Eberspacher air intake length

[Lyndon]

My Eberspacher D1 has worked perfectly for the last 3 years with 1.5m of exhaust and 150mm of air intake. I have just been told that these should be balanced lengths. My question is what improvement am I likely to see if I extend the intake or should I leave well alone as it seems to work well as it is?

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[robbieg]

You don't say where you got your info from. I've just fitted a D4 Espacher & the instructions were (from memory) no more than 1 metre for the air intake with a standard exhaust length of 2m. Seems to work fine.

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[pvb]

Leave well alone...

They don't need to be balanced lengths.

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[poggy]

Given the diameter of the air intake on my D1, I can't see that a difference in length of air intake hose will have any real effect. It is so big compared to the air flow that the restriction would be pretty small I would have thought.

I am not an expert though.

Poggy

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[AlanPound]

Some (domestic) heaters use what is known as a 'balanced flue', which is a combined air inlet and exhaust outlet fitting, although these things are rarely vital (ie. separate pipes usually work just as well...)

Alan

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by AlanPound on 13/11/2003 18:57 (server time).</FONT></P>

 

[Talbot]

My D4 hads a standard length exhaust, but the combustion air intake is 5m - admitedly I have made this out of much larger pipe, but it seems to work fine, and the installation specialists did not seem concerned when I told them my intentions. Main message - if it works don't "fix" it!!!!!!!!!!!!!!!!!1

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[paulrossall]

I have a second hand D3LC. Instructions downloaded from espar.com (the American distributor site) say the combustion air intake and the exhaust lengths should be balanced. I was also sent a set of instructions by a forum member which were shorter than the other ones and they did not state they needed to be balanced. My local installer said they should be balanced.
It does half earn its keep this weather! Paul

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[PeterGibbs]

When I had my heater fitted it was clear that the critical element was the length of the exhaust. If it was beyond spec the fan would not exhaust properly and the boat and its crew were at risk. Technically the combustion air should be drawn from outside the living area, in most cases. Providing the access for fresh combustion air (as opposed to circulated air) is unobstructed and not liable to water ingress etc I see no reason for concern.

Your situation is unknown to me. If you do not get a good technical reason from the supplier or a qualified agent for making changes, I would leave well alone.

PWG



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[Waters reach]

Does anyone know the diameter of the intake pipe as mine hasn't got one fitted at all but there is a outlet vent fitted on the boat which I assume goes to the heater . Any help would be gratefully recieved

 

[oldmanofthehills]

Does anyone know the diameter of the intake pipe as mine hasn't got one fitted at all but there is a outlet vent fitted on the boat which I assume goes to the heater . Any help would be gratefully recieved

Assuming you mean the combustion air intake, not the cabin heat air intake, its usually 22mm for Ebi the same as the exhaust, but other brands use 24mm. Probably would need to be heat resistant as v close to the exhaust near the body of the heater. Mine has not got one fitted on present boat, and we did not have one on our previous boat. The important thing declared for my propex gas heater is that inlet and exhaust are a sensible distance apart (30cm ish), but as one is out through the stern and the other under the stern deck, there was no real issue for the Ebi, and both exhaust pipes were about 40cm which was probably close enough to balance zero on intake if that was a real issue.

However no one balances the car or truck exhaust length with the engine air intake so I am puzzled by the apparent requirement

 

[Waters reach]

On mine one end has I 75mm pipe which sends the heat around the the boat and the other end is the same diameter , so surely it's the same pipe ?

 

[Waters reach]

That's 75mm diameter pipe

 

[LittleSister]

The instructions I have for an old Eberspacher D3L certainly do not require either the combustion air intake and exhaust, nor the heating air intake and hot air ducting to be balanced. (These particular instructions are geared towards installation in a vehicle, but the principles would apply to a boat.)

Combustion air intake and exhaust have different minimum lengths and various other considerations, though both have a maximum length of 2m. They are not required to be the same length (which in any case would not alone necessarily make them balanced).

Heating air intake and hot air outlet do not have any requirement to be the same length or be balanced, either. There's no minimum to the intake length - it could just be the protective grid on the heating air inlet on the heater itself. The two could not in any case be balanced unless you took the heating air intake from inside the boat's or vehicle's accommodation, which is inadvisable on humidity and CO2 build up considerations. (But if anyone wants to do that regardless in order to save fuel, that's up to you.)

I can send you copy of these instructions if you PM me an email address.

 

[oldmanofthehills]

On mine one end has I 75mm pipe which sends the heat around the the boat and the other end is the same diameter , so surely it's the same pipe ?

There is no reason to balance the heating pipe at all as it cant affect combustion. It is suggested that to get fresher air one has inlet with access to out doors or to get greatest warmth have inlet indoors though as Little Sister said that has drawbacks. Never seen an inlet pipe as heater generally in locker and away from cabin

 

[Plum]

My Eberspacher D1 has worked perfectly for the last 3 years with 1.5m of exhaust and 150mm of air intake. I have just been told that these should be balanced lengths. My question is what improvement am I likely to see if I extend the intake or should I leave well alone as it seems to work well as it is?

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There was nothing in the Eberspacher instructions about balancing when I installed my D2. The eberspacher instructions can be found online.

 

[oldmanofthehills]

There was nothing in the Eberspacher instructions about balancing when I installed my D2. The eberspacher instructions can be found online.

If the exhaust was facing into an unbaffled very strong draught then it just might help if the inlet was exposed to the same draught to stop wind blowing the wrong way down the system and blowing flame out - the balanced gas flue effect. I have never heard of this being needed on a boat as the pipe is probably curved and certainly much narrower that the chimney on your domestic boiler.

 

[Plum]

If the exhaust was facing into an unbaffled very strong draught then it just might help if the inlet was exposed to the same draught to stop wind blowing the wrong way down the system and blowing flame out - the balanced gas flue effect. I have never heard of this being needed on a boat as the pipe is probably curved and certainly much narrower that the chimney on your domestic boiler.

There is nothing in the Eberspacher instructions about this and i have never had a problem with very strong wind creating a very big difference in pressure between my inlet and exhaust on my heater so I think this is a red herring.

 

[oldmanofthehills]

There is nothing in the Eberspacher instructions about this and i have never had a problem with very strong wind creating a very big difference in pressure between my inlet and exhaust on my heater so I think this is a red herring.

Neither have I but sometimes people think theoretical but vastly improbable issues need addressing. Doom merchants everywhere - sometimes ignoring actual dangers

 

[steveeasy]

Without drifting the thread. the heaters have an air intake and an intake pipe. Im guessing the larger air intake is for cooling the heater and the air intake is for combustion ?. These heaters are designed for the smaller air intake to be separated by a floor/wall from the heater unit. IM no expert at all infact little understanding on the workings but if no small air intake pipe is fitted or the heater is not vented there is a risk. Why do I know this. when I installed mine I did not fit a small air intake pipe. no warning on two Carbon monoxide alarms, but a bad head in the morning. I fitted a pipe to the smaller air intake and vented it to the cockpit and problem solved.
Recently I went in to a hardware shop and they were selling large diesel heaters for a lot of money. the USP was they could run indoors without a fresh air vent as they had significant filters filtering the air intake. That said there was a minimum room size they could operate in.

Appologies for drifting but my comment sort of covers the two intakes and an issue that I feel may be important to mention.

Steveeasy

 

[oldmanofthehills]

Its basically a diesel powered fan heater throwing hot air down a large pipe to get to far end of boat with the ability to draw fresh air from further away than the heater body if wanted.

The combustion air intake can also be remote and steveeasys case this seems to have improved air quality and reduced carbon monoxide build up. As the CO was already being vented outside the boat, it is unclear to me why external intake helped.

No filter will remove CO and no diesel heater, or gas heater of any kind can be run without an external exhaust unless in a very well ventilated space, not even if it uses catalytic combustion elements.