Ok, so originally Elijah was supplied with hot water via an LPG fired instant water heater – think of the Paloma type like this.
To say that they were dangerous on a boat would be something of an understatement. They take combustion air and vent combustion products directly into the cabin, or in the case of Elijah, directly into the tiny head compartment. The result would be that having a shower would reduce the oxygen content of the air while replacing it with carbon monoxide and other exhaust products – not ideal for one’s continued good health!
Fortunately this device had been removed before we purchased the boat, thus saving me a quick trip to the skip, but leaving us without hot water. Thus I have begun investigating what we can do to remedy this unfortunate state of affairs and thus keep our domestic life on a even keel. Given that Elijah is based in the UK, and good weather if far from guaranteed at any time of the year ( we are at almost 50 degrees North after all), I also figured that some form of heating would be a good idea. Enter the solution, or at least the business end of the solution at least – The Eberspacher Hydronic 5dw.
This is a diesel fired water heater producing 5Kw of heated water with a fully sealed exhaust vented overboard. The device is really quite small measuring only 220 x 86 x 102 mm, it takes between 10 and 37 watts of electricity, burns between 0.27 and 0.62 litres of diesel per hour. Because it is a wet heater system, it can feed conventional radiators, fan assisted heat exchangers and of course hot water tanks or calorifiers. This means that this tiny package can provide both hot water and heating – Happy days! These things are very reliable and are fitted as auxiliary heaters in vans and SUV’s all over the world. As such, spares are readily available all over the place. They require next to no maintenance and are fully automated needing little more than some fuel and 12v DC supply. The water in the heating circuit is circulated using a 12v circulation pump in the same way as a domestic wet heating system.
We are installing a sizable calorifier in order to provide a large amount of hot water. This is not strictly necessary, but the Stainless steel calorifier can along at the right price so that is what we will use. In addition we will also install a custom fabricated warm air heat exchanger, based on a simple and reliable vehicle heater core – in our case, one originally intended for a kit car. This will be installed in the central saloon seat and may allow warm air ducts into each hull of required, although small cabin radiators may be preferable.