Does anyone know if the heater uses lake water or antifreeze?

[SG]

I have a 2005 SAN 211 T that I am going to winterize soon. Does anyone know if the heater uses raw water or coolant from the engine?

[CHassmann]

If you're boat has raw water cooling, the heater will use raw water also. It needs to be drained during winterization.

[SG]

My boat has the Fresh Water cooling system that uses DexCool anti-freeze running through the engine. I’m guessing that antifreeze is also circulating through the heater core but the manual does not specify. The boat also uses lake water through the heat exchanger so I don’t want to find out next Spring that I froze the heater core.

[doug69]

My boat has the Fresh Water cooling system that uses DexCool anti-freeze running through the engine. I’m guessing that antifreeze is also circulating through the heater core but the manual does not specify. The boat also uses lake water through the heat exchanger so I don’t want to find out next Spring that I froze the heater core.

I’m not sure I understand. Fresh water system using antifreeze? Are you saying you have fresh water cooling and running anti freeze to Winterize it? My understanding is the heater system does not start to circulate until the boat reaches a higher temp (not sure what exactly that temp is). I blow out the heater system and use a pump to pump antifreeze through it. You could try and get boat up to a high temp and immediately start running the antifreeze to get it through the system and hope it works…


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[bturner]

I believe he has a hybrid system many of the LS style engines have. The easiest way to tell is see where the hose from the heater core goes. If you have antifreeze circulating in the engine block and the heater hose goes to the block like all other heaters then its antifreeze. I could certainly be wrong but I don't see any other way to do that in a non closed loop system.

[SilentSeven]

Yup. Like bturner says - follow the hoses. Almost for sure the heater is part of the closed loop cooling system and thus has antifreeze.

[scottb7]

Yeah, always been kind of confusing. On the partial system freshwater means antifreeze, raw water means lake water.

[SG]

I should have said I have the ZR6 engine with a closed cooling system. It has anti-freeze circulating through the block and the anti-freeze is cooled by lake water running through a heat exchanger. It makes sense that it would be antifreeze running through the heater core. I will try to locate the hoses for the heater core. Anyone know where they are located on the engine? Also, anyone know where the heater core is located? Thanks

[SilentSeven]

On my direct drive engine (much easier to see typically and mounted 180 out from a v drive), the heater is fed by two takeoffs - one near the thermostat housing and another below an exhaust manifold where a brass fitting replaces a block drain. Yours shouldn't be too hard to find, look for a pair of automotive heater hoses running forward. My blower box is under my dash.

BTW: I'll be a monkey's uncle if your heater system is not part of the closed system. If it's not, there needs to be some way to heat and pump raw water to the heater core and bypass the best and hottest water in the system - the water in the engine block. Would take some slick engineering and extra complexity for basically no benefit.

[SG]

Good point SilentSeven. It has to be using coolant. Thanks!

[Ryan747400]

I can confirm, it is definitely coolant running through the heater core. No need to drain or winterize. The only line running raw water past the heat exchanger will be the one going to the dripless packing. Youll need to pinch that off when filling with antifreeze or youll loose a lot of it.