Fresh air while using webasto airtop

I am about to embark into pretty cold envions (0F). I have thinsulate 600l with reflectix on top and and webasto airtop.

I will have wet ski gear from time to time so want to let the moisture escape, how have people accomplished this ? I was thinking the fan vent on low and a wondow cracked ?

Somewhere here I was reading about having the heater draw in outside air, as outside heated air will be dryer than recirculating inside air.

Let me see if I can find the post.....

Ok here it is, https://sprinter-source.com/forums/showpost.php?p=421857&postcount=12

I doubt that the Webasto will be able to heat the air enough if the intake comes from outside (0F); it's not that powerful... but I agree that this would solve the issue of condensation.

We're about to go through our first winter with the van too (with ski gear); like you, we have the thinsulate, ez-cool (reflectix) & Webasto. Managing the condensation will be the biggest challenge. I guess that ventilation will be the key, at the detriment of heat loss.

Subscribing to this thread!

I've been thinking about how to do this with the Sprinter we have on order. Same situation - TH's and ski lots in the winter here in Colorado. As well as the red-eye drives to jackson.

I've ruled out cracking windows and using a roof vent. They both will let in spindrift if you have a fantastic fan. Plus, you're airflow will be a function of wind speed, so windy locations could mean lots of heavy drafts coming in.

I thought about venting the D2 to pull exterior air, but then you're dealing with dust or adding filters when it's summer (but cold). I've settled on 2 different ideas

1 - Espar maks an HVAC controller that turns on the factory fan when the car is shutoff. This is pulling air through the HVAC filter (no issues with dust in the summer), draws a small amount of power, and fan can be setup to run really low to trickle in the fresh air. I saw the option listed on Lubrication Specialist's website. I'm sure there are other ways to wire a switch and power to the HVAC fan, though.

2 - Maxxair fan. This is the alternative to a fantastic fan. Same hole cutout in roof, but the maxxair takes up a few more inches of longitudinal space on the roof. The air intake is always pointed down, so not much issue with spindrift. It also has ten speeds with the lowest pulling 0.1 amps. Because of the hood design, you can power it rain or shine, driving or stationary. I'm thinking that cracking the hood a tad, putting it on 1 or 2 for a speed setting, leaving the windows shut, the fan will then draw air in from the HVAC vents as long as that system is left in fresh air mode. It'll be just enough to introduce a steady stream of fresh air without dealing with spindrift coming in through the windows or fan.

Not sure how the webasto's are, but the espar units tend to get carbon'd up at high elevations (even with the high-altitude kits). I've spoken with Thermo King here in Denver, and they suggest finding ways to get the Espar to run at high power to keep that carbon build up to a minimum. Or, run the thing on high once back at Denver elevations to clean it out. So, having a bit of air coming into the van should allow the furnace to run at a higher setting to keep things clean.

Here is a diverter valve. Install on the heaters intake. Then have one side intake fresh and the other recirculate. This way you can decide how much fresh air you want.

http://www.heatso.com/regulating-flap-valve-y-branch-60mm/


I have not heard about coking problems on Espar heaters with the altitude kit. The only exception is when the heater is not installed properly. If you do not follow the install guidelines for duct length and bends as well as the fuel line/pump you will have problems.

Midwestdrifter said:

Here is a diverter valve. Install on the heaters intake. Then have one side intake fresh and the other recirculate. This way you can decide how much fresh air you want.

http://www.heatso.com/regulating-flap-valve-y-branch-60mm/


I have not heard about coking problems on Espar heaters with the altitude kit. The only exception is when the heater is not installed properly. If you do not follow the install guidelines for duct length and bends as well as the fuel line/pump you will have problems.

Click to expand...

Do you know what the balance of fresh to inside air is by default by any chance ?

Midwestdrifter said:

Here is a diverter valve. Install on the heaters intake. Then have one side intake fresh and the other recirculate. This way you can decide how much fresh air you want.

http://www.heatso.com/regulating-flap-valve-y-branch-60mm/

Click to expand...

Oh, I like it!

And add this....
http://www.heatso.com/eberspacher-flap-valve-operating-cable/

Wrinkledpants said:

I thought about venting the D2 to pull exterior air, but then you're dealing with dust or adding filters when it's summer (but cold). I've settled on 2 different ideas

1 - Espar maks an HVAC controller that turns on the factory fan when the car is shutoff. This is pulling air through the HVAC filter (no issues with dust in the summer), draws a small amount of power, and fan can be setup to run really low to trickle in the fresh air. I saw the option listed on Lubrication Specialist's website. I'm sure there are other ways to wire a switch and power to the HVAC fan, though.

Click to expand...

Correct me if I am wrong, but I believe that with the HVAC set to fresh air, it is possible to passively draw air in, and thus through the filter. Does that make sense?

I'm in the same position with cold weather and wet gear. I also have a requirement to not add any more height to the van so it will fit in the garage. That rules out a ceiling fan.

An idea for ventilation I am kicking around now is to put a floor vent in with a chase or hose that runs to the ceiling. The thought being that I can pull the warm wet air from up high and exhaust it through a floor vent. I have read that any sort of negative pressure in the van will draw air in through the vans vent system. There are a number of inline fans that are capable of doing this sort of thing with a minimal draw.

Ovrlnd_Trvlr said:

Correct me if I am wrong, but I believe that with the HVAC set to fresh air, it is possible to passively draw air in, and thus through the filter. Does that make sense?

Click to expand...

Yep - that's correct.

Midwestdrifter said:

Here is a diverter valve. Install on the heaters intake. Then have one side intake fresh and the other recirculate. This way you can decide how much fresh air you want.

http://www.heatso.com/regulating-flap-valve-y-branch-60mm/


I have not heard about coking problems on Espar heaters with the altitude kit. The only exception is when the heater is not installed properly. If you do not follow the install guidelines for duct length and bends as well as the fuel line/pump you will have problems.

Click to expand...

Thermoking said that if you spend an appreciable amount of time at 10K ft, you'll need to take it in for service annually to have it cleaned. This is coming from their experience with the kit. The two things that said will help is running the heater on high, and running it on high for 20-30 minutes when back at lower elevation.

Has anyone found a filter for this setup? My only fear would be dust accumulating in the hose between the Y and the wall.

That control dial would make this a pretty nice setup.

Did anyone use the y and damper cable to draw fresh air for dry air snd have success in the last 4 yrs. I’m starting a build and having these exact same thoughts.