Last week we came third in the Wheatsheaf Quiz at Crick under our new team name of the Airheads. Not many quiz teams get named after a composting toilet. Well we thought it was appropriate for our team of me, Kath, Rick and Marilyn since Rick and I had spend a good part of the day solving the smelly Airhead problem. Regular reader will recall that I previously reported a leak of fumes around the fan housing. Here, in case anyone else is considering fitting an air head to their boat is how we think we have fixed it.
First let me describe the setup. A hose about two inches in diameter leads from the toilet to an extractor fan which draws the air from the toilet and exhausts it to the outside of the boat either through a hole in the roof, or in our case, through the side of the hull. Of course the inside of the boat is lined with panelling behind which is an insulation gap, so a plastic tube takes the fumes across the gap to the hull or roof. The fan housing, which is flanged is screwed to the cabin lining so it exhausts through the aforementioned tube. Simples.
Air is, as you know, naturally leaky stuff and will creep out anywhere where there is not a good seal. We found a couple of problems with the original installation.
1. Where the hole in the lining had been cut to take the plastic tube it was not a perfect fit to the tube and tiny gaps allowed the air to escape into the boats insulation space and thence down to the bilges and up through ventilation holes in the bottom of the washbasin cupboard. Using an all weather acrylic sealant (Wickes) looking extraordinarily like Nutella chocolate spread, we sealed off those tiny gaps, and also put an extra layer of sealant where the tube met the hull at the other end.
2. The cabin lining panel is not really thick enough to take strong screws, so they could never be tightened enough to get a proper seal to the fan housing. So we decided to thicken up the wall in that area. Rick made a small panel about 9mm thick which we glued and sealed to the lining using “I can’t believe it’s not nails” or some such brand plus a ring of the aforementioned chocolate spread. So now we had a much stronger surface to screw on to. This little panel had of course the requisite hole in it to allow the passage of the fumes from the fan. Once the glue had set, we were able then to use some more beefy screws and really clamp the fan housing to the panel, using more chocolate spread as well.
3. The hose from the toilet looks corrugated. In fact the corrugations are a left hand thread which allows it to be screwed into a similar thread in the back of the fan housing. This is not a naturally tight fit and maybe that shouldn't matter much as it is on the suction side of the fan, but we were taking no chances. The ever brilliant Rick realised that by winding some thinnish electrical cable in the thread of the hose allowed us to get a much tighter fit of hose to fan. More acrylic Nutella made matters even better.
The result? Well short term it seems good. No pongs at all. It remains to be seen how well it endures the inevitable stresses and strains of the movement of the boat under power, but I’m quietly optimistic. If you’re worried about all that chocolate spread making things look messy, well in our case it’s all hidden in the cupboard under the washbasin, but we did it reasonably neatly anyway.
The Airhead it self operates very well and is easy to use. Here I must mention the heroism of Kath who braved the first emptying of the solids bin after some weeks of use. Her comment was that whist it wasn’t anything you’d do for fun, it was far preferable to emptying cassettes every couple of days.
As to the Airheads quiz team, we were delighted to get third prize, especially since we had our customary disaster in the music round. These quizmasters always seem to assume that everyone listens to radio one. I feel like one of those old High Court judges asking “What are the Rolling Stones?” – “ A popular beat combo m’lud.”