for your precise cylinder exist .. .. you would have to find them. Good quality foam insulated cylinders will lose heat at different rates [surface area] depending on size. A 90 litre would have a standing heat loss of about 0.8 kWh per 24hrs, a 90 litre would have a standing heat loss of about 0.8 kWh per 24hrs and a 250 litre would have a standing heat loss of about 2.10 kWh per 24hrs.

Figures are 'ish' !

Also worth pointing out that the heat is not 'lost' as such - it heats the fabric of the house.

Admittedly that heat costs more than gas; and not required for some months in the year; but it does mitigate the loss.

lilac_dawn

That would be a plus, but as it's in the bathroom, not really that helpful. It has reduced the bathroom in size to 60 cm width so certainly won't be lingering in there!

lilac_dawn

Have had the plumber leave a message to say that he building regs have changed and the gas cannot share the same flue as that of another apartment. Based on that, he ripped it out. Not sure why he could not have moved it to the kitchen, which has an outside wall and put in a new flue. Would that have been possible? That's the set-up on my home in the UK.

lilac_dawn

Have been looking to see if it is possible to switch to night tariff so this monstrosity heats overnight but presumably that will still mean running out of hot water as it is such a basic model it has no boost or override switch on it so one the water is gone, there will be none until it switches back on at night. Does anyone know if it is possible to fit these retrospectively? Otherwise I think it will do 2 showers and maybe one bowl of washing-up.

matelodave

I reckon you must be wasting water if 150 litres of it at 60 degrees doesn't last you more than a day. We can manage a decent 4 minute shower in our caravan with 10 litres of hot together with about the same of cold.

Try reducing the amount of time you stand in the shower or you could even, wet yourself, turn it off, soap and shampoo then turn it back on to rinse. Check the flow rate of your shower. Time how long it takes to fill a 10 litre bucket anything less than a minute means you could fit a flow restrictor to reduce the volume of water being used.

We only heat our 200l tank to 45 degrees** once a day and it does us for several showers, all the washing up that we need to do and the water is still hot enough for a shower the next morning if we want one before the heating kicks back in.

** to satisfy the H&S lot, it gets an automatic boost once a week to 60 degrees to sterilise it against legionella

Pincher

What are you worried about?


The main heating cost is using a shared gas boiler, probably in the basement. It's probably more professional and efficient than a domestic one.


In the UK, electricity is three times that of gas per kWh, but yours is only double. If your old gas water heater was 60% efficient, and the electric element is 100% efficient, it's only a little bit more expensive to do it by electricity, and certainly safer.


If you had to heat your flat by electricity, moan like hell, but hot water doesn't even justify a whinge.