Webasto air duct / fuel pump silencing

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Anders_P42

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I fired up the Webasto heating for the first time in anger at weekend and noticed a fair amount of fan noise through the air duct in Saloon. The exhaust was surprisingly quiet so I assume silencer was fitted by Beneteau (air intake in cockpit was louder than exhaust). Although fuel metering pump is installed in lazerette, the clicking is still quite loud in forward cabin and would be worse in guest bunks.

I searched online and found air ducting silencer kits are available, do they make a noticeable difference? There's a fuel pump silencing kit available too, rubber mount and revised fuel line is it worth an upgrade?

The photos below show install location.

Anders

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install_location.JPG


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webasto2.JPG
 
Adding a rubber mount for the pump will help - doesn't have to be a Webasto part, just wrap the pump in soft foam and restrain it with cable ties, etc.

Air silencers are available, and work well. I had one on my old boat with an ancient Eberspacher, and it was almost inaudible. The new boat has a Webasto without a silencer, but I find that assoon as the boat warms up, the fan speed reduces and the heating is almost inaudible again.
 
The pump will already be rubber mounted, do not wrap in anything other than the fire jacket option as this reduces pump life due to overheating. The mounting position and backing material are as important as the rubber mount as transmission is usually the problem rather than radiated noise, there is a Webasto/Mercedes Benz motor-caravan mounting that I have been experimenting with on boats including my own that does give significant improvement as the pump is suspended in two very soft rubber slings, an easy if not cheap mod. Ducting attenuators need careful consideration on later heaters as they rip into the allowed back pressure numbers, if you are already up toward the higher numbers it easily tips things over the edge and cause cut outs (blame the latest EU regs on overheat sensor temperatures for that) From the photo's you already have the pre insulated Flexiflyte Webasto ducting so little point in further work there, also you have the proper gas tight marine silencer so will at least not disturb the neighbors. Basically a little noise is a decent trade off for being warm, I find the pump ticking if properly subdued actually lulls me off to sleep (either that or the beer) As Pete says one up to target the duct noise will reduce quite a bit. Sorry, forgot to say, from the photo's you alrady have the Tygon fuel tubing, the mod is to change from copper to that where regulations permit. You omitted the most important photo, that is the fuel pump and mounting so let's have a look at that.
 
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I have an Eberspacher D4 setup on a Dufour 34. I fitted an exhaust silencer (actually the webasto part), this significantly reduces noise for any anchored or marina neighbours, and for ourselves if sitting out in the cockpit:-). I also recently fitted a 90mm Eberspacher duct silencer (they take up a bit of space), I am not totally convinced that this has reduced internal noise, but as already pointed out, once the boat reaches the desired temperature, the fan speed reduces, and the noise reduces in any case. Isolation and careful placing of the fuel pump is important, soft rubber mounts are good, and avoid fixing to bulkheads or flat surfaces as these may create the perfect loud speaker!
Angus
 
Thanks for the replies. I'll take a photo of the fuel pump mounting at the weekend, trust me to forget that. Ticking was annoying, may be an excuse to drink more beer :)

I'll see how the air duct noise goes for the next few weekends, you're right it does go quieter once temp is reached. Sounded like a 747 taking off when I first switched on. I'm impressed with lack of noise from exhaust, can hardly hear it running.

Duct insulation worth a look, I noticed heat output was less in forward cabin.

Anders
 
Anders_P42 said:
Duct insulation worth a look, I noticed heat output was less in forward cabin.

Anders
Click to expand...

As your pipes are already in place, two layers of foil backed bubble wrap insulation, cut into manageable lengths and secured with aluminum tape will be easier to install and a fraction of the cost. I reckon doing it to my D2 pipe work over a 9m run increased the heat output by around 30%.
 
Actionmat said:
As your pipes are already in place, two layers of foil backed bubble wrap insulation, cut into manageable lengths and secured with aluminum tape will be easier to install and a fraction of the cost. I reckon doing it to my D2 pipe work over a 9m run increased the heat output by around 30%.
Click to expand...

I think the pipework is already 'lagged' I think it is the saloon outlet that is noisy.

David2452 said:
From the photo's you already have the pre insulated Flexiflyte Webasto ducting so little point in further work there, also you have the proper gas tight marine silencer so will at least not disturb the neighbors
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We have a similar set up with a 5.5kw Webasto on our Benny and the saloon outlet is noisy when first fired up; 747 is about right! Once up to temperature it settles down to be pretty unobtrusive.
 
Is there duct insulation on there, looks like bare duct? I'll check at weekend and measure duct sizes, there are different sizes throughout boat.
 
Ours has the Flexiflyte ducting, the noise for us is not escaping from the ducting but the force of the air and associated noise through the saloon outlet.

I can't see (although happy to be proved wrong) that extra lagging will help this issue.
 
Anders_P42 said:
Is there duct insulation on there, looks like bare duct? I'll check at weekend and measure duct sizes, there are different sizes throughout boat.
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The Flexflyte already has a degree of insulation, but it can be improved, The Webasto Thermoduct Thinsulate stuff is also available unstitched for retro installs.
 
David2452 said:
The Flexflyte already has a degree of insulation, but it can be improved, The Webasto Thermoduct Thinsulate stuff is also available unstitched for retro installs.
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The clip on stuff would be ideal. Shame they don't do it on build, would only add a few hundred to install cost.
 
Use bungee cords to "hang" the pump in a suitable position. On a boat you obviously have to allow for movement in all directions.
 
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Being a light sleeper I always have a problem with noises, so a couple of tips. Firstly make sure you are using the plastic fuel line to the pump. The copper one transmits far more noise and changing over was the single biggest improvement. Secondly I built a plywood mounting plate that was attached via rubber grommets to the bulkhead. I then attached the normal rubber isolating mount to the plywood thereby giving double the isolation. This made it just about acceptable for me to sleep.

for the fan noise I would rely on the fan winding down when getting up to temperature, so didn't do anything on the ducting.
 
Actionmat said:
I don't think the plastic fuel line is Boat Saftey Test compliant.
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It's not, and why kits are supplied with copper, no problem there even as it is permissible to use 7840 rubber hose at the pump , heater & standpipe joints. Somewhat irrelevant to most here though as non inland waterways craft are (for the moment) exempt. Also the OP shots clearly show Tygon is used. One point I had forgotten to mention, for those with newer Evo model heater, you will notice an increase in noise from the ducts during initial warm up as the fan speed and hence air volume has been increased during the initial boost along with more fuel to give the extra 1/2 kw for rapid warm up.
 
What set up do you recommend for the quietest installation? The clicking sound isn't too bad on mine and doesn't bother me, it's the fan noise that does. Is the fan noise produced by the blower or is it the sound of an unsilenced D2 exhaust and combustion air intake travelling down the pipes?
I want to make my system quieter this winter. Should I fit all three silencers(exhaust/ducting/air intake)?
I set mine up to circulate, so would I also need a duct silencer on the intake side?
 
Actionmat said:
What set up do you recommend for the quietest installation? The clicking sound isn't too bad on mine and doesn't bother me, it's the fan noise that does. Is the fan noise produced by the blower or is it the sound of an unsilenced D2 exhaust and combustion air intake travelling down the pipes?
I want to make my system quieter this winter. Should I fit all three silencers(exhaust/ducting/air intake)?
I set mine up to circulate, so would I also need a duct silencer on the intake side?
Click to expand...

For your neighbors sake as well as your own, you should have an exhaust silencer, next step is a combustion air intake silencer, then last consider a duct attenuator but do the back pressure numbers before considering one of those. After that, more beer and ear plugs.
 
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