In an earlier contribution to this discussion,
Andy Kirkland wrote:

Hi,

I've got a hot water tank (approx 4' high) and it's currently got a
tiny immersion heater element (11" from what I can guess off the
label and also the pitiful amount of water that a single heating
produces).
I would like to replace it to enable it to heat the majority/entire
tank. Is there any rule of thumb/limit on what length of heater you
can use versus the size/height of the tank?

Andy

One thing is certain - any water *below* the element won't get heated
significantly by it.

If it goes in horizontally near the bottom of the cylinder, length doesn't
matter too much - but it makes sense to get one whose length is just short
of the cylinder diameter.

If it goes in (near) vertically from the top, you need one which extends as
far down as you can get. I doubt whether you can get one that's anywhere
near 4' long.

I assume that the immersion heater isn't your *only* way of heating the
water, and that the cylinder also has an internal coil carrying hot water
from a gas boiler boiler or somesuch as the principal means of heating the
DHW?
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!