Onboard water tank question

[johnfrosty]

Hi, I am doing up an early 90s Bessacarr Cameo 550GL. Not quite worked out the water system yet. It has an onboard tank under the seats at the end, and there's something resembling a petrol cap on the outside for filling that tank. What I don't understand is how to pull water from an outboard tank (or plug in mains water perhaps?).
There is a very old Shurflow 12v pump next to the onboard tank which comes on when pressure drops (when taps turned on), that surprised me as I have only seen microswitched taps before, I actually think it's a good system as the taps are easier to replace and presumably don't go wrong as often. But anyway.... how do i prevent the onboard tank running out if we have visitors staying in the caravan, do we just have to lift the seating to check it and stick a hose in to top it up when needed or is there a more clever system usually?
thanks

 

[Jcloughie]

Don’t know about yours but vans with an on board tank normally have a level gauge, or perhaps a low level light. And outside there may be a 12 volt socket to power a submersible pump from an aquaroll.

John

 

[Damian]

With a van of that age it most likely does not have any level indicators, or if it does they probably wont work.
There is no "clever" system to keep the on board tank topped up, it is a case of when the water stops coming out of the tap, it needs filling !!!

As far as the pump is concerned, it is activated by its pressure switch , which is a very common way of controlling water flow and avoids the usual problem with microswitched taps of the microswitch failing.

 

[johnfrosty]

Thanks both. That makes sense. No level gauge anywhere, i was a bit worried about the pump running dry and burning out that's all. Maybe it won't. Having said that the pump hasn't run for so many years it sounds very creaky and squeaky so it either needs a refurb or replacing. I might go for the latter to try and get a bit more pressure for the taps.

I would love to get hot water working but I think the gas boiler is safer to be ripped out, although I have a boiler man coming to look it over hopefully. I am considering a small immersion tank much like you get in a house, maybe half size. It would obviously be 240v (I saw one which consumes 2.2kw, that will be ok on the cable supply we have here). Not sure if anyone knows, or even if I can ask this question properly but.....

If you have the onboard tank, pump next to it, then hot pipe into immersion tank then taps, cold straight to taps, that would work wouldn't it? I mean specifically with relation to pressure, I assume the pump would just push water into the tank until the pressure hit the desired level and then it stops, and when someone turns on a hot tap it would pump and push cold into the tank just like in a house setup, does that sound about right? Hope so, as it would be nice to have hot water. thanks

 

[Jcloughie]

If you have the onboard tank, pump next to it, then hot pipe into immersion tank then taps, cold straight to taps, that would work wouldn't it? I mean specifically with relation to pressure, I assume the pump would just push water into the tank until the pressure hit the desired level and then it stops, and when someone turns on a hot tap it would pump and push cold into the tank just like in a house setup, does that sound about right? Hope so, as it would be nice to have hot water. thanks

I think the tank would have to be primatic. I don’t think you could get one of them any more, particularly a small one. Otherwise, immersion tanks are vented and water is fed by gravity, so would need to be on the roof, 😀. Or the hot would be drawn off from the top by a second pump. Let’s hope that the old system can be got running.

Sounds like you are thinking of permanently siting The van, is that so?

I used to have a Bailer Senator with an inboard tank, and thinking about it I don’t remember that having any indication of how much water was left. But I put a sensor into it. I also fitted a domestic ball valve near the top, this had a small length of hose terminating in the gas box. This way, if we had mains water I could simply plug into it.

Since that van, I have been put off inboard tanks as they can be out of sight out of mind and easily build up a layer of slime. Aquarolls are easier to keep hygienic.

John

 

[ProfJohnL]

Its really a matter of personal preference whether to have an in board tank or just rely on the external barrel, but my personal preference is to use an external barrel, for a number of reasons.

Its easier to refill,
You can reclaim the space for in board tank as stowage.
The caravan will be lighter when towed.
And you don't have such a large algae farm to clean.

Your present inboard pump is Shurflow. these pumps are pretty durable, so it might be fine. With a little simple plumbing it will happily draw water from the external tank with just a hose dropped into it. The down side to these pumps is they vibrate when they operate, and largely depending on how they are mounted the walls of the caravan can make then sound quite loud.

Do not be tempted to go for a pump with a higher pressure, as the internal pipework and fittings in the caravan is only designed to operate at a maximum of about 2Bar

I think your description of how the hot should work is correct, and certainly the leading water "heaters" (not boilers, as they don't boil water) are storage devices and do require cold to be pumped in to displace the hot. Its is essential that the cold water feed to the heaters has a non return valve, to prevent hot water back feeding into the cold pipework.

Most caravan water heaters are designed to have an air cap that can be pressurised by the incoming cold water, and also allow for the expansion of the water as its heated.

Also bearing in mind that caravans have a limited mains capacity of 16A, a 2.2Kw water heating element would leave little spare capacity for space heating or any other mains powered items. This is why most water heaters designed for caravans limit their electrical heating elements to no more than about 1kW.

 

[johnfrosty]

Two great posts thanks very much both of you. I am not totally clear on the immersion tank idea and whether that could work. I suspect it could, and I could uprate/check the electrics to the tank to make sure the cable is rated for that wattage, but yes I hadn't thought about a small electric oil filled radiator which is all we would use for heating, although heating is almost never needed and could actually be gone without completely.

Yes the caravan will be permanently sited, never will move or be towed again (chassis isn't roadworthy but above that is pretty nice after weeks of restoring and fixing her up, removing damp and replacing some wall linings etc. She will be put on blocks and left to die a dignified death

Good point re the algae, the on board tank is a nice size. I wouldn't mind using an external aquaroll, if I can rig it up. Or we could just keep the on board tank empty, only filled when we have visitors a few times per year.

Aside from the electrical factors, I am still not quite sure I understand whether or not a hot water tank would work. I am not sure what the "vented" thing means really. A header tank on the roof, with mains to a ballcock inside that - now that could actually work! (I once set a system like that up to provide constant water supply to chickens, from a stream actually! Egg shells doubled in thickness and no more cracked eggs, which was handy with 1400 chickens ). Prof J - When you say the immersion tanks need to be "gravity fed", am I right in thinking all gravity does is provide a bit of pressure. Couldn't I just plumb a supply in from our outdoor tap system, perhaps with a regulator to keep the pressure low?

Regarding pressures - ha, yes I learned that the hard way. We had an old Knaus caravan before. The plumbing was awful in it. I got sick of filling up the aquaroll for visitors so I just stuck a hose on from the outside tap. I think the kids turned it on the first time for a friend who was staying, and maybe turned it up higher than I did, but in that one hour before my friend arrived, the caravan had flooded and was several inches deep inside with water gushing everywhere! So if I did try some kind of mains feed into the caravan I would definitely check and regulate the pressures, although the water connections in this Bessacarr are damn good by comparison to the old Knaus. I was just disconnecting some taps today to replace the washers and the fittings were rock solid and the pipes were much bigger diameter too (not that that affects pressure tolerances of course). It all seems pretty heavy duty but I won't try to chance a leak.

The pressure from this Shurflow really isn't great, I hoped to up it slightly but hard to work it all out. the pump has litres per minute, imperial gallons per minute, and then we have bar etc, and hard to know what flow rate relates to what pressures etc.

I will give the pump an overhaul (if it can be overhauled), although maybe the noisiness of it is normal. I MAY get the gas burner working but if not I want the simplest and cheapest way to provide hot water for hand washing and showers. She has a nice shower cubicle (one of reasons we have decided to use it for visitors) so a bit more than a dribble would be nice! I did see those lethal looking gas instant camping showers, designed for OUTDOOR (!!!) use only on the back of a van to shower at beach or whatever. I did even consider one of those but with some very careful checks and installation OUTSIDE (!!) in a waterproof box. But given the age and tghe fact we have a good leccy supply, I would like to find a 240v solution ideally, even if its just a 1KW under sink type water heater. I am looking for stuff which is NOT designed for caravans as they cost a fortune due to having multiple options like 12v and gas. I just need a 240v water heater which is reasonably easy on current draw (above caravan stuff but below normal household modern stuff) and a way to pump it to the shower head with semi-decent pressure, again not nearly as powerful as a modern household shower, but somewhere between the usual shower dribble and that!

Much to think about! But some great info there, thanks again