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Broughton 2

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Do's and Don't's advice for Webasto installation says we should "not take power for the heater from or through a switch panel and never via a seperate switch." We are invited to connect the heater direct to battery terminals. Shall be grateful for comments on this advice.

 

Firstly, it is said that if the heater is turned off from the main supply damage can occur to the heat exchanger. I suppose this is ref to "never via a seperate switch" and I'm Ok with that as I see the need to allow the heater to go through its run down cycle. Nonetheless, if I'm careful not to to use such switch to turn off the heater until it is at rest then I think a seperate switch is OK. Anyone disagree?

 

Secondly, it is said "switch panel supplies are unreliable and can cause surges or spikes from other equipment which will cause the heater to trip out."

What do we think of this advice for a boat electrical system running only straightforward 12V componentry such as lights, water pumps, TV, radio and no inverter (not a livaboard and I prefer to power everything from 12V)?

 

For tidiness of wiring (not keen on extra cables hanging off battery terminals) and a preference for the option of being able to switch the heater circuit on/off conveniently I would rather connect through a trip in my 12V switch panel. Why not?

 

Alan

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The reason they state for having no switch (just a fuse) is that if the Webasto were to be turned off whilst running, your boat will fill with dense white smoke from hot unburnt diesel, which may also damage the heat exchanger. So, if you want a switch, simply take the fuse out - much simpler and safer.

 

The reason for the advice not to wire into a switch panel supply, but to wire separately to the Webasto directly from the battery (through a fuse), is because when you switch other devices ON, some of them will momentarily draw a heavy current which can cause an instantaneous volts drop at the switch panel. If this volts drop goes below the cut-off voltage of the Webasto, it will trip out and you will be breathing the dense white smoke again.

 

Even light bulbs draw a heavy current for an instant while the filaments are still cold.

 

My humble advice would be to do what Webasto tell you to do - there's method in their madness.

 

Chris

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The reason they state for having no switch (just a fuse) is that if the Webasto were to be turned off whilst running, your boat will fill with dense white smoke from hot unburnt diesel, which may also damage the heat exchanger. So, if you want a switch, simply take the fuse out - much simpler and safer.

 

The reason for the advice not to wire into a switch panel supply, but to wire separately to the Webasto directly from the battery (through a fuse), is because when you switch other devices ON, some of them will momentarily draw a heavy current which can cause an instantaneous volts drop at the switch panel. If this volts drop goes below the cut-off voltage of the Webasto, it will trip out and you will be breathing the dense white smoke again.

 

Even light bulbs draw a heavy current for an instant while the filaments are still cold.

 

My humble advice would be to do what Webasto tell you to do - there's method in their madness.

 

Chris

 

 

OK Chris you've sold it to me. All I have to do now is find a way of positioning the heater loom so that the loom fuses are conveniently accessable from inside the cabin rather than having to lift engine/battery decking each time for access. At first sight it won't be easy.

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OK Chris you've sold it to me. All I have to do now is find a way of positioning the heater loom so that the loom fuses are conveniently accessable from inside the cabin rather than having to lift engine/battery decking each time for access. At first sight it won't be easy.

 

More on what Chris said.

 

I have friend with this heater, his biggest problem was in having his domestic battery's fully charged.

This heater it seems switches off every 1-2 hours to perform a reset test.

This heater also takes a large amount of current to start it, 30-40 amps maybe.

He had constant problems with starting it automaticaly in the mornings.

He almost always had to start his engine to boost the voltage/current befor it would start.

He suspected his electric fridge was draining the domestic battery's overnight.

His cure was to connect the heater to his starter battery, risky until he had monitored the discharch on this battery but on his boat it was OK .

 

Alex

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More on what Chris said.

 

I have friend with this heater, his biggest problem was in having his domestic battery's fully charged.

This heater it seems switches off every 1-2 hours to perform a reset test.

This heater also takes a large amount of current to start it, 30-40 amps maybe.

He had constant problems with starting it automaticaly in the mornings.

He almost always had to start his engine to boost the voltage/current befor it would start.

He suspected his electric fridge was draining the domestic battery's overnight.

His cure was to connect the heater to his starter battery, risky until he had monitored the discharch on this battery but on his boat it was OK .

 

Alex

 

In Webasto's defence:

 

1. The Webasto doesn't switch off every 1 or 2 hours. It will run continuously. It can be set to switch off after one hour if desired.

 

2. The start-up current is about 10A for a few moments whilst firing up (uses a pulsed ceramic glow pin), after which it drops to 3A for 15 minutes approximately and then to 2A @ a 50% duty cycle

 

3. I have had no problems with starting automatically on the timer in the morning or any other time of day.

 

4. There is no need to start one's engine to get it to fire up and run. In the example above, the guy must have had knackered batteries. The cut-out voltage is around 10.5v

 

Chris

Edited by chris w
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More on what Chris said.

 

This heater also takes a large amount of current to start it, 30-40 amps maybe.

He had constant problems with starting it automaticaly in the mornings.

He almost always had to start his engine to boost the voltage/current befor it would start.

 

Alex

 

On starting mine takes 10A, dropping to 7A in a couple of seconds. Maximum 2A when running.

 

I had the morning starting problem, close examination showed that the previous owner had fitted 2 x 10A fuses in series (One on the fuse board, one supplied in the installation kit) Removing one of the fuses improved things tremendously!

 

HTH

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On starting mine takes 10A, dropping to 7A in a couple of seconds. Maximum 2A when running.

 

I had the morning starting problem, close examination showed that the previous owner had fitted 2 x 10A fuses in series (One on the fuse board, one supplied in the installation kit) Removing one of the fuses improved things tremendously!

 

HTH

 

Hi

 

Thanks for that info.

On reflection I am probably confused with my Eberspacher taking this large current to start it.

My starting problems went away when I replaced the feed cables with 6mm, but I still run it from the start battery without any problems.

My friend is not much of an electrician so I dont know how he has wired it. I will tell him about yours and Chris's experiences.

I am sure he does not realise you can turn off the hourly reset.

 

Alex

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I am sure he does not realise you can turn off the hourly reset.

 

Alex

 

Behind the timer panel you will find 4 wires. One of these is a black loop going from one pin to another on the back of the timer. The loop can be cut and wired to a simple ON/OFF switch. If the switch is closed (ie: a continuous loop) the Webasto will switch ON at the set time (or when switched ON manually) and run continuously until you switch it OFF. If the switch is open (ie: loop broken) the Webasto will start via the timer or manually but will switch OFF after exactly 60 minutes.

 

Chris

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