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water tank freeze?


MRBear

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Hi Guys

 

Odd question but, i am away from my boat for a few days and i have left my water tank full, i have left an electric heater on in the saloon set at 22 degrees and have put a small greenhouse tube heater in the step where the tank tap is. do i need to worry about my tank freezing if it goes down to -2?. my tank is stainless steel and my boat is only 18 months old. appreciate all advice given

 

thanks

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10 minutes ago, MRBear said:

Hi Guys

 

Odd question but, i am away from my boat for a few days and i have left my water tank full, i have left an electric heater on in the saloon set at 22 degrees and have put a small greenhouse tube heater in the step where the tank tap is. do i need to worry about my tank freezing if it goes down to -2?. my tank is stainless steel and my boat is only 18 months old. appreciate all advice given

 

thanks

 

I'd worry more about paying the electric bill - trying to heat the boat to 22 degrees for 24./7  got to be £7-£8 per day (£240 per month)

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Not good if it is really full, water expands between 4 and zero degrees so hopefully there is room for the expansion.   Back in 1976 we did have a frozen in boat that split its bow slightly, integral water tank left brim full.  Filler pipe froze solid first we suspect, no overflow pipe and outlet tap closed. Nowhere for the expansion to go.

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16 minutes ago, Detling said:

I don't even heat my house to 22 degrees   its what jumpers were made for.

 

Bathroom is about 22 though.

Those house places are horrible cold places. Just taken this on my boat and it's gone down nearly 2 degrees since 5 pm. Why live in horrible cold houses? 

 

IMG_20201227_185545.jpg

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1 hour ago, MRBear said:

Hi Guys

 

Odd question but, i am away from my boat for a few days and i have left my water tank full, i have left an electric heater on in the saloon set at 22 degrees and have put a small greenhouse tube heater in the step where the tank tap is.

 

What sort of electric heater? If it's an oil filled radiator or something similar that's ok as long as it's got relevant safety features such as tilt cut-out in case it falls over for some reason. I hope it's not bar or fan heater as they're not really safe if left unattended.

 

To be honest you'd probably be fine just with the tube heater, but if you're going to use a separate electric heater too you need one that's thermostatically controlled. Just set it at about 5 or 6C and it will stop anything from freezing and won't waste energy during the daytime if it's warmer than that.

Edited by blackrose
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The fact that much/most of the contents is below the waterline means freezing down there is rare, so provided that you haven't brimmed it and left no space, you'll probably be ok.  When you get back to the boat though, make sure you always leave plenty of room for expansion in case of some freezing of any contents above the waterline. Mine's never above about 50% in winter.

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2 hours ago, MRBear said:

Hi Guys

 

Odd question but, i am away from my boat for a few days and i have left my water tank full, i have left an electric heater on in the saloon set at 22 degrees and have put a small greenhouse tube heater in the step where the tank tap is. do i need to worry about my tank freezing if it goes down to -2?. my tank is stainless steel and my boat is only 18 months old. appreciate all advice given

 

thanks

You shouldn't have a problem. My cold water tank is stainless steel under the well deck and never had it freeze..  My calorifier is vertical inside a a cupboard and I have never had it freeze despite leaving it for long periods over winters without any heating. I have never drained the tank.

Edited by Flyboy
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1 minute ago, Flyboy said:

If your tank is well insulated you will have no problem.  My tank is vertical inside a a cupboard and I have never had it freeze despite leaving it for long periods over winters without any heating. I have never drained the tank.

 

Are you talking about your main water tank or your calorifier?   Some main tanks are integral to the hull at the bow and completely uninsulated.

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27 minutes ago, TheBiscuits said:

 

Are you talking about your main water tank or your calorifier?   Some main tanks are integral to the hull at the bow and completely uninsulated.

I'm talking about my calorifier. My cold water tank is stainless in the bow and never had it freeze. I've edited my previous post for clarity. Thanks for pointing it out.

Edited by Flyboy
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7 minutes ago, TheBiscuits said:

 

Are you talking about your main water tank or your calorifier?   Some main tanks are integral to the hull at the bow and completely uninsulated.

Ooh, good question! I and others have clearly assumed fresh water tank.  If it's Cauliflower, mine has stayed full every winter of its life. I try to use the boat too often to keep farting about with draining that every time I leave and refilling it every time I get onboard when it doesn't seem to mind. (YMMV, depending on siting and insulation). 

Edited by Sea Dog
Drain and refill sense
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I assumed the OP was talking about a stainless freshwater tank rather than a calorifier, in which case it should be left partially empty to allow for expansion. No need to worry about that with an integral water tank.

 

A bloke I know with a stainless tank filled it to the top and then left the boat shortly before the temperatures dropped. When he returned to the boat unbeknownst to him, the connections between the filler and vent pipes to the deck fittings had frozen solid and while he was having a shower there was a loud bang as one of the pipes thawed & cleared and the vacuum he'd pulled inside the tank released and the tank returned to it's normal shape. Fortunately there was no damage, but you wouldn't want to do that too often.   

Edited by blackrose
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thanks guys. i was talking about my fresh water tank, its in the bow. its stainless steel and there is foam on the front section thats under the bow door step but i'm not sure if its insulated between the hull and the tank where i cant see it . it was brim filled then had about 10 litres drawn off, so, i'm hoping that has created enough space for expansion. 

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Just now, MRBear said:

thanks guys. i was talking about my fresh water tank, its in the bow. its stainless steel and there is foam on the front section thats under the bow door step but i'm not sure if its insulated between the hull and the tank where i cant see it . it was brim filled then had about 10 litres drawn off, so, i'm hoping that has created enough space for expansion. 

 

Depends how big the tank is.  Working on 10% expansion for ice compared to water at 4 degrees is close enough for a safety margin, but I suspect your tank is bigger than 100 litres ...

 

Don't worry too much though, it will take a long time and a lot colder than we have had so far to freeze all of your tank water - it's sat in a big puddle of water that very rarely goes below 4, and the hull and basepalate conduct heat quite well.

 

I'm with @seadog on this one - I'd always try and leave my tank around half full if leaving the boat in cold weather, but that's just being overcautious.

 

 

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Even in the harshest northern winters, when leaving my boat I have never drained  my fresh water tank (stainless steel). As others have said, less than 100% full allows for any expansion.

Winterisation would consist of turning off the main stop tap, opening all taps and placing the shower head in the tray, then switching the water pump off. I never left any heating on and perhaps I was lucky but never suffered any issues from frost.

As an aside, I know someone who (unknowingly) didn't have any anti -freeze in his engine (semi-trad) for 10 years and got away without any known issues. I wouldn't recommend that though!

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Pipes will definitely freeze so be careful. Back boilers will freeze or the heating circuit from them so explosion is definitely possible so anti freeze is a must. If your water pump is in a vulnerable place it can freeze and crack and the entire water tank will empty into the boat. Gas water heaters and the workings of some toilets can freeze and crack too. Even batteries can freeze. We're talking about a harsh freeze here and a boat left empty for a while but it really can happen. I have known all these apart from the exploding back boiler - it just cracked instead.

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1 hour ago, Bee said:

and the entire water tank will empty into the boat.

but not if your takeoff is in the top of your tank (and you have cracked the syphon before you leave the boat).

 

I dump "FreezeBan" ( I think thats the name) in the shower drain and the china toilet. Its non-toxic.

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16 hours ago, Detling said:

I don't even heat my house to 22 degrees   its what jumpers were made for.

 

Bathroom is about 22 though.

in olden days when central heating was controlled by a Satchwell or Honeywell switch, there was a default minimum setting for keeping the house frost free that we would set at 5 degrees.  

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43 minutes ago, system 4-50 said:

I dump "FreezeBan" ( I think thats the name) in the shower drain and the china toilet. Its non-toxic.

 

I just pour a 'generous amount' of salt down each plug hole and then the toilets.

 

It costs pennies for big containers from the likes of Aldi

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