11" and 27" electric immersion heaters

[Dave Baker]

Screwfix list both lengths of heater in two types - suitable for hard water areas and not suitable and all four are 3kw.

It says nothing about whether they both fit both lengths of cylinder (900mm and 1050mm) or whether the short is for 900mm and the long for 1050mm. I know that the heater out of my old tall cylinder was too long to fit into my new 900mm cylinder so I have to buy a new heater. 27" ought to fit into

900mm easily enough but maybe the coil will be in the way. However that would surely be the case with a 1050mm tank too?

So why the two totally different lengths and is the short (cheap) one going to be ok for me? All I can think is that the longer one also fits both cylinders but for a few quid more does a better job of heating the water evenly down to the bottom of the cylinder.

-- Dave Baker Puma Race Engines

Camp USA engineer minces about for high performance specialist (4,4,7)

[Dave Fawthrop]

|Screwfix list both lengths of heater in two types - suitable for hard water |areas and not suitable and all four are 3kw. | |It says nothing about whether they both fit both lengths of cylinder (900mm |and 1050mm) or whether the short is for 900mm and the long for 1050mm. I |know that the heater out of my old tall cylinder was too long to fit into my |new 900mm cylinder so I have to buy a new heater. 27" ought to fit into |900mm easily enough but maybe the coil will be in the way. However that |would surely be the case with a 1050mm tank too? | |So why the two totally different lengths and is the short (cheap) one going |to be ok for me? All I can think is that the longer one also fits both |cylinders but for a few quid more does a better job of heating the water |evenly down to the bottom of the cylinder.

Beware hot water rises, so an immersion heater only heats water **above** the element. So you need the longest one which will fit. I have however

*heard* of, but not used, fitting the immersion heater in a tube which causes the heat to suck the water from the bottom of the tank. Thinking about this you will need a good sized gap/holes at the bottom and top of the tube to allow circulation.

Wish I had done that with mine :-(

[hzatph]

The idea is that some booster immersion heaters are just at the top of the tank to reduce electricity costs - long ones reach all the way down and heat the whoel tank on cheap rate electricity. I think some tanks have side entry points for immersion heaters too and these may need the shorter element.

The specifications for your new tank should help you find what you need.

[Christian McArdle]

27" are for top mounting pointing down. 11" mount on the side of the cylinder, horizontally. I prefer this type, as it is much more likely to accurately heat the entire cylinder (or half of it, if mounted appropriately). However, you do need a flange to fit it into.

Christian.

[Michael Chare]

Try

you live in a hard water area you could consider their Titanium ones which only cost a few quid more

I am sure that I read somewhere that an immersion heater should be no longer than 100mm less than the height of the tank (assuming top fitting) but I can't find the link. Certainly I have a 27" heater in a 900mm tank. It passes through the centre of the primary coil.

[The Medway Handyman]

If its fitted from the top then you need the longer one - of only part of the tank will heat up.

[legin]

. 27" ought to fit into

Useful tip. If you find that the immersion element is hitting the coil, remove the element and using the round of a claw hammer you can adjust the boss slightly to enable the element to clear the coil, obviously aiming for the middle of the coil. Legin

[Stuart]

Not in direct answer to your post but

have a more of a selection ..

Stuart

[Doctor Drivel]

You can fit a bronze shunt pump controlled by a cylinder stat, that pumps out of the top of the cylinder and into the bottom, circulating all the water. Then a short 11" immersion can be used. You can get 11" 6 kW immersions too, so a faster warm up, but expensive though. And all the cylinder heated too.

Putting on a shunt pump and using an 11" immersion means that only the top half of the cylinder may be used for sinks, and using the shunt pump a full bath is given.

Having moving water across the immersion element gives longer life as the hot spots are eliminated/reduced.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "legin" saying something like:

If you have one kicking around, screw a blanking piece in and tap it gently to move the threaded portion to the right angle.