I have a hot water cylinder which is heated by an immersion heater in the summer months and a boiler (indirectly) in the winter. When heated by the boiler I get plenty of hot water for a full bath. However in the summer the heater element gets the water piping hot but it runs out very quickly. I have the old style non-resettable thermostat heater but it seems to be working as i have a live current on both terminals. Might I need a longer element? or a new one altogether? also if I do have the 11" element is there any benefit in having the 27"?
Why not just continue to heat the water from the boiler through the summer ? If you have fully pumped primaries, simply set your time-clock to hot water only and if, like me you have gravity primaries ( upstairs radiators get hot when hot water only is selected ) just go around and close the valves on the upstairs radiators through the summer, just don't force them. off is not " get shut or you die ". Off is turn until it stops.
Working on the principle that hot water rises, then if the immersion only reaches 11 inches into the tank then it's only going to heat the top 11 inches of water so the longer the element.............
But you know secondary heating cylinders are not really designed to be heated by immersion alone. It's only really a backup so a bath full of water is in my experience about as good as it gets. (Well, if you fill the bath like I do!) (Shhh don't tell anyone - wasting water and all that) . :wink:
Another point; unless you are using Economy 7 then it's probably costing more to heat the water than by your gas boiler. And of course the water cools as the day progresses.
Thanks for your comments. I am not really getting a full bath at all so may need to investigate the size of the element. Have heard its cheaper to use an immersion heater in the summer because its a direct heating element rather than a coil from the oil boiler? Thanks again.