Water tank heaters query

[LordThornber]

Hello all, can anyone advise me on how difficult it would be to fit the heating rods, (or whatever they're called), to our 2003 Nuevo fresh and waste water tanks to help prolong our winter camping exploits.

 

We normally have "muddled through" but this recent sharp frost caught us unaware and we struggled a bit.

 

I have a friend to who is a very competent DIY er and in your expert opinions, is this a reasonably straight forward job? Also does anyone have any cost ideas?

 

Usual thanks in advance

 

Martyn

[mco]

We would be interested in any replies too Martyn as we were frozen up last weekend.

[David B]

I have a 2005 Nuevo ES. I have not been frozen yet, but I have not been camping in severe weather! To my mind the first thing to do is to insulate the very vulnerable water pipe which runs under the chassis between the fresh water tank and the point where it enters the floor on the offside and goes to the water pump. This pipe is very exposed and its small mass ensures it will freeze well before the water in the tank.

 

I put split foam insulation (as supplied for house plumbing) on the pipe and secured it with cable ties. Some would argue that while this may slow down freezing, it also slows down thawing when/if the pipe eventually freezes.

 

Water heaters are available from www.caktanks.co.uk but I have no experience of them.

[LordThornber]

Thanks for this David, at least that's a start for us.

 

Martyn

[Andy T]

CAK tanks supply elements, www.caktanks.co.uk.

The defrost element fits through a plate which is sealed and screwed to the tank.

Ring CAK on 0844 414 2324, always very pleasant and helpful.

No connection other than as a satisfied customer.

Andy.

[Derek Uzzell]

My February 2008 CAK catalogue (page 18) shows two types of tank heater, one (Part No. DFE-01 - £38.19) "manually switched" and the other (DFE-02 - £69.05) with an in-built automatic thermostat. Although both heater types would normally be bolted through a water-tank's wall prior to the tank being fitted to the motorhome, CAK offers a mounting plate (DFE-06 - £5.03) that screws to the outside of the tank and permits either heater to be installed without the tank having to be removed.

 

A potential problem with the CAK heaters is that they draw 30W (2.5A) of 12V power, so, if you employed them a lot without your leisure-battery's charge being topped up, you'd need to beware. (My Hobby has a 12V heater in its exterior waste-water tank and (because of the heater's current drain) the motorhome's electrical system only permits tank-heater operation when the vehicle is being driven or is on 230V hook-up.) To minimise heater usage it makes sense to insulate a tank well (CAK sell suitable material), but you'd almost certainly need to remove a tank to do this.

 

As David highlights, there's little point heating the water in a tank if the tank's connection-hoses/pipes/taps can easily freeze solid. Many (most?) Auto-Sleepers motorhomes are decidedly not designed for freezing conditions as far as their water systems are concerned and this design limitation needs to be taken into account. If I owned an A-S with exterior fresh- and waste-water tanks and felt a need to use it in very cold weather, then I'd concentrate on insulating and heating the fresh-water tank and all its pipework and use the drain-through-and-bucket ploy for the waste tank.

 

I don't envisage installing a tank-heater as a particularly challenging DIY job (though you really need to insulate the tank as well and that will be trickier) - CAK thermostatic heater, mounting-plate, On/Off switch, wiring - perhaps £100 per tank. However, I'm tempted to think that, with an A-S, it might be preferable just to re-jig the fresh-water system to permit water to be drawn from, say, a couple of 10 litre water containers (or one of those Aquaroll thingies) kept temporarily inside the motorhome in the warm, rather than play about trying to keep the external tank operational.

[peejay]

Hi Martyn;

 

I used to have a Nuevo and took it to Alpine regions a few times, its a nice little van but not up to really cold conditions unless you make a few mods.

 

I specified an inboard tank at build, they fitted this no problem, but ran the pipe outside the vehicle and across to the other side to the pump which defeated the whole object really. When I took it back, they found a partial solution. There is a crossmember near the fridge that runs across the van, they managed to run the pipe through there and out the other side, then into the area where the pump is, this was much better but the pipe still froze occasionally as there was still a small outside run from the crossmember to the pump, I never did find a total solution as I then sold on the van.

 

As for the waste, we found on our first visit to Germany that even the "let it drain through to a bucket outside" wasn't a good option either as the pipe diameter is so narrow coupled with those pathetic homebrew type taps it still froze. My solution was to abandon using the bathroom sink/shower in the real cold and use the kitchen sink for most ablutions, I disconnected the waste pipe at the sink and re routed a new one down into a 5 gall container located in the kitchen cupboard, that did the trick and was a simple job to switch between the two options depending on how cold it was.

 

In conclusion, if I had another Nuevo I would probably have an inboard tank on the other (drivers) side of the van nearer to the pump, then no pipes would be running outside, shouldn't be too difficult but you'd have to check you don't exceed any axle weights of course) and use the waste option I mentioned above. I'd also ditch those awful homebrew drain taps, worst bit of design i've seen!

 

Autosleepers are nice vans but making them suitable for all year use doesn't seem to be a priority for the company which is a shame as I'm sure they would sell more vans if they did.

 

I've now got a Hymer with a double floor, sheer bliss!

 

Pete

 

ps, I also took a branch off the blown air to keep the gas compartment and bottles warm but thats another story.

[Brian Kirby]

In truth, there is little that you can do to prevent water freezing somewhere in your system, other than to re-site all potentially affected items within the heated parts of the van. 

If I remember, cold is merely defined as a absence of heat.  That is to say cold is the default state, and heat the exception.  When external temperatures fall below the freezing point of water, any water exposed to the ambient temperature will, eventually, freeze. 

Whether or not it does, will depend on the extent to which the temperature is below freezing, and the efficiency of the heat transfer.  Insulation merely makes the transfer of heat less efficient, it does not prevent it.  Therefore, at sustained sub-zero temperatures, whatever the amount of insulation applied the water will, in the absence of heat gained from elsewhere, eventually, freeze.  It is all a matter of time. 

As stated above, it is the pipe runs that are most vulnerable.  Water pipes running beneath the floor of motorhomes, whether waste pipes or fresh water pipes, will be exposed to the further cooling effect of the van's motion when driving.  If the road is cold the pipes will be cold, probably damp, and exposed to a high wind.  Wind chill, in fact.

You could heat an external tank, but would also need to insulate with a moisture resistant insulant - wet insulation doesn't work.  You would also need to trace heat and insulate, as above, all external pipework.  As Derek says, all this adds to the electrical load and you will need a hook-up, or the engine running, to ensure there is adequate power available.

If you habitually camp at low temperatures it is preferable, in my opinion, to buy a van with an inboard water tank and inboard pipework.  Otherwise, just avoiding the really cold days will be easier and cheaper!

[LordThornber]

Thankyou to you all for such informed responses, as ever.

 

Battery power isn't an issue for us, we're hook-up merchants apart from an odd summer night. We're not intending going to the alps or anything "extreme", (by our mundane standards), indeed, I think last weekends 2 nights of frozen pipes in N Yorks still only adds up to say 10 nights or so in the 5 years of usage.

 

I think lagging the the inlet pipe will be a cheap start and the waste pipes too, we do empty into a Fiamma container rather than leave in the vans tank.

 

I'm not looking to turn the van into something capable of going to the Antarctic, ( we didn't buy it for that), so I'll see how we fare and then if it's not enough, have a go at CAK's website. We're changing the van in 18mths or so but I don't mind spending a few bob. I do fully appreciate that the van isn't and wasn't built for last weekends conditions, it was minus 8...brrr

 

Thanks again

 

Martyn

[rupert123]

I have just returned from my last trip of the year and last seven days were spent in the Yorkshire Dales and the Peak. The last four nights were all hard frosts and my Swift has all external tanks. I had a look in the fresh water tank and it had a little ice on the top surface but by no means frozen solid. The grey waste outlet froze for two nights but no problem as it did not need emptying, although it would need some action if the conditions continued. I did have a loss of hot water for one day and suspect it was an internal pipe maybe running close to a vent. I would not bother with insulation, unless going to the Alps for the winter, other than has been suggested to insulate exposed pipes. Incidently Brian wind chill will have no effect as it does not lower actual temperature.

[Brian Kirby]

rupert123 - 2008-12-03 3:51 PM .............. Incidental Brian wind chill will have no effect as it does not lower actual temperature.

It will under the conditions I describe, although I'll plead guilty to sloppy English!  What I'm really on about is evaporative cooling (which is what wind chill really is), where the damp on the pipe would be evaporating off in the slipstream, further lowering the surface temperature of the wet pipe.  Only a little, I agree, but as a certain supermarket chain likes to say, every little helps!