Webasto / Espar Installation Question

B

beermanPDX

New member
I just got a new Webasto AT 2000 which I'll be installing in the galley cabinet. Obviously I'll be routing the exhaust directly through the side of the boat near the other thru-hulls (sink, head discharge). But I'm having a hard time figuring out where to route the combustion air intake. I don't want it too close to the exhaust or in a location in the cockpit where gas fumes may settle.

Can anyone who's installed a Webasto (or Espar / similar style furnace) tell me where they routed the combustion air intake? My kit comes with a second thru-hull for that. I've searched the threads and viewed install pics and I only see that mentioned once (Anna Leigh routed the intake from near the cockpit shelf). The only thru-hull pics I ever see are of the exhaust. I would have assumed that if people had to drill a 2nd hole through their boat, it would be photographed as much as the exhaust thru-hull. Hopefully people are routing combustion air from outside the cabin....right?

Again, I'm talking about combustion air intake, not cold air intake / return. The cold air return will be pulling from inside the cabin.

Thanks in advance.
 
I installed an Espar D-2 heater. I did not run a fresh air external air intake. I just let the intake hose pull air from the cabinet where the heater is located. Pictures in the Will-C's photo album. I would assume the concern is about the heater depleting the oxygen in the cabin. I don't sleep with the heater on and usually have a window cracked for fresh air if it is running. The heater is puts out an impressive amount of heat and we often leave the back door open if the camper canvas is in place. It also heats up pretty quickly. Our boat is insulated so it seems to hold heat pretty well. I'm not saying not to run an external combustion intake. I'm just saying we did not and have seen no ill effects but we use common sense when operating the heater.
D.D.
 
combustion air should be isolated in the combustion chamber. Thus not subject to CO or exhaust gasses. I had a different brand, and much larger heater (45,000 BTU) which took the combustion air concentrically in around the exhaust port--since there was a forced draft--as I believe there is in your heater, there was fresh air brought in around the area where the hot gas exhausted. The nice side effect of this system was that the exhaust air was cooled, and the intake air warmed.
 
Thanks for the info Dave. Maybe your setup is the common method and why I haven't been able to find any other pictures of intake thru-hulls.

Bob....I wish the Webasto (or Espar D2 for that matter) had the concentric exhaust / intake hose like you mentioned, but unfortunately they don't. If you note the two separate nipples on the bottom of the unit:

1_2_7_1_airtop_how_does_it_work_05.jpg


I'm thinking of potentially routing the intake somewhere in the side or cockpit wall of the head, above gunwale height.
 
IMG_3922.sized.jpg

Rob, Here is a picture of the heater installation on Discovery. You can look at all the Espar heater pics in the heater install album, in the Discovery albums. The combustion air intake is the smaller black hose near the center of the pic. The intake runs for a few feet rearward with the wiring bundle, behind the head compartment. The fresh air comes in from the cockpit around the wires.
 
My combustion fresh air pick up is on the floor behind a cabinet. The reason the instructions demand that the intake originate out side is that the units where designed for trucks. Trucks with the door seals and windows up are rather air tight. Not as tight as a sub but much more so then a boat. There is concern in a truck of depleting the air supply. Not so in a boat like our sea dorys. I run my heater all night with out a problem. a added benefit of using the intake in the cabin of the boat is it drys out the air by sucking out the cabin air and burning then expelling the air out side the boat. We have woke on cold damp mornings and started the heater and you can feel the air getting dryer while it runs. this is why I suggest a Espar heater over a Wallas stove/ heater. Much better solutions to the problem of heating a boat.
 
Tom,

I've wondered how that works with "modern" heaters for which the intake comes directly into the burner from outside and then leaves via the burner. I can see where the heater wouldn't add moisture to the cabin air, like a non-vented heater would do; but I wasn't sure how it could actually dry the air (besides as a factor of temperature rising) like a stove that draws outside air into the cabin (not just the burner), and then exhausts it, like my old woodstoves did. So with your stove/method, outside air comes into the boat, then gets into the burner, and is then exhausted? Which model heater do you have and how loud or quiet is it? (I'm "shopping" for a heater-only heater for my boat - will cook with a separate stove - and considering all my options.)

Jean-Marie: Not to hijack your thread, but I think you are getting your info too?
 
Sunbeam":9t80t4ib said:
Tom,

I've wondered how that works with "modern" heaters for which the intake comes directly into the burner from outside and then leaves via the burner. I can see where the heater wouldn't add moisture to the cabin air, like a non-vented heater would do; but I wasn't sure how it could actually dry the air (besides as a factor of temperature rising) like a stove that draws outside air into the cabin (not just the burner), and then exhausts it, like my old woodstoves did. So with your stove/method, outside air comes into the boat, then gets into the burner, and is then exhausted? Which model heater do you have and how loud or quiet is it? (I'm "shopping" for a heater-only heater for my boat - will cook with a separate stove - and considering all my options.)

Jean-Marie: Not to hijack your thread, but I think you are getting your info too?
Click to expand...

Sunbeam - it doesn't actually dry the air but typically it will reduce the relative humidity (which has the same practical effect). It does this by drawing in outside colder air which (since it is colder) can carry less moisture than the inside air. As this air is warmed by circulation through the heater it will have a lower relative humidity than the cabin air. By using the cabin air in the burner, it get's exhausted and, since the cabin is not air tight, exchanged with the outside air.
 
When I was looking at installing one I thought the way Discovery did it was ideal; using the space between the shower and hull to run the intake and having it exit in the cockpit. I thought using the fiberglass shelf as the end point was easiest. Drill a hold at the top and run a little extra hose to make getting it in/out simple. No water would get in and no hole in the boat itself. Just an idea.

I've put it on the back burner for now.
 
I hope to install one on a 19 in the future. On the 25, that wiring space behind the head is open to the cockpit and cabinet inside the boat. If you just let it draw from the cabinet, any "vacuum" (need for air) created would just be pulling air from openings like that anyway. So running a hose out part way is just wasted unless it goes all the way to the cockpit and eliminates the draw of fresh air from outside to inside through any gaps available. Bringing fresh air into the cabin without the hose may have a drying effect (climate dependent) as Tom mentions and thats good. The only loss would be the cooling from intrusion of that outside air. I think these little heaters can overcome that small amount of cooling easy enough.

Is heat or drying the priority? I think it would be drying for me as it is for Tom. The heat can take a backseat. These are wet boats in the morning.

Greg
 
Thanks for all the replies. Both drying and heating are reasons for getting the Webasto, but if I had to pick one as most important it would be the drying. I can always put on a heavier coat, but the darn foggy windows are a royal pain as is the general dampness.

Adding to Greg's point about running the hose part way to the wiring space being a wasted effort, it also has the potential to suck in fumes from the fuel fill / vent plumbing that it would end near.

So it seems my valid options are to just let it pull in cabin air or plumb the intake directly to the outside via thru-hull in the cockpit or elsewhere. Given that the first option requires no work...I'll go with that one and just see how it goes.
 
rogerbum":7vd6jm3h said:
Sunbeam - it doesn't actually dry the air but typically it will reduce the relative humidity (which has the same practical effect). It does this by drawing in outside colder air which (since it is colder) can carry less moisture than the inside air. As this air is warmed by circulation through the heater it will have a lower relative humidity than the cabin air. By using the cabin air in the burner, it get's exhausted and, since the cabin is not air tight, exchanged with the outside air.
Click to expand...

But does this happen if one has a direct vent type heater wherein the combustion air is drawn from outside, in through a pipe to the burner, and then exhausted outside through another pipe, but the heated cabin air is never in direct "contact" with it? In other words, with my old wood stove, air came in (through cracks in the house), was heated in the stove, and then was exhausted through the chimney. But with my direct-vent heater, the "in/out" was all within the heater itself, and did not involve "cabin" air...... as I understand it (?). So I always wondered if that would really "dry" (change relative humidity?) in the same way as the old woodstove.
 
Sunbeam":364e4fa6 said:
rogerbum":364e4fa6 said:
Sunbeam - it doesn't actually dry the air but typically it will reduce the relative humidity (which has the same practical effect). It does this by drawing in outside colder air which (since it is colder) can carry less moisture than the inside air. As this air is warmed by circulation through the heater it will have a lower relative humidity than the cabin air. By using the cabin air in the burner, it get's exhausted and, since the cabin is not air tight, exchanged with the outside air.
Click to expand...

But does this happen if one has a direct vent type heater wherein the combustion air is drawn from outside, in through a pipe to the burner, and then exhausted outside through another pipe, but the heated cabin air is never in direct "contact" with it? In other words, with my old wood stove, air came in (through cracks in the house), was heated in the stove, and then was exhausted through the chimney. But with my direct-vent heater, the "in/out" was all within the heater itself, and did not involve "cabin" air...... as I understand it (?). So I always wondered if that would really "dry" (change relative humidity?) in the same way as the old woodstove.
Click to expand...

In short, not as much. When the cabin air is heated, the temperature change is not as much as when the outside air is heated. So all other things being equal, the change in relative humidity is much greater. However, in addition to that is the fact that the cabin air is continually getting moisture added to it from the humans within. So by using it as combustion air and exhausting it out of the boat, it generally makes the air drier.
 
I don't think where the combustion air comes from makes much difference other than a threat of lower oxygen if it was a sealed environment. The combustion air gets mixed with fuel ignites and burns creating heat, then the goes out the exhaust via the thru hull. The air intake for actual air to be heated is fan driven and pulls cabin air over the outside of hot heater combustion area and the warm air is exhausted in the cabin. I would think the intake air would have to dry out some after being ducted and fan driven over the outside of the heater's hot combustion area. We have an Espar D-2 and they are noisy but have a rubber mount for the fuel pump to lessen the clicking the fuel pump makes while pumping fuel. The exhaust is what is noisy. It sounds like a little jet engine. They make mufflers for the exhaust but they are said to just change the pitch a little and don't really do much to lessen the overall noise. We have had ours a few years and it has always has performed. They suggest firing them up once a month. I start them on high and shut them off on the high setting to avoid soot or carbon build up. I don't run it a night as it would be on a low setting as our boat is pretty well insulated which reduces the condensation issues and we are plenty warm in the bunk with out the heater. We do not use the boat much in below freezing conditions. It does from our experience make the boat on a 39 degree morning very comfortable in short order.
D.D.
 
Thanks again everyone for the replies. I just thought I'd post a follow-up now that I've finally completed the install.

I bought the heater separate from the marine installation kit. I purchased the installation kit from Sure Marine along with their thermostat and Surewire board. It really simplified the wiring and gives me some diagnostic tools along with an hour meter. FYI - The guys at Sure Marine are fantastic.

Initially I was going to mount the heater and diesel tank in the galley cabinet. I just could not come up with a good place to mount the heater and ductwork that would not require me re-routing a bunch of other plumbing and cables. I also didn't want to mount the heater transversely so I'd have to add an immediate 90 degree turn. The installation guide is pretty clear that you want to minimize sharp turns in the first few feet of ductwork. I then thought about installing everything on the port side, but couldn't come up with a way that didn't require me to permanently remove the water heater or completely lose the hanging locker for storage.

I ended up with a hybrid approach. The heater and duct work is on the port side. Heater unit is mounted behind the hot water heater and eats up no storage space. It's mounted on an angle to minimize sharp duct turns. The exhaust exits the hull near the top of the hanging locker (had to cut an access hole between the water heater compartment and the hanging locker). I really didn't lose any hanging locker storage since the back 6" or so were already taken up by other plumbing. I took the advice of some here and just let the combustion air be pulled from the cabin. The 6 gallon aluminum diesel tank is mounted on the starboard side of the boat....on the shelf in the galley cabinet. The only drawback was that it required a longer fuel line run, but I'm still way under the max allowable length. I added a new deck fuel fill on the gunwale so I wouldn't have to lug diesel fuel in to the cabin and risk spilling it. I also added a new Attwood p-trap flush mount tank vent. I really like it and may change out the other thru-hull vents to this flush style over time.

I added some installation pictures in to my album:

http://www.c-brats.com/modules.php?...ame=gallery&file=index&include=view_album.php

The following picture from a 44 degree day sums things up best:

20131109_085633.sized.jpg


We were warm and happy inside. Note that the windows are FOG-FREE!!!
 
Nice - I always like to read the follow-up :thup

beermanPDX":2bhejiwr said:
I also added a new Attwood p-trap flush mount tank vent. I really like it and may change out the other thru-hull vents to this flush style over time.
Click to expand...

I replaced both of my fuel tank vents with those. I chose them because they solved a problem for me (vents were so close to gunwale that there was no room for a loop or for non-flush P-trap installation), but in the end I liked them "just for themselves" anyway.
 
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