Fitting an Eber water heater

[ip485]

I would like to fit a Eber water heater dedicated just to heating the water in the calorifier.

The calorifier at the moment is either heated by the engine or the immersion via shore power or the Genset. The Eber will make me independent of shore power or the need to run the Genset just to heat water.

I have the following questions.

1. I think I can run the in and out water supply to the Eber into the existing pipes from the engine to the calorifier, but I assume it is probably not a good idea to pump the hot water produced by the Eber around the engine as well. Does that suggest non return valves in the system and where would you place them? What type and where can they be sourced from?
2. I have an existing Eber hot air heater. It will make fitting easier if I use the existing fuel supply. I cant see any issues "Ting" off from this supply with a metering pump in each.

 

[pvb]

I wouldn't have thought the calorifier alone would soak up enough heat to stop the Hydronic cycling frequently. For that reason, I'd stick with the genny.

 

[Barbican]

Wish I hadn't been persuaded to stick to air heating when we got the boat, so I have had similar thoughts about this. The smallest Hydronic would be enough I think, so I would be very interested to hear how you get on with this.

 

[ip485]

PVB - the idea is not to leave it switched on for long periods - rather to heat the water, switch off and on as needed and as and when the water is used. I would have thought that would reduce or pretty much eliminate too much cycling? Once there is a calorifier of hot water it lasts well until the next shower etc.

As I mentioned earlier it takes a reasonable long run of the Genset just to produce hot water, as with large solar panels I rarely need to use the Genset to produce power other than for the odd high load 240V item. Also the Genset is inevitably quite noisy and realistically more likely to go wrong (although it has proved pretty reliable so far) than a water heater.

At LIBS this approach was recommened but a couple of suppliers did suggest the valve system to prevent pumping hot water around the engine and also suggested tapping into the existing engine / calorifier circuit rather than directly to the calorifier which almost certainly doesnt have any other existing water feeds.

 

[pvb]

PVB - the idea is not to leave it switched on for long periods - rather to heat the water, switch off and on as needed and as and when the water is used. I would have thought that would reduce or pretty much eliminate too much cycling? Once there is a calorifier of hot water it lasts well until the next shower etc.

As I mentioned earlier it takes a reasonable long run of the Genset just to produce hot water, as with large solar panels I rarely need to use the Genset to produce power other than for the odd high load 240V item. Also the Genset is inevitably quite noisy and realistically more likely to go wrong (although it has proved pretty reliable so far) than a water heater.

At LIBS this approach was recommened but a couple of suppliers did suggest the valve system to prevent pumping hot water around the engine and also suggested tapping into the existing engine / calorifier circuit rather than directly to the calorifier which almost certainly doesnt have any other existing water feeds.

I understand how you'd plan to use it, but still think the heat load is insufficient.

Rather than valves, a more robust solution would be to fit a dual-coil calorifier.

 

[lw395]

I had this on one boat.
All you need is a valve or two to stop slow around the engine.
However, short-cycling was an issue, you need a lot of calorifier coil area to keep the eber running.
So we just let it heat the engine.
The heat from the engine slowly warms the boat like a storage heater, so it's not really wasted, although it might be unwanted in the med or once-in-a-decade heatwave.

You may of course have a calorifier with enough coil area....
Or maybe ours was a bit scaled etc..

 

[[2574]]

I have done exactly this project and for the same reason as you. I fitted a D5W Eberspacher. I removed the engine hot water feed to the calorifier and replaced it with a connection to the D5W. I was concerned about the low demand on a 5KW heater so I fitted blown heat exchangers in the saloon and heads. The total demand of the heat exchangers is a nominal 6KW. In reality I think they demand less than that amount but they do output a fair amount of heat.

The D5 heats up the calorifier water to a temperature which is too hot to immerse one's hand in after about 30mins. Our routine is:

1) Heater on
2) After 30 mins wash up breakfast
3) After 20 mins 2 x showers
4) After 30 mins shutdown system leaving a tank of hot water for the day

If we've been out sailing for the day and fancy hot water on arrival at the anchorage I push the button half an hour before our ETA. We then have a warm boat and hot water which wins massive brownie points from ther Admiral.

Using that routine I've had no heater cycling.

I fitted silencers to the two Eber exhausts (one D3L (warm air) and the D5W) to keep the noise down. Nothing worse than some bloke firing up a noisy Eber early in the morning in a quiet anchorage. The new marine exhausts are not cheap but they are very effective.

I used push fit plumbing and plastic pipe for the pipe runs with radiator hose for the attachments to the services. I didn't insulate the water pipes - the idea was to keep a heavy load on the heater. I also fitted valves on the T's of the ring main - this enabled the balancing of pressure around the pipe network ensuring even heat distribution - otherwise the water takes the route of least resistance meaning cold water and hot heat exchangers or vice versa.

I was advised not to T off the D3L diesel tank feed pipe so I fitted a second. I was told that a T may well cause problems for the D3L fuel pump and I didnt want to risk it.

Make sure that you use adequate gauge wire for the 12v feed; the initial draw is 20A+ and you cant afford a voltage drop.

It is a very succesful setup which has run without fault for the past ten years or so.

Rob

 

[Steve_N]

I too have pretty much the same as the installation that you're planning with an Airtronic D4 for heating (plus a Taylors 079D) and a D5W for water heating.
I retained the existing single coil calorifier but fitted standard plumbing type brass T valves in the run from the engine to the calorifier. You just switch the valves to select which heat source to use. Normal usage is to use up the free hot water from the engine then switch to the Hydronic when necessary. I tee'd off the Airtronic's fuel line close to the standpipe and haven't had any fuel supply problems but I am careful not to run both Ebers at once. There isn't a short cycling problem with my installation; the D5W switches happily between max and min heat until the cylinder thermostat switches it off i.e. there is only one ignition phase per tankfull of hot water.

 

[ip485]

Thank you both for your very helpful replies. They make much sense. I had also thought of T valves to isolate one or other circuit and that seems by far the simplest solution. I havent yet looked in detail at the parts I will need, but I am interested in your point about the cylinder thermostat switch turning off the D5W. I assume this suggests part of the installation is to fit a thermostat to the cylinder that is connected to the Eber - I guess I had thought the Eber was controlled by a thermostat on the return pipe close to the heater. How is the thermostat mounted on the cylinder?

 

[Steve_N]

My cylinder is an upright copper one, essentially just like a smaller version of a traditional domestic hot water cylinder so I used a domestic cylinder thermostat mounted at about 1/3 cylinder height, just like you would at home. The 'call for heat' circuit of the Eber is routed through this thermostat. Once up to temperature it switches off the burner but the Eber and circulation pump remain live to allow the cool-down cycle to complete.