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Thread: My Caravan Positive Air System

  1. #1
    Join Date
    Oct 2011
    Location
    Fremantle WA
    Posts
    3,029

    My Caravan Positive Air System

    After much research, including a couple of AULRO gurus (particularly Don/goingbush for pre-planning and Alan Tovey for the remote system design), I bit the bullet and decided to install a roof mounted positive air system for our 20 foot caravan aka The Brick. I wasn’t satisfied that the existing roof mounted scuppers alone would keep the dust out from oncoming traffic, although they did handle dust minimisation on slow gravel travel well Plus I had some less than ideal dusting instances from my younger mineral exploration/construction days when we moved from tents to mobile caravans in the very 1970s.

    This system was never designed to run continuously, but only when dusty conditions prevailed.

    There is already a very good local system here in WA – Lyon’s link below - which may have worked out a little cheaper (and a bit lower height for a roof mount option too), but the other initial pump price I selected would have worked out cheaper had it not been 3 years out of date. Also, the Lyons system has a larger surface area than I wanted.
    cabin-filtration, Model CP700 caravan pressuriser filter unit

    I originally budgeted $2,000 (Pump $1,200, Install $800), but unusually for me, well and truly blew the budget, coming in at $3,303, albeit this including an additional originally non-budgeted $300 remote operating system so the pump could be started and stopped whilst travelling in the towtug. The remote should be very handy for sudden dusty roadworks etc on a hot day.

    I used and replaced the existing roof mounted front central scupper to get air into the cabin.

    I had previously located a very good small family business (The Caravan Shed) located just off Stock Rd in Bibra Lake for my van maintenance. I have been most impressed with their professionalism, commitment and ready assistance as a few caravan “teething” problems arose in the past. I can’t recommend them highly enough.
    I contracted them to do the install along with some warranty/insurance repairs after problems driving on a gravel road – that’s another story, and compliments to our insurer (APIA) for coming to the party.
    The less said about the manufacturer and particularly the WA agent the better.

    The installers had to run wiring from the pump to the battery, and I had the solenoid for the remote power switch fitted next to the battery (under the dining seat. The wiring ran from the external roof pump down through the full height pantry cupboard, under the floor, and then re-entering again straight into the battery box.

    Of course the other important consideration is temporarily blocking those vents that are not critical to remain open during travel. I leave the top (exhausting) fridge vent open – the bottom inlet vent is replaced by the positive air pump. There is no gas in the van whilst travelling, with gas for fridge oven and HWS all externally switched off.

    Costs as follows
    LSM RESPA CF (12vdc) External Air PFP UNIT M16+ FILTERS-NO ICPS Monitor 1,473.19

    Rubber Mounting Feet – Recommended 55.51

    GST 138.97 1,528.70


    Installation Labour 11 hrs 1,210.00

    Roof Mounting Plate (alloy) 220.00

    Fittings, misc 44.80 1,474.80


    Remote 300.00

    TOTAL 3,303.50


    I suspect with practice, the labour content for the install would reduce, but the quality of the work was excellent.
    Alan’s idea for the remote included the link below.
    The Caravan Shed did the wire runs, and my auto elec who had purchased the parts after first checking their suitability out for me did the solenoid connections with the towtug attached to ensure everything would work.


    DC 12V 10A Relay 1CH Wireless RF Remote Control Switch Transmitter + Receiver DB 892586573630 | eBay



    The final product

    Pic 1 - Side view - it sits about 280 mm above the roof. The filter is at the back.
    Time will tell if I need to add rigid conduit in lieu of the flexible black stuff. Not keen to put too many more penetrations into the roof.

    Pic 2 -

    Looking down


    Pic 3 -
    Internal vent where the scupper used to be.


    Attached Images Attached Images
    D4 MY10 2.7 6 speed from Apr 19 with LLAMS, long range tank and other goodies - for towing "The Brick"
    MY95 RRC LSE Vogue Softdash "Bessie" from Aug 13 - with MY99 TD5 and 4HP24 transplant. Back home Aug 20 after being off road for periods totalling 3.5 years
    SADLY SOLD MY04 D2a TD5 auto Classic

  2. #2
    Join Date
    Jun 2009
    Location
    Tangambalanga
    Posts
    7,552
    Thanks for that info Gavin, having not long bought ourselves a van recently, and as we’ll be looking at doing many dirt roads ourselves, we may well be looking for some kind of similar solution.

  3. #3
    Join Date
    Oct 2011
    Location
    Fremantle WA
    Posts
    3,029
    Quote Originally Posted by Chops View Post
    Thanks for that info Gavin, having not long bought ourselves a van recently, and as we’ll be looking at doing many dirt roads ourselves, we may well be looking for some kind of similar solution.
    Cheers. Hope it is of some use. I do have a few pages of other stuff (text and pics) collected in my research travels, including goingbush's version if anyone would like a copy. Too big to PM but I'm happy to email.
    D4 MY10 2.7 6 speed from Apr 19 with LLAMS, long range tank and other goodies - for towing "The Brick"
    MY95 RRC LSE Vogue Softdash "Bessie" from Aug 13 - with MY99 TD5 and 4HP24 transplant. Back home Aug 20 after being off road for periods totalling 3.5 years
    SADLY SOLD MY04 D2a TD5 auto Classic

  4. #4
    Join Date
    Oct 2011
    Location
    Fremantle WA
    Posts
    3,029
    Well, having now done the Great Central Road gravel section from Laverton to Uluru, I'm sad to advise that the van is not (yet) dustproof.
    The good news is that most of the road is still in excellent condition, with apparently regular grader attention. Can't say the same about the last 30 km into and then out of Docker River, or some of the remaining NT side.

    I suspect my error was in not sealing all vents, which in turn reduced the effectiveness of the fan pressurisation. Plus, I have a "front opening onto veranda" section, which although it didn't appear to cop much dust, may well have contributed to the lack of created internal pressure. More research and experimentation required.

    As another aside, the Stone Stomper did its job well, although I need to get back to Christian in Adelaide to feedback on possible modifications to the bracket used with a D3/4 Mitch Hitch when the car also has a complicating rear wheel carrier and low mounted trailer connections. Can't say enough about the support provided by Christian and his crew - excellent.

    I'll also start a separate thread on the longevity (otherwise) of my shock absorbers.
    D4 MY10 2.7 6 speed from Apr 19 with LLAMS, long range tank and other goodies - for towing "The Brick"
    MY95 RRC LSE Vogue Softdash "Bessie" from Aug 13 - with MY99 TD5 and 4HP24 transplant. Back home Aug 20 after being off road for periods totalling 3.5 years
    SADLY SOLD MY04 D2a TD5 auto Classic

  5. #5
    Join Date
    Jul 2011
    Location
    Yarrawonga, Vic
    Posts
    5,992
    You do need to seal all obvious pressure leak areas. Including gas vents , door vents, stove exhaust fan vent , I glued 100mm sewer pipe threaded ends over my external vents and cap them off when on dirt.
    Don't forget to put plug/s in sink and push them down. There are going to be unseen leak areas or places you dont think of , I even took off my powerpoints and blocked the cable ducts with some spongy stuff, but don't think thats a problem area.

    Even then we get a little dust entry but at least you wont be getting crunchy ice cream from the dust on spoons in your cutlery drawer.

    I should put some sort of barometer inside the van to see what the relative pressure is when the fan is blowing.

  6. #6
    Join Date
    Oct 2011
    Location
    Fremantle WA
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    3,029
    Quote Originally Posted by goingbush View Post
    You do need to seal all obvious pressure leak areas. Including gas vents , door vents, stove exhaust fan vent , I glued 100mm sewer pipe threaded ends over my external vents and cap them off when on dirt.
    Don't forget to put plug/s in sink and push them down. There are going to be unseen leak areas or places you dont think of , I even took off my powerpoints and blocked the cable ducts with some spongy stuff, but don't think thats a problem area.

    Even then we get a little dust entry but at least you wont be getting crunchy ice cream from the dust on spoons in your cutlery drawer.

    I should put some sort of barometer inside the van to see what the relative pressure is when the fan is blowing.

    Goingbush - Not having the wherewithal to check one at the moment, do the slots on powerpoints in the van that a plug slides into go right through the PPT, and therefore potentially provide a location for air loss?

    I've made up covers for all external vents (not just the lower ones as initially suggested by my local caravan man back home) with the next exercise being to trace back dusty spots for dust entry locations. Even so, I'm still disappointed in the lack of performance of the pump.
    D4 MY10 2.7 6 speed from Apr 19 with LLAMS, long range tank and other goodies - for towing "The Brick"
    MY95 RRC LSE Vogue Softdash "Bessie" from Aug 13 - with MY99 TD5 and 4HP24 transplant. Back home Aug 20 after being off road for periods totalling 3.5 years
    SADLY SOLD MY04 D2a TD5 auto Classic

  7. #7
    Join Date
    Jul 2011
    Location
    Yarrawonga, Vic
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    5,992
    Quote Originally Posted by gavinwibrow View Post
    Goingbush - Not having the wherewithal to check one at the moment, do the slots on powerpoints in the van that a plug slides into go right through the PPT, and therefore potentially provide a location for air loss?

    I've made up covers for all external vents (not just the lower ones as initially suggested by my local caravan man back home) with the next exercise being to trace back dusty spots for dust entry locations. Even so, I'm still disappointed in the lack of performance of the pump.
    Also don't have a powerpoint handy to look at, as we are out bush . But I'm pretty sure the modern ones are sealed. If you have a 3 way fridge it will need some sealing between it and the cabniet sides as there are whopping vents on the outside.

    We've given ours a hammering on dirt roads last week and working very well at last. This is the last trip for our van, getting traded on a bigger one when we return & I'll have to start the process again. At least it will have a compressor fridge at the outset.

  8. #8
    Join Date
    Dec 2008
    Location
    Northside, Brisvagus, Qld
    Posts
    391
    Quote Originally Posted by gavinwibrow View Post
    Goingbush - Not having the wherewithal to check one at the moment, do the slots on powerpoints in the van that a plug slides into go right through the PPT, and therefore potentially provide a location for air loss?
    While post 2000's GPO are not "sealed" for your purposes you could consider them to be sealed

    Cheers Glen
    MY12 Defender
    Sold 99 D2 TD5
    When I grew up there were 9 planets.

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