A dose of the flue

Sometimes on this boat problems creep up on you and jump out, boogeyman-like, when you least expect. Other times you can see them coming for ages but you try and prioritise the stuff that needs doing and the troublesome bits can wait just… a bit… longer…

This one was kind of a combination of both. We could see that the fire cement sealing up the joins in the diesel stove flue were cracking and weathering badly – it’s really not meant to be used outside, and it’s so inflexible that walking past the flue could cause it to crack. But it was still a surprise as we were drifting off to sleep one night and the smoke alarm went off. Enough cement had fallen away to open up a hole, and in the high winds last week it was enough to allow a downdraught into the stove and fill the room with smoke. Clearly a better solution was needed.

The first job was to swap over the cowl at the top of the flue. When we first put the flue up the only spare cowl we could make fit was one that keeps the water out but isn’t really suitable for diesel stoves. The cowl was considered to be a contributing factor to the downdraught incident so we swapped it for another spare, which had to be made to fit. Nikolaj spotted the best way was to chop down the spare length of slightly larger diameter flue the cowl was already sitting in, so after a few minutes with The Best Toy Ever it was cut to the right dimensions. I also bonded the two bits together using Chemical Metal.

The newly-constructed flue cowl in position

That should ensure a freer exhaust and better weather protection.

Next, the joints themselves, which needed to have the cracking cement pulled off and the residue brushed away before I could attack them with – and I count this choice of adhesive as a stroke of genius – Exhaust Repair Putty. It’s designed to sit under a car so it’s more weatherproof and vibration-resistant, but it can still handle the heat. It’s nasty stuff to use though, as it’s very gummy and full of what looks like horse hair, and it’s the precise colour of cat sick. So I covered it up nice and neat with silver tape:

Flue joint on the upright section

By the way, the chalky stains you can see are from the old cement dissolving in the rain.

All in all there were five joints to fix up, but they get progressively harder to access as the flue kinks on its way down and then goes into a cupboard!

The tricky part of the flue, with 2 45 degree joints

Finally I gave the innards of the stove a good vacuuming – all the crumbling cement on the inside of the flue ended up down inside the stove and broke up what can only be described as a 1/8” thick biscuit of pure soot off the little insert that manages airflow. She’s been purring away happily ever since.

And Bosco still hasn’t learnt not to touch the stove while it’s hot.

Oh and as to the title? I had time to write this update today because I’m doing it from my sick bed…

- posted by James O'Brien on 30 January 2008, 15:55 in