Insulating / heating external water / waste tanks.

[fishplug]

I've had a bit of a read through this section and have mainly learned how much Funsters enjoy a toilet thread

However, I've not found much about insulating and/or heating external water/waste tanks.

I'm doing a DIY conversion and will most likely buy the Bobil vans tanks as they are specifically designed for the Relay/Boxer/Ducato vans.

I've seen a lot of people 'insulate' the tanks with the silver foil bubble wrap stuff but I suspect people do it because they've seen people do it. From my brief 'YouTube' education about insulation that stuff is good at reflecting heat but needs an air gap. When in direct contact with something it becomes pretty ineffective at reflecting anything much and inherently doesn't have a good R value. At best, it's keeping road dirt off your tanks!

I've been considering using some 10mm closed cell foam which should provide a bit more R value and I'm also looking at heater pads.

I'd love to hear people's thoughts and experiences on the subject.

However, there's a niggling doubt in my mind about insulating / heating tanks and that's the fact that no-one seems to really talk about it.

I've got fifty tips on how to keep my waste from smelling in the van, how to flush my toilet with re-used washing up water but nothing on heating / insulating tanks.

Is that because most of us are only going away in the warmer months or because it's something I don't really need to be worrying about unless I go to the Arctic?




Oh, and separating toilet for me, so no flushing required. (Oh good - a toilet thread! )

 

[PlacidoD]

"I've got fifty tips on how to keep my waste from smelling in the van, how to flush my toilet with re-used washing up water but nothing on heating / insulating tanks."

That is likely because people buy their van with waste water heating/insulation pre-fitted and it causes few problems in use.

The only "problem" for me was not realising what that button on the control panel did and suffering a battery drain until I learned!

I cannot comment on the technology. You know more than me!

 

[bigtwin]

If you’re going to need to heat external tanks then you're going to need a decent battery bank otherwise your endurance will be limited.

Pound for pound, LiFePO4 batteries provide the lowest Wh cost (certainly over their lifetime) so it would be a false economy to plump for lead.

Ian

 

[Ridgeway]

If you’re going to need to heat external tanks then you're going to need a decent battery bank otherwise your endurance will be limited.

Pound for pound, LiFePO4 batteries provide the lowest Wh cost (certainly over their lifetime) so it would be a false economy to plump for lead.

Ian

Most I’ve seen use the hab heating system (Truma/Alde) with outlets into the water tank area that is enclosed.

 

[fishplug]

I have 300Ah of Lithium batteries so think I'm OK on that front. A combination of solar and DC-DC charging means I should be able to put power back into them reasonably quickly if needed.

Oh, and I just realised that I didn't explicitly say that these are external underslung tanks.

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[Rollingwheels]

If it is possible make up a box to go around the exposed part of the tank leaving about an inch air gap put some closed cell foam around the outside or inside whilst still leaving an air gap and then you can divert some of the trunking from the Truma heating pipe by reducing it to perhaps an inch diameter pipe and then drill a hole through the floor and directly into the void around the tank,. My brother had a Hymer dynamic line and this is what was done only the box was only made of polystyrene.

 

[bigtwin]

Most I’ve seen use the hab heating system (Truma/Alde) with outlets into the water tank area that is enclosed.

The OP has indicated that these will be external tanks.

The best solution, from a water/energy perspective, is to put the tank(s) inboard where existing heating sources can be deployed. However, and I suspect this is the reason that they are being mounted externally, inboard tanks take up a lot of space in a panel van conversion.

Ian

 

[lorger]

When we had our Possl PVC we ordered it with the winter pack, the waste tank was external but inside an insulated box. To access the tank you had to remove a panel under the van which gave access to the cap. We used the van in temperatures of -15 at Glenshee ski resort with no issues, also a good idea to leave a bucket under the outlet with tap open when possible.

 

[fishplug]

The OP has indicated that these will be external tanks.

In fairness to Ridgeway, I hadn't made it clear at the time of the reply, which is why I clarified it later!

The best solution, from a water/energy perspective, is to put the tank(s) inboard where existing heating sources can be deployed. However, and I suspect this is the reason that they are being mounted externally, inboard tanks take up a lot of space in a panel van conversion.

Exactly that.

I've opted for an L3 H2 van for the convenience of driving / parking but that does restrict your living space so things like the water and gas are going on the outside to keep as much of the modest space available inside free.

My previous van had a very rudimentary water system in the form of a couple of 25lit plastic containers behind the wheel arches, and a foot pump. Hot water was provided by boiling a kettle and pouring it into an insulated catering beverage dispenser in the morning.

It worked well enough but there's a bit more budget for this second build so the plan is to use my excess solar or the power from my DC-DC charger when driving to heat my water, with the backup option of a diesel heater via a heat exchanger if I'm parked up for several days with poor solar yield.

The kit will cost more, but hot water on demand is going to be a real luxury!

 

[bigtwin]

In fairness to @Ridgeway, I hadn't made it clear at the time of the reply, which is why I clarified it later!

In fairness to me, it was evident to me when I responded and I responded before Ridgeway.

Ian

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[fishplug]

yeah - but you've owned GSes so that puts you in an exalted position

(I'm assuming you're the same bigtwin anyway...)

 

[bigtwin]

yeah - but you've owned GSes so that puts you in an exalted position

(I'm assuming you're the same bigtwin anyway...)

Do you have the same forum name on UKGSer?

Ian

 

[Bessy765]

Over40 years motor homing bucket under waste tank every time we stop. Most time of use is out of season even with lithium the power has to come from somewhere, and 700 watts still can not be enough in inclement weather.

 

[fishplug]

Do you have the same forum name on UKGSer?

Ian

almost... same avatar though so I'm easy to spot!

 

[fishplug]

Over40 years motor homing bucket under waste tank every time we stop. Most time of use is out of season even with lithium the power has to come from somewhere, and 700 watts still can not be enough in inclement weather.

What's the thinking behind the bucket Bessy765?

Are these taps prone to failure?

My previous waste was a simple pipe through the floor and one of those plastic jerry cans with an opening on the side - so I'd always put it under whenever I stopped. Was hoping not to have that faff anymore with a proper waste tank installed!

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[bigtwin]

What's the thinking behind the bucket @Bessy765?

For grey waste if you just keep the tap open then there’s no need for tank heating.

However cold it is the water you’ve just poured down the sink will end up in the bucket before it gets a chance to freeze. If it freezes in the bucket you can still empty it.

Ian

 

[fishplug]

Ah, makes sense in that context.

Sort of defeats the point of a tank in some ways as you're effectively creating a 'straight through' system.

Heater pads are inexpensive so I'll probably just fit some and insulate, but also build in a diverter valve inside the van that can be set to drain straight out.

All bases covered that way.

 

[bigtwin]

Sort of defeats the point of a tank in some ways as you're effectively creating a 'straight through' system.

Kind of, but only deployed like that if there’s a risk of really low temperatures. Otherwise collect in the tank as normal and dispose of at your convenience.

Ian

 

[CAB96]

I think one of the issues is what you do with the vent / overflow.

I am no expert, but I am looking at putting tanks under our VW T6. Both fresh and waste would come with breather vents, which can presumably let out water as well when full.

Shouldn't be a problem with waste if you keep on top of emptying, but would be with fresh when you want to fill to the brim.