Immersion versus Mainland heater system

lotusz31

I am currently studying the difference between the immersion (with lagging jacket) versus the type of 24/7 water cylinders we get in mainland Europe. An Irish comedian in the US has a gag about this, and I see everyone in Ireland going mental about leaving "d'immersion" on. In France and Belgium I never even thought of switching it OFF in teh first place, so I decided to find out, but there is little to go by, it seems that the sealed units you get in Europe just don't exist here.

So far, I've established that there is a huge difference in the operating temperature, EU units typically set around 55C, whereas here in Ireland I can easily burn myself. I've heard claims that it is more efficient as you only heat when you need water, but I'm not convinced of that...

Heating the water up to high temperatures is going to result is huge losses during the transportation phase, as well as the loss of heat because the "lagging jacket" you can see in the picture is a lot less efficient then the fully sealed insulation on the water tank.

This just reeks of the equivalent of heating up the house for an hour or so a day, with high heat radiators instead of keeping the heating on a low level throughout the day, only to lower by a few degrees at night. There is plenty of evidence that the latter is a lot more economical.

One friend put it down to the lack of guaranteed water pressure and incompatibility of such a water supply with the sealed tank system, but I still struggle with that as I don't see a principle difference in both type of heaters, apart from the operating temperatures and the way they are constructed/insulated

Anybody have experience with both systems and coudl shed some light?

Cheers
Karel

touchdown77

You'll get better answers posting this in Plumbing section or electrical.

One key point to bear in mind is that Ireland is one of a handful of countries that offers cheaper electricity at night. This encourages water heating at night which means storing it for daytime usage and hence the industry of lagging jackets etc.

colm_mcm

there would have been back boilers used in open fires and ranges as well back in the day

Joe1919

I once done a comparison between a Ariston 10 litre water heater and a copper cylinder immersion heater set at sink only. The Ariston standby consumption at 60 degrees was slightly under 1 unit (kw/hr) per day whereas the immersion also set at 60 was slightly under 3 units/day. The copper cylinder was modern and had that green foam insulation stuck to it.
There was also very heavy losses in the long 3/4 inch pipes between the cylinder and bathroom as almost 1- 2 litres of cold water needed to be drained out of the hot tap before it got hot.(and there is a corresponding amount of hot water left in pipes after use).
My conclusion is that copper cylinders with immersion heaters are very inefficient compared to undersink units (unless one frequently takes baths).

John T Carroll

Joe1919 wrote: »

I once done a comparison between a Ariston 10 litre water heater and a copper cylinder immersion heater set at sink only. The Ariston standby consumption at 60 degrees was slightly under 1 unit (kw/hr) per day whereas the immersion also set at 60 was slightly under 3 units/day. The copper cylinder was modern and had that green foam insulation stuck to it.
There was also very heavy losses in the long 3/4 inch pipes between the cylinder and bathroom as almost 1- 2 litres of cold water needed to be drained out of the hot tap before it got hot.(and there is a corresponding amount of hot water left in pipes after use).
My conclusion is that copper cylinders with immersion heaters are very inefficient compared to undersink units (unless one frequently takes baths).

Its interesting that the 10 Litre water heater loss seems quite high, it works out at almost 3.6C/hr (1*860/24/10) but is definitely the way to go if relatively small volumes of water are required. Combined with an electric shower would/should result in very low energy costs particularly in an "adults only" house where a 5 minute shower costs only around 15 or 16 cents/shower. Instantaneous hot water taps are another option which take up no space whatsoever but I would personally be a little wary of their reliability because of all the switching but good quality ones might work away fine.

For anybody thinking of fitting under sink water heaters I'd fit them to UK water regs as there are no regs in Ireland and most water heaters installations are not safe.