Hi Paul This is a truly excellent discussion on the principles of condensation on walls. One mildly interesting point that I didn't see explicitly mentioned is that the interstitial condensation becomes worse with additional insulation thickness.
Ken, I mentioned interstitial condensation very briefly as it is such a big subject. I have seen some appalling installations (particularly van builds and houses - mostly DIY extensions) where you would think people were trying to encourage interstitial condensation. I have seen it a bit on boats where people simply put flat insulating board on the hull and just because they don't get condensation on the innermost surface, think the problem has gone away. I have also seen people with interstitial condensation problems who simply add more insulation, and as you say, simply make it worse. Cheers Paul
Absolutely brilliantly explained, you have really demystified a lot on this tricky subject. I appreciated a lot that you put all this effort into this episode. Thanks and cheers.
Thanks for the feedback. It can be a bit of a mystery. I was taught it using complex mathematical formulae many years back. None of it ever sunk in. Then I discovered the graphs - I think they help a lot. Pictures are always better as far as I am concerned. Cheers Paul
Very interesting analysis! I have already got 10 mm Armaflex for the insulation job in my 27 ft Albin Vega. Will monitor inside humidity once everything is in place. Thank you for posting this! Regards from Norway
Thanks for the comment - very interesting. I haven't decided on the thickness of Armaflex I will go for yet. But I am thinking that 10mm should be plenty for me. 5mm would probably be OK. I will do a bit more 'real world' testing once the Winter sets in before I decide. Cheers Paul
Thanks for the comment. There is literally nothing that can't be explained with a sheet of A4 paper on a clipboard and a packet of felt pens. - Except the offside rule in football (soccer) of course. Cheers Paul
loved it , nice thermo teaching. On our alloy vessel we used a thermo paint as first layer specially for the "contact" dew point. We found out to throttle the cold air "mix" it with the circulating air , with an "air condensator " catching the water.
Interesting. Thanks for that. I have wondered about painting a layer of thermo paint on the inside of the hull before sticking on the Armaflex. I will be doing the actual test with the two different air intakes over the next couple of days. It is always interesting to know how theory works out in practice. Cheers Paul
I think a heat recovery unit is worthwhile exploring and just bring in 10% ‘make up’ air from outside plus high(er) capacity exhaust fans for heads and galley.
In the not too distant future I am sure that someone will come up with a device that will do all of this automatically. All you would need is some sort of smart controller that will keep the relative humidity at around 50% and at the same time waste as little heat as possible. I have noticed that most modern cars don't even have the re-circulation button any more as the air-con software controls all this stuff. I don't have a fan above the galley - it would be good to have one. And the fan in the head is a but rubbish - it moves about 20 m3 per hour, but is solar powered with a back up battery, so doesn't always work. Cheers
Paul...I figured my heating out ling ago...sail where its warm, that's a big reason why I got a sailboat, to get away from the cold and apparently math, LOL...for now I'm stuck in hell...great explanation on humidity and dew point...cheers and Favorable winds! P.S. Simplicity is the ultimate sophistication. Leonardo DaVinci
@@verynearlyaboutsailing8114 yes plenty of felt pens...I prefer Sharpe fine point markers, but felt pens are a close second LOL...an amusing FYI...I am a painter by trade and my last name is....Leonardo, thus the DaVinci quote...You have me thinking on whether or not to insulate Oria?... the time for me to do it is coming up, if I do!
Vince This is a very interesting idea. I'm not sure that I have enough room to install one. But I am sure that a slightly larger boat would have room. I can't see any reason at all why they shouldn't work. Let me know if you come across anyone (or any videos) where this has been done. Cheers Paul
Yep. Condensation and humidity can make living aboard a complete nightmare. Of course I am talking about humidity and condensation at the lower temperatures found in the UK. Once you stray into 'Miami' type conditions, that opens another complete set of parameters. - Probably even more difficult to deal with. Cheers
Hi Paul. A different video this one. But I was yet again hooked. I just read the instructions on my heater and fitted. My eberspacher on the boat and now Chinese nock off in my stealth camper. I can't wait to if I did it right or not. Really looking forward to you findings pal.
We will have to wait and see if this physics stuff actually works. Hopefully within the next 7 days. 'Unfortunately' the weather has gone a little bit warm fro a heater test. I will probably go ahead and do the test anyway. Good to hear from you. Cheers Paul
Great Video and explanation. As Mac M. mentions below, A Heat recovery device will be something to consider here in regards to Cost/Heating/outsideAir Once you are heating up the incomming low Rh Air with the outgoing warm air you will save on heating costs while keeping the RH and temp where you want it. Obviously you can't shoehorn in a residential one as alluminium exchangers and salty air.... But there are some polypropylene heat exchangers about, Or you could make a simple one with a couple of small fans a tube and a surface sufficiant to exchange heat.
Yes, great idea. There is obviously a lot of wasted energy going on with my setup - A lot of the combustion heat simply goes out of the exhaust. Let me know if you do this - and make a video. I would watch that. Cheers Paul
I do like your videos but after 5 mins I had to fast forward and glad I did. I've fitted solar vents to my boat to keep the air flowing on mine and it helped a lot. Just moved into a marina and got a heater on 24/7 set to 12 degrees at the moment. Hoping it will keep the damp out and stop things freezing in winter. Any idea on what would be a good temperature for this?
Lee Sorry about the physics lesson ;) The key part of the video is the few minutes from 8:45 looking at two different relative humidities for the same temperature. Relative humidity really is the key factor. I was mainly talking about condensation whilst being aboard the boat (cooking and breathing - particularly when asleep etc). Condensation isn't really dependent on temperature alone, but is when the temperature drops (suddenly) to the outside temperature and the air can no longer the water in vapor form and it turns into actual water. This can happen on the windows and the hull, but also inside soft furnishings (pillows, duvets etc). Having a powered vent is probably the best thing for an unoccupied boat - I have just bought one myself. That will hopefully keep the air inside at about the same relative humidity as the air outside. If the air inside is static and warmer than the air outside, it will just absorb more water until there is a drop below the dewpoint. I'm not sure what the best temperature would be. I would guess that it is probably the lowest you can go to and avoiding frost. It sounds to me that 12 degrees is reasonable. I used the dessicant de-humidifier 24/7. But I was plugged into shore power. It produces heat as it sucks the water out of the air. I never had any damp problems at all for about 2 years. I think the coldest it got was about -10. The next video is much more practical, and should hopefully be finished in the next week. Thanks for watching. Cheers Paul
James What I really should have done is do the experiment first and then recorded the theory video to fit the results. Unfortunately I have only just thought of this, so it's too late. Hopefully the experiment will happen over the next couple of days. I did use to work in a laboratory many many years ago - and I did have a white coat, we all did. Great fun; loads of very expensive toys to play with. Cheers Paul
An idea from Sven Yrvind. His boats are built with a thick foam core but he leaves the windows uninsulated so that condensation forms on them. He puts water catchers under the windows. These have drains on them which can be opened and the condensation used for drinking if desired. He reckons that even in freezing weather this keeps the rest of the boat dry.
This all sounds spot on to me. Etap yachts were famous for their foam cored double skin yachts. Apparently you could leave all your bedding in the yacht all year - and never have any damp problems through condensation. They also had the advantage of positive bouyancy. You could open all the sea-cocks and knock a hole in the side and they would still stay afloat. I guess they became too expensive for production boats. Imagine that - we could all have condensation free yachts if the designers followed the physics. Cheers Paul
Here’s an idea. If it works I’m claiming the rights! It strikes me that the best objective here would be to maintain the relative humidity to your selected level of 50%. Your suggestion of pulling air in from outside must be more costly to run as you are heating (potentially) very cold air to the required 22 degrees. Why not make a dehumidifier that sits between the cabin and the heater (I assume the heater has a fan to draw air in) comprised of copper plate heat exchanger cooled by water or air from outside? For extra excitement you could use the temperature difference between the heater air and the outside water/air to run a Sterling engine to gently pump cold outside water or air through the heat exchanger. You could collect the condensed water to make tea thereby creating a circular evaporation/condensation system. A humidistat could control the system to maintain your 50% relative humidity. We could retire on this! I’m off to the pub to celebrate.
I think you had better get a drawing sent off to the patent office straight away. This looks like a winner to me. But be quick - you do know James Dyson watches this channel from his luxury penthouse in Singapore don't you ;)
I agree here. I have the same desiccant dehumidifier Paul, and am sure most of that 300w is it’s heater, then just a few watts on a fan, and I think the desiccant rotates too. Replace the heat n fan with your diesel heater and you’re on to a winner 👍👍
That sounds like a waste of a perfectly good set of felt pens to me ;) I lived in a caravan for a while once. I didn't bother to heat it at all (it got down to -10). But I did have a lot of thick jumpers back then.
That saturated/unsaturated line can also be understood when dissolving sugar in water. You can only dissolve so much sugar in room temperature water. Heat it up, and it holds more. Cool it down, and that concentration moves left, across the dew point line, and you get sugar crystals form. Like dew. If the air in the boat was the same temperature as the cold hull, you'd wake up with fog inside the boat. Well done explanation!
Brilliant analogy. I like that. I was keen to avoid the math(s) - and at the same time not go into Partial Pressures, Ideal Gas Laws, Daltons...blah blah blah. Although I do find that stuff very interesting. Cheers Paul
Dan, I didn't make it. I bought it from ebay. It is much stronger than the thing that comes with the heater. There are a few out there. Here is a link www.ebay.co.uk/itm/EBERSPACHER-D2-D4-WEBASTO-Planar-night-heater-MARINE-MOUNTING-BRACKET-316/143409240472?hash=item2163db5998:g:otwAAOSwWKtUymYx
Hi Paul
This is a truly excellent discussion on the principles of condensation on walls. One mildly interesting point that I didn't see explicitly mentioned is that the interstitial condensation becomes worse with additional insulation thickness.
Ken, I mentioned interstitial condensation very briefly as it is such a big subject. I have seen some appalling installations (particularly van builds and houses - mostly DIY extensions) where you would think people were trying to encourage interstitial condensation. I have seen it a bit on boats where people simply put flat insulating board on the hull and just because they don't get condensation on the innermost surface, think the problem has gone away.
I have also seen people with interstitial condensation problems who simply add more insulation, and as you say, simply make it worse.
Cheers
Paul
Absolutely brilliantly explained, you have really demystified a lot on this tricky subject. I appreciated a lot that you put all this effort into this episode. Thanks and cheers.
Thanks for the feedback. It can be a bit of a mystery. I was taught it using complex mathematical formulae many years back. None of it ever sunk in. Then I discovered the graphs - I think they help a lot. Pictures are always better as far as I am concerned.
Cheers
Paul
Very interesting analysis! I have already got 10 mm Armaflex for the insulation job in my 27 ft Albin Vega. Will monitor inside humidity once everything is in place. Thank you for posting this! Regards from Norway
Thanks for the comment - very interesting.
I haven't decided on the thickness of Armaflex I will go for yet. But I am thinking that 10mm should be plenty for me. 5mm would probably be OK. I will do a bit more 'real world' testing once the Winter sets in before I decide.
Cheers
Paul
What a great video. I know I bandy about phrases like dew point and had a sort of hand wavy understanding but this made all so obvious. Many thanks.
Thanks for the comment.
There is literally nothing that can't be explained with a sheet of A4 paper on a clipboard and a packet of felt pens. - Except the offside rule in football (soccer) of course.
Cheers
Paul
Beautifully explained! Just my level :-)
Thanks. The rule is, if I can't explain it without the use of felt pens, then I can't explain it.
Cheers
Paul
loved it , nice thermo teaching. On our alloy vessel we used a thermo paint as first layer specially for the "contact" dew point. We found out to throttle the cold air "mix" it with the circulating air , with an "air condensator " catching the water.
Interesting. Thanks for that. I have wondered about painting a layer of thermo paint on the inside of the hull before sticking on the Armaflex.
I will be doing the actual test with the two different air intakes over the next couple of days.
It is always interesting to know how theory works out in practice.
Cheers
Paul
@@verynearlyaboutsailing8114 you are welcome
I think a heat recovery unit is worthwhile exploring and just bring in 10% ‘make up’ air from outside plus high(er) capacity exhaust fans for heads and galley.
In the not too distant future I am sure that someone will come up with a device that will do all of this automatically. All you would need is some sort of smart controller that will keep the relative humidity at around 50% and at the same time waste as little heat as possible.
I have noticed that most modern cars don't even have the re-circulation button any more as the air-con software controls all this stuff.
I don't have a fan above the galley - it would be good to have one. And the fan in the head is a but rubbish - it moves about 20 m3 per hour, but is solar powered with a back up battery, so doesn't always work.
Cheers
Paul...I figured my heating out ling ago...sail where its warm, that's a big reason why I got a sailboat, to get away from the cold and apparently math, LOL...for now I'm stuck in hell...great explanation on humidity and dew point...cheers and Favorable winds!
P.S. Simplicity is the ultimate sophistication.
Leonardo DaVinci
Randy, I think you have it spot on. Sail away from problematic weather. But don't forget to take plenty of felt pens ;)
Cheers
Paul
@@verynearlyaboutsailing8114 yes plenty of felt pens...I prefer Sharpe fine point markers, but felt pens are a close second LOL...an amusing FYI...I am a painter by trade and my last name is....Leonardo, thus the DaVinci quote...You have me thinking on whether or not to insulate Oria?... the time for me to do it is coming up, if I do!
Heat exchanger (recovery) air vents work on a boat?
Vince
This is a very interesting idea. I'm not sure that I have enough room to install one. But I am sure that a slightly larger boat would have room. I can't see any reason at all why they shouldn't work.
Let me know if you come across anyone (or any videos) where this has been done.
Cheers
Paul
Keeping humidity down is job 1.
Yep. Condensation and humidity can make living aboard a complete nightmare.
Of course I am talking about humidity and condensation at the lower temperatures found in the UK. Once you stray into 'Miami' type conditions, that opens another complete set of parameters. - Probably even more difficult to deal with.
Cheers
Doesn’t she have to be in the water to make the experiment valid , Gibraltar might be the spot to try it
No, being on the hard is fine. It's just the same as running aground - not that I've ever done that (many times).
Just chuck her in the oggin and set off somewhere you were doing ok out there
Thanks. It will happen ;)
A life. Get one.
Ah, you spotted the 'secret of life' bit hidden in the video.
Cheers
really interesting and at just the right level, for me anyway
Thanks for watching and commenting.
I find these things easier to understand with pictures or graphs rather than mathematical equations.
Cheers
Paul
Hi Paul. A different video this one. But I was yet again hooked. I just read the instructions on my heater and fitted. My eberspacher on the boat and now Chinese nock off in my stealth camper. I can't wait to if I did it right or not. Really looking forward to you findings pal.
We will have to wait and see if this physics stuff actually works. Hopefully within the next 7 days. 'Unfortunately' the weather has gone a little bit warm fro a heater test. I will probably go ahead and do the test anyway.
Good to hear from you.
Cheers
Paul
Great Video and explanation.
As Mac M. mentions below, A Heat recovery device will be something to consider here in regards to Cost/Heating/outsideAir
Once you are heating up the incomming low Rh Air with the outgoing warm air you will save on heating costs while keeping the RH and temp where you want it.
Obviously you can't shoehorn in a residential one as alluminium exchangers and salty air.... But there are some polypropylene heat exchangers about, Or you could make a simple one with a couple of small fans a tube and a surface sufficiant to exchange heat.
Yes, great idea. There is obviously a lot of wasted energy going on with my setup - A lot of the combustion heat simply goes out of the exhaust. Let me know if you do this - and make a video. I would watch that.
Cheers
Paul
I do like your videos but after 5 mins I had to fast forward and glad I did. I've fitted solar vents to my boat to keep the air flowing on mine and it helped a lot. Just moved into a marina and got a heater on 24/7 set to 12 degrees at the moment. Hoping it will keep the damp out and stop things freezing in winter. Any idea on what would be a good temperature for this?
Lee
Sorry about the physics lesson ;) The key part of the video is the few minutes from 8:45 looking at two different relative humidities for the same temperature. Relative humidity really is the key factor.
I was mainly talking about condensation whilst being aboard the boat (cooking and breathing - particularly when asleep etc). Condensation isn't really dependent on temperature alone, but is when the temperature drops (suddenly) to the outside temperature and the air can no longer the water in vapor form and it turns into actual water. This can happen on the windows and the hull, but also inside soft furnishings (pillows, duvets etc).
Having a powered vent is probably the best thing for an unoccupied boat - I have just bought one myself. That will hopefully keep the air inside at about the same relative humidity as the air outside. If the air inside is static and warmer than the air outside, it will just absorb more water until there is a drop below the dewpoint.
I'm not sure what the best temperature would be. I would guess that it is probably the lowest you can go to and avoiding frost. It sounds to me that 12 degrees is reasonable.
I used the dessicant de-humidifier 24/7. But I was plugged into shore power. It produces heat as it sucks the water out of the air. I never had any damp problems at all for about 2 years. I think the coldest it got was about -10.
The next video is much more practical, and should hopefully be finished in the next week.
Thanks for watching.
Cheers
Paul
Thank you professor. Await the experiment with bated breath. Shouldnt you have a white coat and mad hair though? All the best.
James
What I really should have done is do the experiment first and then recorded the theory video to fit the results. Unfortunately I have only just thought of this, so it's too late. Hopefully the experiment will happen over the next couple of days.
I did use to work in a laboratory many many years ago - and I did have a white coat, we all did. Great fun; loads of very expensive toys to play with.
Cheers
Paul
An idea from Sven Yrvind. His boats are built with a thick foam core but he leaves the windows uninsulated so that condensation forms on them. He puts water catchers under the windows. These have drains on them which can be opened and the condensation used for drinking if desired. He reckons that even in freezing weather this keeps the rest of the boat dry.
This all sounds spot on to me.
Etap yachts were famous for their foam cored double skin yachts. Apparently you could leave all your bedding in the yacht all year - and never have any damp problems through condensation.
They also had the advantage of positive bouyancy. You could open all the sea-cocks and knock a hole in the side and they would still stay afloat.
I guess they became too expensive for production boats.
Imagine that - we could all have condensation free yachts if the designers followed the physics.
Cheers
Paul
Here’s an idea. If it works I’m claiming the rights! It strikes me that the best objective here would be to maintain the relative humidity to your selected level of 50%. Your suggestion of pulling air in from outside must be more costly to run as you are heating (potentially) very cold air to the required 22 degrees. Why not make a dehumidifier that sits between the cabin and the heater (I assume the heater has a fan to draw air in) comprised of copper plate heat exchanger cooled by water or air from outside? For extra excitement you could use the temperature difference between the heater air and the outside water/air to run a Sterling engine to gently pump cold outside water or air through the heat exchanger. You could collect the condensed water to make tea thereby creating a circular evaporation/condensation system. A humidistat could control the system to maintain your 50% relative humidity. We could retire on this! I’m off to the pub to celebrate.
I think you had better get a drawing sent off to the patent office straight away. This looks like a winner to me.
But be quick - you do know James Dyson watches this channel from his luxury penthouse in Singapore don't you ;)
I agree here. I have the same desiccant dehumidifier Paul, and am sure most of that 300w is it’s heater, then just a few watts on a fan, and I think the desiccant rotates too. Replace the heat n fan with your diesel heater and you’re on to a winner 👍👍
@@davidbarrett7424 Yes, the heat in the exhaust gas isn't doing anything else....Shall I book a slot on Dragon's Den?
Totally lost me, I just open a hatch and no condensation.
That sounds like a waste of a perfectly good set of felt pens to me ;)
I lived in a caravan for a while once. I didn't bother to heat it at all (it got down to -10). But I did have a lot of thick jumpers back then.
@@verynearlyaboutsailing8114 I know the feeling!
That saturated/unsaturated line can also be understood when dissolving sugar in water. You can only dissolve so much sugar in room temperature water. Heat it up, and it holds more. Cool it down, and that concentration moves left, across the dew point line, and you get sugar crystals form. Like dew. If the air in the boat was the same temperature as the cold hull, you'd wake up with fog inside the boat. Well done explanation!
Brilliant analogy. I like that.
I was keen to avoid the math(s) - and at the same time not go into Partial Pressures, Ideal Gas Laws, Daltons...blah blah blah. Although I do find that stuff very interesting.
Cheers
Paul
Paul you made a mounting bracket for your diesel heater. Do you have a drawing for it as I want to make exactly the same bracket, great video
Dan, I didn't make it. I bought it from ebay. It is much stronger than the thing that comes with the heater. There are a few out there. Here is a link
www.ebay.co.uk/itm/EBERSPACHER-D2-D4-WEBASTO-Planar-night-heater-MARINE-MOUNTING-BRACKET-316/143409240472?hash=item2163db5998:g:otwAAOSwWKtUymYx
That is why to clear condensation fasterbon car windows you should set the draw outside air option on the heater
@@sukalanger Yes, i agree! The physics backs this up. Cheers
Just about sailing thanks Paul got it ordered and very helpful