Immersion heater question?

HappyMJ

moneysaver78 wrote: »

ok PLEASE can you lot help me? im expecting my first bambino soon & the bad weather is fast approaching so i need to sort my heating out ASAP. i have been reading so much on the net & on here that i am so confused & literally have square eyes....
my house has ceiling heating (heat mats) which are breaking & yes i hear you say heat rises so whats the point? i have no gas in the road so am all electric. the ceiling heating is on all day which is expensive (it cannot go on E7) but my emersion is on E7 although this seems pointless because it is a 3bed house and all 3 adults work 8am-5pm . the water that was heated on E7 over night is wasted as we all shower in the evening & so ive had to put a timer on the emersion which heats up at peak time :O(
i have been reading about water filled rads/ air source pumps/ storage heaters/electric boilers/wet systems..... allsorts... and its driving me literally insane i just want some sound straight forward advice please on a system thats not going to cost me the earth to install and is as economical as possible to run.....i was thinking of electric boiler & water filled rads plugged into E10? but as i say the more i read the more i get confused...i need to decide and install fast PLEASE HELP ( Cardrew you seem harsh but knowledgable! :O)
many thanks in advance

No Gas? Then install storage heating. Don't switch to E10 it's not competitive enough. You will get the best tariffs on E7. It has some major disadvantages such as controllability and they may if not sized correctly and it's cold enough they will run out of heat by the late evening. Learn about how to use them and they can be good. People either like them or hate them.

Otherwise if you don't like that then switch your electric tariff to a standard 24 hour tariff (10p per unit or less for all units) and use daytime heating such as cheap to buy convector heaters which will be quick to install and then think about installing an air source heat pump later on. Then just leave the immersion on all the time turning it's temperature down to save a bit of money.

I would avoid water filled radiators or anything to do with electric wet central heating. It will cost the earth to install and instead of just heating one room as you would with a convector heater you will be heating the whole house therefore costing more.

I agree with you with the need to stop using the heat mats. Turn them off. Pointless heating the ceiling.

Why is your water cold by the evening? Is the tank insulated to some degree? My tank stays warm for 3 days. Hot for 1 day then a bit cooler on the second but still quite warm on the third. Not quite warm enough for a bath but fine for hand washing.

Install an electric shower.

Options...options...options... It's my opinion too and you'll get a lot of different ones from elsewhere. Try and get gas if you can get it cheap enough. Otherwise just switch to a good tariff and save as much as possible. How much electric did you use over the past 12 months on the E7 rate and how much on the day rate?

jalexa

alastairq wrote: »

..As it is a single element cylinder..I am aware that the bottom levels will always remain cold...

I am presuming here that you and your plumber have conspired to select a like for like cylinder size with a single top mounted element boss? In that case selection of the correct element length is crucial, they commonly come in a range of sizes up to 36". Where is the evidence that what the plumber says is correct?

so I presume the old thermostat had a higher upper temperature limit, thus providing 'more' hot water?

Perhaps a combination of that and a longer heating element.

So..are there any thermostats out there with a higher temp range?

Bath water delivery at 70deg is irresponsible (and for sound reason illegal in "new build"). Your landlord will not thank you when the next tenant's child gets scalded.

alastairq

Bath water delivery at 70deg is irresponsible (and for sound reason illegal in "new build"). Your landlord will not thank you when the next tenant's child gets scalded.

Firstly, that is not the'delivered' temp, but the temp the thermostat switches the immersion off at......secondly, as soon as even a modest amount of hot water is drawn off, the cylinder re-fills with fresh cold water, thus lowering general water temps.....thirdly, a LL's inspection on change of tenant will find the stat turned down anyway....I don't intend to move in the near future,which pleases the LL as for some reason long-term reliable tenants are not so commonplace.

I am presuming here that you and your plumber have conspired to select a like for like cylinder size with a single top mounted element boss? In that case selection of the correct element length is crucial, they commonly come in a range of sizes up to 36". Where is the evidence that what the plumber says is correct?

No conspiracy at all.....original immersion failed, agent informed, plumber arrived for inspection, made report to agent. Report based on like-for-like exchange...since old cylinder fulfilled my needs as the rent-payer, no reason to suspect new cylinder would not provide likewise........LL consulted and funds authorised.....job carried out.

Plumber had no reason to inspect old equipment on removal..so does not know whether old immersion was extra long.

Where can extra long elements be obtained?

I am happy to fund upgrades, since it is my quality of life which is important to me...

HappyMJ

alastairq wrote: »

Firstly, that is not the'delivered' temp, but the temp the thermostat switches the immersion off at......secondly, as soon as even a modest amount of hot water is drawn off, the cylinder re-fills with fresh cold water, thus lowering general water temps.....thirdly, a LL's inspection on change of tenant will find the stat turned down anyway....I don't intend to move in the near future,which pleases the LL as for some reason long-term reliable tenants are not so commonplace.

Your water must work different to mine. Mine is delivered at the thermostat temperature until it runs out then it's 10 degrees. The tank is next to the bath behind a wall through less than 2 metres of insulated copper pipe so has no time to cool.

alastairq

through less than 2 metres of insulated copper pipe so has no time to cool.

That would appear to be a factor....I am loathe to rip out walling and cupboards to insulate the pipes....when fully hot [immersion not running] only the top 3 inches of exposed pipework from the tank top are hot to touch.

Even when running a bath, the water temp is sub-60 degrees [measured last night]...so either the thermostat is new-but-faulty...or the tank input cools the hot water too quickly? [the immersion is off when baths are run..although the immersion has a boost immediately beforehand....the cylinder is heated when the off-peak [E7] tariff cuts in]

The house is quite old....3 foot thick walls, etc...and I cannot easily access the plumbing apart from within the airing cupboard.

jalexa

alastairq wrote: »

Where can extra long elements be obtained?

To answer your specific question, e.g. here...
http://www.tlc-direct.co.uk/Main_Index/Water_Heating_Index/Immersion_Heaters/index.html

However... 27" is the most common length, which for typical cylinder sizes (and modern bath sizes) for most people provides adequate performance. I do not believe you have correctly identified the reason for the performance shortfall in your new cylinder, *if* it is correct that a 27" element is installed.

In your case, evening bath with off-peak heated water indicates a need for a properly sized E7 cylinder. If your plumber didn't *suggest* that to the landlord then that was less than competent. Of course the landlord may have baulked at the extra cost, which is another matter.

Given that you have provided no technical details about the new cylinder (even after being prompted), meaningfull advice is impossible.

alastairq

If you only have one element I do not understand the role of the timer. How long "*exactly* is "proper heating time" and at what time?

As stated earlier, the timer controls the immersion, switching it on during the off-peak [E7 as there are storage heaters too]...and as stated earlier, the off-peak supply affect the complete wiring system, not just a separate circuit.

As stated earlier , there isn't even a supply for two immersion elements, so an [E7?] cylinder wasn't considered.....there being no obvious evidence it would have been beneficial anyway...at the time.]

tank dimensions over lagging, approx...1050 mm tall, with circumference of 1400 mm....measured outside lagging......as said before,restricted space..tank is half buried inside stoothed wall!

I have no documentation regarding the new cylinder...so cannot be any more precise.

Plumber is helpful, contracted to Agents....and seems sure the element is a 27 inch one.

Without withdrawing the element and measuring, I have to accept what he says is correct, I suppose..

Apart from height of cylinder...what other issues surround fitting a longer element?

I cannot tell from the images......but would the thermostat also extend down the extra length of the element?


I don't think cost was an issue...there being but a few pounds difference all round.

In your case, evening bath with off-peak heated water indicates a need for a properly sized E7 cylinder. If your plumber didn't *suggest* that to the landlord then that was less than competent. Of course the landlord may have baulked at the extra cost, which is another matter.

Although the house is equipped with E7 for heating....the off-peak applies, as said before, to the whole electrical system....

The immersion can be 'run' at any time...but is timed to come on during the off-peak period, and if needed, a boost at other times....I pre-set the digital timer to this effect...much will depend on work times, presence of my child, etc.

Apologies for less-than-ideal details.....not sure where the prompting occurred....?

{confusion arose with another poster asking questions on this thread?]

I will pursue the 'longer' immersion element approach...happy to pay for it myself...although I have no doubt whatsoever the LL will insist on paying anyway..

such is life renting in a rural area...?

jalexa

alastairq wrote: »

tank dimensions over lagging, approx...1050 mm tall, with circumference of 1400 mm....measured outside lagging......

OK, *probably* that is a 144l size (1050mm x 450mm dia). I would say that was adequate capacity. Also assuming that it is "direct" ie no heating coil to obstruct the element you will need to measure (from the boss position and angle) if a longer element would fit. Personally I remain unconvinced that the assumed 27" element shouldn't be adequate.

It would be worth checking your overnight consumption to verify how much energy is being consumed heating the cylinder. (edit: a 3kW element should reheat a 144l cylinder from 10 deg to 60 deg in 2hrs 48m)

Apologies for less-than-ideal details.....not sure where the prompting occurred....?

see Richie-from-the-Boro

Richie-from-the-Boro

- element length - a pointless task relative to its outcome - I don't agree - if you could fit one twice the size you would heat the same area of water water in half the time before the stat switches the element off - the problem is its an immersion heater type tank .. .. not an E7 bottom element tank.

Get one of these

Put a 27" element in the bottom and you will get a dustbin full of boiling water.

Put a 27" element in the top and you will get a 1/4 dustbin full of angry bubbling boiling water if you are lucky.

The size is ok the 27" is ok for overnight - its just in the wrong place

Cardew

jalexa wrote: »

It would be worth checking your overnight consumption to verify how much energy is being consumed heating the cylinder. (edit: a 3kW element should reheat a 144l cylinder from 10 deg to 60 deg in 2hrs 48m)

How could he measure that, for just the immersion, if all his electric is on cheap rate for the 7 hours?

It will do no harm to have his immersion heater timed to come on for the full 7 hours. Modern HW tanks lose heat equivalent of between 1kWh and 2 kWh in a 24 hour period with water @ 65C(tested to a BS)

Any heat lost warms the fabric of the house anyway - it will work like a 'very slow release' storage heater;)

If left on the full 7 hours natural convection currents within the HW tank should ensure that all the water in the HW tank is at the same temperature.