Stus-List draining water heater

Marek Dziedzic dziedzicmj at
Fri Feb 17 14:14:25 EST 2017


If your water tank is 6 gal capacity and you don't drain or push out (compressed air) water, you would need more than 6 gal to displace the water (more like 10-12). If you are not doing it and if your water heater is still functioning, it only means that the temperatures are (were) not low enough to freeze whatever is left in the tank. One of the problem with the antifreeze is that if it is diluted, its antifreeze property very quickly deteriorate, so you don't want to have a diluted AF in your system. The fact that what comes out is pink does not mean that it is not diluted.

Since we do have low temperatures (below -20 °C; well below 0 °F), my procedure involves draining the water (if you can drain into the bilge, it is easier; otherwise you have to pump it out); using the compressed air to "flush" the water from the tank (and of course, from all the piping) and then filling the system with AF and again pushing the AF out using compressed air. One of the best additions that helps me with winterising the system is the water heater bypass (two Y valves and a connecting hose); you can get one on Amazon or from your local RV dealer. This allows me not to put any AF into the water heater.

One word of caution: as far as I know, if you leave any AF in the water heater and you heat it up (e.g. by running the motor); the AF may solidify into a pink cotton - it would be pretty impossible to remove it from the water heater.

1994 C270 "Legato"
Ottawa, ON

From: CnC-List [mailto:cnc-list-bounces at] On Behalf Of David Knecht via CnC-List
Sent: Friday, February 17, 2017 11:17
To: CnC CnC discussion list <cnc-list at>
Cc: David Knecht <davidaknecht at>
Subject: Re: Stus-List draining water heater

On Feb 17, 2017, at 10:42 AM, Josh Muckley via CnC-List <cnc-list at<mailto:cnc-list at>> wrote:

The water heater has a ~6 gallon capacity.  If you attempt to freeze protect it then you would need to flush out the water with glycol and probably end up using 3 or 4 gallons in the process.  Glycol isn't cheap and considering that you can eliminate the risk of freezing simply by draining, glycol in the water heater is a waste of money.

What Josh says makes perfect sense, but now I am really confused.  When I winterized the boat, I pumped all the water out of the tanks, then poured antifreeze into the tanks and pumped until pink came out the cold and hot lines at each faucet.  But it did not take anything like 3-4 gallons.  What am I missing?  Dave
1990 C&C 34+
New London, CT

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