Grey waste outlet in freezing weather

[helzie2020]

We are going on a wee trip this week in our PVC and the weather is very cold. We will be using the Truma blown air heating while we are in the van in the evening and morning but we'll be out during the day with the heating off.

Do I need to leave the grey waste outlet open to prevent issues with freezing (as some people recommend) or is it okay to shut the grey waste outlet, saving the waste water to discharge when we get home? I'm not sure if the heating will be enough.

Thanks.

 

[peterc10]

Where is your grey tank situated? Inside the heated van or outside? Same question for your fresh water tank if the weather is going to be that cold.

 

[Bailey 15]

Shouldn’t be no problem if your using the heating
If concern empty in bucket regularly should be fine

 

[helzie2020]

Where is your grey tank situated? Inside the heated van or outside? Same question for your fresh water tank if the weather is going to be that cold.

It's a Globecar Roadscout. The manual says that the waste water tank is located under the vehicle floor. However, I've just spotted that the Globecar manual recommends adding some kitchen salt to the waste water tank in case of frost so we'll try that. Apparently, a 10% solution (about 107g salt per litre) will lower the freezing point to -6.6ºC.

It was -4ºC here last night. The Govee thermometer in the (open) fridge gave a low of -1ºC in the last hour. We heading off tomorrow so I've turned the heating on at 10ºC now. The water system is still drained and we won't put any water in until we are ready to leave tomorrow.

 

[starquake]

Didn't think about putting salt in the waste tank, we carry loads of table salt, what a good idea. Would reccomend you put it in via a saline solution though (ie, mix with some warm water) as otherwise it'll probably just not mix well.

Should add it will take less space than a waste container too.

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[Pausim]

If you have a drain hose with a tap on the end this is very vulnerable to freezing. I think Globecar will have done the job properly by having a remote drain valve on the tank where it is better protected.

 

[Itsmcb]

Leave a bucket under the waste tap and leave the tap open. That's standard practice on ski aires. Empty the bucket regularly before it freezes or knock out the bucket shaped ice block if it's frozen

 

[Itsmcb]

Didn't think about putting salt in the waste tank, we carry loads of table salt, what a good idea. Would reccomend you put it in via a saline solution though (ie, mix with some warm water) as otherwise it'll probably just not mix well.

Should add it will take less space than a waste container too.

Minus 4 centigrade overnight is colder than a bit of frost. Sea water freezes at minus 2.

 

[poppycamper]

Minus 4 centigrade overnight is colder than a bit of frost. Sea water freezes at minus 2.

Yes indeed, and in a 12mm pipe might be an issue but not in a largish tank..
Never had any issues with our aquaroll freezing solid when we were tuggers, coldest I remember was -14deg overnight at Braemar.
As suggested if any doubts leave drain open and put bucket or if not enough height, a basin under tap and empty regularly..

 

[Whippet93]

My drain tap is right next to the tank with a length of pipe from there to the side of the van, so when closed, the pipe is empty. Never the less, I've recently put pipe insulation round it.

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[starquake]

My drain tap is right next to the tank with a length of pipe from there to the side of the van, so when closed, the pipe is empty. Never the less, I've recently put pipe insulation round it.

Our tap is by the end, but when in storage we leave partially open to allow any drips to leave so any small drips remaining can exit (we also have some nylon over end to stop other things entering).

When using van we have an extension to put in a bucket if it's seriously going to be below -2. However I am tempted for normal frost conditions to just run some salted water down as likely wouldn't freeze in just frosty weather like we had last winter. We didn't freeze even with snow on ground last year.

 

[Ian_H]

It's a Globecar Roadscout. The manual says that the waste water tank is located under the vehicle floor. However, I've just spotted that the Globecar manual recommends adding some kitchen salt to the waste water tank in case of frost so we'll try that. Apparently, a 10% solution (about 107g salt per litre) will lower the freezing point to -6.6ºC.

It was -4ºC here last night. The Govee thermometer in the (open) fridge gave a low of -1ºC in the last hour. We heading off tomorrow so I've turned the heating on at 10ºC now. The water system is still drained and we won't put any water in until we are ready to leave tomorrow.

10% is pretty strong. A couple of showers might easily be 15 litres - 1.5kgs salt req, without the water for dissolving! Might be ok for just some washing up water, but if thats all it is a bucket would be easiest. We carry a collapsible one so takes very little space.

 

[TheTwoOfUs]

In our early days of m/homing we made the mistake of closing the waste valve in really cold weather with the result that when it came to emptying the valve was frozen shut. After that we always leave the valve open with a bucket under the outlet if it looks like being freezing temps.

 

[PaulW2]

It's a Globecar Roadscout. The manual says that the waste water tank is located under the vehicle floor. However, I've just spotted that the Globecar manual recommends adding some kitchen salt to the waste water tank in case of frost so we'll try that. Apparently, a 10% solution (about 107g salt per litre) will lower the freezing point to -6.6ºC.

It was -4ºC here last night. The Govee thermometer in the (open) fridge gave a low of -1ºC in the last hour. We heading off tomorrow so I've turned the heating on at 10ºC now. The water system is still drained and we won't put any water in until we are ready to leave tomorrow.

Interesting idea. So 10.7 kg of salt per 100 litres of water? I wonder what that will do to the metal bits of the valve.

Are you likely to use more than the 100 litres that your waste tank holds?

If you have it say 70% full you can be sure most of it will still be liquid. If you then dropped a kettle or two of warm water in before dumping it I'd be surprised if it doesn't work.

The Globecar rotating valve should, I would have thought, still work even with a bit of frost around it.

If, on the other hand, you leave it open and develop laminar ice in the pipe outlet, icicles and the whole polar experience, would you not maybe struggle to close it?

The fresh water tank is in the vehicle so should be fine, though when you're out and about during the day you probably won't want the temperature to drop to the point where your boiler valve clicks open from the cold (from memory about 4 degrees?)

It may be worth leaving the boiler on and maybe even having the heating on a low setting while you are out.

 

[franknjan]

Try to not drive with grey water in the tank if temperature is below freezing. The wind chil will definitely freeze your waste pipe, and if it's a solid pipe it will split, speaking from experience.
I now empty the grey water and leave the valve open when travelling in the winter.

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[Coolcats]

We have an insulated and heated grey tank, having said this it’s never been cold enough when in it to switch it on.

 

[poppycamper]

Try to not drive with grey water in the tank if temperature is below freezing. The wind chil will definitely freeze your waste pipe, and if it's a solid pipe it will split, speaking from experience.
I now empty the grey water and leave the valve open when travelling in the winter.

Ah the old wind chill gremlin again..poppycock!!!
No sorry.. Wind chill does not affect inanimate objects so your tanks, pipes etc would not be affected by it!!
In your experience your pipe froze because the temp was such that they would freeze anyway...... Nothing to do with wind chill.!!! Too cold and no minimun insulasion/heating..

 

[Jim]

The wind chil will definitely freeze your waste pipe, and if it's a solid pipe it will split, speaking from experience.

A warm water tank, might drop to ambient temperature quicker in a cold stiff wind, but no matter how fast the wind or how much your pipes are exposed to it, the wind won't drop the temperature below what it actually is.

 

[starquake]

No idea how accurate it is, ref; Saltwater concentration in waste I came across a diagram linked below:

BUT:

File:Saltwater freezing point.jpg - Wikimedia Commons

commons.wikimedia.org

Looks like adding 100g per 1l of waste is required for about -6 coverage in the waste tank, so about 10kg for 100l coverage ... thats a lot. As such a container is likely (a lot) lighter. I'll stick with the (folding) bucket this year then. We only have 1.5kg of salt onboard most of time (mostly to deice paths a bit).

Given 10kg of salt is rather a lot, I think the plan of using salt is quite flawed. (this is based on 1l of water being 1kg, so you can do maths based on above picture if you ever do need to lower freezing points).

 

[Ian_H]

I wonder what septic tank bugs would make of 10% salt solution in larger quantities? I would guess even a bucketful would be pretty toxic to hedgerow plants.

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[Landy Andy]

I wonder what septic tank bugs would make of 10% salt solution in larger quantities? I would guess even a bucketful would be pretty toxic to hedgerow plants.

I know a salt solution kills grass and plants, and it is very good at it.

 

[KennyW]

Do you not have a frost setting? We're in NE Scotland and it gets a wee bit chilly here so I leave the heating on the frost setting and haven't had any issues, uses minimal gas as well.

 

[Ian_H]

Do you not have a frost setting? We're in NE Scotland and it gets a wee bit chilly here so I leave the heating on the frost setting and haven't had any issues, uses minimal gas as well.

Is that a frost setting that keeps an external waste tank warm?

 

[PaulW2]

If I were to do anything like that (I'm not about to - will take my chances) I think I would not use salt, but more probably something like a proprietary antifreeze.