Derek Uzzell Posted October 5, 2012 Share Posted October 5, 2012 I agree that, from the photos Michele provided, the Heki rooflight immediately behind the motorhome's overcab 'bulge' looks vulnerable to ingress from rainwater pooling on the vehicle's roof if the vehicle were parked nose-down and it rained very heavily. However, as far as I can see from pre-2012 Auto-Trail brochures, this is not a new position for a Heki rooflight on these large-roof-area high-overcab designs. There's also Michele's original comment to consider "...whilst driving here to the South of France on route on the motorway it rained and water came in the Heki as we were in transit soaking the kids..." Herald "hi-line" designs with a tall overcab bulge were recognised as having serious draughts come through their rooflights when the vehicle was being driven, to the extent that some owners produced their own DIY seals. These draughts did not occur on the same models, but having a 'non-bulgy' lo-line overcab shape, and received wisdom was that the bulge produced an aerodynamic effect that resulted in the draughts. But, although it could be uncomfortable for people sitting in the rear passenger seats of a draughty bulgy Herald, they did not get wet when it rained. It's unlikely that rainwater pooling will form on a motorhome's roof when the vehicle is being driven, or at least to the extent that the water would rise above a Heki's upstands, so there remains the possibility that there was something basically wrong with the rooflight originally and/or its installation. No leisure-vehicle rooflight will have been designed to remain waterproof if submerged above the level of its upstands. Ventilation seals will restrict air-movement through a closed rooflight, but, if the water ingress while the Michele's motorhome was static was due to the inability of the roof to drain adequately, then (unless something has been done to address the draining - which may well be impracticable) the problem's still there. Time will tell... Link to comment Share on other sites More sharing options...
Brian Kirby Posted October 7, 2012 Share Posted October 7, 2012 Derek Uzzell - 2012-10-05 9:50 AM I agree that, from the photos Michele provided, the Heki rooflight immediately behind the motorhome's overcab 'bulge' looks vulnerable to ingress from rainwater pooling on the vehicle's roof if the vehicle were parked nose-down and it rained very heavily. However, as far as I can see from pre-2012 Auto-Trail brochures, this is not a new position for a Heki rooflight on these large-roof-area high-overcab designs. There's also Michele's original comment to consider "...whilst driving here to the South of France on route on the motorway it rained and water came in the Heki as we were in transit soaking the kids..." ............................................... Time will tell... I'm not completely discounting the possibility that there may be a defect in the Heki, or even a defective batch, but I am more drawn to the shape of those roof outlets as probable main cause. A V shaped cross section outlet can only pass low volumes of water without causing the water to back up and form a pool. The harder, and the longer, the rain, the deeper that pool, until the pool depth gains a sufficient cross section of outlet to match the inflow of rain. Pools on motorhome roofs seem to me an inherently bad idea, the more so when they have at their midst a roof opening with minimal upstand height. It looks to me like a flood waiting to happen, and an engineered solution is perfectly possible. There are construction industry codes of practise on the design of roof drainage systems that give volume calculations for roof areas under varying conditions of rainfall, so the volume to be dispersed is calculable, and applying that to a motorhome roof to calculate what area of outlet is required shouldn't overtax the abilities of a competent designer. Whether shooting all that water off the roof, down the windscreen, and straight onto the scuttle tray, is wise, is however quite another matter. I think it isn't, and didn't Michele say the engine was flooded to boot? I just think some re-thinking is in order. When the van is in motion, all bets are off! :-) It would seem the slipstream over the front fairing will tend to carry any accumulating water back: but under braking, or when going downhill, or when travelling more slowly, or when it is windy from various directions? Then again, wind eddies and swirls, and vortexes form around obstructions, so which way the wind goes at at moment of time at roof level around that Heki is pretty much anyone's guess: it may just as easily be moving forward faster than the airspeed of the van, as passing backward. As you say, time will tell!! Link to comment Share on other sites More sharing options...
Brian Kirby Posted November 8, 2012 Share Posted November 8, 2012 Just a footnote. Neighbours have recently bought a similarly large, 2 year old, AT to Michele's. While away on their maiden voyage, they found water coming through the windows during a thunderstorm. Being quick witted, our neighbour stripped to his swimming trunks, grabbed his ladder, and shinned onto the roof because he thought the leak must be somewhere up there! :-) I recounted Michele's experience with the Heki to him, and he immediately said he had landed in a deep puddle as soon as the got onto the roof, due to inadequate drainage out over the two V shaped roof outlets above the cab. The risk of this over-topping his Heki upstand had not occurred to him at that stage, and he found no actual leak. He later discovered that the leak was due to inadequate sealing of the windows on the nearside of his van. Later again, he discovered, during another downpour, that the offside windows weren't sealed either! The ingress was less severe than Michele's flood, but it still caused them a lot of nuisance, and required a lot of drying out. I am aware that AT monitor this forum, so hope they will find this information useful to them, as it points to clear failings of quality control, and an urgent need to re-think the profile of those roof outlets to cope with exceptionally heavy rain, such as during continental thunderstorms. There is no logic to designing vehicles that incorporate accommodation, that can therefore freely travel the length and breadth of Europe once across the Channel, on the basis of British weather. So, come on AT, let's make British best. Link to comment Share on other sites More sharing options...
rolandrat Posted November 8, 2012 Share Posted November 8, 2012 Brian, I couldn't agree with you more. I will contribute some of my experiences to the forum soon as I am experiencing water ingress difficulties at the moment but I am waiting to see how it's going to be resolved by Auto-Trail. Link to comment Share on other sites More sharing options...
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