11" and 27" electric immersion heaters

|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

Wish I had done that with mine :-(

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.

Try

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.

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

. 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

Not in direct answer to your post but

Stuart

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.

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.