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Overwintering - Using Non Toxic Antifreeze


Withywindle
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Looking ahead to winterising our boat for the first time this year I’m thinking about the most efficient way to drain or protect the potable water system. 

 

I’m sure just draining down in the usual way is what almost everyone will do, but I’m aware that you can also go down the route of using non-toxic pink Propylene Glycol antifreeze (eg Starbrite) run through the pipe work and left for the winter. The only down side I can see is the hot water cylinder which has to be drained in the normal way then the inlet and outlet pipes joined with a hose to allow the antifreeze to flow through and reach the hot water pipes. Well that’s what Starbrite recommend anyway - see their instructions below. 

 

Why go to this trouble of using this stuff I hear some of you say? Well I once owned a static caravan which I drained down thoroughly each year, or so I thought. After one particularly cold winter I returned in the spring turned on the water and found I’d got a burst. It turned out there was one short run of pipe that hadn’t properly drained. When I replaced it I found it looked like a string of sausages! Clearly it had frozen and thawed each winter, stretching the copper more and more every year until finally it gave up and split. It was a lesson well learned. You can’t be 100% sure pipework is fully drained, so I quite like the idea of a non toxic antifreeze. 

 

Do any of you use this stuff in your potable water systems and do you have any observations or advice?

 

 

CD06EB55-E61D-4507-807E-F396595B64E3.jpeg

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Remember that it's very rare canals freeze solid in the UK.  The baseplate of the boat will usually be at or above 4 Celsius even if there is very thick surface ice.

 

A caravan doesn't usually sit in a massive heat storage reservoir so gets down to air temperatures which can often be well below freezing.

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I live on my boat so don't winterise at all really.  When I have to go away for a few days in winter, I turn of the fresh water pump and turn all the taps on.  This takes all the pressure out of the pipes.  Works fine.  On occassion I've left my boat a couple of weeks in very cold temperatures like this and no problem.

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3 minutes ago, doratheexplorer said:

I live on my boat so don't winterise at all really.  When I have to go away for a few days in winter, I turn of the fresh water pump and turn all the taps on.  This takes all the pressure out of the pipes.  Works fine.  On occassion I've left my boat a couple of weeks in very cold temperatures like this and no problem.

It’ll be up to three months in my case so I really need to do a thorough job just in case. 😊

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I used to work in the flood damage restoration business so I am paranoid about this sort of thing.  Even so, despite assiduously draining down my boat every winter, a few years ago I returned to discover a burst water heater matrix.  It had been a particularly hard winter, but I was so sure I had drained the matrix thoroughly it never occurred to me there would be a problem.  

 

I think if you don't have regular access to the boat in the winter the non toxic anti freeze is a wise precaution - no-one knows how bad/cold the winter is going to be.  

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3 minutes ago, Neil2 said:

I used to work in the flood damage restoration business so I am paranoid about this sort of thing.  Even so, despite assiduously draining down my boat every winter, a few years ago I returned to discover a burst water heater matrix.  It had been a particularly hard winter, but I was so sure I had drained the matrix thoroughly it never occurred to me there would be a problem.  

 

I think if you don't have regular access to the boat in the winter the non toxic anti freeze is a wise precaution - no-one knows how bad/cold the winter is going to be.  

I don't even know what a water heater matrix is?  Do all boats have them?

16 minutes ago, Withywindle said:

It’ll be up to three months in my case so I really need to do a thorough job just in case. 😊

You're missing some good cruising time there!

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55 minutes ago, doratheexplorer said:

I don't even know what a water heater matrix is?  Do all boats have them?

 

 

Matrix is probably the wrong term - the heat exchanger, the mass of tubes in an instant GWH that the water flows through whilst it's being heated by the gas flame.    I must have left a small amount of water in there and the tubes are small bore and quite fragile.

 

One of the many things about boat design, not just narrowboats, that annoys me is how difficult it often is to thoroughly drain the water system.  In some case there is no provision at all.  Yet the vast majority of boats spend their winters unoccupied.

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1 hour ago, ditchcrawler said:

I drain everything including the calorifier, not always easy on some boats.

Thanks. Yes I was intending to do that too that’s what I meant by the hot water tank - sorry  not fully up to speed with my marine terminology yet 😊.

 

Here’s my village idiot question.... I presume you don’t drain the actual heater coil too as that would be full of the actual engine coolant containing antifreeze and would mean draining the entire engine cooling system too. Sorry to sound a bit dumb, I’m still getting my head around this stuff. 

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I have always left the coil from the engine (and engine) full as it has the antifreeze in. If the boat is new to you check the strength is OK.

 

Do you have a diesel heater that runs radiators and another coil in the calorifier. If you do, the radiator circuit also needs anti freeze.

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4 minutes ago, PeterF said:

I have always left the coil from the engine (and engine) full as it has the antifreeze in. If the boat is new to you check the strength is OK.

 

Do you have a diesel heater that runs radiators and another coil in the calorifier. If you do, the radiator circuit also needs anti freeze.

Thanks Peter, that was my understanding. My confusion here comes from domestic water heaters where just the coil is sometimes called a calorifier on boats it seems to be the entire unit, tank and all. 

 

The boat is 15 years old, a Colecraft, but yes I’ve checked the strength of both the engine antifreeze and the webasto with a hydrometer and both seem good. Interesting my engine is a Beta and reading the service manual they actually warn against using too high a concentration of antifreeze as they say it can influence cooling efficiency during normal running conditions. It’s all fascinating stuff!

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1 hour ago, Tracy D'arth said:

Always be aware of thermostatic blending valves, it is impossible to drain the cold side unless you loosen the union because of the non return valve.

Thanks I’ll check that. I also have one of those Franke water filter systems so I’m thinking I’ll need to remove the cartridge and tip the water out. Not sure what pink antifreeze will do to one of those either 🤔. Something else to research!

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I make sure the water tank is less than 3/4 full (to allow for expansion if it freezes), isolate the tank then open the taps and run the pump until no more water comes out.

 

As I have a mains supply, I then block the vents and use a dehumidifier to prevent mould. I also use a couple of oil filled radiators connected to a thermostat to being them on when the internal temperature of the boat falls to 5 degrees C.

 

Never had any issues with anything freezing.

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56 minutes ago, cuthound said:

I make sure the water tank is less than 3/4 full (to allow for expansion if it freezes), isolate the tank then open the taps and run the pump until no more water comes out.

 

As I have a mains supply, I then block the vents and use a dehumidifier to prevent mould. I also use a couple of oil filled radiators connected to a thermostat to being them on when the internal temperature of the boat falls to 5 degrees C.

 

Never had any issues with anything freezing.

I'm in the same position ie on a marina with a shoreline connected so could adopt the same solution as you.

 

Just out of interest, over the average winter do the heaters kick in very often and how much power (credit) gets used? I'm not particularly concerned about the cost but more worried that my credit on the meter could get used up and the power go off.

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Just now, Withywindle said:

I'm in the same position ie on a marina with a shoreline connected so could adopt the same solution as you.

 

Just out of interest, over the average winter do the heaters kick in very often and how much power (credit) gets used? I'm not particularly concerned about the cost but more worried that my credit on the meter could get used up and the power go off.

 

I'm lucky enough to have an end of garden mooring, so I can check if the electricity supply needs resetting, something that a marina may or may not do.

 

I reckon on £5-£10 per month for the extra electricity, depending on how long the cold spells last.

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The only frozen pipes I've had were in the feed to the shower controller. UK controllers have NRVs in the outlet: the only way to empty them may be to suck on the end of the shower head tube. The temperature was around -20 C though.

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6 hours ago, Withywindle said:

Thanks. Yes I was intending to do that too that’s what I meant by the hot water tank - sorry  not fully up to speed with my marine terminology yet 😊.

 

Here’s my village idiot question.... I presume you don’t drain the actual heater coil too as that would be full of the actual engine coolant containing antifreeze and would mean draining the entire engine cooling system too. Sorry to sound a bit dumb, I’m still getting my head around this stuff. 

Some boats it very difficult to drain the calorifer by the way they are configured with an internal none return valbe 

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For the 5 years we had our boat and the previous 7 years under the previous owner, the boat was left totally unattended for 6 1/2 to 7 months every winter afloat in Aylesbury.

There was no shoreline electrics connected. Winterising consisted of ensuring the water tank was less then half full, and turning off the tank outlet valve, placing the shower nozzle in the shower tray and then opening all taps and running to dry. And the shower gulper pump. Toilet cassettes were left empty and the toilet flushed as much as possible. And ensuring the stern tube was not dripping water, and the bilge pump was functional.

Although the site manager had access codes, in our time they never had to use them, but did once under the previous owner when a smoke detector went into low battery alarm. 

It certainly was not the recommended battery maintenance regime and most probably shortened battery life although in our five years we replaced all batteries, once only.

The previous owner had the calorifier fail, and a ceramic toilet bowl, perhaps as a result of an unusually cold winter about 2010. 

Recommisioning was a few days on shoreline electricity, and refilling the water tank.

The biggest problem we ever had  on recommisioning after winter layup was lime buildup over the winter on the toilet clam shell valve until we discovered dosing with vinegar.

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19 hours ago, Withywindle said:

 

CD06EB55-E61D-4507-807E-F396595B64E3.jpeg

 

Do you have an airline available to blow out the existing water?

How do you introduce the antifreeze into your pipework?

Are you really going to run all your taps for 15-20 minutes in the Spring, to clear the stuff out?

How are you going to collect 15-20 minutes worth of antifreeze/water from all your sinks, basins and shower trays and dispose of it responsibly?

 

Edited by David Mack
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1 hour ago, David Mack said:

 

Do you have an airline available to blow out the existing water?

How do you introduce the antifreeze into your pipework?

Are you really going to run all your taps for 15-20 minutes in the Spring, to clear the stuff out?

How are you going to collect 15-20 minutes worth of antifreeze/water from all your sinks, basins and shower trays and dispose of it responsibly?

 

Good points here. Running the system through in spring will mean all the antifreeze ends up in the cut.  That can't be good surely?

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1 hour ago, David Mack said:

 

Do you have an airline available to blow out the existing water?

How do you introduce the antifreeze into your pipework?

Are you really going to run all your taps for 15-20 minutes in the Spring, to clear the stuff out?

How are you going to collect 15-20 minutes worth of antifreeze/water from all your sinks, basins and shower trays and dispose of it responsibly?

 

Thanks.

 

I'm talking about Propylene Glycol antifreeze which biodegrades extremely quickly and is considered non toxic and completely harmless to both the aquatic environment and humans. It's widely used as a food additive but does also have some properties that make it suitable as an antifreeze. It's actually far safer than regular detergent which, of course, boats discharge into the waterways all the time, every time someone washes up.

 

I think you may be thinking I mean to use regular Ethylene Glycol Antifreeze which conversely is extremely toxic and would be highly dangerous in this application.

 

Here's a good summary but there's plenty of other information about Propylene Glycol out there...

 

https://www.monarchchemicals.co.uk/Information/News-Events/700-/The-difference-between-Propylene-Glycol-and-Ethylene-Glycol-in-antifreeze

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36 minutes ago, Withywindle said:

 

I'm talking about Propylene Glycol antifreeze which biodegrades extremely quickly and is considered non toxic and completely harmless to both the aquatic environment and humans.

On the product blurb you posted it says "Dispose of used antifreeze properly, according to Government regulations"

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14 minutes ago, David Mack said:

On the product blurb you posted it says "Dispose of used antifreeze properly, according to Government regulations"

That's in reference to another product ie their 'extended life antifreeze' which is an ethylene glycol product used as an engine coolant only. However, I'll contact Starbrite and get their take on this - I'll post their reply when it arrives.

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