Off grid heating...

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Ifraser

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Hi all, first post on this forum as I am shortly to be moving on to a 40' approx cruiser moored in a harbour on the south coast. My question is about heating without using a lot of battery power. The boat I'm looking at has a large saloon, foreward and aft cabins... so 3 spaces to heat. I'm aware of the Refleks type diesel heaters and I've seen them used with radiators. Question is if you have radiators attached do you need a circulation pump like a household system or can the water circulate using thermal currents. Also has anyone used a stand alone Refleks type heater then moved the air around either with clever ventilation or using very low current computer type fans. Is there another way that I have missed altogether. I currently use an Eberspacher on my 26' cruiser but i reckon it would use far to much battery power for a liveaboard type application... thanks in advance... Iain
 
Battery pwoer is not the issue. Don't think anybody would seriously use 12v for heating, although electric heaters (fan or radiators) are great if you are on shorewpower.

Hot air heaters such as Ebers are the most common choice and you would have no problem building a system for a 40 footer. This is sort of the tipping point when pumped hot water, but diesel fired sytems become possible but they take up more space and are more expensive.
 
Tranona

Thanks for your reply... maybe didn't make myself clear... certainly would never have dreamt of using 12v for the actual heating.. I was talking about Ebers as they draw a couple of amps so batteries would not support them for more than a couple of days. I guess I am mainly just canvassing opinions from you guys as to what systems you use if you don't have shore power...Maybe ebers are an option but I guess you'd have to run the engines every couple of days to top up bats ( if you don't have a genny ) Like I said I'm new to the living aboard... Got thousands and thousands of hours as a motor cruiser, commercial skipper and instructor but never had to think of heating without running the engines every day... thanks for any info... Iain
 
Quite. Ebers are not suitable long-term unless you have shore-power. I think you are going to struggle a bit to get 'home comfort' in all cabins in the winter. We found heating round the clock (electric convectors from shore power) and a couple of dehumidifiers were needed to be really comfortable. A lot depends on your requirements. You could manage with one central drip-feed diesel and use that as your focus then wrap up warm elsewhere. A water pump is going to be a big drain on your batteries on top of lights, computer, TV, music, fridge in the darkest part of winter. You'd need a diesel generator running for several hours a day especially if you are going to make your hot water by electricity not gas.

Not a comfortable proposition and maybe not as inexpensive as you imagine. Check out alongside prices with shore power. If you are lying to a mooring buoy you will also have a problem with TV reception unless the signal is very strong locally and you can use an omni. You will also need to take on fresh water regularly. Your tender will need to be up to the job on a daily basis.
 
thermal circulation requires pipes at least 25mm dia to be effective (at least, that's what we have at home).

I see a bit of a problem with the the heater and the rads being roughly on the same level, though. Unless you can have one rad a fair bit higher than the heater, circulation may be rather slow.

You can put a 12v circulating pump into a parallel circuit to get the water circulating first, and then rely on cooled water returning from the rads to keep it going.

Heated air seems to be the best bet, as it will also reduce the ventilation / condensation problem of living aboard in winter. But you are going to need to shift a lot of heat around, and/or have good insulation.

I suggest you have a look at how caravans do it. My Burstner had a gas heater plus a fan pushing hot air through 75mm-ish ducts. Just like toast.

http://www.trumauk.com/
 
Boat heeting

Have you thought of a wood burning stove or "multi fuel stove" maybe fitted at the lowest point in the boat and ventilated well, the warm air will find its way "up" the boat much in the same way that the cold air finds its way into the boat? after all there are cheap chainsaws and old pallets about most everywhere. Depends where you are moored I guess.
Rob
 
If you are going to liveaboard then you need to have an alternative method of charging if you are not on shorepower, so now is the time to think Solar power and/or wind. You need enough to run the Eber in the winter and the fridge in the summer!
 
Diesel drip feed was fine on my 33´er in London with ice outside. Keeps the boat nice a dry as well though bit heavy on the diesil, maybe £20 a week when really cold outside but I was toasty warm. I have little car fuel pump which transfers fuel from main tank to header tank in the heads. Computer fan sounds like good idea though you´ll still need to run some largish pipe in, but spose that will be the case with ebers as well. Ebers noisy antisocial things for liveaboards. My boat is steel with sprayed foam insulation above waterline so might keep the heat in better than grp, dunno.
 
sarabande said:
thermal circulation requires pipes at least 25mm dia to be effective (at least, that's what we have at home).

I see a bit of a problem with the the heater and the rads being roughly on the same level, though. Unless you can have one rad a fair bit higher than the heater, circulation may be rather slow.

You can put a 12v circulating pump into a parallel circuit to get the water circulating first, and then rely on cooled water returning from the rads to keep it going.

Heated air seems to be the best bet, as it will also reduce the ventilation / condensation problem of living aboard in winter. But you are going to need to shift a lot of heat around, and/or have good insulation.

I suggest you have a look at how caravans do it. My Burstner had a gas heater plus a fan pushing hot air through 75mm-ish ducts. Just like toast.

http://www.trumauk.com/
Click to expand...

Eberspacher do an extremely effective hot water system using microbore pipes and heat-exchangers - less power consumption than the blown variety and far more effective. It also supplies hot water.
I've seen one in use on a Swedish boat owned by a Lloyds surveyor.
However I doubt batteries will support it indefinitely, without either PV or wind-charger and engine runs. It's about x3 price of blown air if self-installed and about x5 if professionally done.
Finally there is the cabin stove such as the Hot-Pot, burns anything, one kept a 35' as warm as toast.
Personally I find shorepower and fan heaters (no need for de-humidifiers) the most practical and have found that quite adequate in -8C ambient. Had to break the ice round the boat every morning and walk very cautiously on iced-up decks and pontons.
 
Don't know if it's of any interest, but I've got a used Force 10 Cozy Cabin diesel/kerosene heater in the shed needing a good home. As diesel heaters go it's very small, not heavy, knocks out 6000BTU and looks to be pretty straighforward to fit. http://www.go2marine.com/docs/8/3/1/0/83101F-mi.shtml

I bought it on a whim and have now decided not to fit it as I can't find anywhere on my boat that would a good place to locate it. PM me if interested
 
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circ pumps

Thanks for all the replies... they've been very useful.. I have now also discovered 12v circ pumps that draw just over one amp... so with 4 120ah batt that should last quite a few days and I would hope to have a solar array to supply as much power as poss to minimise the neccessity for genny running... Is anyone running a refleks or similar with a hot water coil using a circ pump of the type I mention..? thanks again...Iain
 
reflek heating

Ifraser said:
I'm aware of the Refleks type diesel heaters and I've seen them used with radiators. Question is if you have radiators attached do you need a circulation pump like a household system or can the water circulate using thermal currents. Also has anyone used a stand alone Refleks type heater then moved the air around either with clever ventilation or using very low current computer type fans.
Click to expand...

We use a reflek with a low power fan blowing air across the chimney pipe (inside the boat as it goes up to deck). Works quite well on our 47'er. Does not draw much power and heats the boat pretty well. It helps a lot it you put carpet down on the sole, otherwise you will be warm from your knees up but your toes will be cold.

We have seen two boats with reflek radiator systems with 'natural' circulation (eg not electric pumps) but it took quite a bit of tinkering to get both to work.

The Espars do take too many amps for a low power live aboard approach and also have a reputation for poor reliability.
 
I am working on a boat right now that does not have a good place to install a reflek (tight on space and no good way to route the chimney). So we are instead installing two Corona heaters (www.corona.co.jp/en/index.html.

These are excellent Japanese 'state of the art' kerosene heaters. There are trade-offs but they are quite acceptable if the reflek is too complex to install.
 
Ifraser said:
Thanks for all the replies... they've been very useful.. I have now also discovered 12v circ pumps that draw just over one amp... so with 4 120ah batt that should last quite a few days and I would hope to have a solar array to supply as much power as poss to minimise the neccessity for genny running... Is anyone running a refleks or similar with a hot water coil using a circ pump of the type I mention..? thanks again...Iain
Click to expand...

We have a diesel gravity fed heater, a Dickinson Newport, on our 38' and it has kept the boat warm in temps down to -15C in Norway. It uses a small fan to start then no power other than use of fan sometimes in strong (30knot+) winds to stop blowouts.

It can be fitted with a hot water coil for hot water production.

Lookie here for more details
 
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