Water in Webasto Duct

[cedarbrook63]

Hello all and I hope you had a great Christmas in spite of Covid. I have a problem which is eluding a solution: I have water appearing and draining out of the mouths of two heating ducts which come off the main duct taking warm air from a Webasto diesel-powered air heater. The heater unit is located in a port aft lazarette. The big duct then travels upward from the heater unit and then forward on the port side under a rather old teak deck and server ducts then drop down off this main duct to appear in cabins, saloon, heads etc. A while back I noticed a pool of water on the floor and found a pool of water inside the duct before it emerges through a wooden panel. This water appears after heavy rainfall which we have had a lot of over the past two months. I now have to keep a collecting bowl under two the ducts. No recent work has been carried out on the deck leading to a perforation. I cannot understand how even if there were some water getting in from the deck, it could then find its way to the inside of the main duct in such an amount unless a substantial hole or crack were in the duct which was located just under a major leak site in the deck. I run tube heaters in the main compartments of the boat and have two good dehumidifiers running, so I don't think it is condensation. Next time I am on the boat, I intend to run an endoscope up the ducts to see if I can identify anything but I have to say my Amazon endoscope has not especially inspired me in previous uses - might by me not using it properly of course. I would be very grateful for any advice or suggestions to this head-scratcher. Thanks all and Happy New Year!

[tkeithlu]

QUOTE "under a rather old teak deck."

Well, you need to track it down, and before it does serious damage to your beautiful boat. The only question in my mind is whether to go from the top or the bottom.

From the description, the most likely bet is that deck. I'd go looking for cracks in the caulking between the wood strips and wood that stays wet after the rest has dried from a rain.

On the bottom side you might spot the point of entry with your endoscope, but I'd be tempted to go ahead and disassemble the interior along that stretch. It is likely that there is retained wetness. Drying it out and replacing any roitten wood is in order.

I rather suspect you will be re-caulking your deck soon. If that task raises questions, do come back to the forum with them. The question has come up before, and there are experienced people on the forum who can help.

So, my recommendation is that you take a careful look from above, and then get out your gentle prybar and carefully remove the woodwork below the most likely spot. Best of luck with it.

[Pete7]

Is this on a Moody 44? if so the chain plates should be investigated soonest for the leaks. That can't be condensation, so as you say has to be a leak and warrants fixing soonest before other damage occurs. If it is the chain plates, its an easy if slightly time consuming job, with a tube of sealant.

Pete

[cedarbrook63]

Thank you both. It's a Moody 40. The wood work inside is all very beautiful and soundly put together and looks to be fitted without visible screws. If I have to start disembling from the inside, then there it is, but I'm a bit apprehensive about damage and reassembly.

[Pete7]

Are you members of the owners association? I would ask there about taking the inside apart. There will be screws, they are just well hidden.

https://moodyowners.org/

[Cadence]

I may be all wet, no pun intended. It sounds like some ducting is in an unheated area so I might guess it is condensation. If it is a deck leak getting into the ducting you also have a duct leak. JMHO

[cedarbrook63]

Originally Posted by Pete7

Are you members of the owners association? I would ask there about taking the inside apart. There will be screws, they are just well hidden.

https://moodyowners.org/

Hi Pete,
Yes I am a member of MOA and have posted there but I thought I would cast the net wide in search of a solution. Thanks for the suggestion.

[Boatwright]

Have you considered water vapor from the combustion exhaust as the source of your problem?

You must make sure there are no leaks or cracks in your heat-exchanger as this could be a way for combustion gases: water vapor, CO2, and most dangerous carbon-monoxide to get in your duct work.

Please take this seriously. Home furnace service folks are trained to look for moisture and rusty ductwork as an indicator of potentially very dangerous heat-exchanger failure.

[paulie4203]

I think a combination of replies from Cadence and Boatwright are correct. I know there is condensation in the exhaust pipe from heat and that correlates to the furnace in my land home-there's actually a tube running from the furnace to the outside, constantly dripping when the heat is on! Btw, I did at one time have a diesel heater (same as Webasto).

[Boatwright]

Forgot to mention. We have an Espar, that we love for late season cruising. It also lets me work on the boat in comfort all winter.

[cedarbrook63]

I can't get to my boat now because of lockdown, so goodness knows what's coming in through the Webasto duct. Oh well, not much I can do about it currently. I was rather stupid in my initial analysis of the situation, as I was trying to imagine how water coming in from a deck leak (and I'm not certain yet that this is happening) could get inside a duct unless it had a conveniently-situated big hole or defect. Then I realised that there has to be a plastic splitter to which the main duct attaches on one side and then continues from the other side, in order for the tributary ducts to go to their various outlets. So for a start, that may be a way in for water, if a jubilee clip has failed for example. I need to get there with my endoscope before I have to cause any dismantling of beautiful woodwork or deck. I still cannot see how so much water could arise from condensation with the heaters that I have going along with strong dehumidifiers. I will post again once I know more.