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How do you ventilate and heat the van? Aren't the two at odds with one another?

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Gueyog8a7

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For reference this is for UK weather and using diesel (aka dry) heating.

Isn't that like putting on the heating and opening all doors and windows? It seems extremely wasteful no?

Currently I see heating is not enough for me because I will run the heating for an hour say and see the condensation lift from metal on the walls and some on the windows (the heater is at the other end of the van to the windows) then only about 10 minutes after I turn the heater off then the condensation returns to the windows.

If I run for longer than about one hour 30 minutes though the heat would be uncomfortable for me when it is getting into the 20s range (celcius).

So will active venting with fans do better work at preventing this? Even so isn't it just going to suck out any hot air that is produced meaning the space will never get warm?
 
Have the heater air intake pull air in from the outside.

You can then also run small vent fans.

You just have to burn more fuel to heat.

Who cares? First-world problems.
 
Checkthisout said:
Have the heater air intake pull air in from the outside.
Click to expand...
That is the normal setup of diesel heaters and what I have done. However I think you may misunderstand how they work if you think that will bring fresh air into the living space because it doesn't. I only learned this recently myself. The intake for the combustion is completely separate from the air it heats. Intake and exhaust for combustion are both external and the heated air is taken from the van and just passes over the heat source of the closed chamber.
 
Gueyog8a7 said:
That is the normal setup of diesel heaters and what I have done. However I think you may misunderstand how they work if you think that will bring fresh air into the living space because it doesn't. I only learned this recently myself. The intake for the combustion is completely separate from the air it heats. Intake and exhaust for combustion are both external and the heated air is taken from the van and just passes over the heat source of the closed chamber.
Click to expand...
you really need to insulate your van (i assume youre doing a van build?) to stop the condensation build up and install permanent vents. air circulation is the key to reducing condensation. its really difficult to get rid of it completely, even with no heating. we carry a karcher type window cleaner to vacuum up all the condensation from our windscreen, especially this time of year, irrespective of whether weve left our heater running or not, you will be surprised how much we produce at times! we have found one of the best methods to reduce condensation is to fit external windscreen covers when we are parked up. it also adds privacy and keeps our motorhome warmer, not ideal though if youre stealth camping?

Greg Virgo does a very good video on why and how much insulation is required on youtube - i like his videos and i think theyre worth watching, unlike a few other UK van builders.vloggers!

youre correct re the air intake on the heater side being inside the van, and the air for combustion being taken from the outside (i have one installed in my home adding additional boost to the kitchen/conservatory). you may find that if youre running your diesel heater on low all the time, that it will soot up and you will have to strip it down to clean all the carbon build up. turn it on and run on maximum for 10 minutes before turning it down!
 
Gueyog8a7 said:
That is the normal setup of diesel heaters and what I have done. However I think you may misunderstand how they work if you think that will bring fresh air into the living space because it doesn't. I only learned this recently myself. The intake for the combustion is completely separate from the air it heats. Intake and exhaust for combustion are both external and the heated air is taken from the van and just passes over the heat source of the closed chamber.
Click to expand...

I know the units have closed combustion.

I'm talking about drawing the air to be heated from the outside so that new and hopefully drier air is heated and then forced into the cabin rather than drawing in air from the Cabin, heating it and spitting it back out.

In other words "fresh air" instead of "recrirc".

Edit: Different than what I just said but in my travel trailer, you could run the propane furnace and air conditioner at the same time. They were on separate thermostats. That dried it out super quick. On my motorhome, I run the main engine and chassis a/c and then run the propane furnace to dry the air out.

In either case, overnight, I would just open a ceiling vent and crack a side and just fresh air draft naturally. The furnace comes on more often but it stays dry inside.
 
Last edited:
MisterB1959 said:
you really need to insulate your van (i assume youre doing a van build?) to stop the condensation build up and install permanent vents. air circulation is the key to reducing condensation. its really difficult to get rid of it completely, even with no heating. we carry a karcher type window cleaner to vacuum up all the condensation from our windscreen, especially this time of year, irrespective of whether weve left our heater running or not, you will be surprised how much we produce at times! we have found one of the best methods to reduce condensation is to fit external windscreen covers when we are parked up. it also adds privacy and keeps our motorhome warmer, not ideal though if youre stealth camping?

Greg Virgo does a very good video on why and how much insulation is required on youtube - i like his videos and i think theyre worth watching, unlike a few other UK van builders.vloggers!

youre correct re the air intake on the heater side being inside the van, and the air for combustion being taken from the outside (i have one installed in my home adding additional boost to the kitchen/conservatory). you may find that if youre running your diesel heater on low all the time, that it will soot up and you will have to strip it down to clean all the carbon build up. turn it on and run on maximum for 10 minutes before turning it down!
Click to expand...
I have insulated my van. Rockwool and 20mm cork. The condensation builds beneath. Greg is mostly good info but his vapor barrier stuff I am not a fan of. I tried that using waterproof material as he suggested and it still gathers water behind. I am sure most people don't rip out their newly installed insulation to check but I did and there are air pockets which hold water and release it once it is sealed in so it is then trapped there.

In his videos he says things like "I am absolutely 100% satisfied no moisture is getting through now". Really? Ok technically that is right because the moisture is trapped inside not coming from outside! I saw another video where he addressed this with some impressive figures saying that only half a teaspoon of water will be behind the insulation. Well that just wasn't my experience.

He does deliver his videos in a straightforward fashion though, unlike some of the other insufferable vanlife youtubers you allude to putting on some ridiculous personality, and I would say largely the information is good. I just know to double check the points with other sources.

I am of the breathable insulation camp. The stuff he says on dew point still applies so long as it is flush with the metal but if you do get some pockets which you inevitably will it is able to dry out rather than being trapped in the case of the waterproof barriers.
 
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Checkthisout said:
I know the units have closed combustion.
Click to expand...
My bad. I asked about this elsewhere and people said not to do that as it could cause a vaccuum. Not sure about that but I feel it is much simpler to just have separate fans to pull in air through their own vents.

I already have vent holes I cut for intake and out just with no powered fans. I have bought a couple of computer fans of the rough size so plan to add those for intake and exhaust.
 
Don't need to open all the windows. Don't need a fan to force all the heat out in a few minutes. Need to adjust for any bathing or cooking that also adds moisture. The more people in the van will also need more venting. Otherwise heat as needed and vent to the minimum. A dehumidifier could resolve some of the issue.
 
I think a fantastic vent set on low with the cover opened just enough for the fan to spin forcing air in with a lower vent somewhere to let air out (adjustable as well) balance the two to get the airflow you need you want the top air forcing air in though, coldest air will exit via the lower vent along with a lot of the moisture.
 
Gueyog8a7 said:
My bad. I asked about this elsewhere and people said not to do that as it could cause a vaccuum. Not sure about that but I feel it is much simpler to just have separate fans to pull in air through their own vents.

I already have vent holes I cut for intake and out just with no powered fans. I have bought a couple of computer fans of the rough size so plan to add those for intake and exhaust.
Click to expand...

If you notice, cars nowadays do not allow you to select "recirc" and "defrost" at the same time because generally, and especially in winter, the outside air is less humid than the warm air inside the vehicle especially after a bunch of people have been breathing and sweating.

Drawing the air to be heated from outside will place positive pressure on the cabin, not negative.
 
I have a diesel heater in a small camper that puts out too much heat even on the lowest setting so I waste heat by leaving a window open.The heater uses so little diesel that it really doesn't matter. Condensation isn't a problem at all with a diesel heater but it was a big problem when I was using a Buddy heater, even with a partially open window.
 
hugemoth said:
I have a diesel heater in a small camper that puts out too much heat even on the lowest setting so I waste heat by leaving a window open.The heater uses so little diesel that it really doesn't matter. Condensation isn't a problem at all with a diesel heater but it was a big problem when I was using a Buddy heater, even with a partially open window.
Click to expand...

They are impressive little buggers, especially given the price they sell for. Way smoother operation than what I was expecting.
 
I thought it was very cool also! When I found it, I was looking for a solution for my cabin. Most operate on ac like the one below. Although it has a dc motor. A person might be able to run on dc with a converter. But a lot more $$$.

shop.vents-us.com

Vents TwinFresh Comfo RA1-50-2 "PureAir" Ductless Energy Recovery Vent

Introducing the Twinfresh Comfo RA1-50-2 "Pure Air" Bundle, featuring our best-selling Comfo ventilation system and a MERV 14 filter, all conveniently packaged for easy installation. This bundle is meticulously designed to enhance air purification, a capability only achievable with our upgraded...
shop.vents-us.com
 
Daddy Tanuki said:
I think a fantastic vent set on low with the cover opened just enough for the fan to spin forcing air in with a lower vent somewhere to let air out (adjustable as well) balance the two to get the airflow you need you want the top air forcing air in though, coldest air will exit via the lower vent along with a lot of the moisture.
Click to expand...
This goes directly against the theory of convection which states the exact opposite. Hot air rises and is pushed out the top. Think of how chimneys work.
 
Checkthisout said:
If you notice, cars nowadays do not allow you to select "recirc" and "defrost" at the same time because generally, and especially in winter, the outside air is less humid than the warm air inside the vehicle especially after a bunch of people have been breathing and sweating.

Drawing the air to be heated from outside will place positive pressure on the cabin, not negative.
Click to expand...
So less humid air creates positive pressure when more humid air is in the space? Did not know that. I only know about cool air being pulled into warm spaces via convection. Or you are talking about convection here as well?
 
hugemoth said:
I have a diesel heater in a small camper that puts out too much heat even on the lowest setting so I waste heat by leaving a window open.The heater uses so little diesel that it really doesn't matter. Condensation isn't a problem at all with a diesel heater but it was a big problem when I was using a Buddy heater, even with a partially open window.
Click to expand...
How long are you leaving it on out of interest? I only run mine for about an hour at a time but people are saying they run theirs 24/7. I am sure that would make a big difference to the amount of water that gets evapourated but I just don't want it on all the time when I am not in the van. I am working on putting 12v computer fan or two in as much lower power requirements and think that might offer as good or better effects than heating especially when I am in there breathing.
 
Gueyog8a7 said:
So less humid air creates positive pressure when more humid air is in the space? Did not know that. I only know about cool air being pulled into warm spaces via convection. Or you are talking about convection here as well?
Click to expand...

No.

Your diesel heater has a fan that blows the air to to be heated through it.

It has an intake on one end and blows the heated air out of the other.

Duct the intake to the outside so it pulls the air to be heated in from the outside....th


Nevermind.
 
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