Calorifiers

[Actionmat]

I'm looking to fit a calorifier on my boat. I've seen them in 15, 22, 40L sizes but as I haven't a clue what size I need. My freshwater tank holds 200L and I want to be able to generate enough hot water for 2 with just a couple of hours running time. I have no shore power so it will only be heated from the engine.
I know the hot mixes with cold first, so you get more than 22 litres of hot from a 22 litre tank, but does anyone know how much hot water they generate and how long they take to heat up?

 

[David2452]

I'm looking to fit a calorifier on my boat. I've seen them in 15, 22, 40L sizes but as I haven't a clue what size I need. My freshwater tank holds 200L and I want to be able to generate enough hot water for 2 with just a couple of hours running time. I have no shore power so it will only be heated from the engine.
I know the hot mixes with cold first, so you get more than 22 litres of hot from a 22 litre tank, but does anyone know how much hot water they generate and how long they take to heat up?

That is a bit of a how long is a piece of string question, hot water for a couple, to do what? one (boaty) shower each with a bit of washing up and hand washing not too long after turning off the motor? then a 25l should suffice, they don't all mix with cold water on leaving the calorifier, they need to be fitted with a mixer and although some come with that as standard it is by no means universal but and easy retro fit anyway.

 

[Momac]

At river speeds I would say something approaching 3 hours running from our diesel engine is needed to get the tank hot. No doubt a lot less time if going fast.

 

[PCUK]

20 minutes ticking over gives us a hot tank full. If the engine runs at 80c then the water in the calorifier will also be 80c so you don't need much for a nice shower when mixed with cold!

 

[Sandyman]

My advise would be to fit the biggest one you have room for.

 

[Actionmat]

Thanks for the helpful advice everyone, much appreciated.

 

[blobby47]

Hi
last year same questions , found a manufacturer Surecal on isle of white, do twin coil version so engine water passes through unit twice heats quicker ,good prices ,come with all valves and fittings , most helpful
cheers bob

 

[Hadenough]

Hi
last year same questions , found a manufacturer Surecal on isle of white, do twin coil version so engine water passes through unit twice heats quicker ,good prices ,come with all valves and fittings , most helpful
cheers bob

Never heard that one before, I suppose you could link the two coils, have you done it?
I thought main reason for twin coil was for heating from an alternative source such as a Hydronic.

 

[blobby47]

Hi again folks

you can pipe these any way you like but engine heated water into coil 1 and out,and straight back into coil 2and back to engine..the guy at surecal told me approx. heat input into hot tank water was approx. 1.25 kw per coil dependant upon engine water temp(for 25 litre calorifier)give twice as fast heat up as a 1 coil unit.cheers bob

 

[David2452]

Never heard that one before, I suppose you could link the two coils, have you done it?
I thought main reason for twin coil was for heating from an alternative source such as a Hydronic.

That is the reason, well the original one anyway (also twin engine supply) but I have installed them using both coils from one heat source on occasion before. Also I have disconnected the joining loop from some previously installed that way to use one when installing a new coolant based heater, they will not heat up twice as quickly as a single coil of half the size but certainly quicker by a good margin.

 

[blobby47]

Hi Actionmat

I guess a domestic water tank of some 200 ltrs means a 30 ft + boat ,what engines and what do you use it for.
||Just for your information some bigger diesels on inland water ways (5 knots) don't work hard and don't, or take forever to get up to temp, so you wont be happy with your hot/ tepid supply this when a webasto type coolant heater comes into its own,12/24 v diesel powerd, no mains required. heats 25 ltrs in 20 minutes
cheers bob

 

[Assassin]

It all depends on the amount of heat going in and the efficiency of its thermal transfer rate, this can be affected in many ways but the best is buy a quality unit with a good thermal transfer rate.

 

[bendyone]

I have a 22l size heated by the engine and 240V 1.2KW heater, Will do 2 good showers from hot.

 

[Actionmat]

Thanks for all your advice. She's a 1970 RLM with twin perkins 4107s and at thames speeds rarely gets above 80degrees.
The space between the engines looks like the easiest place to fit a tank, but putting it on the other side of an engine would give me more room for servicing the old sewing machines.
Are they best placed in the middle for weight distribution or should I be more concerned about engine access for maintenance? A couple of boaty showers and the washing up would be great, but sometimes we rarely run the engines for more than an hour if just visiting Hampton Court for the night.
Apart from long summer breaks, she gets used little and often.

 

[Matt341]

I previously fitted a 15 litre calorifier to a 30foot boat, I wanted to fit something around 25 litres but limited space made the 15 litre the only choice. I was surprised how efficient it was, it would provide enough hot water for a day at anchor - dish washing, couple of showers, use of the transom shower for washing down etc before it would start to cool down. The make was Quick nautic and from memory it was pretty well priced.

 

[NormanS]

The closer that you can fit the calorifier to the place where you expect to use most of the hot water, the better. It saves running off water before the hot water comes, and then leaving hot water in the pipe, when you shut the tap.
Calorifiers are great. You're making use of heat which was going to waste, and you're saving the planet.