Block heater questions

[dar636]

On my 871TI's I replaced one of the block heaters a couple of years ago with the same brand (Hotstart, 1000w) and it has worked well. This last PNW cold snap had the other engines unknown brand or rated heater fail and I replaced it with another Hotstart system as I had bought a spare when the first engines heater failed. Only then did I realize that I can't have both heaters running now as the 2x 1000w units pull 16.6 amps overloading the 15 amp breaker....my bad for not doing the math first.

So I need a solution. I can either upgrade the breaker to 20 amps, downgrade the heating elements to 750w each (12.5 amp draw) or put the heaters on timers so they aren't able to run simultaneously, or a combination - or all of the above.

I had been pretty much leaving them on continuously with the water temps in Seattle.

This got me thinking of asking you folks how you operate your block heaters before I go further, do you run them continuously? Turn on before needed? (how?) Put them on timers? Phone app controlled? Or? Those are my questions for today.

Standing by.

Random pic included.

 

[Play'N Hooky Too]

Mine are on a breaker in the engine room. I just switch the breaker on the night before I'm going to use the boat. Of course I'm in NW Florida, so the heaters just make it easier to start the engines on "cold" mornings without fogging out the whole marina. You could upgrade the breaker, but I would make sure that your wire to the breaker is the appropriate size and that you are not going to overload the panel with the heaters and other equipment that may be running at the same time.

If you are running them all the time, I don't see why the 750w heaters wouldn't get the job done.

 

[SKYCHENEY]

I agree. Don't swap the breaker out without checking the wire sizing first to see if it can handle the extra amperage. If not, then downsize the heat elements.

Flat coated retriever?

 

[dar636]

Flat coated retriever?

Gordon Setter, Maggie. 3 yrs old.

 

[MadHatter53]

My block heaters are the plug in type so I have an outlet in each er on separate breakers and only used prior to start up.

 

[Scarlett]

Check your electric panel and see if you have a spare breaker and wire only one per breaker, that’s what I did. Mine were just plug in type before I hard wired them to 2 separate breakers

 

[SKYCHENEY]

Flat coated retriever?

Gordon Setter, Maggie. 3 yrs old.

Great looking dog.

 

[jason.erbecker]

Check your electric panel and see if you have a spare breaker and wire only one per breaker, that’s what I did. Mine were just plug in type before I hard wired them to 2 separate breakers

I did the same. The block heaters are plugged into 2 individual outlets in the engine room. Each outlet has it's own breaker on the main panel. I run them continuously this time of year with no issues. Having them on their own breakers makes it convenient to turn them off/on as well.

 

[Sadey]

Not sure if I’m doing it correctly but when we put the boat in the water in May I turn the heaters on. When we pull the boat out in October I turn the block heaters off.

 

[Dan Mapes]

When we had our boat surveyed back in 1999, the mechanic was against leaving block heaters on all of the time. The notion was they would dry up oil lining the cylinders if the boat was not regularly run.
But they certainly did keep the floor warm in the Fall up in Kingston NY.

 

[jmooney]

My heaters are plug in. I use them the night before we are going to use the boat . I turn them off before I start , as I have heard that the heat elements might burn out with turbulent water flow . I have no idea if this is correct. What I do know is that the aluminum heat sensor will corrode and fail dramatically, letting the coolant out . It’s good to have a working alarm system. I would check the state of the aluminum sensors at least every 5 years.

 

[JD5652]

Replace with 750W and put them on the HotStart thermostat. That way they cycle ON/OFF only when they need to.

My experience is that leaving them energized all the time on the thermostat has more positive aspects than negative. Also helps significantly reduce engine room condensation and rust.

 

[GCSI]

My boat has 3412Es, leave the block heaters on 24/7 year round.

 

[brico]

On my 671 NAs I have 1000W on each engine wired to the original breaker and switch them on a day ahead of starting engines from October to May here in PNW. Definitely helps starting the engine with a slight touch on the start button. This prolongs battery and starter life and I am sure helps the engine too. I do not leave it on all the time.

 

[Hat52MY]

We boat year round and turn them on when the temps drop below 85 and off once above 85. We leave the engine room AC lights on 24x7 which produces enough heat to take care of any humidity/condensation when above 85. This has served us well over the years.

 

[dar636]

Thanks everyone for the info, I've decided to first replace the 'Engine Room Outlet' breaker shown in the picture, it's not an original circuit from my delivery diagrams and I'm assuming its a 15a breaker but cannot tell until removing it. I received a new 15a breaker from Sam's which is marked as tripping at 16.75 amps. With the 2 - 1000w heater elements there'll be a 1 amp margin. If it turns out to be higher or lower rated, I'll go from there. I have a 20a breaker as well.

If that's not the solution, I am back to either replacing the 1000w elements with 750w elements, or adding another circuit to separate the L and R engine room outlets. The easiest place to start is with the breaker, sort of. The bus bar connects every breaker in the column, well see how many I have to actually remove.

Anyway, thanks for the feedback, I will update once I hit the right solution.

Dinette pic just for the heck of it.