WINTERIZING: is there a best order when running RV fluid through FRESH water lines?

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.

capran

Senior Member
Joined
Apr 11, 2022
Messages
222
Vessel Name
Honu
Vessel Make
Helmsman 38/Mariner Saville 37
I am starting to keep better notes this year, but can't remember last year. As I run RV fluid through each line, is it better to start with the fittings closest to the source, or further away? For example, I think last year I first did the lines to the aft toilet and then the forward toilet, then all COLD faucets starting with the cockpit shower, kitchen, aft bath. forward shower and forward sink, then repeat sequence with the HOT water faucets. (Last year when I was done, I used compressor to remove as much RV fluid from lines as possible to reduce the RV fluid taste I get if I leave the fluid filling the lines all winter (which helped I think). Whatever I did last year helped, as we heard quite a few boats had broken lines from an extreme cold period coinciding with a power outage.
 
For the water system, I drain the tank, run the pressure tank down to zero. Remove the filters from their housings and reinstall the empty housings. Drain and bypass the water heater. Add a few gallons of antifreeze to the tank. Then run through all of the cold lines starting from the furthest points and working back towards the closest points. Repeat for the hot water lines, then drain any leftover antifreeze out of the tank.

For avoiding the taste, make sure you use at least the -50* stuff that's glycol only (no alcohol). If there's any risk of dilution, use stronger antifreeze, as once the concentration gets much below the strength of the -50* stuff, it can start to grow stuff in the system.

In the spring, I put a few gallons into the tank, flush it through, and repeat a few times. Then start filling the tank and run a few hundred gallons through both the hot and cold systems. Bleach shock it all, then flush again. After that flush, it's time to scrub the filter housings and install new filters, then valve the water heater back into the system and get the air out of everything. Then we're good to go with no taste or smell issues.
 
For the water system, I drain the tank, run the pressure tank down to zero. Remove the filters from their housings and reinstall the empty housings. Drain and bypass the water heater. Add a few gallons of antifreeze to the tank. Then run through all of the cold lines starting from the furthest points and working back towards the closest points. Repeat for the hot water lines, then drain any leftover antifreeze out of the tank.

For avoiding the taste, make sure you use at least the -50* stuff that's glycol only (no alcohol). If there's any risk of dilution, use stronger antifreeze, as once the concentration gets much below the strength of the -50* stuff, it can start to grow stuff in the system.

In the spring, I put a few gallons into the tank, flush it through, and repeat a few times. Then start filling the tank and run a few hundred gallons through both the hot and cold systems. Bleach shock it all, then flush again. After that flush, it's time to scrub the filter housings and install new filters, then valve the water heater back into the system and get the air out of everything. Then we're good to go with no taste or smell issues.

Ah. Guess I did it wrong. I will reverse the order and start with the furthest away on my Helmsman/Seville 37. Instead of putting RV fluid in the tanks, I disconnected the water line when it comes out of the tank and put that line directly into the RV fluid. That way I can monitor exactly how much fluid I am using as it flushes through the toilets as well as all the lines. Unfortunately I did not create a bypass system for the hot water tank. The lines going into the hot water heater are at a bad angle and access where the hot line diverts is in a next to impossible area to access. (and Pex is not my friend. LOL). I don't have a filter system, but we did similar to you in the spring and after a couple of flushes got most of the after taste gone.
 
Without bypassing the water heater, I expect you're going through quite a bit of antifreeze to drain the water heater and then refill it with antifreeze. If you're not draining it first, then it's likely so diluted as to be nearly pointless in the hot water side.

I'm not sure the order of faucets actually matters, but furthest first just seems logical to me.
 
I would absolutely bypass the water heater. Besides diluting the antifreeze for the winter it will be difficult to get all the antifreeze out of the water heater in the spring. It is pretty easy to make a bypass and you will save a lot of antifreeze and hassle in the spring.
 
For what it's worth, I prefer to blow out the pipes with compressed air. Then there is no antifreeze to begin with, so no possibility of growth, and no residual taste.
 
For the life of me, I do not understand why adding fluid to the fresh water tanks and the water heater is necessary given that they have been drained to near empty. My thinking - consider an ice cube tray. It is filled and put into the freezer. The water freezes into cubes but the tray container does not split open. Why? Because there is room for expansion, vertically. Is it not the same for our water tanks? Well, it has been for my tanks. Nope. Never any antifreeze in them and never a problem.
 
For the life of me, I do not understand why adding fluid to the fresh water tanks and the water heater is necessary given that they have been drained to near empty. My thinking - consider an ice cube tray. It is filled and put into the freezer. The water freezes into cubes but the tray container does not split open. Why? Because there is room for expansion, vertically. Is it not the same for our water tanks? Well, it has been for my tanks. Nope. Never any antifreeze in them and never a problem.

The tanks aren't an issue after they're drained. In my case, they're just an easy way to get antifreeze into the lines. Only reason I run antifreeze through the lines is because I'm not confident I can avoid little bits of water accumulating in low spots in the system.
 
I am starting to keep better notes this year, but can't remember last year. As I run RV fluid through each line, is it better to start with the fittings closest to the source, or further away? For example, I think last year I first did the lines to the aft toilet and then the forward toilet, then all COLD faucets starting with the cockpit shower, kitchen, aft bath. forward shower and forward sink, then repeat sequence with the HOT water faucets. (Last year when I was done, I used compressor to remove as much RV fluid from lines as possible to reduce the RV fluid taste I get if I leave the fluid filling the lines all winter (which helped I think). Whatever I did last year helped, as we heard quite a few boats had broken lines from an extreme cold period coinciding with a power outage.
make sure you by pass the hot water tank, and just leave it drained
 
make sure you by pass the hot water tank, and just leave it drained

And lock out or tape off the breaker for the water heater. If you turn on power to an empty heater the element will burn out almost immediately.
 
And lock out or tape off the breaker for the water heater. If you turn on power to an empty heater the element will burn out almost immediately.

That is what I always believed. But we bought a boat that had been unattended for months. They left the water heater on and empty. I could hear the sizzling sound from the element so I immediately filled the heater and the sizzling sound went away. The water heater was still working fine when I sold the boat 8 years later. Who knows?
 
I think this may help:


FRESH WATER SYSTEM :
There are two ways to winterize fresh water and sanitation plumbing: with antifreeze and without antifreeze. If you opt for the “no antifreeze” method, ALL the water MUST be removed from the entire system. Why? Because it’s not freezing temperatures that break pipes and crack tanks, it’s because ice occupies about 10% more space than the same amount water…and when it expands, something has to give—and that something will be your water or holding tank, water heater, hose connection, water pipe, or toilet bowl.
ANTFREEZE METHOD (Easiest)
1. Drain the water tanks completely (just turn on all the faucets).
2. Drain water heater. Most have a drain petcock; follow manufacturer’s instructions to find it and use it. Remove both the inlet and outlet hoses, and if necessary use a shop vac to be sure of getting all the water out of it.
3. Do NOT put antifreeze in the water heater. (Ok, you can if you want to, but it’s not necessary). Connect water heater inlet and outlet hoses together to bypass it. Bypass kits for this purpose are available from boat stores and RV supply stores.
Why drain the water heater and bypass it instead putting antifreeze into it? Because it’s not freezing temps that damage pipes, tanks and water heaters, it’s water sitting in a confined space with nowhere to expand. The very small amount of water that may be lleft in the bottom of a water heater has plenty of room to expand, plus water heaters are insulated which protects them from freezing, and it takes forever to flush the taste and smell of antifreeze out your hot water in the spring!
4. Put a few gallons of non-toxic antifreeze ("the pink stuff") into the water tank and pump that through the system until all outlets--hot and cold in the galley, head, shower, and any deck wash--run only antifreeze. Leave all the faucets open to make sure there is no pressure in the system.
NO ANTIFREEZE (“dry”) METHOD:
1. Follow the first three steps listed above.
2. Using an air compressor, blow ALL the water out of ALL the plumbing, disconnecting it where necessary to achieve this. The first time you opt for this method can be difficult and labor intensive, but if connections are reassembled in the spring using quick-connect fittings, it becomes a lot easier in the future.

SANITATION SYSTEM
The sanitation system is the easy job:

Pump out the holding tank, then rinse thoroughly to flush out any sludge. This does not require filling the tank and can even be done with sea water. Here’s how:
Put enough water into the tank via the deck pumpout fitting—because that sends the water into the tank at the bottom to stir up any sludge and hold it in suspension so it can be flushed out-- to cover the bottom to a depth of at least four inches. Pump that out. Repeat…repeat…repeat…till you’re pumping out clean water. Then add water one more time and turn on the macerator to rinse it out along with the overboard discharge plumbing.
Alternatively, you can use a washdown pump to do the whole job. Stick the nozzle into the deck pumpout out fitting and turn on the water. When the depth reaches a few inches, leave the water running and turn on the macerator pump. Let both run till the water runs clean (it may be best to do this offshore outside the “3 mile limit”).
By the way, this should be done at least 2-3x a season, more often if live aboard or use your boat year round and in preparation for any extended layup, not just winter layup

Now you’re ready to winterize the system.
Sea water toilet, manual or electric: Just flushing antifreeze through the bowl will not protect the intake line, the toilet pump or the bowl...it'll only go out the discharge to the tank. To protect the whole system, it's necessary to close the toilet intake through-hull, disconnect inlet hose and stick it in a gallon of non-toxic ("the pink stuff") antifreeze. Pump the whole gallon through the system into the holding tank. Do not reconnect head intake hose to the through-hull.
If your toilet’s flush water intake line is teed into the head sink drain line, you can add the antifreeze by just pouring it down the sink--after you've closed the drain seacock, of course! Pump the head or hold the button down long enough to get the excess fluid out of the system as possible.
Fresh water toilet: If your toilet uses onboard pressurized fresh water, you winterized it when you winterized your fresh water system. All that remains is, flush the appropriate amount of non-toxic antifreeze ("the pink stuff") down the toilet into the tank.

Do not use antifreeze in an ElectroScan, Lectra/San, PuraSan, or any other Type I or Type II MSD. Follow manufacturers instructions to winterize all Type I and II MSDs.

After the boat comes out of the water, open all the sea cocks to drain any trapped water. (Omit this step if the boat will remain in the water).

And you’re done!


--Peggie
 
For the life of me, I do not understand why adding fluid to the fresh water tanks and the water heater is necessary given that they have been drained to near empty. My thinking - consider an ice cube tray. It is filled and put into the freezer. The water freezes into cubes but the tray container does not split open. Why? Because there is room for expansion, vertically. Is it not the same for our water tanks? Well, it has been for my tanks. Nope. Never any antifreeze in them and never a problem.

I wasn’t worried about the tank but rather the plumbing pipes. I always put antifreeze through the freshwater system after I bypassed the water heater because I didn’t trust that all the water would get out of the plumbing by compressed air. In the hoses if the water expands something has to give and I hate doing plumbing repairs. I found it simple to drain the water tank and put in antifreeze. Run it through every outlet and test the antifreeze with a reflectometer to make sure it wasn’t diluted too much. It was surprisingly easy to see color and call it good but when I put some in the reflectometer it would show +20 degrees, not -20. So I would test every outlet except the freshwater flush head, but I would test all the outlets next to the head and then give the head 3 or 4 flushes to get the concentrated antifreeze into the head.

Since we bought our current boat we have been using heated winter storage so we don’t winterize anymore, and I don’t miss doing it…
 
Last edited:
Without bypassing the water heater, I expect you're going through quite a bit of antifreeze to drain the water heater and then refill it with antifreeze. If you're not draining it first, then it's likely so diluted as to be nearly pointless in the hot water side.

I'm not sure the order of faucets actually matters, but furthest first just seems logical to me.

I first run all faucets until they are sputtering. Then I do drain the hot water heater via the petcock/drain valve before running the RV antifreeze through the system and get a pretty solid pink even though another reply said the color is not a good indicator. and this year will take the advice to do furthest first.
 
The best way to ensure that the antifreeze is good is to use either -100 or -200 antifreeze. It is more expensive but you don’t need as much. Also those are good to use a reflectometer on, where the -60 don’t usually work with a reflectometer. By using the reflectometer you are sure that the antifreeze is good to the temperature you want it to be. I usually would look for -20. It only takes a couple of seconds to do the test.
 
Thanks for your detailed response. The reason I was using both the compressor method AND the antifreeze is as another person replied, that in the slight chance the compressor doesn't remove all water, if the residual amount is RV fluid, hopefully I avoid problems. The Helmsman I have has PEX, and removing the PEX lines would require completely redoing the shark bites that hold it all together. (not in my skill set or tool box). And, as I said, the water line disappears under an inaccessible area shortly after leaving the in line filter/back flow preventer. I sure wish the whole boat was old school hoses and clamps. Also, when I blow out all the lines with the compressor, I disconnect at an inline filter that is right after the pump. When I add the RV fluid, I put the line that comes off the water tank directly into the RV antifreeze bottle(s).

As to the Sanitation system, I have fresh water Tecma toilets, but have no clue if they are in the category that you suggest not to use with RV antifreeze. I have very little paperwork and nothing indicates what Type they are. All I know is I did three flushes into each head last year, fed through the hose going into the pump from the jugs of pink, and had very pink color going through into the bowl. In addition, I ran the macerator until pink fluid came out and into the bucket I was holding under the boat, so I had nice pink coming through from the original very empty and clean holding tank, so there's pink in the line and macerator, with the only fluid in the holding tank being the six flushes. (we spent considerable time flushing the holding tank until we had perfectly clear liquid while we were at the pump out dock.)

I think this may help:


FRESH WATER SYSTEM :
There are two ways to winterize fresh water and sanitation plumbing: with antifreeze and without antifreeze. If you opt for the “no antifreeze” method, ALL the water MUST be removed from the entire system. Why? Because it’s not freezing temperatures that break pipes and crack tanks, it’s because ice occupies about 10% more space than the same amount water…and when it expands, something has to give—and that something will be your water or holding tank, water heater, hose connection, water pipe, or toilet bowl.
ANTFREEZE METHOD (Easiest)
1. Drain the water tanks completely (just turn on all the faucets).
2. Drain water heater. Most have a drain petcock; follow manufacturer’s instructions to find it and use it. Remove both the inlet and outlet hoses, and if necessary use a shop vac to be sure of getting all the water out of it.
3. Do NOT put antifreeze in the water heater. (Ok, you can if you want to, but it’s not necessary). Connect water heater inlet and outlet hoses together to bypass it. Bypass kits for this purpose are available from boat stores and RV supply stores.
Why drain the water heater and bypass it instead putting antifreeze into it? Because it’s not freezing temps that damage pipes, tanks and water heaters, it’s water sitting in a confined space with nowhere to expand. The very small amount of water that may be lleft in the bottom of a water heater has plenty of room to expand, plus water heaters are insulated which protects them from freezing, and it takes forever to flush the taste and smell of antifreeze out your hot water in the spring!
4. Put a few gallons of non-toxic antifreeze ("the pink stuff") into the water tank and pump that through the system until all outlets--hot and cold in the galley, head, shower, and any deck wash--run only antifreeze. Leave all the faucets open to make sure there is no pressure in the system.
NO ANTIFREEZE (“dry”) METHOD:
1. Follow the first three steps listed above.
2. Using an air compressor, blow ALL the water out of ALL the plumbing, disconnecting it where necessary to achieve this. The first time you opt for this method can be difficult and labor intensive, but if connections are reassembled in the spring using quick-connect fittings, it becomes a lot easier in the future.

SANITATION SYSTEM
The sanitation system is the easy job:

Pump out the holding tank, then rinse thoroughly to flush out any sludge. This does not require filling the tank and can even be done with sea water. Here’s how:
Put enough water into the tank via the deck pumpout fitting—because that sends the water into the tank at the bottom to stir up any sludge and hold it in suspension so it can be flushed out-- to cover the bottom to a depth of at least four inches. Pump that out. Repeat…repeat…repeat…till you’re pumping out clean water. Then add water one more time and turn on the macerator to rinse it out along with the overboard discharge plumbing.
Alternatively, you can use a washdown pump to do the whole job. Stick the nozzle into the deck pumpout out fitting and turn on the water. When the depth reaches a few inches, leave the water running and turn on the macerator pump. Let both run till the water runs clean (it may be best to do this offshore outside the “3 mile limit”).
By the way, this should be done at least 2-3x a season, more often if live aboard or use your boat year round and in preparation for any extended layup, not just winter layup

Now you’re ready to winterize the system.
Sea water toilet, manual or electric: Just flushing antifreeze through the bowl will not protect the intake line, the toilet pump or the bowl...it'll only go out the discharge to the tank. To protect the whole system, it's necessary to close the toilet intake through-hull, disconnect inlet hose and stick it in a gallon of non-toxic ("the pink stuff") antifreeze. Pump the whole gallon through the system into the holding tank. Do not reconnect head intake hose to the through-hull.
If your toilet’s flush water intake line is teed into the head sink drain line, you can add the antifreeze by just pouring it down the sink--after you've closed the drain seacock, of course! Pump the head or hold the button down long enough to get the excess fluid out of the system as possible.
Fresh water toilet: If your toilet uses onboard pressurized fresh water, you winterized it when you winterized your fresh water system. All that remains is, flush the appropriate amount of non-toxic antifreeze ("the pink stuff") down the toilet into the tank.

Do not use antifreeze in an ElectroScan, Lectra/San, PuraSan, or any other Type I or Type II MSD. Follow manufacturers instructions to winterize all Type I and II MSDs.

After the boat comes out of the water, open all the sea cocks to drain any trapped water. (Omit this step if the boat will remain in the water).

And you’re done!


--Peggie
 
The best way to ensure that the antifreeze is good is to use either -100 or -200 antifreeze. It is more expensive but you don’t need as much. Also those are good to use a reflectometer on, where the -60 don’t usually work with a reflectometer. By using the reflectometer you are sure that the antifreeze is good to the temperature you want it to be. I usually would look for -20. It only takes a couple of seconds to do the test.

Thank you. Do you have a brand name and place to purchase your reflectometer? I'd like to add that to my kit. In the PNW winters are relatively mild and the boat yard uses the -50 when they winterize. I'm hoping that is enough to keep me from bursting. I looked around locally in Spokane and couldn't find the -100 last year. (the boat is in Anacortes Wa.)
 
This is what I have. Got it on Amazon for $15.95.

Antifreeze Refractometer 4-in-1 Coolant Tester Refractometer for Checking Freezing Point of Automobile Antifreeze Systems, Anti Freeze Tester Refractometer for Battery Acid, Ethylene Propylene Glycol

I used to order the antifreeze online since where we live there aren’t a lot of stores. We do a lot of Amazon. But we got the antifreeze somewhere else, don’t remember where.
 
make sure you by pass the hot water tank, and just leave it drained

I do drain it once before I use the compressor as well as after I have run RV fluid through all lines and toilet. I sure wish I had better access and that it was hose and clamp rather than PEX. The line coming from the pump goes about 3 or 4 feet and disappears under a non accessible floor. A red PEX line appears to come out of that space and goes to the aft cockpit lazarette where it comes up at an angle from the hot water heater. wish I could get pics and post.
 
And lock out or tape off the breaker for the water heater. If you turn on power to an empty heater the element will burn out almost immediately.

Thanks. I'll add that. we are very careful about everything being off, but wouldn't hurt to flag it.
 
For the life of me, I do not understand why adding fluid to the fresh water tanks and the water heater is necessary given that they have been drained to near empty. My thinking - consider an ice cube tray. It is filled and put into the freezer. The water freezes into cubes but the tray container does not split open. Why? Because there is room for expansion, vertically. Is it not the same for our water tanks? Well, it has been for my tanks. Nope. Never any antifreeze in them and never a problem.

I don't think the worry is the tanks. I think it's the lines freezing that worry me. Thanks to input last year I did both blowing out with a compressor as well as the RV fluid, followed by another blow out which got most of the RV fluid out of the lines, with the off chance that if there was anything residual left in the lines, it was the RV fluid. An over abundance of caution, to be sure, mostly because the fresh water system is PEX and repairing that is not something I am familiar with.
 
I don't think the worry is the tanks. I think it's the lines freezing that worry me. Thanks to input last year I did both blowing out with a compressor as well as the RV fluid, followed by another blow out which got most of the RV fluid out of the lines, with the off chance that if there was anything residual left in the lines, it was the RV fluid. An over abundance of caution, to be sure, mostly because the fresh water system is PEX and repairing that is not something I am familiar with.

And it is pretty much a given that if you split a line it will be in the most inaccessible place in the boat…
 
I am starting to keep better notes this year, but can't remember last year. As I run RV fluid through each line, is it better to start with the fittings closest to the source, or further away?


When we winterize, we go back and forth through our system several times... so in that case, I don't think it matter what order your first pass is.

FWIW, we use only compressed air instead, except for a small "bump" of AF through the (disconnected) freshwater pump itself. Compressed air will force slightly more water out of the water heater while draining that, too...

-Chris
 
Last edited:
For the refractometer thing, it'll work on any pure propylene glycol antifreeze (regardless of temp rating). It just won't work reliably on the glycol / alcohol blends.
 
For the refractometer thing, it'll work on any pure propylene glycol antifreeze (regardless of temp rating). It just won't work reliably on the glycol / alcohol blends.
Thanks. Just my luck. guess I will put that off until I switch to the other antifreeze
 
... I sure wish I had better access and that it was hose and clamp rather than PEX. ...

That's interesting. I switched mine to PEX / SharkBite fittings just to make this bypass easier. The bypass valves are built right into the fittings.

BD
 

Attachments

  • HW bypass.jpg
    HW bypass.jpg
    50.8 KB · Views: 58
I avoid adding any non-tox anti-freeze to the tank, it's hard to get that taste and odor out no matter how much you flush it. A small amount of water left in the bottom of a tank, won't be an issue even if it freezes, because it has room to expand. As others have noted, bypass the water heater and simply drain it.

If you have access to compressed air, this is an excellent and low impact means of winterizing a potable water system. Barring that I use inexpensive vodka, as it imparts no taste or foaming and requires little flushing in the spring. Non-Tox can be used for other systems like raw water washdown, engines and sanitation systems.

More here https://stevedmarineconsulting.com/wp-content/uploads/2020/07/Winterizing-your-Vessel.pdf
 
Winterizing fresh water lines

If your boat is like mine you probably have a FW pump that feeds the house.

I open all, that is ALL faucets.

I disconnect the intake line between the tank & the pump and I have a short piece of hose that I connect to the pump.

I bypass the section that goes to the water heater.

I've opened several bottles of AF to be ready.

Placing the hose in a gal of RV AF I have the mate turn on the pump at the panel.

She goes around and closes a faucet as it spits out pink. When all faucets are done we go back around and open all the faucets.

House fresh water system now winterized.

Pretty easy that way for us.
 
Hey Capran: here are two things to make your life easier. (i have the same boat)
1: cut the fresh water hose between the tank and the pump and install a simple disconnect garden hose coupling. Makes draining tank and putting pink into the pump easy. Just connect a short hose to the pump side and stick in the pink jug.
2: The lowest part of our boat is by the forward bilge pumps. There is a hot and cold water line that runs close by. Cut these lines and install a "T" and attach two shut off taps. (home depot). After you have run through the pink, you open these taps and drain the system. much of the pink can be recaptured in a low tray and dumped in the holding tank. Leave taps open all winter for drainage into the bilge.

Bonus answer: As others have said there is no need to put anything in the fresh water tank when empty. When my marina lifts the boat out he always goes stern high, which any little bit of water in the tank runs out and into the bilge.

My problem is now laying in bed thinking if i missed anything!!

Barrie
 

Latest posts

Back
Top Bottom