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mickqc

hello,

Just fitted a direct combination cylinder 900 x 450 (120 ltrs.) cylinder plus header tank
the immersion was an 11` 2.7 - 3kw.
Everything working fine but water not very hot and it was set to 70.
Will it just take longer to heat up as only waited around for an hour.
Worried that the immersion was under sized should i have gone for a 14`one
thanks for your help
 
I take it's side entry? The 3 kw apply to all domestic immersion heaters it just the position in cylinder that causes a short fall in hot water.
 
hello,

Just fitted a direct combination cylinder 900 x 450 (120 ltrs.) cylinder plus header tank
the immersion was an 11` 2.7 - 3kw.
Everything working fine but water not very hot and it was set to 70.
Will it just take longer to heat up as only waited around for an hour.
Worried that the immersion was under sized should i have gone for a 14`one
thanks for your help

11 14 24 these are just size the immersion is 3kw max?.did it have another tapping for another immersion
 
yes its side.
was going to get a 2 tapping one but when the builder found out it was a special order and we had to wait a week he went for the single.
Thought a single would be fine though to be honest.
 
Using one short immersion the lowest side tapping needs to be where its put, giving you maximum volume of hot water.
 
its very low down and as you said heats the water above but would it of made any difference if i`d of gone for a 14` one
 
It will take over 2hrs to heat a 117litre cylinder by 50º.

Work it out for yourself near enough using the formula mcΔT
where
m=mass in kg (1 litre of water = 1kg)
c=specific heat capacity of water = 4.18kj/kg/ºC (approx)
ΔT= the change in temperature in ºC (T2 - T1 eg. 60-10=50º)

the answer is in kj

your immersion is 3kw so divide your answer by 3 and that is the time in seconds it will take to heat the cylinder and divide by 3600 to get it in hours.

Btw a 3kw element whether it is 11" or 15ft long is still just a 3kw element.
 
if its 14`.
being longer it would cover more area, surely?
i should expect a phone call off the customer then !!!
thanks for help.
 
The time taken before you have (some) up to temperature water depends on where the immersion is positioned in the cylinder.
A top entry will give you some hot water quickest as parts of the element are in contact with the water at the top.
A side entry in the bottom will take the longest time to heat as it has to heat the full cylinder at the same time. This is due to stratification. This is the worst choice. A longer element going across the cylinder makes very little difference.

Old bolt on side entries had a sleeve over the element and a spreader tube on them which allowed the warmer water to reach the top of the cylinder quickly.
This can't be done on screwed immersions for obvious reasons.
Here is a photo of a Howden 6 bolt side entry. IMG_2411.jpg
 
you would think nowdays there would be an option to drill a hole and fit an extra one in the cylinder.
Maybe with a sealing flange on the immersion.
i originally ordered a 2 immersion cylinder but the merchants got it wrong.
bummer!!!
 
You can still buy 2, 4 and 6 bolt side entry immersions like the one in the photo.
Look up Howden.
 
do they connect into the 1` BSP spare conections on the top or bottom.
it would have to go in the top so as not to interfere with the current fitted one (at the bottom) ?
what kind of price are we looking at?
 
I was going to explain it but it is easier to do this.
6 bolt.jpg
Just saw the date on that sheet.
Had that old immersion lying around the yard for 20 years:)

There are other ways to add one but all involve cutting a hole in the cylinder.
 
looks a very nervous procedure.
can you not use the screw in one through the spare 1" BSP.
the drawing shows it to be fixed at the bottom would that not interfere with the already fitted one.
thanks for help
 
Nothing to it. It is easy to fit. I've done them with a 3/8" drill, a half round file and a pair of curved tin snips:p

Other alternative is this
2¼ domed essex flange.JPG
and a top entry.
 
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