Electric Heater for Liveaboard in Boston

[JK n Smitty]

Originally Posted by Tim R.

We installed a 12v diesel hydronic system so that we could extend our sailing season in comfort. It also allows us to heat our boat for days without shore power. The electricity was only out for a couple hours this year but the heater kept on running.

Considering your boat wiring as mentioned by rw58ph is paramount to installing safe and functional electric heaters. Too many boat fires caused just from owners over extending their boats wiring and not maintaining their shore power plugs properly.

Thanks Tim. Yeah MaineSail definitely drove that point home over at sailboatowners.com. I plan to switch to the smart plug this year.

Do you use the diesel heater all the time or do you have electric and the diesel is the backup?

Thanks,

Jesse

[Tim R.]

Jesse, we use our reverse cycle in the fall at the dock until it gets too cold out to keep the boat warm. We then switch over to our diesel system for the winter. This year has been a very long heating season. We fired up the diesel at Thanksgiving.

In case others here have not seen it, here is the write-up over at MaineSail's website:

Shore Power Cords - SmartPlug vs. 1938 Photo Gallery by Compass Marine at pbase.com

[robert644]

How cold is your reverse cycle good for ? The unit I purchased said effective to about 23 degrees (f). However I am going to guess that means to about freezing.

[Cheechako]

Two small heaters will burn up a 30 amp cord in one season. Just keep that in mind. I think your shore power capability will keep you at two heaters not over maybe 900 amps each.
In Mass you will be cold at times in the winter no matter what with space heaters. A ducted diesel/kerosene heater is the only way I know around this.
I favor using small space heaters that you can move around in lieu of installing something.... especially until you sort things out. You may find on cold winter nights you want to move a heater so it's about one foot from where you are sitting! Been there done that in more temperate climes than the Northeast.

[Tim R.]

Originally Posted by robert644

How cold is your reverse cycle good for ? The unit I purchased said effective to about 23 degrees (f). However I am going to guess that means to about freezing.

I have run mine when it is 10°F out as long as the water is not too cold. Once the water temps drop below 45°F and the air temp below 20°F it cycles constantly to keep the boat at 65°F. Just not efficient.

[Tim R.]

Originally Posted by Cheechako

Two small heaters will burn up a 30 amp cord in one season. Just keep that in mind. I think your shore power capability will keep you at two heaters not over maybe 900 amps each.
In Mass you will be cold at times in the winter no matter what with space heaters. A ducted diesel/kerosene heater is the only way I know around this.
I favor using small space heaters that you can move around in lieu of installing something.... especially until you sort things out. You may find on cold winter nights you want to move a heater so it's about one foot from where you are sitting! Been there done that in more temperate climes than the Northeast.

A Hydronic system works very well also. In fact, I think better. The hoses that you run through the boat can be run inside the settees which keeps them dry and also acts like a radiant heating system. Then the fan units warm the air. Hoses are much easier to run and take up much less space. This type of heater can also be setup to pre-heat your engine or create on-demand hot water. A ducted system cannot.

[robert644]

Tim R, does you heat pump work with air or water ? The unit I purchased in a domestic model that works with outside air. I have read that modern air to air household units are effective to below freezing, and that water based units are much more effective.

[ranger58sb]

FWIW...

I recently reviewed the system one of our liveaboard neighbor couples installed here. Their 34' gasoline-powered power boat is now apparently adequately served by a single self-contained reverse cycle AC unit with a built-in auxiliary heat source.

Their old reverse cycle AC was just replaced with a new Cruisair Stowaway Turbo 16K-BTU unit (model # is STQ-16, and the Q means it's a new Q-Logic user control panel with some bells and whistles).

Then that was simply augmented by inserting a Cruisair HDML auxiliary (resistive) heat module, which essentially adds "toaster coils" in between STQ air handler and supply-side ductwork. When seawater temps are below 40°F the seawater pump and compressor don't need to run (in fact, inlets are closed) so it's only the air handler part of the STQ unit and the HDML that's doing all the work.

As it turns out, even with this really cold winter, they've been pretty happy with it, though. They said inside temps could always get up to 65°F -- even better during the day with sunlight on the windows -- and at night they'd sometimes warm up the stateroom before bed, briefly, with an auxiliary space heater... or use an electric blanket... etc.

This is of course on the Chesapeake, not Boston. OTOH, our marina has been frozen in for several weeks this winter, and temps were down single digits a few times...

-Chris

[CarinaPDX]

There is a range of wattage on the HDML heaters, from 500W to 2000W. I am guessing that this installation had the 2000W unit, which of course is equivalent to 1 1/3 space heaters, so is a great base.

I looked at the CAT heaters after the earlier post (not sure why they are no longer sold through marine distributors). The larger of the two is about 1500W, which is less than the SigMar and Dickinson models, and the same as an electric space heater.

There is a lot of variability in what is needed/acceptable. To start with I want to hit nearly 70 deg F - 65 feels too chilly these days. I'm impressed with the 1" hull insulation; I have only 0.5" installed (during construction) with 0.5" cedar ceilings where exposed. When water temps are below 40 there is a lot of heat lost there. I have found even a tarp over the top of the cabin makes a big difference in heat loss. With bronze and glass hatches and portlights I find it useful to add a layer of thin clear or translucent plastic to create some dead air either inside or outside of them.

Greg

[boatpoker]

Originally Posted by CarinaPDX

I looked at the CAT heaters after the earlier post (not sure why they are no longer sold through marine distributors).
Greg

Probably because the surveyors write them up as not compliant with ABYC and the insurance companies insist the owners get them off the boat.

[Dockhead]

Originally Posted by Tim R.

A Hydronic system works very well also. In fact, I think better. The hoses that you run through the boat can be run inside the settees which keeps them dry and also acts like a radiant heating system. Then the fan units warm the air. Hoses are much easier to run and take up much less space. This type of heater can also be setup to pre-heat your engine or create on-demand hot water. A ducted system cannot.

+1

Hydronic is the best heating system for a boat if you need heating in weather too cold for reverse-cycle and/or you don't the power for it.

I sail all year round and can't imagine how I could do it without hydronic heating. I'm sitting on my boat basking in its warmth as I write this. At a latitude above 50 degrees N.

Keep in mind that there are a few disadvantages, however:

1. Cost.
2. It does use electrical power, unlike passive diesel heaters like drip-fed stoves, so you need to have a reasonable battery bank and reasonable way of keeping it charged.
3. It is not really user serviceable. And it is not totally reliable. So it's not too good for those who venture far from civilization.


Nevertheless, there is a time and place for electric heaters even on a boat with hydronic heat. I heat with two electric fan heaters, 2kW each, at docks (where I am rarely, since my boat lives on a mid-river mooring). I prefer to use the shore power which I already paid for instead of expensive diesel fuel, and I prefer not to put hours on the hydronic furnace, which needs service and decarbonizing every certain number of hours.

I have 230v AC power, which handles the load much more easily (exactly twice as easily, in terms of amps) than 110v. I have 16 amp service, so I can use one fan heater on high and one on low (1kW), with a little left over for other purposes, which is really enough heat when I'm alone on the boat, as I don't need to heat the fo'c'sle.

The fan heaters are vastly better than oil-filled radiators, as the latter can't dissipate their entire rated power and cycle on and off.

[Cheechako]

Originally Posted by Tim R.

A Hydronic system works very well also. In fact, I think better. The hoses that you run through the boat can be run inside the settees which keeps them dry and also acts like a radiant heating system. Then the fan units warm the air. Hoses are much easier to run and take up much less space. This type of heater can also be setup to pre-heat your engine or create on-demand hot water. A ducted system cannot.

Yeah.. good point forgot about the Hydronics...

[sparrowhawk1]

I'm surprised no one else has pointed this out. You need to keep your engine from freezing which will easily crack your block. All it takes is a 100 watt light bulb or even better 100 watt ceramic heater designed for keeping reptiles warm. screws into a standard light socket . The best electric heater I have ever used is a quarts heater it puts out heat equavilant to the Sun( in feel not temperature) Forced air heaters Will warm the boat but I never liked the way it felt. Electric blankets or heating pads are a great idea I have enough solar to run a refrigerator in the summer so in the winter I can use the extra electricity to run my heat pad indefinitely.

[Greggegner]

To much to read...my hot water heater keeps the block warm...

[CarinaPDX]

Originally Posted by Dockhead

The fan heaters are vastly better than oil-filled radiators, as the latter can't dissipate their entire rated power and cycle on and off.

Not quite right: pointing a fan at the radiator works for me. When I have really needed the high output I just augment the air flow, usually with a fan heater. But good point, as without a fan it does have a frustratingly low duty cycle.

As for freezing the engine block, I think that is mostly an issue for those who need to run the engine in the winter. I always drained the seawater from the cooling system in the autumn, and the antifreeze in the fresh side should protect the engine (but always check when winterizing).

Greg