Eberspacher air take - recycled cabin air?

[ChattingLil]

Sorry for another Eber q within 10 mins...

Our eber air intake is inside the engine room.
Our survey and previous surveys all recommended trying to find a way to duct to fresh air. This is going to be difficult (not impossible, but difficult in the short term).
Instruction book says it is ok to recycle cabin air. Think we will do this as book says it is ok to, but wondered what the panel think...?

 

[Colvic Watson]

Definitely recycle cabin air but duct it from the cabin not the engine room. Installation advice is to duct the combustion intake from outside but ours intakes from the engine room and removes that smelly air

Taking the air from outside would be like heating your marina, the eber pushes out vast quantities of air.

 

[macnorton]

I have mine set up to recycle cabin air, not had any problems.

 

[Spi D]

I changed mine from engine room to cabin intake, putting the return duct near the ceiling, where the heated air is.
a) makes better use of warm air in the cabin (inlet to all cabins are near floor, ensures circulation)
b) the boat is far from airtight, so some fresh air will be added anyway

Works nicely but you need to ensure the thermostat / switch will support the setup. My heater has a sensor in it's intake and to make it work with all fresh air intake, it needed a sensor in the cabin instead. I kept that after changing the setup.

 

[rob2]

The Eberspacher is a sealed heater, so the combustion flow is taken to the outside, but the heated air can be drawn either from outside or inside the cabin. On a car or truck, the volume of the cabin is small enough for the intake to be taken from outside but when heating a whole boat, you'll get better performance by recycling the air already warmed in the cabin. As someone has already said, the heater has a sensor in its intake which suits the recycling system - it uses the intake to judge how warm the cabin actually is, although if you choose to fit a remote sensor, you can position it so as to ensure the forecabin is getting the benefit too. If your engine room isn't inclined to be smelly then you don't have a problem, but most will impart a slight oily/diesel smell which can be eliminated by a short hose from the cabin to the heater intake.

Rob.

 

[BlueChip]

Isn't the air intake in the cabin noisy?

 

[David2452]

Best is to use both with a controlable Y piece, this allows rapid warm up using cabin air the either blend or all fresh air. This does mean using a remote temp sensor and having a properly specced heater to start wth, all marine heaters have remote sensors but judging by your description of the install it was probably not. Taking recirculated air from the site of the heater is a no no, whether engine room or in a locker as it can recirculate CO2 in the case of an exhaust leak.

 

[vyv_cox]

Mine is as most of the others but without the sophistication of David2452's! Photos of my installation at http://coxengineering.sharepoint.com/Pages/Heating.aspx

 

[Spi D]

In the past, and in various connections, I have made heating systems with full/partial recirc and fresh air. Some doomed impossible by professionals, yet made working by persistent enthusiasm...


While the optimal solution is as David2452 suggests, the practical might be different according to exisiting setup and possibilities. Unless you want to scrap the heater and start from scratch, you need to find best compromise.

Regardless of preference, an Y valve ducting will always provide a selection, be it manual or more advanced. Space is commonly dictating solutions...

Begin by routing an intake duct to the highest possible place, then test and check. If needed, add the Y. Test again.

Re noise: The intake will produce some, but a silencer near the vent will reduce it notably. On mine there was no room, so I live with the modest sound..

 

[David2452]

Isn't the air intake in the cabin noisy?

It can be if not done right, helps to use larger duct than the outlet hood size, attenuators work reasonably well but seriously eat away at the numbes when designing the ductwork, which means on large installs they are a non starter.

 

[scottie]

Taking air from a potential source of any engine exhaust leak could end up with fatal cosequences

 

[David2452]

Taking air from a potential source of any engine exhaust leak could end up with fatal cosequences

not just the engine, the heater itself is a potential source.

 

[GrahamM376]

We had one boat with heater set up to recirculate and this one which draws in outside air via a locker. The first heated up quicker but this one is drier and cooking smells and damp air are expelled via the positive pressure. I prefer external air.