Frosty weather procedure

[Cameron Carter]

Hello, we were awoken last night at 3am by a whirring pump sound and water gushing out of the tank. We knew that the tank automatically expels water when the temperature is very low and we were caught out a bit because we didn't realise it was so cold when we went to bed.
So we panicked a bit and emptied all waste tanks in the dark and freezing cold.
Does anybody know what is the best way to prepare for this in the future???
We remember the dealer put a peg on a valve in the boiler and we thought this would prevent the automatic flush????
This didn't seem to work, so should we take the peg off????
Thank you.

 

[Duck Truck]

Hi pegging the dump valve should only be done if you leave the heating running

 

[Duck Truck]

Pull the dump valve to a closed position
refill the tanks and expel any air in the system
Then switch the heating and hot water on
The peg the dump valve but leave the heating on low over night

 

[Duck Truck]

NEVER peg the dump valve on the boiler in winter unless the heating is running
and dump water from the boiler and the fresh tank if you are not using the van
leave the taps open

 

[Cameron Carter]

Thank you for your help, that makes perfect sense. Just double checking, should we leave the heating on overnight or the hot water or both?

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[TerryL]

The water heating should be enough to prevent the dump valve opening. However if your freshwater tank is underslung and not protected there's little you can do about that. That said it takes quite a long time at very cold temperatures to freeze the tank, especially if you keep it full. It's just the pipes that'll then freeze up but having the heating on might help that too. I would emphasize that it takes a very low temperature to freeze everything up - I'm talking skiing in the Alps type cold.

If the dump valve operates again just turn the water pump off, that will save you losing all your water as the boiler tries to keep refilling itself. Check your instructions but it's usually okay to run the heating with the boiler empty which will then enable you to close the dump valve and it should stay closed once the temperature is above it's tripping point.

 

[Duck Truck]

Terry is right
However boilers and pipework are expensive and very fiddly to fix
If you are using your van and the temp is cold I still suggest leaving the heating on low and the hot water.
It's amazing how cold the van gets in hidden areas behind lockers etc
All where the pipework runs

If you are not using the van fully drain it down

 

[Jim]

If the heater is running there's no need to peg it open as it won't dump. You should only ever peg it open when you know it's not going to freeze. They can get twitchy in spring and autumn on a cold morning and the peg can save you unnecessarily dumping. But if you must, that is the only time you should disable the auto-dump and only then when you are very sure you are not freezing.

Last night it did what its designed to do, it was minus 4 here, if it was a cold with you it might have saved you some cash

 

[Cameron Carter]

Thank you Jim, Duck Truck and Terry. We really appreciate your good advice and how quickly you gave it. Just to clarify, because we're both slow to understand this kind of thing, is it OK for us to just leave the dump valve alone in its default open position, without a peg on, and keep the hot water on at night, on low, when we think it's going to freeze. Our mistake may have been that when we are on a site and using EHU.we don't use the boiler at all, just an electric fan heater. Maybe we should use the boiler more? The inconvenience of a nocturnal automatic dump is obviously less important to us than a costly bill for frozen pipes/tank?!!!

 

[Ridgeway]

Plan B put a bucket under the drain and save the water and then put it back in when once the heating is on (no need for it to be on all night, yet..)

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[TheTwoOfUs]

IF you have a boiler with the option of electric only setting (ie not gas) you can leave the heating on when EHU without any water in the boiler.

 

[two]

Your dump valve should be closed to keep water in your tanks (knob up). When it senses low temperatures, it drops open to let the water out before it has chance to freeze. The dump valve should be situated in the fabric of the motorhome (a few are not). If it is in the same cupboard as the boiler the heat from the boiler, keeping the water hot, may be enough to stop it dumping, otherwise keep the heat on low. We run the heating running overnight at 11°C. Just enough to keep the chill off and stop the valve from operating. You may need to experiment, especially if the valve body is exposed to cold.
Dump all water when you leave the van unused. Leave taps open, to let water drain back, and remove the pump filter. Some blow air through the taps, but I don't bother with that.
Just remember to do the reverse when you start off again. As said, you can run the heating to warm the van up without water in the tank.
We're looking forward to a warmer week-end, coming up. You were unlucky to be caught out this early in the year but at least it was a useful thing to discover.

 

[Boringfrog]

I would be to warm overnight with the heating on, especially as the boiler is under the bed. What outside temperature would make the boiler freeze?

 

[Allanm]

I would check where the dump valve is. If it’s next to the boiler, you could leave the boiler on as the warmth from the boiler will stop the valve opening. If the valve is anywhere else, leave the heating on low.
Our dump valve is next to the fresh water tank, the other side of the van from the boiler, and has a warm air duct running next to it, so we leave the heater on low (15 degrees) overnight if it’s cold.
That way, the valve stays warm, the water won’t freeze, we stay warm and most importantly the dog stays warm in his bed next to a warm air outlet.