Copper pipe and hot seawater

[Capt_Scarlet]

I am making a calorifier to connect to a Yanmar 2GM20 (seawater cooled). I was intending to wind some 10mm copper pipe to make the heating coil.

Is it likely to dissolve itself or my engine/prop, or is copper pipe in the seawater circuit okay?

What are the commerial ones made of?

Thank you.

 

[boatmike]

Copper pipe is OK. Usual practice is to hook up a calorifier to the fresh water cooling side not seawater though.

 

[fireball]

We've got a calorifier hooked up to our Rawwater cooled Yanmar 2GM20, I would say that the water didn't get very hot ... but that was because the impellor failed to produce any reasonable pressure ...
The hotwater it produced when we first picked up the boat was reasonable though...

 

[LittleShip]

Use 15mm copper to get better flow.

 

[Mirelle]

results may disappoint

Copper pipe should be fine.

Raw water cooled engines generally run cooler than fresh water cooled ones, to reduce deposits in the passageways. Which is why calorifiers are usually in the FW circuit of a FW cooled engine.

 

[stephenmartin]

I'd be interested in how you get on....how will you deal with the over presseure and temperature safety valves....are you using a commercial hot water cylinder or making one up specially

 

[Capt_Scarlet]

Due to a combination of being a tight-arse, and for enjoyment (?) I decided to make one out of a "King Keg" brewing barrel - a tough plastic pressure vessel - 25 litres capacity, with a 4" wide screw cap. The plan is to feed all the pipework in through the cap, (which includes a pressure release valve already fitted for the beer), and to fit an accumulator vessel externally to cope with pressure increases due to heating.

I am going to divert the hot seawater through this before mixing with the cold seawater bypassing the block, so hopefully may get a reasonable temperature out.

Time will tell, but at least I can open a floating brewery.

 

[cliff]

[ QUOTE ]

Due to a combination of being a tight-arse, and for enjoyment (?) I decided to make one out of a "King Keg" brewing barrel - a tough plastic pressure vessel - 25 litres capacity, with a 4" wide screw cap. The plan is to feed all the pipework in through the cap, (which includes a pressure release valve already fitted for the beer), and to fit an accumulator vessel externally to cope with pressure increases due to heating.

I am going to divert the hot seawater through this before mixing with the cold seawater bypassing the block, so hopefully may get a reasonable temperature out.

Time will tell, but at least I can open a floating brewery.

[/ QUOTE ]O.K. tight arse, budget for a circulation pump or else you will not have any hot water worth talking about also you will need oodles of insulation round the barrel.

Hot raw water flow should be from near top of engine / head to circulation pump to coil and back to the block at low level. You will also need to use 15mm pipe for the coil at least 10' in the coil. I would also suggest you buy proper tank fittings and feed the coil in the side of the barrel as low down as possible and feed the hot raw water in the upper end of the coil and out the lower end back to the block. Raw water cooled engines run at around 65°C maybe up to 70°C which although not as hot as fresh water cooled engines is plenty hot enough for washing purposes and you minimise the risk of boiling the calorifier.

The circulation pump will cost around £60 ~ £70 from Johnson pumps but will last a lifetime if you buy the correct one (I have one 18 years young and still going strong with just over 2000 hours on it)
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