I have an 18HP yanmar 2cyl and would like to put in an aux heater from the
internal cooling system (glycol). There are many plugs, thermhousing, side
of block etc... so i am unsure where to tie in for a send return that
won't affect the cooling of the motor. any thoughts?
rick

Not sure of your engine/heat exchanger configuration, but the hottest
cooling water would where it comes out of the engine and goes into the heat
exchanger, then the return water would go into the heat exchanger, where you
disconnected to divert the water. Let the engine cooling pump do the
circulation through the hot water tank coil.

That is the simplest since there won't be much flow until the engine
thermosat opens up. If you circulate the water from the wrong point, you
will warm the cooling water with the already hot water in the tank.

You might check with your engine dealer or manufacturer.. They may have
already addressed this question and can speak with some authority that you
could fall back on if something goes wrong.

It would be adviseable to have the water heater/storage tank higher than the
engine. This will keep you hot water heat from escaping back to the engine
block by thermal convection.

I puzzled over this question recently because I want to have a way for the
generator to heat the water as well. The valve complications cause me to
consider adding another heating coil in the water heater tank.. Simpler and
but not cheaper. One possibility I have is to remove the electric element
and put the second coil in that hole. Right now I just want to see how well
the engine does at heating the water.. My Volvo still has the OEM 140 deg
thermotat installed. (Volvo says leave it even if I switch to fresh water
cooling because all the clearance/tolerances, etc are for SW cooling at 140
deg.)

Steve
s/v Good Intentions

My Volvo still has the OEM 140 deg
thermotat installed. (Volvo says leave it even if I switch to fresh water
cooling because all the clearance/tolerances, etc are for SW cooling at 140
deg.)

on some Volvo raw cooled engines the factory specifically recommends against
using cooling water to heat hot water for showers, as this can crack cylinder
heads. Not sure of the dynamics as I do not have a Volvo, but certainly the
man who told me such is one fine mechanic.

My water heater, as I assume most do, has a 'one way valve' on the intake.

SV


"Steve" wrote in message ...


It would be adviseable to have the water heater/storage tank higher than the
engine. This will keep you hot water heat from escaping back to the engine
block by thermal convection.

I am referencing the Official Yanmar Service Manual for the 2gm20f.

One connection is a plug on the fresh water pump on the hose side that
leads from the heat exchanger. The other is a plug on the side of the
thermostat housing that leads to the heat exchanger. They are both
3/8" npt fittings.



On Mon, 29 Mar 2004 16:27:45 -0400, none
wrote:


I have an 18HP yanmar 2cyl and would like to put in an aux heater from the
internal cooling system (glycol). There are many plugs, thermhousing, side
of block etc... so i am unsure where to tie in for a send return that
won't affect the cooling of the motor. any thoughts?
rick

If you put an inline tee fitting with a cap, you can fill the hoses
with anti freeze and bleed them much more easily.

On Tue, 30 Mar 2004 11:22:09 -0400, none
wrote:

thanks a lot Marc.
Out thru the T-stat housing (which i see) return thru the water pump low
press side...which i will locate.
My manual doesn't appear to have that info.
Rick
.
On Tue, 30 Mar 2004 14:29:16 GMT, Marc wrote:
I am referencing the Official Yanmar Service Manual for the 2gm20f.

One connection is a plug on the fresh water pump on the hose side that
leads from the heat exchanger. The other is a plug on the side of the
thermostat housing that leads to the heat exchanger. They are both
3/8" npt fittings.
snip...

thanks a lot Marc.
Out thru the T-stat housing (which i see) return thru the water pump low
press side...which i will locate.
My manual doesn't appear to have that info.
Rick
..
On Tue, 30 Mar 2004 14:29:16 GMT, Marc wrote:
I am referencing the Official Yanmar Service Manual for the 2gm20f.

One connection is a plug on the fresh water pump on the hose side that
leads from the heat exchanger. The other is a plug on the side of the
thermostat housing that leads to the heat exchanger. They are both
3/8" npt fittings.
snip...

note that a 2GM20f is **freshwater** cooled. a raw water cooled engine is a
different breed of cat.

I am referencing the Official Yanmar Service Manual for the 2gm20f.

One connection is a plug on the fresh water pump on the hose side that
leads from the heat exchanger. The other is a plug on the side of the
thermostat housing that leads to the heat exchanger. They are both
3/8" npt fittings.



On Mon, 29 Mar 2004 16:27:45 -0400, none
wrote:


I have an 18HP yanmar 2cyl and would like to put in an aux heater from the
internal cooling system (glycol). There are many plugs, thermhousing, side
of block etc... so i am unsure where to tie in for a send return that
won't affect the cooling of the motor. any thoughts?
rick

"JAXAshby" wrote in message
...
note that a 2GM20f is **freshwater** cooled. a raw water cooled engine is
a
different breed of cat.


Most common marine water heaters are equipt with a copper or brass engine
water coil.. Therefore raw water shouldn't be circulated through it..

If a person wants to us raw water to heat domestic water, this coil should
be replace with something in CuNi.

However, most raw water cooled engine have a low temp thermosat and the
water temp may never get over 150 degree. Not very much of a rise for stored
hot water. A 6 gal tank wouldn't provide more than a couple showers. (the
main reason I want hot water).

Steve
s/v Good Intentions

Also a good idea to put a bypass on the heater lines, that way you
don't have to fill (6gals) the heater with pink stuff. Or at least
make the lines long enough and accesible. Mine is a PITA to get to.
And don't forget to drain the heater for winter.

Scott


Marc wrote in message . ..
If you put an inline tee fitting with a cap, you can fill the hoses
with anti freeze and bleed them much more easily.

On Tue, 30 Mar 2004 11:22:09 -0400, none
wrote:

thanks a lot Marc.
Out thru the T-stat housing (which i see) return thru the water pump low
press side...which i will locate.
My manual doesn't appear to have that info.
Rick
.
On Tue, 30 Mar 2004 14:29:16 GMT, Marc wrote:
I am referencing the Official Yanmar Service Manual for the 2gm20f.

One connection is a plug on the fresh water pump on the hose side that
leads from the heat exchanger. The other is a plug on the side of the
thermostat housing that leads to the heat exchanger. They are both
3/8" npt fittings.
snip...