Leaving your immersion on 24/7...

Ronan H

I had been wondring about this for a while and discussing it with various people, as in, if you left it on all the time would it send your ESB bill through the roof etc... Some said it would, some said it wouldnt... I couldnt decide who to believe so at the start of June i switched ours on and its not been switched off since...

Our ESB bill arrived today... ... ...€1,867... ... ... :eek: Only joking, it was €176 from June 16th to August 15th, AND, that included constant use of the tumble dryer due to the poxified weather, and we all know how they hog the auld ESB... So im very happy with that!

So there you go, for anyone who was wondering about the above scenario, theres my experiment for them two months anyway...

Enjoy...

Hot Head

311

Fair play to you for trying it.

Not sure how this would affect the life of the element, A really big cylinder with a thermostat down lower ,would probably be more efficient.

10-10-20

This is a very interesting topic due to the factors that have to be taken into account with each situation. It's worthy of a forum in its own right!

The first item to take into consideration is the frequent misnomer about the bill 'hitting the roof'. By the very design of a cylinder immersion system, the unit will NOT remain on non-stop. The heating coil will cycle between the maximum water temperature setting (usually above 65 degrees) and the low point usually 10 degrees lower than the max. This is called hysteresis within the thermostat. http://en.wikipedia.org/wiki/Hysteresis

The rate of cycling will be determined by the rate of loss of heat from the cylinder. An unlagged cylinder will cycle faster, a well insulated unit will be slower. The surrounding area (typically the hot press) will of course be warmer with an unlagged cylinder. The lagging on the draw-off and supply pipes will also affect the cycle rate.

The rate of loss of heat increases with the higher temperature - for example, a cup of coffee will cool down faster from 90 degrees to 80 degrees, than it would from 60 degrees to 50 degrees. Therefore, temperature is a major factor of loss.

Other factors to be taken into account are the requirements for hot water in the premises. Do you require a constant flow of hot water, or do you have two or three 'pinch-points' where the flow is required? If you have the latter, it can be said that it is uneconomical to have the water remaining at a higher temperature between these times due to the previous point.

So, in all, the question of whether the cylinder is better off left on a timer, or just switched at the mains depends on the situation. Insulation and common sense is the difference between having an efficient system or a carbon dioxide generator.

DO0GLE

I wonder if the continuous heat would shorten the life span of the cylinder??

10-10-20

We are talking about a ~+25 year lifespan of a cylinder, it's not going to have a major effect.

311

DO0GLE wrote:

I wonder if the continuous heat would shorten the life span of the cylinder??

A cylinder will leak either because it's sitting on concrete and it corrodes ,electrical static causes copper to corrode or lack of use causes continous condensation and oxidisation ,then corrosion.
With new insulated cylinders ,it's actually less likely they'll start to leak.

magicbastarder

i assume you checked the bill to ensure it's not an estimate?

NextSteps

magicbastarder wrote:

i assume you checked the bill to ensure it's not an estimate?

prospect

An easier, and probably less risky way to check this is to go to your meter and note the total number of units consumed. Leave your immersion on its normal setting and check the meter at the same time the following day. Then put the immersion on constant and check the meter again at the same time the following day.

You can then calculate the number of units consumed on each setting. You will need to do this a few times to get an average and account for use of other items in the house.

10-10-20

Yes, as prospect said, you do have to monitor the consumption over a period of time, but don't forget that the chosen days should have the same flow of hot water as the other, otherwise it's not a controled environment. Also, other devices will consume power (TV etc) so this is not ideal.
You can get power meters from Maplin but you'd have to modify the method of use to suit the instalation as they only measure from a three-pronged plug output.

olaola

In our last apartment the immersion was wired incorrectly and it was permanently 'on'. There was a significant savings in the bill when we had it rectified. But then, we also used gas to heat the water in the morning instead of the immersion.

ninty9er

magicbastarder wrote:

i assume you checked the bill to ensure it's not an estimate?

I'd wonder about that too

bakerbhoy

I have my imersion on 24/7 for the last two years with the stat turned down to it's lowest setting. The cylinder is reasonably insulated , WELL FITTED JACKET. i have it on sink setting which gives adequate water for kids baths and washing up. Our esb bill never jumped.

Ronan H

:eek: - Jaysus i didnt get any Emails for ages saying that there were any replies so i never checked the thread, just got one now though! Sorry about that, i wasnt ignoring everyone.

It was a very basic experiment with very few variables, i wasnt really taking into account the time of year, usage of other stuff in the house. Ya would need to be doing it ove a long period of time in order to be able to get an accurate reading of the situation, and speaking of reading, i havent checked if its estimated or not :eek:. Im doubt that its an estimate as our box is always accessible to the meter reader, but in saying that im assuming that it gets read regularly... ... ...you know what they say about assumptions though, they can get you killed or else you will have a WOPPER ESB bill in a few months time .

Mental note to self to check that in the morning... What an oversight that would be! I will let yis know... If yis dont hear from me its either because my wife has killed me or ive cancelled my broadband to be able to afford my new high yield shares in ESB...

eHead (Get it?)

Ronan H

10-10-20 wrote:

This is a very interesting topic due to the factors that have to be taken into account with each situation. It's worthy of a forum in its own right!

The first item to take into consideration is the frequent misnomer about the bill 'hitting the roof'. By the very design of a cylinder immersion system, the unit will NOT remain on non-stop. The heating coil will cycle between the maximum water temperature setting (usually above 65 degrees) and the low point usually 10 degrees lower than the max. This is called hysteresis within the thermostat. http://en.wikipedia.org/wiki/Hysteresis

The rate of cycling will be determined by the rate of loss of heat from the cylinder. An unlagged cylinder will cycle faster, a well insulated unit will be slower. The surrounding area (typically the hot press) will of course be warmer with an unlagged cylinder. The lagging on the draw-off and supply pipes will also affect the cycle rate.

The rate of loss of heat increases with the higher temperature - for example, a cup of coffee will cool down faster from 90 degrees to 80 degrees, than it would from 60 degrees to 50 degrees. Therefore, temperature is a major factor of loss.

Other factors to be taken into account are the requirements for hot water in the premises. Do you require a constant flow of hot water, or do you have two or three 'pinch-points' where the flow is required? If you have the latter, it can be said that it is uneconomical to have the water remaining at a higher temperature between these times due to the previous point.

So, in all, the question of whether the cylinder is better off left on a timer, or just switched at the mains depends on the situation. Insulation and common sense is the difference between having an efficient system or a carbon dioxide generator.

Nice reply by the way, i only saw that now! Cheers...

Ronan

BostonB

Head wrote:

I had been wondring about this for a while and discussing it with various people, as in, if you left it on all the time would it send your ESB bill through the roof etc... Some said it would, some said it wouldnt... I couldnt decide who to believe so at the start of June i switched ours on and its not been switched off since...

Our ESB bill arrived today... ... ...€1,867... ... ... :eek: Only joking, it was €176 from June 16th to August 15th, AND, that included constant use of the tumble dryer due to the poxified weather, and we all know how they hog the auld ESB... So im very happy with that!

So there you go, for anyone who was wondering about the above scenario, theres my experiment for them two months anyway...

Enjoy...

Hot Head

Is that lower or higher than it was before? I'm assuming its no different.

Ronan H

Its pretty much the same as it usually is, but in the winter it might be a different matter altogether...

I suppose my main aim was to prove to myself that leaving it on all the time does not mean that its heating the water constantly, but only when it drops below a certain temperature, as per the Hysteresessesesis stuff that someone quoted above. So many people had said it will be heating constantly and were coming up with all sorts of reasons why that definitely was the case, some of which sounded almost credible. I just wanted to see for myself, it never really made any sense that it would be heating the water constantly but its amazing how convincing people can be when they want to be right, seemingly regardless of how ridiculous their arguement is! :rolleyes:

Funny yokes people are on occasion...

Temperature Head

BostonB

I would have said no. But anytime I've seen this argued either way I've never seen a decent technical argument for leaving it on. But 10-10-20 comments do just that. A scientific test, with controlled conditions, or simulated conditions would be needed to see what is actually happening.

10-10-20

BostonB wrote:

... I've never seen a decent technical argument for leaving it on. But 10-10-20 comments do just that.

I hope what I wrote won't convince people to leave the immersion on all of the time. That's not what I was encouraging and I'm very much against that. But, my article was as impartial as I could make it.

You've just got to look at the local situation in terms of when you need hot water - My own situation is that we have a house with a pumped shower which is used mainly in the morning, and we do a wash-up in the kitchen at night... hence my gas boiler services our requirements by coming on at 06:00 for 45 mins, and again at 16:30 for 45 mins. Of course we don't use the full tank of hot water in the evening, so the gas isn't heating for all of these 45 mins.

dingding

If there is an E after the reading it is estimated, even though may have an outside cabinet, they do not read the meter before every bill, You could read the meter and see if the reading corresponds with what should be the meter reading.

Also this time of year the mains water would be hotter and it would take less electricity to heat it than in the winter.

You can notice this with a electric shower, you need to turn it colder i.e. allow more water to flow through it in the summer to obtain the same temp as the winter.

oleras

AFAIK the ESB only do 3 physical reads a year now.... :eek:

lets hope it was your turn OP !!

AlanD

I have one of those electrisave units that measure electricity usage in the house.

Turning on my immersion to sink costs about 30c per hour.

An hour a day is all that would be required to heat enough water for what we need. On previous calculations, it would take me about 15/20 years to pay off a solar panel for some hot water. Solar? I don't think so.

Guy:Incognito

oleras wrote:

AFAIK the ESB only do 3 physical reads a year now.... :eek:

lets hope it was your turn OP !!

You can do t over the phone though. You key in the actual meter readin so it makes sure you have proper bills each month. It may stil come up as an estimated bill but when it does get read you wont be hit with a big bill.

ircoha

AlanD wrote:

I have one of those electrisave units that measure electricity usage in the house.

Turning on my immersion to sink costs about 30c per hour.

An hour a day is all that would be required to heat enough water for what we need. On previous calculations, it would take me about 15/20 years to pay off a solar panel for some hot water. Solar? I don't think so.

As noted elsewhere on this thread, the arguments are not just about payback: in part they are about doing the right thing and reducing the national demand for current.

The second point is that if you store ALL the HW the panels can produce then u can use it for heating. IMO, it is a better option than PV panels and batteries.
Using solar for just the hot water is not the correct decision in my view.