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Old 18-10-2017, 06:09   #1
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Heating a small cabin with hydroponic heat

Hello,

Have read through the older threads on hydroponic heat. Lots of great information to think about.

Looking for recommendations for a small bunk cabin (approx 115 ft3). According to the formulas I have found online the cabin only needs a heater with a rating of 1400 BTU/Hr. Most of the air handlers I have found online are much more capable. Any recommendations ? Can I use a small household radiator that is potentially a bit fit from a BTU perspective ?

Background: We are full time cruising on our Stevens 47 with our family of five. Presently in the South Pacific but intending to head back north to British Columbia via the Marshalls Islands and Alaska. We have a functional Webasto 3500 diesel air heater than heats primarily the aft cabin and aft head and to a lesser extent the saloon and forward head. We have been given two Espar 4 Diesel hydroponic heaters. I want to install one of them to primarily heat the kid's bunk cabin and provide hot water as well as assist with the saloon. At some point we will also need to heat the V Berth (also about 115ft3) but than can wait until we get home to BC.


Based on my limited research to date I can see that the little Espar unit will be overtaxed to heat all of the front of the boat at the same time but the bunk cabin only needs to be heated at night when at anchor. I can see that a better system would be a big Webasto or Espar hydroponic system which is what we may do eventually but not until we are settled back into BC.

Also thinking of adding a heat exchanger (such as https://www.suremarineservice.com/W001-235K.aspx) to utilize some of the heat from the Perkins 4.236 engine to assist with heating the cabins and the domestic water.

Thanks,
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Old 18-10-2017, 07:07   #2
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Re: Heating a small cabin with hydroponic heat

I am surprised you feel the Webasto and the Espar can't heat the boat between them as that is nearly 9 Kw. We heat our house with 5Kw.

However, since you have the expensive bits why not fit both the forward cabins now with household radiators. They are both cheap as chips and silent when folk want to sleep in the cabins with the heating on.

Are you also going to insulate the underside of the deck and hull sides to reduce heat loss and form a barrier between cold hull and warm air inside to reduce condensation?

For the price of that heat exchanger you might be better off choosing a new calorifier with a twin coil. One for the engine heating and one for the Espar circuit so either can heat hot water for cooking and showers etc.

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Old 18-10-2017, 07:27   #3
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Re: Heating a small cabin with hydroponic heat

This is a large thread about Hydronic heating .

Lots of information here .

Hydronic heating. cabin/water

Regards John.
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Old 18-10-2017, 07:32   #4
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Re: Heating a small cabin with hydroponic heat

Yes, I am hoping the two systems will be sufficient but I still think a better longer term solution is one big boiler but is more than we want to take on at this point. Once we are back to Canada we can figure out where we will live during the winter and therefore if we want to do the big investment in the big boiler.

I like the idea of the household radiators but am hoping to find out if others have used them with marine hydroponic systems. I remember when we lived in the UK our house was heated with radiators and it worked fine (RNAS Culdrose - a great three years).

Good point on the dual heat exchanger water tank. More research required on my part especially when considering shipping to NZ or the Marshall Is.

Yes, condensation is also an issue that we have not really thought about yet.

Thank you for your advice.
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Old 18-10-2017, 09:40   #5
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Re: Heating a small cabin with hydroponic heat

Another data point...

We have a Tayana 47 with a 5kw Hydronic Espar heater. We were in DC for Snowmaggedon with sustained below freezing temperatures, snow deep on the decks and ice over the water.Much too cold for me. The boat easily maintained a temperature of 18 centigrade with the heater cycling between high and low about half the time. Basically, it had no trouble sustaining these temperatures once the boat was warm.

The problem was if the boat had been allowed to get cold (stuff happens) it would take forever to build the temperature back up again. We also had dock power and generator so if I added 4kw of electrically derived heat the boat would come up to temperature in an hour.

I have a blower radiator rated at 5kw which I plan to keep seperate from the hydronic system and install on the main engine coolant circuit. The idea is to have redundancy and also the capacity to stay warm while motoring or quickly warm a cold boat.

However, there is little attraction to being on the boat in cold wx so the project remains very delayed.

Hope this helps.

Ross

ps we also added cheap thermostats to our air handlers so that different zones can be kept at different temperatures and so that oversized airhandlers did not over heat smaller cabins.

PPS a section of copper pipe makes an excellent poor mans radiator and is great for keeping hanging lockers dry or small cabins comfortable. Commercial domestic towel racks make great boat radiators as well.

we are now based in Falmouth UK within ear shot of RNAS Culdrose.. nothing like the sound of a hundred thousands bolts flying in loose formation.
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Old 18-10-2017, 11:23   #6
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Re: Heating a small cabin with hydroponic heat

Some good info here - I will try not to re-state it too much, but describe what has worked for us.

Currently living aboard in Petersburg, AK on our 40 ft Pacific Seacraft and plugged into shore power. I would venture to guess we are @ 2/3 to 1/2 of your volume heating requirements. We came from the Puget Sound - Seattle - and I can say it is much wetter here than down there. Very humid and cold = a lot of condensation.

We have the same Webasto 3500 that you do and it literally toasts us out in short order if we leave it cranked up, even with the forward and main saloon hatches cracked open. We leave those hatches open for ventilation, just covered from the outside. The heater is in the aft lazarette, with four outlets in the boat; main and aft cabins, main saloon, and head. We augment the Webasto with a small electric oil filled radiator that we plug in at night and then turn the Webasto off just for less noise. We also use a small electric forced air heater during the day. Getting the boat up to livable room temps is not an issue, even if we have left for a day and turned everything off. The Webasto alone could get us comfortable in 10 minutes.

The small forced air heater is to try to get as much warm airflow to every nook and cranny in the boat. Our hull is not insulated really well (Alaska well), and we have been producing a lot of condensation everywhere, especially in closed lockers. We are starting to do quite a few things to help that situation. In no particular order:

We try to leave lockers open when we can to increase warm airflow. Only a small step, but has done a little to allow airflow to get to places, even those with louvered doors.

After using one that a friend here let us borrow, my wife picked up a couple of GoldenRod heaters to move around to various lockers and cabinets. Small and low power, the constant heat has helped. URL is blow:

https://www.amazon.com/GoldenRod-inc.../dp/B005FRG03O

That obviously doesn't work for storage under the settees or some other places. We have started to actively insulate the areas that get a lot of moisture and that has helped. What we are using is simply 1/2" closed cell foam from the local hardware store that we cut to fit each area and seal the edges with clear duct tape. We are early in the process for that, but so far has been a big benefit, especially to places where we have produced a lot of moisture like the sleeping areas.

Apologies if this is too much of a thread drift - but we have basically discovered that it really hasn't been heat production that has been the biggest problem, but managing the condensation.

Hope this helps
Ron - S/V Just Lucky
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Old 18-10-2017, 15:01   #7
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Re: Heating a small cabin with hydroponic heat

Quote:
Originally Posted by yachtgemini View Post
Another data point...

We have a Tayana 47 with a 5kw Hydronic Espar heater. We were in DC for Snowmaggedon with sustained below freezing temperatures, snow deep on the decks and ice over the water.Much too cold for me. The boat easily maintained a temperature of 18 centigrade with the heater cycling between high and low about half the time. Basically, it had no trouble sustaining these temperatures once the boat was warm.

The problem was if the boat had been allowed to get cold (stuff happens) it would take forever to build the temperature back up again. We also had dock power and generator so if I added 4kw of electrically derived heat the boat would come up to temperature in an hour.

I have a blower radiator rated at 5kw which I plan to keep seperate from the hydronic system and install on the main engine coolant circuit. The idea is to have redundancy and also the capacity to stay warm while motoring or quickly warm a cold boat.

However, there is little attraction to being on the boat in cold wx so the project remains very delayed.

Hope this helps.

Ross

ps we also added cheap thermostats to our air handlers so that different zones can be kept at different temperatures and so that oversized airhandlers did not over heat smaller cabins.

PPS a section of copper pipe makes an excellent poor mans radiator and is great for keeping hanging lockers dry or small cabins comfortable. Commercial domestic towel racks make great boat radiators as well.

we are now based in Falmouth UK within ear shot of RNAS Culdrose.. nothing like the sound of a hundred thousands bolts flying in loose formation.
Thanks for the information. Nice to know what is achievable as our five years in the tropics likely has not been good preparation for the cold. We did plenty of cold weather sailing in Halifax, NS and Victoria, BC before we left to go cruising but not living aboard so lots to learn.

Will keep researching the pros/cons of small appropriately sized radiators or oversized air handlers with thermostats for the small cabins.

Enjoy Falmouth. We did our first yacht sailing courses there.
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Old 18-10-2017, 15:15   #8
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Re: Heating a small cabin with hydroponic heat

Quote:
Originally Posted by Smokeys Kitchen View Post
Some good info here - I will try not to re-state it too much, but describe what has worked for us.

Currently living aboard in Petersburg, AK on our 40 ft Pacific Seacraft and plugged into shore power. I would venture to guess we are @ 2/3 to 1/2 of your volume heating requirements. We came from the Puget Sound - Seattle - and I can say it is much wetter here than down there. Very humid and cold = a lot of condensation.

We have the same Webasto 3500 that you do and it literally toasts us out in short order if we leave it cranked up, even with the forward and main saloon hatches cracked open. We leave those hatches open for ventilation, just covered from the outside. The heater is in the aft lazarette, with four outlets in the boat; main and aft cabins, main saloon, and head. We augment the Webasto with a small electric oil filled radiator that we plug in at night and then turn the Webasto off just for less noise. We also use a small electric forced air heater during the day. Getting the boat up to livable room temps is not an issue, even if we have left for a day and turned everything off. The Webasto alone could get us comfortable in 10 minutes.

The small forced air heater is to try to get as much warm airflow to every nook and cranny in the boat. Our hull is not insulated really well (Alaska well), and we have been producing a lot of condensation everywhere, especially in closed lockers. We are starting to do quite a few things to help that situation. In no particular order:

We try to leave lockers open when we can to increase warm airflow. Only a small step, but has done a little to allow airflow to get to places, even those with louvered doors.

After using one that a friend here let us borrow, my wife picked up a couple of GoldenRod heaters to move around to various lockers and cabinets. Small and low power, the constant heat has helped. URL is blow:

https://www.amazon.com/GoldenRod-inc.../dp/B005FRG03O

That obviously doesn't work for storage under the settees or some other places. We have started to actively insulate the areas that get a lot of moisture and that has helped. What we are using is simply 1/2" closed cell foam from the local hardware store that we cut to fit each area and seal the edges with clear duct tape. We are early in the process for that, but so far has been a big benefit, especially to places where we have produced a lot of moisture like the sleeping areas.

Apologies if this is too much of a thread drift - but we have basically discovered that it really hasn't been heat production that has been the biggest problem, but managing the condensation.

Hope this helps
Ron - S/V Just Lucky
Great info - thanks. Nice to know the Websto 3500 can keep up with most of the boat. I love the idea of the 1/2" closed cell foam. We will start on that project when we get to NZ as it would help in the heat as well with our blue hull. We have thin silver insulation there at the moment but it is very tired. I have added the rod heaters to our list of things to find when we reach North America again.
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Old 18-10-2017, 21:46   #9
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Re: Heating a small cabin with hydroponic heat

This is the heat exchanger I installed to swap heat from the engine to the hydronic system.

https://www.amazon.com/gp/offer-list...&condition=new

It's a heck of a lot cheaper and Sailor Chick, the expert, says it will move 17,000 BTU.

I ran the return lines around the perimeter of the boat, in the bottom of storage behind the settee cushions, below storage lockers and around the v-berth storage.
Rainy season has just started but the boat is much drier and no dampness at the bottom of the storage.

If I were you, I'd use 1 of the Espars to heat the cabin and hot water tank.
The Lerway ST1000 thermostats are cheap and easy to use.
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Old 18-10-2017, 21:57   #10
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Re: Heating a small cabin with hydroponic heat

Just to elaborate on the condensation issue. Having had boats in Alaska for many years now I would opt for a forced air vs the hydronic; and I know they come with blowers but... Running the ducting under the cabin sole and through lockers making small perforations in strategic locations to allow some air leakage into key areas to keep the moisture down, rather than having to leave lockers open etc. While the condensation being noticeable in accessible lockers Iím sure you can imagine whatís going on in the crevices below that you canít see. And any part of the hull thatís in the water will be colder than the indoor air and sweat like crazy the warmer the cabin gets.
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Old 18-10-2017, 22:51   #11
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Re: Heating a small cabin with hydroponic heat

From an engineering perspective, two smaller "boilers" would be better than one large one. Why? Because at lower loads you are not using one big one at an inefficient low demand.

By now you have figured out that it is not hydroponic, right?
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Old 18-10-2017, 23:25   #12
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Re: Heating a small cabin with hydroponic heat

Heating a small cabin? Well, here in Florida it does get nippy (30F.) at times and we don't have heaters at anchor.
This is what I have done many times: Using a kerosene lamp, adding a flexible clothes aluminum dryer exhaust tube and putting this 'chimney extension' out the hatch directly above the lamp and covering the rest of the slightly open hatch with some wood, we get heat and light and no smoke, Carbon Monoxide or smell.
Sweet warm glow, just don't touch that hot chimney!!. Cooling Fins made from pie plates on the chimney every few inches makes a big difference. (I realize it's not for everybody, sounds and looks ridiculous but....it's just for an occasional nippy night).
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Old 19-10-2017, 02:56   #13
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Re: Heating a small cabin with hydroponic heat

I have a boiler and baseboard system that came with the boat. A cold boat around freezing took 4 hours to get comfortable. Just 2 zones in 83'. I removed the baseboards and put in small, forced air heaters (like car heater only marine) in 5 zones and now can have the boat warm in about 30 minutes. I also have diesel, wood and pellet stoves. All have water coils. The diesel stove heats the hot water tank and the other two can heat the boiler. Also the mains can heat the boiler. Or the boiler can preheat the mains.
I stopped using diesel at $4/gallon and found pellets the cheapest way to heat $2-10/day. Diesel was double. Wood is only cheaper if I cut & haul. Wood only heat in really cold weather was 2 cords a month.
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Old 19-10-2017, 04:48   #14
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Re: Heating a small cabin with hydroponic heat

Lots of to the point tips in this thread! We live abord in Sweden and the climate here can, and will generally be cold and damp during winter. But can also be dry and very cold. What I fand has been absolutely necessary, as pointed aut by others is to insulate. Its like the three L's in realestate Insulate, Ins...

I have added 21mm Armaflex underneath the entire deck area in both hulls and have also done some on the hull under the bunks. This allow us to use this as storage without getting mildew on whatever we store under there.

There is a super insulation fabric used by NASA that is only 6,5mm or 1/4" thick and can be glued directly to the hull and also acts as a vapor barrier. Also a dry boat require much less energy to keep warm.

To deal with the humidity issue we have bought a Meaco dehumidifier, and according to the Admiral is the next best thisng to a lover! It keeps the humidity at 55%, which isideal for humans and makes heating easier.

So, something in the way of heating, I have been doing some thinking while not being able to sleep at night and the use of electric car heat pump could be worth looking at. Not quite sure if they are widely used in US or Canada, but they are provided in electric cars here in Scandinavia to increase the milage during winter by only draw approx 1/3 of the power that's needed for heating the car pluss batteries that should ideally maintain 35degrees C.

This system would save a lot on shore power and provide dry air for the boat.

I believe the heater capacity in most boats are more than adequate, but high humidity and poor or lack of insulation is the culprit.

Happy lead free sailing from Lucky
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Old 19-10-2017, 07:47   #15
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Re: Heating a small cabin with hydroponic heat

I have been thinking about something like this for a small cabin:
https://www.ebay.com/itm/90-91-92-93...19.m1438.l2649

it is the rear heater for a Toyota 4 runner - complete with fan and very compact.
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