Hot water options

[Brooksie89]

I'm in the process of buying a boat, where the engine has been recently replaced from a yanmar 3gm with indirect cooling to direct cooling.

I only twigged on to this as the calorifier hadn't been reconnected. Seems like a massive oversight to me.

What are some realistic options to get hot water from the engine or other means? I'm pretty annoyed that getting hot water when not in marinas is off the cards at the moment.

Convert the engine to indirect cooling? Fit a (expensive) 3rd party heat exchanger and pump? Electric heating?

 

[Iliade]

If you have the necessary spare port in the calorifier, adding a 12v immersion is probably the cheapest option. If you have the space, consider a gas instantaneous water heater. (Many don't like these, for usually unjustified reasons.)

 

[Fr J Hackett]

There are two options, connect the hot water hose that goes to the exhaust elbow to the inlet of the calorifier and the outlet from the calorifier to the exhaust. The other method is if there are blanking plugs on the engine use those but you will almost certainly need to fit a pump either mechanical or electrical. Try the first option as it's the cheapest just requiring a couple of lengths of tubing.

 

[Obi]

Yep, had an engineer remove a blanking plate on my Perkins and fitted the calorifier tank to that, fitted the tank inside the engine compartment. It was excellent.

 

[johnphilip]

There are two options, connect the hot water hose that goes to the exhaust elbow to the inlet of the calorifier and the outlet from the calorifier to the exhaust. The other method is if there are blanking plugs on the engine use those but you will almost certainly need to fit a pump either mechanical or electrical. Try the first option as it's the cheapest just requiring a couple of lengths of tubing.

Any knowledge on whether the calorifier can withstand salt water? Also the sea water ejected from either cooling type is in my experience only a few degrees warmer than it goes in, certainly not hot enough to give a calorifier a usful temperature.

 

[Fr J Hackett]

I did it on a Bukh engine lasted the 5 years I had the boat, try putting your hand on the exhaust elbow it gets quite hot. The OP was asking how to do it without fitting an indirect cooling unit from my limited experience the only two methods are those I have outlined.

 

[capnsensible]

You can get small gas fired boilers to mount near your galley sink if you have room.

 

[PCUK]

No problem. Connect intake and return where you can and fit a 12 volt circulating pump that runs all the time the ignition is on and the engine running. Engine should run at around 52 degrees so more than hot enough.

 

[dansaskip]

What is wrong with a kettle?

 

[johnalison]

What is wrong with a kettle?

A poor solution, which in any case uses gas or electricity. Re-establishing a calorifier has to be the only viable option. Having lived without for nearly thirty years, I soon found out what a morale-booster it was to have hot water on tap when on passage.

 

[vyv_cox]

There are two options, connect the hot water hose that goes to the exhaust elbow to the inlet of the calorifier and the outlet from the calorifier to the exhaust...........Try the first option as it's the cheapest just requiring a couple of lengths of tubing.

That will not give hot water. The flow to the exhaust includes bypass water and is typically at a temperature of 40C.

 

[vyv_cox]

See this page on my website Calorifier installation

 

[ylop]

I did it on a Bukh engine lasted the 5 years I had the boat, try putting your hand on the exhaust elbow it gets quite hot.

It shouldn't! That's the reason the water is injected into the elbow - to cool the hot gas!

I only twigged on to this as the calorifier hadn't been reconnected. Seems like a massive oversight to me.

Does seem like a backwards step. Is it definitely raw water cooled, and not just that they didn't add the calorifier back in?

 

[Fr J Hackett]

That will not give hot water. The flow to the exhaust includes bypass water and is typically at a temperature of 40C.

All I can say is that for 5 years it gave perfectly satisfactory hot water from a Bukh for 5 years the temperature being high enough to require dilution with cold. It may of course be different on a Yanmar.

 

[vyv_cox]

All I can say is that for 5 years it gave perfectly satisfactory hot water from a Bukh for 5 years the temperature being high enough to require dilution with cold. It may of course be different on a Yanmar.

I have extensive experience of calorifiers with Bukhs as my link shows.

 

[Fr J Hackett]

I have extensive experience of calorifiers with Bukhs as my link shows.

I had 5 years of running one of a direct cooled DV20 as I said it worked, it may not be the best solution but it was a working one. I am not disputing either your knowledge or recommendation by the way.
Of course the obvious way to do it is to buy the Yanmar indirect cooling unit but the OP doesn't want to do that.

 

[Fr J Hackett]

No problem. Connect intake and return where you can and fit a 12 volt circulating pump that runs all the time the ignition is on and the engine running. Engine should run at around 52 degrees so more than hot enough.

There is a potential problem with interrupting the cooling circuit if the pump does not have the capacity to transfer sufficient water it can cause overheating. I inherited such a system on a Yanmar 3GM 30 and it did, I ended up buying the correct Yanmar unit.

 

[[70521]]

Will you be using the engine for long enough to heat the water?

 

[Poignard]

Will you be using the engine for long enough to heat the water?

That's a good point.

 

[vyv_cox]

There is a potential problem with interrupting the cooling circuit if the pump does not have the capacity to transfer sufficient water it can cause overheating. I inherited such a system on a Yanmar 3GM 30 and it did, I ended up buying the correct Yanmar unit.

I did advise someone quite a few years ago about fitting a calorifier to a 3GM30 by adding a pump. Same method as the Bukh, circulating water from and back to the block. I heard from him that it worked but I know no more.