Non-toxic antifreeze in closed loop engine/waterheater.

[exkma367]

Does anyone have experience using non-toxic engine antifreeze. I am planning on using the engine coolant with my water heater and would hate a leaking water heater heat exchanger to put antifreeze into the tank.

[Nicholson58]

Originally Posted by exkma367

Does anyone have experience using non-toxic engine antifreeze. I am planning on using the engine coolant with my water heater and would hate a leaking water heater heat exchanger to put antifreeze into the tank.

Non-toxic anti freeze is not rated for engine coolant.

You will know if your water heater is leaking no matter what you use.

[exkma367]

I was thinking of something like this.

Prestone Antifreeze/Coolant - Choose your region | Prestone®

I guess it is not 'Non" toxic. But if someone ever had a coolant loop leak into the tank, we would probably hear about in here.

[TeddyDiver]

Would it matter? Water from warm water tank should be used for washing purposes anyway not to drink it..

[TeddyDiver]

And expansion tank would flood if there were a leak and the water system is pressurized.

[wrwakefield]

Originally Posted by exkma367

Does anyone have experience using non-toxic engine antifreeze. I am planning on using the engine coolant with my water heater and would hate a leaking water heater heat exchanger to put antifreeze into the tank.

Assuming you are talking about a diesel engine, you may want to read this article in Practical Sailor before making any decisions...

In hopes this is helpful.

Cheers!

Bill

[Tugwit]

Some years ago I installed a "hydronic" cabin heating system consisting of a closed loop of fluid heated by an Espar diesel heater (with an integral pump) and a couple of radiators in the cabin. It works well.

A bit later, in order to recover engine heat for cabin heating when under power, I installed a separate heat exchanger in the engine cooling circuit that would heat the fluid in the hydronic circuit from the heat in the engine cooling circuit. (I also installed a separate pump in the hydronic circuit for use when under power and when the Espar furnace is not operating.) This arrangement works well, too.

I use Zerex G-05 ethylene glycol antifreeze in the engine cooling circuit (as recommended in the Practical Sailor article referenced above). I use "non-toxic" Sta-Clean propylene glycol in the hydronic circuit (http://stacleanantifreeze.com/ )--in anticipation of installing a potable water heater in the hydronic circuit at some point in the future (when my desire for creature comfort overcomes my inherent laziness). Presumably, any leakage of a propylene glycol antifreeze into a potable water system would be less toxic than an ethylene glycol equivalent.

The two circuits are completely isolated and independent--mechanically connected only at the heat exchanger.

Sta-Clean is advertised as a heavy duty antifreeze suitable for use in diesel engines--but I have no way of evaluating its relative merits compared to Zerex G-05 and chose to stick with Zerex for engine cooling.

[bcboomer]

Tugwit

Shameless hijack but can you point me to a source of suitable heat exchangers? I've just started into the same hydronic install.

[Aqualibrium]

If you have a standard pressurised Water system then the FW pressure should always be higher than the CW system with the antifreeze.
Normally FW system pressure pumps cycle between 25 to 40 psi and Radiator caps are designed to spill press to Engine CW expansion tk at about 12psi so any leakage should always be into engine CW

[Tugwit]

Originally Posted by bcboomer

Tugwit

Shameless hijack but can you point me to a source of suitable heat exchangers? I've just started into the same hydronic install.

Sure. They're even in your (south) BC neighborhood!
Custom & Stock Marine Heat Exchangers & Cooling Systems - Orca, WA
http://www.seakamp.com/

I used a 2"x19" purchased from a rep in Seattle....

[Jack Verschuur]

This discussion reminded me of a huge scandal with Austrian white wines many moons ago, which revealed that ethylene glycol was mixed with it to make it sweeter. I don't recall any fatalities :-)
I wouldn't recommend drinking it, but doubt that in itself it is dangerous for your health if it would contaminate your potable water storage.

Likely additives to the coolant pose a more dangerous proposition, I have no idea what is added as an anti-corrosion agent, for instance. A good substitute for that, however, is good old-fashioned tea.

Best,

Jack.

[Tugwit]

Originally Posted by Jack Verschuur

...I wouldn't recommend drinking it, but doubt that in itself it is dangerous for your health if it would contaminate your potable water storage.

Jack.

Well, I guess that the purported toxicity of ethylene glycol is, after all, at the foundation of this whole thread. Can't say that I have actually tasted it (at least not intentionally), but it is reputed to have a sweet taste that is attractive to children and pets. Wikipedia has a reasonable treatment here:
https://en.wikipedia.org/wiki/Ethylene_glycol_poisoning

Toxicity is, of course, dose dependent. The article above suggests:

"...A toxic dose requiring medical treatment varies but is considered more than 0.1 mL per kg body weight (mL/kg) of pure substance. That is roughly 16 mL of 50% ethylene glycol for an 80 kg adult and 4 mL for a 20 kg child...."

"...The orally lethal dose in humans has been reported as approximately 1.4 mL/kg of pure ethylene glycol..or approximately 224 mL (7.6 oz.) of 50% ethylene glycol for an 80 kg adult and 56 mL (2 oz.) for a 20 kg child....".

I agree that it would take more than a few drops of antifreeze leaking into a potable water supply to be a major concern. But why take a chance?

The article also mentions propylene glycol as a less toxic alternative with the additional benefit that it doesn't taste sweet making it less attractive.

Also, it turn out that ethanol is an antidote for ethylene glycol poisoning. I knew there was a good reason to keep a bottle of Scotch in the medicine locker!!

[rwidman]

Regardless of any reason or excuse not to do so, I think it's best to use a coolant that's designed for your boat's engine and approved by the engine manufacturer. There are additives in the approved coolant that are not in the non-toxic antifreeze commonly used for winterizing potable water systems.

If you are really worried about a leaking heat exchanger in a water heater, simply disconnect it and do without engine generated hot water.

[Sandero]

Just curious... what would happen if he ran the engine with the seacock open and let all the water in the cooling get pumped out until there was only engine exhaust fumes coming out? Would all the water / coolant in the cooling system be pumped dry? For a few minutes it would seem that the engine would not over heat.

Or does water always manage to remain in the system which can freeze and split something?

[Jack Verschuur]

Sandero,

Most, if not all engines will not pump themselves dry. Some engines have a stop-cock at the lowest point in the block, but even with those pockets of coolant stay behind.

This can be seen when you take an engine apart: Lift the head off the block and there is coolant coming out of the head.

Apart from that, running the engine without coolant, even for 'a few minutes' is a really bad idea. Heat from combustion is not generated evenly all over, and if not dissipated will cause localised overheating, which may crack big and expensive components.

Best,

Jack.