Diesel heater not producing much heat

[Babylon]

Why do you have 10 meters of ducting on a 27ft boat ?

Because from the heater unit it first runs aft for 1m to the rear of the stbd cockpit locker, then dives down and comes forward in a curve under the fuel tank for another 2m or so, after which it enters into the aftmost deep locker underneath the very end of quarter berth (ridiculously this is directly below the heater itself!), from where it goes forward for another 2m along the cold hull to clear the fridge and the chart-table (both totally inaccessible) before warming the first saloon locker then junctioning off to come out the first vent, after which it proceeds forward for another 2m (warming two more lockers on the way before it comes out the second vent in the forepeak area... okay that's just 7m, conservatively, but you get the idea of just how much of it has been sitting uninsulated in very cold spaces before it even gets into the cabin to start warming up the cabinetwork!

The ducting is 3" (76mm in new money) and the inlet air is simply from the cockpit locker, which has a vent in an open side-locker nearby and also shares the same air as the engine-bay etc.

Maybe there's a blockage somewhere in the latter stages of the journey? I'll check next time I'm down.

 

[Trident]

It seems a terrible installation but there are two golden rules for these types of unit (well three which is as short a run as possible but there's not much you can do about that) - firstly always run on full blast for 10 minutes before shut down if its been on lower power - that way you burn off the crud before shutdown. Secondly insulate, insulate, insulate - and not just the silly expensive blankets that Eber and Webasto sell.

I have two heaters on my 50 foot cat because , well its 50 foot and double wide. They run with about 3m-4m of ducting each . One from the front and one from the back. The ducting is wrapped in insulation blanket and then built in to a box made from taped together foam insulation panels 50mm thick. In one area under the cockpit its double thickness os 100mm thick

Temperature of the air coming out is around 120 degrees

 

[Babylon]

Good points, Trident.

Re running on full power to burn off crud before shutdown, this takes me back to my point earlier in the thread where I just wanted to fit a simple on-off rotary switch...!

 

[fredrussell]

The rotary switch should be a simple plug and play fit, using the same connector block your current controller has. 10 metres of ducting would seem to me to be more than your heater is designed to work with, but I’m not up on these Planar/Autotern units.

 

[Babylon]

The rotary switch should be a simple plug and play fit, using the same connector block your current controller has. 10 metres of ducting would seem to me to be more than your heater is designed to work with, but I’m not up on these Planar/Autotern units.

Thanks.

Yes, I'm beginning to realise that my whole system was probably flawed in its particular design from the outset.

 

[vyv_cox]

The rotary switch should be a simple plug and play fit, using the same connector block your current controller has. 10 metres of ducting would seem to me to be more than your heater is designed to work with, but I’m not up on these Planar/Autotern units.

I think the maximum length of ducting that Owen has fitted in a yacht is 8 metres, at that length probably a 4kW unit with 90 mm (?) ducting. Small ducting diameter and right angle bends are the two most common efficiency killers.

 

[Beneteau381]

I know that Owen runs his test Autoterm heaters on central heating oil (kerosene) without problems. Paraffin (Esso Blue!) is a lighter hydrocarbon that may cause problems.

I did that test on an Eber years ago using heating oil. It does clean the combustion chambers. In fact when we were in Holyhead I used heating oil all the time. Bought it from the pump at the filling station in Carrog on the A5 on the way there.

 

[vyv_cox]

I did that test on an Eber years ago using heating oil. It does clean the combustion chambers. In fact when we were in Holyhead I used heating oil all the time. Bought it from the pump at the filling station in Carrog on the A5 on the way there.

Yes, I remember you got into some discussion about it with Espar in USA!

Owen insists that the Autoterm Planar heaters run hotter than Eber/Webast, so what applies to one does not apply to all.

 

[Hunterlees]

I installed a 3” blower fan towards the front of my boat with a cheap PWM controller, and when I switch it on it pushes more air flow towards the head and forward berth. The controller regulates the speed so I can adjust the relative flows. Works well.

 

[B27]

Repair manual is here:
https://planarheaters.com/wp-content/uploads/2018/01/air-repair-manual-en-v112022-2.12.pdf

They do (or did?) make a petrol-fired variant.
But the manual link for that gives the manual for the diesel model.
Pretty sure lots of these used to run on petrol, probably true of all brands?