Heaters

[Hedgehog2]

A bit nippy this morning, so I put the heater on for the first time (Eberspacher, age unknown, serviced 5 years ago, 32 foot boat, on a swing mooring).
The battery monitor immediately clocked 16A.

I was a bit surprised - I'd assumed the energy came from diesel, needing only a small amount of electricity to pump and ignite the fuel.
How do boat heaters work, are they really only practical if you have shore power ?

 

[oldharry]

I cant speak for Ebers. but the cheap chinese copies run their blowers at full power on start up, then wind back down to the pre-set speed once the unit has warmed up. On mine that can exceed 10 amps for the first minutes.

 

[harvey38]

I cant speak for Ebers. but the cheap chinese copies run their blowers at full power on start up, then wind back down to the pre-set speed once the unit has warmed up. On mine that can exceed 10 amps for the first minutes.

The same for them all - run up the fan to full speed, the glow plug heats up for a few seconds, inject the fuel, hope for ignition, let it all settle down then throttle back to whatever heat setting you have it on. Some serious current draw for a short period.

 

[mjcoon]

Would you not hear the fan whining away at full pitch to justify the (electric) current? And feel the flow?

 

[Hedgehog2]

Definitely a fan noise...

Thanks - so sounds like nothing to worry about re batteries - just turn on an wait for heat before creeping out of sleeping bag !

 

[dunedin]

If on anchor for a few days, we sometimes run the engine for 15 minutes or so early evening, both to warm the water for showers and to provide extra voltage as the Eberspacher fires up and gets into it’s stride.
Indeed, on a previous boat the Eber sometimes would not start at all, and we took a while to realise it was a startup voltage issue, and hence running engine briefly solved.

 

[Daverw]

A bit nippy this morning, so I put the heater on for the first time (Eberspacher, age unknown, serviced 5 years ago, 32 foot boat, on a swing mooring).
The battery monitor immediately clocked 16A.

I was a bit surprised - I'd assumed the energy came from diesel, needing only a small amount of electricity to pump and ignite the fuel.
How do boat heaters work, are they really only practical if you have shore power ?

Our eber can pull 12 amps when starting up, fan, glow plug and pump etc, after about 30 seconds drops to about 6 amps until near setpoint then drops to about 2 amps ticking over

 

[Slowboat35]

Plus these things absolutely HATE low battery voltage, and will sometimes draw enough current to make up for it that they pop the fuse or just refuse to start at all.
Just the situation early in the morning after an evening of battery drain. Run the engine and it'll probably start happy as larry.

 

[Hedgehog2]

Thanks fantastic info and advice from everyone!

ps is there a CO risk with them? Should I get an alarm (and if so, does it need to be a specific ‘marinized’ version?

 

[Daverw]

The air blown in should never come in contact with the combustion unless air intake and exhaust are piped incorrectly, ours takes air in from rear cockpit locket and exhaust on transom

 

[dunedin]

Thanks fantastic info and advice from everyone!

ps is there a CO risk with them? Should I get an alarm (and if so, does it need to be a specific ‘marinized’ version?

Yes you should get a CO alarm, or two - but not necessarily due to the heater. Can be other sources if there are faults (including one tragic case from a neighbouring boat)

 

[oldharry]

Mine came with a warning to fit a CO alarm. Had one anyway.

 

[Plum]

A bit nippy this morning, so I put the heater on for the first time (Eberspacher, age unknown, serviced 5 years ago, 32 foot boat, on a swing mooring).
The battery monitor immediately clocked 16A.

I was a bit surprised - I'd assumed the energy came from diesel, needing only a small amount of electricity to pump and ignite the fuel.
How do boat heaters work, are they really only practical if you have shore power ?

Once my 2kW Eber has fired up and settled down to a low setting, That which I set it to run overnight in cold weather, draws less than 1A.

Www.solocoastalsailing.co.uk

 

[Chiara’s slave]

We too were green as grass about this little issue. It’s resulted in us upping our solar generation from 50w to 250w, after repeatedly having flat batteries over winter, with the panel bringing in only 10% or so of it’s rated power.

 

[ibbo]

It is possible to kill yourself with the heater. You do need an alarm. I am wary about leaving one running all night for that reason.
The exhausts sometimes leak.
Freak winds can blow it from the exhaust to the intake, please take care. Check the exhaust etc.

 

[oldharry]

It is possible to kill yourself with the heater. You do need an alarm. I am wary about leaving one running all night for that reason.
The exhausts sometimes leak.
Freak winds can blow it from the exhaust to the intake, please take care. Check the exhaust etc.

The Chinese one I have recirculates the air so that theoretically the heated air cannot be contaminated by exhaust fumes. The reality is of course that if it can develop a leak, it will, and because it is not changing the air in the living space CO would build up more quickly. Fit a monitor anyway.

Someone on our yard set up a paraffin heater in his cabin. He only survived because someone went aboard to see him just in time. He was in hosp for some time, and off work for weeks after. I did hear he never fully recovered, which, sadly, seems quite likely.

 

[wingcommander]

The big power draw as previously stated is the glow plugs, mine pulls circa 15 amps on start up for up to 90 seconds ( tested with a clamp style ammeter) then drops to 2 amps normal running till temperature is reached, then less than 1amp on tickover , on shutdown the glow plugs are energised again as part of the chamber cleaning process this can be a minute or two also.

 

[ColinR]

my Eberspacher power draw is about the same as others have described here. However it does tend to blow quite hot air for a while with the fan blasting away, then switch off. IE, the program is still running but the fan stops and no heat comes out. This when the cabin gets to about 17c. Raising the temp on the digital controller doesn't always help, the only way to get it to produce heat again is to stop the program and restart it. I suspect the thermostat needs changing. Has anyone else had this issue? The heater (not the control or thermostat) was serviced over the winter which seems to have helped a bit.

 

[Pasarell]

ColinR. I have a similar situation to you with my D5L. Seven day timer with multiple heat settings. It often shuts down when it reaches the correct temperature with the controller still saying it's operating but doesn't restart until the temperature drops well below the set level. I find it easier to just switch off and start up again after a few minutes. I don't think there's anything wrong with the thermostat other than its sensitivity
Current draw is about 25A for the first 20 seconds as the glow plugs heat up but then drops to 3A or so when running on full fan speed and 1.5A on low fan speed. This is exactly what the manual says it will do.
The heater draws combustion air from an external locker and exhausts through the transom. Air for heating is taken in from behind furniture in the aft cabin. Shouldn't be any chance of CO escaping into the boat but we have 2 CO alarms. One near the heater in the aft cabin and the other part of the gas alarm with its CO sensor near the cooker at work top height

 

[wingcommander]

my Eberspacher power draw is about the same as others have described here. However it does tend to blow quite hot air for a while with the fan blasting away, then switch off. IE, the program is still running but the fan stops and no heat comes out. This when the cabin gets to about 17c. Raising the temp on the digital controller doesn't always help, the only way to get it to produce heat again is to stop the program and restart it. I suspect the thermostat needs changing. Has anyone else had this issue? The heater (not the control or thermostat) was serviced over the winter which seems to have helped a bit.

Could also be an overheat issue, though usually fault code is thrown up. My old Ebber... used to do 5he same , no fault displayed. Only solution to refire was to turn off , wait 5 min , then switch back on. Would then work for circa 15 to20 min and repeat fault..Turned out to be undersized / too many bends / too long ducting runs causing an overheating problem.. Even the air intake ( not combustion air ) ducting can restrict enough to create same problem...