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Fresh Water System Winterizing

Feb 10, 2004
3,277
Hunter 40.5 East Greenwich, RI
When water freezes, I think I remember that it expands about 5% - don't hold me to this, I'm working from memory and I am old. If you have drained 90%+ of the water and still have a 1/2" or so in the bottom of the heater, IMHO it will be perfectly fine. Ditto for the fresh water tanks - you probably still have a little in the bottom below the hose barb. And the lines if blown out will be just fine, even if there is a small dip someplace. As long as the water can't push against anything solid, it won't do any damage.

And the petcock at the bottom of the Seaward heaters is probably not exactly at the bottom either. So if you think that you have it all out, you probably still have a small amount left.
20 years of draining my Seaward through the petcock has resulted in success every year.

I drain my water tanks and then blow back into the tanks to purge the lines from the tanks to the pump. I blow out the pump- very important. Then I blow out all of the lines to each faucet. I used to use my dinghy pump for this but now I have a CO2 bottle that I pressurize the system to 15# and just walk around opening each faucet in turn. Again, 20 years, no problems.
 
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jviss

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Feb 5, 2004
4,524
Tartan 3800 Westport, MA
I'm struggling a bit with the Tartan. The C36 I can do in my sleep, after 17 years. But this new one is a mystery to me, in many ways. For example, I drained the tanks and after a bunch of screwing around, dumped 2 gallons of pink into the port tank, and still nothing out the line.

I'm going to have to make a plan for when I go back on the weekend.

I think I'll vacuum out any water and pink that's in that port tank through the cleanout port, and then blow the lines for both tanks with the dinghy pump.

Then, on to the accumulator and water heater. The accumulator is mounted with the air valve down, so no easy draining of that. What to do about it? Also, the plumbing is all polybutylene tubing with Parker "O"- Ring/Grab Ring Tube Fittings, so I'd like to remove the input line to the pump and blow that one back to the two-tank manifold, and then fit a short tube to the pump inout, but I'm not sure what tube I can buy that will fit on the pump fitting. Any ideas? I don't know that the homeowner stores sell this kind of plumbing.

I don't know what to do about the heater, other than taking all the plumbing apart.

I'll then get a tube onto the pump input, and ping the lines to the head sink, galley sink, swim platform shower, and anchor washdown. Maybe I'll try blowing them out first.

Open to suggestions.
 
Feb 10, 2004
3,277
Hunter 40.5 East Greenwich, RI
I'm struggling a bit with the Tartan. Open to suggestions.
Since your HW heater doesn't have a bottom drain, If you can pressurize the system and then open the COLD water tap(s), the pressure will go thru the hot water lines to the top of the water heater and force the water in the tank out the cold water inlet to your faucets.

Edited- you need to pressurize the hot water line, not the entire system. Can you connect a air pump to one of the hot water faucets?
 

jviss

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Feb 5, 2004
4,524
Tartan 3800 Westport, MA
I think it does, the petcock I mentioned, but I'm concerned that there doesn't seem to be an easy way to admit air at the top, so that it drains fully. I guess I could just disconnect a piece of hose and see if it drains.
 
Mar 26, 2011
2,611
Corsair F-24 MK I Deale, MD
Data point:

I have the same refractometer and tested three products.

All of these are propylene glycol solutions with no ethanol or methanol.

Dow RV AntiFreeze -50º: -18ºC (-0.4 ºF) $5/gallon at Home Depot
West Marine Pure Oceans -50º: -14ºC (-6.8ºF) $5/gallon on sale at West Marine
Sta-Bil RV & Marine Premium Antifreeze -75º: -11ºC (-12.2ºF) $4/gallon at WalMart

Clearly the Dow stuff is the best. I was surprised, I thought the Sta-Bil would be, and I think the label saying "-75º" is deceptive.
The likely problems is that there is no standard definition of burst point. Is it the point where the solution first begins to expand, where glass will break, where PVC (an sizes and grades vary) will break, or where copper tube will break?

Another way of looking at is is that most of them a lying just a little. However, I believe Wet Marine and several others have begun puting either freeze point charts or at least an explanation of burst points for different materials on the side panel.

Let the buyer be ware. And check the pink stuff coming out the other end to be sure you got the water out. This is why I pushed pocket refractometers over the years.

[I spent 35 years in the chemical industry as a chemical engineer, over 20 of those involved in glycol and antifreeze production, including formulation. I've run burst point tests, and I dislike that there is no ASTM standard. The engine coolant subcommittee (D15) won't touch it.]
 

jviss

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Feb 5, 2004
4,524
Tartan 3800 Westport, MA
[I spent 35 years in the chemical industry as a chemical engnieer, over 20 of those involved in glycol and antifreeze production, including formulation.]
Awesome! So, I have a question. Why don't we just buy pure propylene glycol, and dilute it as needed? Are the supposed additives mentioned on the pink stuff bottles really worth it?
 
Aug 13, 2012
519
Catalina 270 Ottawa
I'll then get a tube onto the pump input, and ping the lines to the head sink, galley sink, swim platform shower, and anchor washdown. Maybe I'll try blowing them out first.
check the OD of the threaded port on the input of the pump. Quite likely it is 1/2". Get a "plastic" flexible tube at h/w store that matches (roughly) that diameter (of course, this time ID). Put that tube on the threaded port and secure with a hose clamp. It does not need to be sealed to any high pressure (you are on the sucking end). You will probably need to prime that hose, before the pump starts pumping AF.

When I winterise, I have a bunch (technical term) of different hoses (at least a couple feet each). Usually, one fits.
 
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May 17, 2004
2,597
Beneteau Oceanis 37 LE Havre de Grace
However, I believe Wet Marine and several others have begun puting either freeze point charts or at least an explanation of burst points for different materials on the side panel.
I did notice on our West Marine -50 PG this year a statement that the -50 protection applies to copper pipe. It said for plastic plumbing that “may” be used in marine systems bursting would be prevented to -10F (pretty close to JVISS’s measurement). Buyer beware indeed - I’m sure all of us buying marine antifreeze at West Marine have only copper pipe in our boats.

Thanks. What is "T&P?"
Temperature and Pressure (the pressure relief valve on the tank).
 
Mar 26, 2011
2,611
Corsair F-24 MK I Deale, MD
Awesome! So, I have a question. Why don't we just buy pure propylene glycol, and dilute it as needed? Are the supposed additives mentioned on the pink stuff bottles really worth it?
They do aid in corrosion protection. However, don't assume that glycol at retail would be meaningfully cheaper, since antifreeze is the standard.

"Supposed" additives? I've run the tests, and only the cheapest products omit good additives.

https://www.practical-sailor.com/issues/37_45/features/PSs-Top-Picks-for-Winterizing_11500-1.html
https://www.practical-sailor.com/issues/37_47/features/Will-Your-Tanks-Be-Clean-Next-Spring_11546-1.html
 
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Jun 14, 2010
1,348
Quorning Dragonfly 1200 home
Usually, the pump is low in the hull so water from tanks will flow via gravity. I use a shop vac setup to blow from the faucet end. This way more water is driven to the lowest point. Beforehand, remove the hose from the pump and blow through the pump as well. I also have a water heater bypass and never put antifreeze in it. Be sure to reverse the vac and remove all water from the tanks. Leave valves open. I also leave the hoses off the pump. I use a LOT less antifreeze and the process is quicker. Don't forget the fridge drain and the manual bilge pump.
I hope you're using a new shop vac or one reserved for this function as a clean machine. It makes me shudder to think of the contamination and residue in my shop vac hoses and filter/motor housing... I don't think it would be possible to clean mine well enough to use it to pump INTO my fresh water lines; my concern being that the contaminated dust would sit and grow microscopic organisms all winter inside the damp lines.
OTOH I might use a clean tip inserted into the pump outlet hose to suck water out of the lines with the shop vac by opening faucets one at a time. Just keep the vac running the whole time and/or orient the hose attachment so water doesn't have the opportunity to drain back from the vac hose into the water lines.
I prefer the dinghy pump method if pumping air into the lines. I use a low pressure electric air pump.
 

jviss

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Feb 5, 2004
4,524
Tartan 3800 Westport, MA
bursting would be prevented to -10F (pretty close to JVISS’s measurement).
David, I believe what my measurements say is that the temps indicated on the refractometer are the temp at which ice crystals would just start to form in the solution under test. So, the lower number on the product is the copper pipe burst temperature. I don't know if plastic pipe is safe to lower temps than copper pipe.

I know I'm becoming a bit obsessive over all of this. A friend has said that for many years (20+) he's just 'pinked' 'til it comes out pink at the other end, and has never had a problem, here in New England, where it sometimes gets "wicked cold" for days in the winter.
 
Aug 22, 2017
1,592
Hunter 26.5 West Palm Beach
propylene glycol (PG) is the food grade cousin of the glycol that is used in automotive coolant. PG is commonly used as a sweetener in various brands of root beer. Just read the labels on the cans if you don't want to believe that.

Back when I was doing some work in the beverage industry & I had ready access to straight PG, I used it as a winterizing fluid in a few places with no problems.

Alcohol has 2 issues when it comes to using it as a winterizing fluid. First, it is corrosive to many rubbers & some other materials. Second, it is never pure when you get it. It always has some water mixed with it. Since alcohol evaporates more readily than water, if you have any ventilation in the system, the alcohol will vent off as time goes by, leaving you with a progressively weaker solution with a progressively higher freezing point. Even in a closed system, temperature changes sometimes cause a distillation effect to take place inside the closed system, which results in some areas having a higher concentrations compared to others. The effect in the closed systems is usually much less dramatic.

When possible, it is usually a worthwhile endeavor to plan ahead when installing the plumbing system on your boat. Installing drain fittings at strategic points & choosing pipe routes with no dips, will make the winterizing process much faster & easier.
 
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jviss

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Feb 5, 2004
4,524
Tartan 3800 Westport, MA
Update on data points.

Dow is no longer available at Home Depot, having been replaced with SouthWin, which is supposedly the same, exact thing as the Dow, but I got different results.

Dow RV AntiFreeze -50º: -18ºC (-0.4 ºF) $5/gallon at Home Depot
SouthWin Ltd. AntiFreeze -50ºF: -16ºC (3.2ºF) $5/gallon at Home Depot
West Marine Pure Oceans -50º: -14ºC (-6.8ºF) $5/gallon on sale at West Marine
Sta-Bil RV & Marine Premium Antifreeze -75º: -11ºC (-12.2ºF) $4/gallon at WalMart

So, still pretty good, but not as good as Dow was. Disappointing.