Is it necessary to do a drain down?

[Harrietliberty]

I've read through the forum on how to do a drain down and also about people using their motorhome extensively during the winter but can't find anything about at what temperature it really needs to be done. We live in Devon and the winters tend to be quite mild and we are hoping to use it occasionally before Christmas for odd days and also (lockdown restrictions permitting) to go and see our son in Leeds at Christmas. Is there a temperature at which it is definitely advisable to do a drain down because if so, we could keep an eye on the weather and do it if the forecast showed we were likely to be close to that temperature. (We're retired so can easily do it at short notice)

 

[Coolcats]

Empty tank and leave all the taps open, running pump until it pumps no more. It is a shurflo diaphragm pump so ok to do that. Do not forget to run the toilet flush pump if it comes from the system rather than it’s own tank. If not, drain that as well, using the little drain tube behind the door

and when the system is empty, it is a good opportunity to remove a flush out the filter

Erm no, you will find that a dry pump will become a broken pump in many MoHo due to overheating. Use the owners manual for the right sequence for draining down.

 

[DuxDeluxe]

Erm no, you will find that a dry pump will become a broken pump in many MoHo due to overheating. Use the owners manual for the right sequence for draining down.

Erm.... yes. I’ve used diaphragm pumps and positive displacement meters most of my time at sea. Clearly I do not leave it running for hours, just enough to expel the water from the pipes, which as a positive displacement pump it does very well and without any damage. Thank you for referring me to the owners manual - even in though it is in French it gives no instructions on draining down, except to open “le robinet de vidange d'eau propre”........

 

[Minxy]

I remember reading that people were using either a dishwasher tablet or Ariel bio in the cassette in order to flush it down a domestic loo. Which was it please?

The favourite is usually a cheap bio washing liquid from either Lidl or Aldi.

 

[Trumpton]

I've read through the forum on how to do a drain down and also about people using their motorhome extensively during the winter but can't find anything about at what temperature it really needs to be done. We live in Devon and the winters tend to be quite mild and we are hoping to use it occasionally before Christmas for odd days and also (lockdown restrictions permitting) to go and see our son in Leeds at Christmas. Is there a temperature at which it is definitely advisable to do a drain down because if so, we could keep an eye on the weather and do it if the forecast showed we were likely to be close to that temperature. (We're retired so can easily do it at short notice)

I drain the

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[Trumpton]

I drain down my Adria twin when the forecast is for 7 degrees or less as the truma hot tank is preset to dump at this setting and leave the taps fully open in the centre position. If we use the van during a freezing spell we keep the hot water tank heated 24/7 and the van heated.

 

[autorouter]

I am very new to all this MH stuff and I live in Estonia where from sometime around November to March we may well see temperatures as low as -30 degrees C but an average of -5 to -15 C.

I think the best advice is, don't listen to Brits who mostly live in a maritime climate where there's a 50-50 chance doing nothing will be OK. But here's my advice anyway.

For simple storage, ie motorhome not used and not heated, drain down all water and blow out as in post #45.

If the motorhome is being used, it needs to be fully winterised.

Imagine a big metal box placed outside in a temperature of -30C. After a few hours, all the inside of the box will be at -30C. If there is a small heater, say 100W, the inside temperature will eventually stabilise, probably at about -29C.

If the box is lined with a 10mm of insulation, the interior will stabilise at a higher temperature, maybe -10C, as the heat flowing out equals the heat input from the heater.

Add another 10mm of insulation, and the interior will stabilise at a higher temperature, maybe +5C.

So increasing the heater wattage, or improving the insulation, will make the stabilised temperature inside higher. Note that if the heater is switched off, then eventually the box interior will stabilise at -30C no matter how good the insulation is.

The principle of winterising is to keep everything vulnerable to frost inside a thermal envelope, and provide enough heat to keep the thermal envelope above freezing point. Many motorhome manufacturers have taken this on board, and have double floors and heated service ducts etc. However quite a few haven't.

I don't know about your Hobby MH, but I'd think it is probably well insulated and winterised. Provided you set the heating at a suitable frost protection level you should be OK. But don't take my word for it, you'll have to check for yourself.

 

[Northern Boy]

Thanks for your input

I don't know about your Hobby MH, but I'd think it is probably well insulated and winterised. Provided you set the heating at a suitable frost protection level you should be OK. But don't take my word for it, you'll have to check for yourself.

I do think my MH is well insulated but as you say it will be an interesting first winter, like a scientific experiment with electric heater and a couple of thermometers. Maybe I can even set up an excel spreadsheet and add some graphs and other equations. (I am not joking, I quite like that sort of stuff!). Oh dear I appear to get sadder as I get older.

 

[gwyntaxi]

I've read through the forum on how to do a drain down and also about people using their motorhome extensively during the winter but can't find anything about at what temperature it really needs to be done. We live in Devon and the winters tend to be quite mild and we are hoping to use it occasionally before Christmas for odd days and also (lockdown restrictions permitting) to go and see our son in Leeds at Christmas. Is there a temperature at which it is definitely advisable to do a drain down because if so, we could keep an eye on the weather and do it if the forecast showed we were likely to be close to that temperature. (We're retired so can easily do it at short notice)

I would definitely drain down from Xmas onwards, no telling if you’re going to get a real cold spell till it hits, draining Down is a lot easier than getting burst pipework or damaged water pumps, boilers replaced or repaired, I have already drained mine Down as we are in lockdown and don’t look like we will be getting out before January if lockdown allows then I will put water in, stops it forming bacteria in the water system too.

 

[gwyntaxi]

I'm glad you're an authority on how to get to my valve (you may need to unpack the garage first) - oh and the nearest water tap is around the back of the house, so good luck with that too!

That maybe so, but when if you’ve got a frost damaged boiler, you’ll have to unload the garage before you drive it lord knows how far to the repairer
And surely it would be a lot less inconvenient to drain down even with the tap behind the house. Just sayin.

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[ramsthom]

The swimming pool professionals drain down the pool and pipes, and blow out all the pipes with compressed air, to prepare for winter frosts. You're trying to do that with the motorhome, if it's left in storage during a freezing period.

There should be drain taps on the hot and cold water pipes, and a drain valve (probably with automatic frost protection) near the water heater. Run the pump to pump out water from the pipes and taps, and the toilet flush valve. Leave taps open, set mixer taps to the centre position so that both hot and cold are open. Turn off the pump switch, or turn the 12V off if there's no pump switch.

If you like tinkering, you could add a tee into the pipe from the pump, and add a shutoff tap and a tyre valve (Schrader valve). Then you can attach a tyre compressor, preferably the digital type that cuts off, set to about 20psi, so it doesn't overstress the water heater. Then blow out the water from the pipes using that. It's a bit over the top, though - most people don't do that. You can pay for a professional system by Floe, to do this, if you really want.

Similar to what I do. Use a compression fitting off a radiator valve suitable for a15 mm pipe. Insert a tyre valve and shower washer. I then fit it to the shower mixer tap and pressurise the the system as above and alternatively blow the cold and hot pipes out on the kitchen and washbasin taps.

 

[Coolcats]

I am very new to all this MH stuff and I live in Estonia where from sometime around November to March we may well see temperatures as low as -30 degrees C but an average of -5 to -15 C.
I plan to keep an electric connection (EHU) as the MH is in my garden with a fan heater set at frost setting as well as draining down everything. I guess my tanks are internal as I cant see any under the MH, its a 2007 Fiat Hobby 600.
I plan to use the MH through the winter (as long as we can get out as sometime we get snowed in!) and will just fill up with say 10 litres of water for a days outing so we can flush the WC, we wash up at home later and drink from bottled water.
Will the WC cassette be ok with blue in it? or should I drain that too if used?
Any further advise would be most welcome as I am like a sponge soaking up information these early days of ownership.

You may want to view this Finnish couple who full time, they have a a few years worth of video blog including winter time in Finland which is probably similar to Estonia temperatures

 

[Coolcats]

Erm.... yes. I’ve used diaphragm pumps and positive displacement meters most of my time at sea. Clearly I do not leave it running for hours, just enough to expel the water from the pipes, which as a positive displacement pump it does very well and without any damage. Thank you for referring me to the owners manual - even in though it is in French it gives no instructions on draining down, except to open “le robinet de vidange d'eau propre”........

There we go what do I know eh, other than the motorised pump we have stated in the manual do not switch on the pump without Water = burned out pump

 

[DuxDeluxe]

There we go what do I know eh, other than the motorised pump we have stated in the manual do not switch on the pump without Water = burned out pump

That is your pump, not mine

 

[Coolcats]

That is your pump, not mine

indeed and apologise for the stroppy looking post

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[mavisnderek]

I drain down after every trip, so no stale water in the tanks. And blow all pipes through with the Floe , particularly before closing down, so no chance of freezing. Floe is very quick, the adapter permanently before the pump, pressurise with 12v tyre pump, open a tap and FFFFFFFFFsh! And repeat till all taps dry including hot water tank with drain cock open ; very easy.

We do this too. The kit only cost about £50 and was fairly easy to install ourselves, having watched the installation video carefully a few times. Prior to the first use we had drained the system in the normal way, and were horrified to see how much filthy, brown water came out - about 2 litres. We now do this every two or three trips, and it only takes a few minutes. The water from the tank smells and tastes fresh, and we don't have to worry about water freezing in the pipes as there isn't any!

 

[Vanman]

That maybe so, but when if you’ve got a frost damaged boiler, you’ll have to unload the garage before you drive it lord knows how far to the repairer
And surely it would be a lot less inconvenient to drain down even with the tap behind the house. Just sayin.

If you read the whole thread you'll see that I leave the boiler on low, so it isn't going to freeze ... it appears I'll die of water mould poisoning at some point, but I've other things to worry about at the moment

 

[autorouter]

I do think my MH is well insulated but as you say it will be an interesting first winter, like a scientific experiment with electric heater and a couple of thermometers. Maybe I can even set up an excel spreadsheet and add some graphs and other equations. (I am not joking, I quite like that sort of stuff!). Oh dear I appear to get sadder as I get older.

If you're new to this, you maybe haven't come across insulated window screens. They can be external or internal. The external ones are more effort to set up and put away, but are generally more effective. Not something that's very obvious.

Another effect worth considering is condensation and a vapour barrier. Warm air hold more water vapour than cold air, and at some point as it cools the water vapour condenses as liquid. Inside the insulation the temperature falls from say +18C to -18C between the inside and the outside. At some point near the middle it will be at 0C. If the insulation is full of water vapour, it will condense and freeze at that point, possibly breaking the insulation apart eventually.

To avoid this problem, the inner skin of the insulation has a 'vapour barrier' - an impermeable layer of metal foil or special plastic. Any joints are sealed with metal foil tape. Any holes, for fixings etc, are carefully sealed to maintain the vapour barrier integrity.

When using external 'silver screens' on the windscreen, the glass acts as a very good vapour barrier.

 

[DuxDeluxe]

indeed and apologise for the stroppy looking post

No worries

Just out of interest and to make sure that everyone with a Shurflo pump is aware - there is no risk to running the pump dry according to the manufacturer. Not recommended for extended periods of course but dry running does not damage the pump

 

[Smudger27]

We do this too. The kit only cost about £50 and was fairly easy to install ourselves, having watched the installation video carefully a few times. Prior to the first use we had drained the system in the normal way, and were horrified to see how much filthy, brown water came out - about 2 litres. We now do this every two or three trips, and it only takes a few minutes. The water from the tank smells and tastes fresh, and we don't have to worry about water freezing in the pipes as there isn't any!

Have you really had a taste of it? Surely not.

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[Nirvanauk]

The favourite is usually a cheap bio washing liquid from either Lidl or Aldi.

I keep looking for bio tabs but all they say is bio in very small letters and looking at the contents it has some horrible sounding chemicals in it. None of them say they can be used in septic tanks so any suggestions please?