Merry Fisher 855 - hot water

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Saintlysimon

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Hello

We've just bought an 855, and believe hot water is 240v marina only.

What are the options to have water heated whilst away from shore power? What are the likely costs for such options?

We're just having a webasto airtop 40 (?) fitted for the heating.

Thanks
 
Small webasto water heater running off the new diesel supply for your other heating system. If you already have the coils on your calorifier, I guess about £1000-1200 fitted.

Or some extra batteries and an inverter. Some big batteries (x2 100Ah) and cheapest 2kw inverter, fitted. About same as above.

Check my pricing with an expert though.

Garold.
 
The option of hot water from the engine(s) is no-go with outboards.

If you leave the marina with a full tank of well heated water it will last for some time, might even cover your needs. I'd do nothing until the need was stated, then boil water and if really needed invest in a fuel-burning solution.
 
Interesting - I thought twin 150's could be used to heat the water?

And I would think that by the following morning, having left the marina, the 5 gallons wouldn't be providing a warm shower. I'd imagine it would remain hot or warm all day, but not into the next day.

Just a guess though.
 
Unfortunately not. Taking heat from an engine has no relation to size or hp - it is purely a matter of exchanging heat from leaving (hot) cooling water, into a water heater.

On outboards sea water is picked up through the intake, circulated around the engine in the water jacket and sent out with the exhaust fumes.

Per definition same process on sea water cooled inboards but, and this is the difference, on freshwater cooled enginges the coolant in the water jacket circulates in a closed circuit (like a car), then cooled in a heat exchanger that use sea water to cool off the engine coolant. And the water heater is connected to the closed circuit to work in principle like the heater matrix in a car.

Since this is not possible on outboards, the alternative is a central heating by means of a fuel burning unit that supplies heated coolant to the water heater in place of an engine.

Did this clarify things?
 
Last edited:
Garold said:
Small webasto water heater running off the new diesel supply for your other heating system. If you already have the coils on your calorifier, I guess about £1000-1200 fitted.

Or some extra batteries and an inverter. Some big batteries (x2 100Ah) and cheapest 2kw inverter, fitted. About same as above.

Check my pricing with an expert though.

Garold.
Click to expand...

2*100Ah batteries through an inverter will not do much to heat water. Will flatten the batteries in next to no time and only give lukewarm water. Electricity is an impractical way of heating water unless you have a 240v supply from shorepower or a generator.

The reality is that unless you have an inboard preferably freshwater cooled where you can tap the waste heat from the cooling circuit, hot water in any significant quantities is virtually impossible. The only viable alternative is a gas water heater such as a Rinai but these have gone out of fashion as difficult to install safely and limited to the amount they produce.
 
For comparison I have 40 liters of heated water from an inboard with shore power backup

Since the heater makes approc 80C hot water we mix it heavily with cold water for showering, so 40 liter actually keeps for several days - including pantry use.
 
I'd still wait and see what the actual need is. Webasto's et al come at a price so would want to know for sure before forking out thousands of hard earned
 
Scrub the Webo evo 40 and have a Webo TTC fitted instead, then use the circuit with a good quality blower box for heat and include the calorifier in te circuit for hot water. That setup will cost you a lot less than most other options and is what I fit to many boats, though I tend to use rads rather than a blower box. Make sure the blower box is capable of providing heat when circulated coolant is at 82 degrees, discuss it carefully with whichever Webasto partner is doing the proposed AT Evo job. Disadvantage over direct blown air is a bit longer to get up to temperature, otherwise an elegant solution. Shouldn't cost much more than an Evo 40 install for the whole job.
 
Last edited:
Garold said:
Small webasto water heater running off the new diesel supply for your other heating system. If you already have the coils on your calorifier, I guess about £1000-1200 fitted.

Or some extra batteries and an inverter. Some big batteries (x2 100Ah) and cheapest 2kw inverter, fitted. About same as above.

Check my pricing with an expert though.

Garold.
Click to expand...


That would buy you the marine kit but not include fitting.
 
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