Eberspacher intake venting?

[Hoolie]

I think there's some confusion here. I don't think anyone has a problem with the heater burner air input extracting air from the same space as the exhaust.

It's the air that's drawn in, heated and circulated via the heating ducts that is the issue. Certainly nowadays best practice says it must not be drawn from the area containing any part of the exhaust system.

As has been pointed out, on older installations this often was not the case, including mine

 

[lw395]

I think there's some confusion here. I don't think anyone has a problem with the heater burner air input extracting air from the same space as the exhaust.

It's the air that's drawn in, heated and circulated via the heating ducts that is the issue. Certainly nowadays best practice says it must not be drawn from the area containing any part of the exhaust system.

As has been pointed out, on older installations this often was not the case, including mine

'Best Practice' and 'Must' are contradictory.
I know very few yachts where the exhaust pipe runs in a space hermetically sealed from the spaces connected to where the blown air is drawn from.

 

[Yacht Yogi]

Thanks, everyone

Thanks for the comments everyone. Conclusions to draw for Yogi:

1. Sort out some decent ventilation for the combustion air supply. This is going to get a new inlet from the (open) cockpit into the locker with a duct to the Eber inlet stub. Might quieten it down a bit too.

2. I will check that the exhaust clamp is sealing properly and might put a goop of RTV Silicone in the joint to help seal it.

3. My heating air supply is drawn from the aft cabin, not the heater/exhaust pipe locker so it meets the current installation requirements.

4. I will give it another longer run and check thououghly all of the points noted.

Cheers all. It's been a help!

 

[Hoolie]

'Best Practice' and 'Must' are contradictory.
I know very few yachts where the exhaust pipe runs in a space hermetically sealed from the spaces connected to where the blown air is drawn from.

Indeed, as Chris_Robb pointed out in post #16. May have been common practice in the past, but not acceptable by current standards.

In my case it's on my "to-do list" but as we don't use the Eber that often it's a fair way down.

 

[Chris_Robb]

In your opinion it's 'just not good enough', but it seems to be standard practice on boat installations. There are many thousands of boats with heaters installed in this way.
The exhaust joints are safety-critical, but that's equally true of the exhaust of your diesel engine, not to mention the gas system.
Perhaps it is significant that the heater is removing a fair quantity of air from its surroundings and pumping it out of the boat via the exhaust? Hence there is a net flow of clean air into the boat via the cabin vents.
Compare with the gas cooker which just exhausts into the cabin space.

I agree that it is standard practice and against the manufacturers clearly stated installation instructions!

But the heater does not remove air from the living areas of the boat. If there is a leak in the installation locker - it will get sucked into the cabin.

Not the same as a cooker when you have the hatches open to use. With the diesel heater you very often close all the hatches, so potentially far more dangerous if you have even a small leak.

 

[single]

Well to get fresh air most of the time why not fit something like http://www.ebay.co.uk/itm/60mm-CLOS...tEquipment_Accessories_SM&hash=item5adea50aad to somewhere in the cockpit with a small length of ducting going upwards then the small intake ducting shoved down inside the large ducting.When sailing or when its really really cold close the vent and it will still draw air from the locker space.

 

[David2452]

Interesting opinions and at last it seems that everybody agrees that the recirculated air should not be drawn from any area which the exhaust runs through. As to the combustion air intake, again it is better to have the combustion air intake away from the heater and exhaust, more for performance than safety, the warm air around the heater carries less oxygen than the colder air you can get from somewhere else and every little helps, cleaner running = less coking. For the record I only ever install to draw air from an area away from any possibility of exhaust gas intake from a faulty exhaust, but agree there are many done that way, when servicing such installations I always give a written warning on the invoice if the customer refuses to have it rectified, usually a cost barrier, at least that way I am covered if it does go mamories up

 

[lw395]

Didn't Eberspacher used to recommend drawing the combustion air from inside the boat, where it should be drier, rather than an external vent?

 

[David2452]

Didn't Eberspacher used to recommend drawing the combustion air from inside the boat, where it should be drier, rather than an external vent?

Not to my knowlege, even in the origional truck guise they always drew combustion air from an exposed pipe under the vehicle with the intake facing rearwards. Don't think I'd be wanting to pull it in through a topsides skin fitting though

 

[charles_reed]

To achieve a balanced combustion flow, on the Eberspacher, it is essential that the air intake hose is the same length as the exhaust flue and, ideally both should be on the same level with the intake drawing cold, clean air.
The majority of marine installations seem not to fulfil these requirements.

 

[David2452]

To achieve a balanced combustion flow, on the Eberspacher, it is essential that the air intake hose is the same length as the exhaust flue and, ideally both should be on the same level with the intake drawing cold, clean air.
The majority of marine installations seem not to fulfil these requirements.

That is true only if there is no silencer on either the intake or exhaust, fitting silencers, introducing numerous sharp bends etc changes things considerably, its not the only deviation I see in many installs but at least its not potentially dangerous.

 

[lw395]

To achieve a balanced combustion flow, on the Eberspacher, it is essential that the air intake hose is the same length as the exhaust flue and, ideally both should be on the same level with the intake drawing cold, clean air.
The majority of marine installations seem not to fulfil these requirements.

Why would equal length matter?
How can having a longer intake hose improve things if the flow resistance is already at the high end due to having a long exhaust?
'Balanced Combustion Flow' sounds like mumbo jumbo to me, what does it mean exactly?

 

[Jon Goodyear]

Just for info.... Always start your heater on full blast otherwise it doesnt burn off the gunk left over from last time you used it....turn it down once up to heat.

 

[David2452]

Just for info.... Always start your heater on full blast otherwise it doesnt burn off the gunk left over from last time you used it....turn it down once up to heat.

A correctly set up heater does that on its shut down, the glowpin kicks in again again, fuel is reduced and then cut off all together after an increase in fan speed to clear the chamber.

 

[David2452]

Why would equal length matter?
How can having a longer intake hose improve things if the flow resistance is already at the high end due to having a long exhaust?
'Balanced Combustion Flow' sounds like mumbo jumbo to me, what does it mean exactly?

A balanced flue is really simply another name for a "room sealed" heater and flue balancing is only really apropriate in naturally convected devices where thermal energy is needed to remove the gas, not forced air combustion, either evaporator or PJ.