Immersion heater question!

Cardo

Cardo

Well-Known Member
Joined
3 Oct 2005
Messages
4,231
Location
In a plastic tub!
www.yacht-tinkerbell.co.uk
I'm afraid the questions never end!

So as with many others, the boat has an immersion heater that runs off the 240v circuit.
There is a switch to turn it on/off by the circuit breakers under the nav seat.

Question is, is there any issue with leaving this on when hooked up to shore power if we'd like hot water available? This would be only whilst on the boat, of course. Will the heater automatically turn itself off if the water in the tank is hot enough or will it just keep running on and on and on until turned off at the switch?

Unfortunately, I don't know what make or model it is, so I guess asking how it generally works?
 
Cardo said:
I'm afraid the questions never end!

So as with many others, the boat has an immersion heater that runs off the 240v circuit.
There is a switch to turn it on/off by the circuit breakers under the nav seat.

Question is, is there any issue with leaving this on when hooked up to shore power if we'd like hot water available? This would be only whilst on the boat, of course. Will the heater automatically turn itself off if the water in the tank is hot enough or will it just keep running on and on and on until turned off at the switch?

Unfortunately, I don't know what make or model it is, so I guess asking how it generally works?
Click to expand...

There'll be a thermostat on the immersion heater which you should be able to adjust to the temperature you want. Ours was a lot better turned down from 80deg to 60deg to avoid scalding :)
 
hotwater

I'd like to know the answer myself but the calorifier is insulated to retain heat for quite sometime, so we put it on for an hour and that usually is enough for showers etc. These more modern units probably have cut-offs built in at a certain temp, but no need to leave it on all the time as in our experience the water does stay hot for quite a while.

Check with the maker of the boat if known but some clever bod on here will know....
 
Cardo said:
I'm afraid the questions never end!

So as with many others, the boat has an immersion heater that runs off the 240v circuit.
There is a switch to turn it on/off by the circuit breakers under the nav seat.

Question is, is there any issue with leaving this on when hooked up to shore power if we'd like hot water available? This would be only whilst on the boat, of course. Will the heater automatically turn itself off if the water in the tank is hot enough or will it just keep running on and on and on until turned off at the switch?

Unfortunately, I don't know what make or model it is, so I guess asking how it generally works?
Click to expand...

should be fine, thermostat should be set around 40-60, just make sure your water tanks are kept topped up.
 
generally imersion heaters have a thermostat fitted as well. the adjustment is under the cap where the wire goes on the cylinder.

so ok to leave on while on board..

usually turn ours off at night though, for less leky waste.
 
Check where the wires connect to immersion heater as thermostat is likely to be located there. A few years ago, in a domestic situation, a thermostat stuck on and overheated the water and calorifier vented into the plastic supply tank with fatal results (baby sleeping in the bedroom below as I recall). Since then, all immersion have not only been fitted with the standard thermostat, but also an overheat stat (belts and braces). Once you confirm it has a stat (very unlikely not to have one), leaving it on should be fine, but be aware, thermostats contacts can stick on, even though the chances of this type of failure are very low, and would show as water boiling up).

Whilst domestic immersions are normally around 3kW, boat ones tend to be lower, with 1 kW being quite common, and although they take longer to heat up.
 
Jean said:
Check where the wires connect to immersion heater as thermostat is likely to be located there. A few years ago, in a domestic situation, a thermostat stuck on and overheated the water and calorifier vented into the plastic supply tank with fatal results (baby sleeping in the bedroom below as I recall). Since then, all immersion have not only been fitted with the standard thermostat, but also an overheat stat (belts and braces). Once you confirm it has a stat (very unlikely not to have one), leaving it on should be fine, but be aware, thermostats contacts can stick on, even though the chances of this type of failure are very low, and would show as water boiling up).

Whilst domestic immersions are normally around 3kW, boat ones tend to be lower, with 1 kW being quite common, and although they take longer to heat up.
Click to expand...

Unfortunately, it's a bit hard to check. The immersion heater is on the opposite end of the tank from the access point and is therefore rather difficult to check without some serious effort in moving the tank!
I may give it a go anyway, just to be happy.
 
Cardo said:
Question is, is there any issue with leaving this on when hooked up to shore power if we'd like hot water available? This would be only whilst on the boat, of course. Will the heater automatically turn itself off if the water in the tank is hot enough or will it just keep running on and on and on until turned off at the switch?

QUOTE]

All immersion heaters have a built in thermostat . You can leave it on and it will cut in and out and it will not boil the water (unless it is faulty).

We have left ours on overnight, on a few occasions, with no issues and at very little cost.
Click to expand...
 
Cardo said:
The marina we have contracted for our berthing requirements from April onwards has unmetered electric :D
Click to expand...

Does this mean you pay a standard fee for the electricity no matter how much or how little you use. It would seem that if you dont use much you will pay a premium for the pleasure, I dont think there are any free meals anymore.
 
All_at_Sea said:
I'd like to know the answer myself but the calorifier is insulated to retain heat for quite sometime, so we put it on for an hour and that usually is enough for showers etc. These more modern units probably have cut-offs built in at a certain temp, but no need to leave it on all the time as in our experience the water does stay hot for quite a while.

Check with the maker of the boat if known but some clever bod on here will know....
Click to expand...

I agree. With or without a thermostat, why try to make hot water even hotter? And not all of them have thermostats.

I find if I turn it off after 30 mins to an hour, I don't have to mix with cold water, and can use one hand to run hot (not scalding) water and that is very helpful when cleaning up with tools and you-know-what in the other hand.
 
Last edited:
Most calorifiers are quite small - just a few gallons - and the heating element is around a kilowatt, possibly more. Without a theromstat, it would boil in less than 30 minutes - with very noticeable consequences. You need them to get quite hot otherwise they can become comfortable homes for legionella and other nasty things.
 
Who knows?

The real question is why bother?

If you are on the boat every day then leave it on. If there is a problem then it will be apparent very quickly.

If you are not on the boat then leave it off. A decent immersion will heat the water in an hour or less, so no need to leave it on unless you are one of those few people who have been away from their boats and require instant hot water without turning on the engine or boiling a kettle.
 
Hot water supply.

The situation used to be that the thermostats would fail in the 'On' position and eventually the water would boil. These days, they fail in the 'Off' position so much safer.
When I lived aboard my boat in France, I used a mains water supply so that water was available with out a pump. This also kept the hot water tank full. All that is necessary is an inlet PRV and a tap to isolate the onboard tank. Much more convenient. Of course there have to be enough taps available. Not a problem in most French marinas where there is often one for each boat.
 
You must log in or register to reply here.

Other threads that may be of interest

UK-WOOZY
Autoterm 4kw heater was blowing smoke out into the cabins
Replies
19
Views
500
UK-WOOZY
UK-WOOZY
B
Heater
2
Replies
26
Views
702
NormanS
N
jamie N
Chinese heater exhaust 'insulation smoking'
Replies
13
Views
686
Dellquay13
Dellquay13

Share this page

Top