Any way to improve calorifier heat-up time?

[catlotion]

I've moved to a swing mooring and now dependent on my engine to heat water.

In neutral, the engine takes some time to warm up the calorifier (and I recognise the potential for engine wear idling for long periods).  It seems fine running under load.  However, with the proximity of other boats, I'm not really able to run it in gear.   

Any tips for improving the heat-up time please?  Didn't know whether a different thermostat could be fitted maybe?

Boat is Bav 30 Cruiser with Volvo D1-20 - standard calorifier.     I have thought about diesel heater for hot water but would need to change to twin coil calorifier so it all gets a bit pricey. 

or maybe one of these fitted to my current Planar heater:   https://www.bobilvans.co.uk/howitworks

[elias]

Bobil looks great ! Think also this ( I saw somewhere in the forum ) , in my heater I changed the heating element with one custom made around 250w. So I use the inverter while engine is running to heat parallel with the engine while motoring from a place to another . If you have strong panels it could work also without engine I guess.

[JEN-et-ROSS]

Just boil the kettle....!! No..??

[symphony2]

Basic physics. At idle the engine is not producing any real power and therefore little heat. Calorifiers work by using some of the excess heat when the engine is working. So only way of heating the water faster is to introduce another heat source. 12v does not work again because it produces minimal heat. diesel fired wet heating systems can have a circuit for the calorifier, but expensive and complicated.

As suggested use your only other source of heat - gas cooker and kettle.

[SimonS]

Why not run the engine at a higher rpm in neutral?

[symphony2]

Still won't produce significantly more heat as it is not under any load - and very bad for the engine!

[Yngmar]

Switch on the inverter and plug the electric immersion heater from the calorifier tank into it. Now the engine heats the water both via waste heat and via the alternator - should be much quicker.

[symphony2]

Assumes you have an inverter big enough to power the immersion heater.

[diverphil]

could run a small genny to power 240 v , use this to power the element, charge batts at same time.

[symphony2]

Seems overkill tp have a noisy smelly petrol generator running in a tranquil place such as the lakes just to get hot water!

[diverphil]

It does. But the option of running boat engine is  the same . Possibly more noise.

[symphony2]

But avoids having to carry the generator on a small boat plus the petrol. Has to be run in the cockpit to be safe. Overkill just to get hot water.

[catlotion]

Switch on the inverter and plug the electric immersion heater from the calorifier tank into it. Now the engine heats the water both via waste heat and via the alternator - should be much quicker.

Quite like this idea.  Any idea what size inverter I'd need though?  Pretty hefty I imagine!

[JEN-et-ROSS]

We have a 2200W Inverter hardwired into the system and use it to power a low-power microwave (500W) and other items that only require a few minutes of use but need 240v.
The problem is that to heat your water you'll require to run the engine for quite a long time at fairly high revs, and during all that time your alternator will be flat out so it'll get very hot, also, if the belt isn't tensioned correctly it'll likely screech, and the fact that any cabling and terminals from the alternator to the battery that aren't up to spec will also heat up alarmingly and make a nuisance of themselves, so making boiling a kettle the only really sensible option...

[Jeffatoms]

This is a topic of which I am quite familiar as my wife and I make a reputable brand of marine water heaters.  Power conversion and consumption are the limiting factors.  Running a decent load off of the inverter is difficult given that most battery banks would be depleted before one hot water heating cycle completes.  If you are considering hydronic, it can be added to a single coil loop and still effectively keep the engine coolant separate from the hydronic coolant using an inline coolant-to-coolant heat exchanger and/or valving (though not elegantly). 

One option we are testing with another yacht manufacturer is 12 and 24 volt immersion heaters run directly off solar panels or as secondary power sinks for wind or solar systems after the batteries are topped off.  In fact, we have a combination 12 VDC & 120 VAC element in testing now that fits in a single element port.  Our Bavaria 38 Ocean has an 18 gallon double element, double coolant coil system that we will be replacing later this summer with a similarly sized, superior prototype.  The key is one must be creative with options while understanding that hot water capacity and considerable energy demands are directly related.

[catlotion]

yes, after some more reading I realise the impact on the battery bank/cabling would be significant.

Tempted to get a Planar water heater but not sure of best way to connect to existing plumbing.  I currently have a fresh water cooled engine (Volvo D1-20) with single coil calorifier.  Do people just connect inline so the water heater runs through the engine circuit too?  Or have an isolation valve?