House Heating Ideas

[SVRapture40]

We are spending our first winter aboard in Kingston, WA. In case you have not heard, it has been COLD for the past couple of weeks or so. I am using electric heat but am limited to a 1500 watt heater. When it gets below 30 degrees the heater can no longer keep up and it gets cold in here!! Our electric blanket works great for sleeping, but we are looking for another idea to keep the house warm during the day. Of course we can use the diesel furnace, but I have an idea for something much more efficient - the propane stove. It works great when we are cooking - it really warms up fast. But once dinner is done, that's about it. So my idea is some kind of heat sink that I can heat on the stove and then push air past it with a fan.

So the question is - what can I use for a heat sink? Heavy metal with fins is obviously ideal. I don't want to pay an arm and a leg for the thing - I just need a cheap chunk of metal. Got any ideas?

[ctl411]

You could try soap stone? I think they use it on stoves to retain heat.

[jtsailjt]

The problem with using your propane stove for anything beyond cooking dinner is that it's not vented, so it will add lots of moisture to the air in your boat, which will condense against your cool hull, which can lead to mildew issues along with just making everything aboard feel damp and clammy. If you have a diesel furnace, especially if it draws from the cooler, dryer, outside air, heats this air, and pumps it into your boat, that will tend to keep your boat dry feeling and minimize condensation or mildew. Also, diesel is cheaper to burn than propane. A heat sink is just a way of storing energy, but you still have to generate that energy, so to heat up your heat sink, you'll have to run your propane stove longer than what it would take to cook dinner, which will cost more than getting that energy from your diesel heater and will make your boat moist. Since you already have it installed, why not just use your diesel heater as needed and enjoy a nice, dry, warm boat all winter?

[SVRapture40]

Originally Posted by jtsailjt

The problem with using your propane stove for anything beyond cooking dinner is that it's not vented, so it will add lots of moisture to the air in your boat, which will condense against your cool hull, which can lead to mildew issues along with just making everything aboard feel damp and clammy. If you have a diesel furnace, especially if it draws from the cooler, dryer, outside air, heats this air, and pumps it into your boat, that will tend to keep your boat dry feeling and minimize condensation or mildew. Also, diesel is cheaper to burn than propane. A heat sink is just a way of storing energy, but you still have to generate that energy, so to heat up your heat sink, you'll have to run your propane stove longer than what it would take to cook dinner, which will cost more than getting that energy from your diesel heater and will make your boat moist. Since you already have it installed, why not just use your diesel heater as needed and enjoy a nice, dry, warm boat all winter?

These are good points, except that we have and use a dehumidifier - it works GREAT! The boat stays dry as a bone.

As far as cost per BTU - I think propane is FAR cheaper. I don't have any numbers to back that up, but I burn very little propane and the house heats up very fast, just by cooking dinner. And I must say, the diesel furnace does heat the house up fairly quick, but it definitely burns more dollars in the same amount of time.

But thank you for your thoughts!!!

[rw58ph]

If you plan on being a full time live aboard in the Puget Sound Area you should think about a more permanent alternative heating. Either propane or diesel as it sound like you already have both. How both will require venting. We first had a CAT catalytic propane heat http://www.ventedcatheater.com/6.html to heat the salon 24/7 9 months per years. Easy to install, 4 hours, and cost about 500 bucks, thermostat controlled. Used 5 to 10 gallon per week depending on the temp. With the CAT heating the salon we could use all the electric to heat the staterooms. After 3 years we installed a Webasto boiler heating that heats the whole boat even the engine room and most of the bilge. Best investment in the boat we made.

[Stu Jackson]

Upside down flower pots have been used for ages.

Oil filled radiators (electrically powered) have been suggested as superior to electric resistance heaters on this and other boating forums.

[Cheechako]

Originally Posted by Stu Jackson

Upside down flower pots have been used for ages.

Oil filled radiators (electrically powered) have been suggested as superior to electric resistance heaters on this and other boating forums.

Yep... those red clay pots work in a pinch, but I agree that the propane is not a good solution. For one thing you are starting with your heat source too high in the boat. You will nee a fan to blow accross the pot... dont let the flame go out!
You have a diesel heater? why in the wrold not use it..?? did I miss something?
Inspect your power cord every few weeks (where it plugs into the boat) using the electric heater will destroy about one a year.
It's been colder than normal lately so things should improve a bit. In a boat (as you've discovered) all the heat seems to go to the cabin top, mixing it around is necessary (mini fan on slow?)
Another option is to use two electric heaters set on low.. like 700 watts each. One in each end of the boat.

[djmarchand]

I don't think that propane is cheaper than diesel, even if the propane heat is not vented. Here are some numbers from our area in NC:

Propane $3.50/gallon 20,000 btu/lb 83,000 btu/gal 4.2 cents/1000 btu

Diesel $3.75/gallon 18,700 btu/lb 131,000 btu/gal 2.9 cents/1000 btu

Venting a furnace (which is good) loses about 20% of the heat out the stack which makes diesel a net of 3.6 cents/1000 btu. But then it takes electricity to remove the moisture that unvented propane produces, so there ain't no free lunch.

But propane prices do vary all over the map. Check your supplier to make sure it really is cheaper. Break even against diesel at $3.75/gal would be about $2.50/gal.

David

[CarlF]

Could you augment your heater with some 250watt heat lamps or is your total electric use limited?. These are cheap, safe, silent and quite efficient. Great in the head.

[ScuzzMonkey]

The other side of the equation, of course, is insulation... adding more heat to the boat is one way of warming it up, but the other way is to keep more of what you've already got.

We have a 36 footer that has an interior volume pretty close to your 40, and we can generally keep it plenty warm with just the 1500 watt space heater. But we have a cored hull and some additional interior insulation, which I think is probably the difference.

This past week, we did have to close off the aft cabin, but that was it. Once we're warmed up inside, the space heater can keep up by itself.

To get it warmed up, we either use the space heater together with the diesel furnace, or a second space heater running at lower power (~700 watts) on a different circuit. YMMV depending on your other draws, but a typical 30 amp circuit can handle just those two heaters without any problems. We just shut down anything else we don't immediately need for the half hour or so it takes to get up to temperature.

So, I guess that's all a bit rambling, but I would look at insulation before putting too much effort into additional heating. You already spent the money putting that heat into the cabin, you might as well hang on to it!

[Dr. Strangelove]

I'm sure you've thought of it, and I see you have power limitation, but have you looked into ceramic heaters? Not the $20.00 Wal-Mart jobs, but a quality unit. We used one for years to heat an approximately 400 sq ft unheated room above a garage, even when the temperature outside was in the teens we would usually have to cut the heater off during the night.

[MarkSF]

I'm surprised that no-one has mentioned the obvious problem with heating the boat with your propane stove : you're going to die.

The stove vents all that nasty CO into the boat, so you have to have plenty of ventilation when using it.

I take it you do have a hard-wired CO detector?

Properly designed diesel, solid fuel, and propane heaters vent the dangerous gases outside the boat.

Designing your own Heath Robinson propane heater based on a stove sounds like a typical beginning of a Darwin Awards entry (including the bit about fixing the moisture problem with a dehumidifier... but they forgot about the carbon monoxide)

Maybe leave it to the experts?

[MarkSF]

An example :

Families sue outdoor equipment company over carbon monoxide deaths | ksl.com

and another :

Carbon monoxide killed mother and daughter on Lake Windermere boat | UK news | The Guardian

[Pete7]

I would start with 2 dozen camping mats cut up and placed against every hull surface you can find. Had friends go through the coldest winter in many years in 2010 on a Beneteau 35 and life was okay for them.

I think insulating the boat will dramatically cut your diesel bill down to make running the heating affordable. Must be a good time to buy up supplies of cheap camping mats.

Pete

[mub]

The diesel is cheaper!
Once you add in the costs of the ventilation and dehumidifier it is far cheaper.

If you want to invest in solution I strongly suggest insulation as one of the best investments.

I have a 47' with uncored hull - but insulated topsides. I'm in Seattle and am hapilly heating with 1kw electric heater - till the furnace parts come in.. grrrrr....

Controlling the ventilation to an appropriate level to manage moisture and health. I don't have a dehumidifier.
Then insulating what is needed.
I installed a soft foam radiant barrier insulation ( called Prodex ) - and lined the headliner - So the bottom of the deck is still vented.
Also lined the outsides of the cupboards and most of the hull above water line.
If cost is an issue bubble wrap can be pressed into service.

I have to do something about my sail locker as it is unheated and I am sure that the ice in there is not good for things.