Immersion Heater / Calorifier replacement

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sprocker

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Our immersion heater is not heating the water very efficiently when on shore power or generator. The calorifier gives piping hot without fail.

I suspect that this is pointing to the immersion heater thermostat being faulty?

The cylinder itself is quite old now, and the heat insulation is not very good, so I'm thinking it may be prudent to change the whole unit, in favour of a slightly larger one, as we do spend a lot of time away from our marina berth and showers each day are a must.

I am not overly familiar with calorifier heating setup, and don't fully understand how/where the immersion heat exchanger and thermostat are in the photo below.
From the photo below anyone recommend a unit that would be as 'straight swap' as possible? Or would a more modern cylinder be a relatively easy installation?

20180415_103226.jpg
 
The electric heater element and thermostat are built in to the bit with the red cap in the photo which is replaceable.
example here:
https://www.asap-supplies.com/domes...n-heaters/supa-hotpot-immersion-heater-520923
Not saying that specific one is right for you but you get the idea.

If the thermostat is set to low you can usually adjust it by removing the red cap and and adjusting slotted head with a screw driver.
You can just see the red adjuster in this link

http://www.vetusdirect.com/calorifier-thermostatic-mixer-whmixer-1552521216/
 
Good advice. Almost certainly an easy no cost fix.

However, if you do decide to buy a larger calorifier the change is relatively easy, one pipe in and out from the engine to the coil, then a cold fresh water inlet and a hot outlet, all the same as you have at present, although maybe in different positions.

I changed one of mine a few years back, took me probably a morning to do. I was surprised at the amount of sludge that spewed out from the old one. I can recommend surecal as a good company to deal with. Surecal.co.uk
 
Also seems to be a Thermostatic Radiator Valve attached to the calorifier side - never seen that before! I agree with dpb, you should get by with adjusting the temp. Obv the hotter the water the less you'll use mixed with the cold for a shower.
 
If you're looking to replace / upgrade to a bigger size (which is always a good idea, you can never have too much hot water) then it's very easy to get one made to your exact specification at relatively low cost.

These people are good, from my own experience

http://www.newarkcoppercylinder.co.uk/

From what I've seen the proprietary ones are quite expensive for what they are.
Best to get quotes for each option and compare
 
Many thanks for all of your help gents. I will try the free fix methods first, and if that works I'll add an extra thermal jacket to help retain the heat longer.

Followed by a replacement thermostat if the free fix doesn't work....

Failing that I will look into replacing the whole unit.
 
Descale it with Citric Acid (1kg around £4) dissolved in hot water.

No tools required, just pour the bucket into the quarter full water tank and run until you taste lemon at the hot tap.

Leave a week, and flush. Safe, no taste, no damage, but it will descale the entire system!
 
Just working this out in my muffled head......the calorifier system is totally enclosed and heats up the water from it's own enclosed system via transfer of heat?

So I assume their is no chance that the descale solution would get into the engine?
 
Just remove the element. You will see if scaled. Replacements are cheap (£20) so it is not worth trying to descale it. You will also get chemicals in your domestic water system and you don’t want to do that
 
sprocker said:
Our immersion heater is not heating the water very efficiently when on shore power or generator. The calorifier gives piping hot without fail.

I suspect that this is pointing to the immersion heater thermostat being faulty?

The cylinder itself is quite old now, and the heat insulation is not very good, so I'm thinking it may be prudent to change the whole unit, in favour of a slightly larger one, as we do spend a lot of time away from our marina berth and showers each day are a must.

I am not overly familiar with calorifier heating setup, and don't fully understand how/where the immersion heat exchanger and thermostat are in the photo below.
From the photo below anyone recommend a unit that would be as 'straight swap' as possible? Or would a more modern cylinder be a relatively easy installation?

View attachment 70912
Click to expand...

You have already has some good answers but may i recommend whatever you do, you improve the way your calorifier if fixed down. The fastenings look very feeble and i would be worried that in a rough sea the whole lot could break free and if that were to ruptue the hoses to the engine you would loose coolant and overheat the engine. If it were my boat that is what i would do.

Www.solocoastalsailing.co.uk
 
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You may find there are two electric thermostats, one for setting the basic operation temperature and one as a safety switch-off set to a higher temperature.
I would have thought the electric thermostat set the temperature not the heating stat on the blue pipes though perhaps that works to stop high temperatures when the water is heated by the engine.
Previous owner may have wanted to avoid excessively hot water.
Our water is very hot when heated by the engine.
 
Fastening is standard princess fix . Radiator valve stops hot water getting to same temp as engine.
Adjust the setting under red cap .
Unless tank leaks keep it as others not as good quality
 
volvopaul said:
Fastening is standard princess fix . Radiator valve stops hot water getting to same temp as engine.
Adjust the setting under red cap .
Unless tank leaks keep it as others not as good quality
Click to expand...

Thankyou Paul.

She still needs a service if you find yourself wanting a trip West........
 
So got down to the boat tonight, checked all electrical connections to the thermostat, all seemed ok.
Turned thermostat up to 70degs, switched immersion heater on for one hour. This have me very hot water, but only 3/4 of a sink full, then it ran cold.

I'm now thinking change the thermostat anyway as it's a cheap option. Would you suggest this is the right course of action? Or could this point to something else being wrong?
 
Now that you mention it, it could be that the cylinder is not getting full. When heated of calorifier the water is very hot but there isn't as much of it as I expected. I had put it down to poor insulation and the water cooling down quickly, but it could be that there simply isn't that much hot water.
I'll spend some time trying to get rid of any potential airlocks tomorrow, and see if I can bleed the cylinder to make sure it is full of water.
Thankyou for your suggestion!
 
sprocker said:
Now that you mention it, it could be that the cylinder is not getting full. When heated of calorifier the water is very hot but there isn't as much of it as I expected. I had put it down to poor insulation and the water cooling down quickly, but it could be that there simply isn't that much hot water.
I'll spend some time trying to get rid of any potential airlocks tomorrow, and see if I can bleed the cylinder to make sure it is full of water.
Thankyou for your suggestion!
Click to expand...

Some thoughts...... If after running the imersion heater for a long while, the water is not at boiling point then the thermostat is controlling the max temperature and is therefore working correctly.

The heated water comes out of the pipe right at the top of the calorifier so there is no opportunity for an airlock in the freshwater reducing the volume in the tank.

As the imersion heater heats the water the hot water rises to the top of the tank and over time the volume of hot water at the top increases until it gets down to the level of the thermostat which then senses the hot water and turns the heater off. But note that your thermostat (inside the red cap) is half way up the tank so it will turn off the heater when the tank is only half full of hot water! So what do you think the volume of your tank is above the thermostat (difficult to judge sizes from your pictue) versus the size of your sink?

Www.solocoastalsailing.co.uk
 
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Just had a look and I would estimate that the thermostat is approximately 1\3 up the tank, and there are maybe 5 or 6 sinks full above the thermostat.
 
sprocker said:
Just had a look and I would estimate that the thermostat is approximately 1\3 up the tank, and there are maybe 5 or 6 sinks full above the thermostat.
Click to expand...

Hmmm. So if you only get 3/4 sink full of hot water after an hour, how much do you get after 2 hours? If double the amount then you have a very inefficient heater. If the same amount then the thermostat is switching off the heater before the level of hot water gets down to it, which is strange ........ Unless there is so much scale buildup on the heating element the scale is in contact with the thermostat so transfering heat to it......

When did the imersion heater last work correctly?

Www.solocoastalsailing.co.uk
 
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