Heating Hot Water

[DuncanHall]

Like Many I have a calourifier heated both by the engine and immersion heater. I am looking at options to fit a diesel water heater to provide hot water at anchor without running the engine. I see three options.

1. Fit a new water tank with twin coils and use a diesel water heater to heat the second coil.
2. Fit the diesel water heater in line with the current hot water from the engine-calourifier loop so that it pre-heats the engine as well and thus avoids the need for a new tank.
3. Fit the diesel water but fit two valves to switch between engine heating so that I can choose between engine or diesel heater heat.

Has anyone done any of these and can offer the benefit of their experience?
I already have a diesel air heater.
Regards

Duncan

 

[superheat6k]

I would opt for option 3 using a three way tee valve on the water supply to the calorifier. I would add an in line isolation ball valve to each leg, but would leave these all open in normal operation.

Have you selected a specific water heater ?

I would also consider a small radiator in the cabin somewhere.

 

[DuncanHall]

I would opt for option 3 using a three way tee valve on the water supply to the calorifier. I would add an in line isolation ball valve to each leg, but would leave these all open in normal operation.

Have you selected a specific water heater ?

I would also consider a small radiator in the cabin somewhere.

I am considering a EBERSPACHER HYDRONIC 3 D4E and thinking of fitting a small 1.7kw fan assisted heater matrix in the heads if plumbing it in is practicable. I need to survey the boat as pipe runs are not easy .

Many thans

Duncan

 

[MAURICE]

Have you considered a Bobil heater?
Basic Bobil Heater - 75mm ducting | Bobil Vans
There are some you tube videos on this and it seems a good way round the problem

 

[ip485]

I have done exactly this with an Eber Hydronic.

It is possibly one of the best changes I have made, so I would suggest dont hesitate.

My system comprises the heater in the rear lazarette. You will need to mount it somewhere that gives good access to the outside for venting the exhaust (just like a hot air blower). I also positioned the header tank (expansion tank) in the lazarette. If you already have a hot air blower I am afraid you will need to run another diesel line, but you can probably use the same electrics. Out and return pipes route to the engine room, where there are T connectors to the hot water and return to the engine that can be switched and then on to the calorifier.

As to changing the existing calorifier if it is in good condition with no leaks I wouldnt change it. Mine was repalced as it did have a leak, but I still didnt install a mutli pipe version mainly due to what was available at the time.

In reality I have barely ever run the system from the engine. It just works so well off the hydronic. It does also have an electric element, and, in the winter, sometimes run both as the heat up time is so quick.

The only major issue and not to be under estimated, is the pipework. There are obviosuly some long and possibly complicated lengths of pipe and we all know these are never as straight forward as you would wish, but you might be lucky. Also think about where you would like the control head. I ended up with this next to the bed. Very lazy, but nice to switch it on when you wake up, to be followed by a lovely tank of steaming water (it does have a timer as well).

As to noise, there is a little noise from the pump, but it is a lot quieter than a Ebber blow heater.

As you can tell I am thrilled with the system. Obvioulys if you are always on mains power, or want hot water after an engine run only, it is probably no advantage, but for anyone spending time at anchorages, in marinas without power, and not wanting to run the main engine or Genset just to heat water it is the best solution.

Edited to add; as to taking off heating be it blow rads or towel rail of course this is relatively easy, subject of course again to running the pipework. If it is to be your sole means of heating in the winter, then dont under estimate the KW rating of the system and definitely matrix blow heaters will be required assuming you want a little more than background heat. I havent done this mainly because I already had an Ebber blow heater with all the ducting in place. I will say the hydronic might make less noise, but obvioulsy this would depend on the noise produced by the blowers. If you have room the system is of course perfect for a towel rail, or even a warm locker for the oilies. A simple matrix in the locker without a blower will result in a very effective airing cupboard.

Adding radiators can off course be done later if this is easier as long as the heater as adequately rated for the heat output you are seeking to achieve.

 

[ip485]

PS the Bobil heater looks a great idea. The main drawback I can see is you might not already have blown air heater, or you might not run this when you would like hot water. I like hot showers all year so the water heaters get lots of use - and also for washing up etc. Never the less a very original idea I hadnt come across before.

 

[AntarcticPilot]

PS the Bobil heater looks a great idea. The main drawback I can see is you might not already have blown air heater, or you might not run this when you would like hot water. I like hot showers all year so the water heaters get lots of use - and also for washing up etc. Never the less a very original idea I hadnt come across before.

If I've understood it correctly, you wouldn't get much heating while the water is heating - the heat exchanger in the ducting would cool the air, while heating the water. I don't suppose it's terribly efficient, but it does look like a good idea for those with existing hot air heaters. And not terribly expensive, either.

 

[ip485]

Yes good point. I am not familiar with the earlier posters recommendation and while it looks like it has some merit (especially the cost), I dont think it would be an all round solution for me.

 

[LadyInBed]

Deleted

 

[catlotion]

Bobil heater looks interesting as I've got the same issue. I've just moved to a swing mooring and water seems to take a while to heat up via engine/calorifier - mainly because it's difficult to run at load I think...

Has anyone on here tried the Bobil? Would you splice it into your engine/calorifier circuit or need another loop in the tank?

 

[mullet]

+1 for the Bobil heater looking interesting. In hot weather, presumably its use would unavoidably pump hot air into the cabin? Can't see a way around this (except using an alternative means to heat the water if you don't want to cook).