Does diesel central heating need its own separate fuel line?

[Joe the plumber]

I've tried a search and not found what I'm after, so if this has already been covered, my apologies (and may I have a link please).

 

Our boat doesn't have central heating on it at present, just a simple solid fuel stove.

 

If I decide it needs it, will I be able to 'tee' off the existing engine fuel feed or do I have to look at adding a completely separate fuel feed (and return?) from the tank? Or should I add a separate diesel tank for the heating?

 

Thanks for any help.

[Silebyman]

Not sure how to create the link but I had a discussion about the same topic. Either search the forums for " fuel supply for diesel water heaters" or look in my content.

Basically you need a seperate stand pipe supply from the tank. Apparently quite simple to do and something I'm going to do this weekend as installing unit at the minute.

[Martin Megson]

My has a separate small bore copper pipe from the engine diesel tank. The link below is the relevant section of the Eberspasher manual. Hope it helps.

 

 

Eberspasher.pdf

[Joe the plumber]

Thanks folks. I thought there would be something about it on here already. It's just getting the 'search' phrase right!

[GUMPY]

I have two standpipes in my lockup where I have done installations where I have not used them.

[Joe the plumber]

My only reservation about adding a separate line to the tank was that of getting swarf from the drilling and tapping into the tank. I'm pretty sure I'll already have the appropriate drill and tap.

 

Should the fuel filter deal with any swarf?

 

Incidentally, the pedant in me wonders if the compiler of the Ebersbacher sheets used to be an estate agent ("The fuel system supplied comprises of...")? They mean 'comprises', or 'consists of', I assume?

 

It's very useful though, thank you.

Edited October 10, 2015 by Joe the plumber

[Alan de Enfield]

Your fuel filter would commonly (depending on type) have two 'inputs' & 'outputs' of which one will be blanked off, simply remove the blanking screw and screw in the pipe from your heater system. Job done, no drilling and no swarf.

 

[GUMPY]

Your fuel filter would commonly (depending on type) have two 'inputs' & 'outputs' of which one will be blanked off, simply remove the blanking screw and screw in the pipe from your heater system. Job done, no drilling and no swarf.

 

As has been said before if you do this the position of the heater relative to the fuel tank is critical because of the larger diameter pipes involved.

[nicknorman]

Your fuel filter would commonly (depending on type) have two 'inputs' & 'outputs' of which one will be blanked off, simply remove the blanking screw and screw in the pipe from your heater system. Job done, no drilling and no swarf.

 

This is a bad idea for various reasons including fluctuating pressure when the engine is running, and the ability of the heater to use all the fuel so that the engine won't start. A separate pipe should be installed with the takeoff point above that of the engine.

 

I recently installed a MCS fuel gauge which involved drilling a new hole in the top of the tank. Very little dwarf gets into the tank ( most of it is on the top side and can be removed during drilling) and what does get through is heavy and will likely just sit on the bottom. Engines take their fuel from a little above the bottom of the tank so the swarf is unlikely to get sucked up and if it does, the filter will contain it.

Edited October 10, 2015 by nicknorman

[bizzard]

Keep the drill bits and tap well greased all the time and they will retain most of the swarf.

[Sea Dog]

It would be sensible to ensure that the heater supply pick up sits a little higher in the tank than the engine supply. This will prevent your heating being able to fully empty the tank, depriving you of engine power.

[Alan de Enfield]

This is a bad idea for various reasons including fluctuating pressure when the engine is running, and the ability of the heater to use all the fuel so that the engine won't start. A separate pipe should be installed with the takeoff point above that of the engine.

 

I recently installed a MCS fuel gauge which involved drilling a new hole in the top of the tank. Very little dwarf gets into the tank ( most of it is on the top side and can be removed during drilling) and what does get through is heavy and will likely just sit on the bottom. Engines take their fuel from a little above the bottom of the tank so the swarf is unlikely to get sucked up and if it does, the filter will contain it.

 

How small is a 'very little dwarf' ? I guess they must be very small if they can get into the tank.

When I had an eberspacher installed (by a boatyard / engineers) in my first NB they did it via the fuel filter. I never had a problem with fuel shortage to the engine but maybe that was just good luck.

[nb Innisfree]

When installing a Mike on Innisfree I decided to run 10mm copper pipe to a convenient point on the swim where it teed off to engine and Mikuni respectively. Once problems with Mikuni smoking was resolved by the introduction of ULSD it ran perfectly.

 

ETA: For 'Mike' read Mikuni!

This spell checking thing is hilarious.

Edited October 10, 2015 by nb Innisfree

[bottle]

or

 

separate tank, dedicated agglomerator , dedicated filter and able to declare 100% domestic for that tank.

 

[nb Innisfree]

It would be sensible to ensure that the heater supply pick up sits a little higher in the tank than the engine supply. This will prevent your heating being able to fully empty the tank, depriving you of engine power.

That was my concern when installing heating so I fitted a solenoid shut off valve, when I bypassed it for a period of time it made no difference.

[Arthur Brown]

Most of the problems with diesel fuelled heaters occur where there are deviations from the manufacturer's intended installation method.

[nicknorman]

How small is a 'very little dwarf' ? I guess they must be very small if they can get into the tank.

 

Yes they really were a nuisance, until I put some mousetraps down and got rid of the pesky things.

[cuthound]

When installing a Mike on Innisfree I decided to run 10mm copper pipe to a convenient point on the swim where it teed off to engine and Mikuni respectively. Once problems with Mikuni smoking was resolved by the introduction of ULSD it ran perfectly.

 

ETA: For 'Mike' read Mikuni!

This spell checking thing is hilarious.

I thought that "Mike" might have been the name of the very little dwarf

[Arthur Brown]

If you install a "eber" (or like) with the fuel Tee's off the engine, then demand from the engine pump may pull air in through the heater causing airlock faults in the heater, engine or both. Both the eber heater and the engine fuel pumps being pulsing pumps then simply the pulses may interfere and cause malfunctions.

 

Of course if the pipes are big enough and the filters clean enough then it may work well.

[Guest]

or

 

separate tank, dedicated agglomerator , dedicated filter and able to declare 100% domestic for that tank.

 

I think given the likely outcome of the diesel situation, should I be fitting diesel heating I would be going down that route.

[Top cat]

We run our Webasto Thermotop E from a feed taken off an unused port on the fuel filter, it works just fine. The heater is mounted on the swim next to the engine which is a 42hp Isuzu. Other heaters, engines and relative placements may behave differently.

We tend to run the heater when the engine is off but have done so when its running without problems, we don't let the diesel tank get below 25% anyway so running out is a remote possibility.

 

 

Top Cat

[Alan de Enfield]

We run our Webasto Thermotop E from a feed taken off an unused port on the fuel filter, it works just fine. The heater is mounted on the swim next to the engine which is a 42hp Isuzu. Other heaters, engines and relative placements may behave differently.

We tend to run the heater when the engine is off but have done so when its running without problems, we don't let the diesel tank get below 25% anyway so running out is a remote possibility.

 

 

Top Cat

 

We had the same experience.

[Joe the plumber]

Thanks folks. What a great help you all are!

 

The fuel filter on our boat only has a single inlet and outlet, so I can't use that, although I could always fit a different filter of course.

 

I quite like the idea of a separate tank. There's plenty of room for one under the right hand seat on the stern (it's a semi-trad), so it would be easy to do. I might

well look into that.

 

Thinking of tank size, can anyone say roughly what sort of fuel consumption you get from a diesel c/h system please?

[Alan de Enfield]

 

 

Thinking of tank size, can anyone say roughly what sort of fuel consumption you get from a diesel c/h system please?

 

Depends on various factors - our eberspacher is about 0.6 litres per hour running.

 

The running time depends on how high you have the thermostat, how cold it is etc etc.

[Joe the plumber]

Thanks Alan. Based on that, I reckon a 10 - 15 gallon tank could be okay as we'll have the stove too and I hope we won't need the c/h on very much apart from water heating.