Summer Discussion: Diesel Heater Installation on Multihulls

[Chotu]

you know, the thing about these new Chinese companies that have come out since the pandemic or so is that they have really really good customer service, parts and absolutely stand by their product.

Look at this.

How many companies do you know that would do this?

I wonder if the ones that cost 10x as much would do this?

I guess I'll have 5 of these now. Hopefully I can return one of them to Amazon

[Chotu]

Result of Vevor Support:

Free heater to replace the one that malfunctioned.

I’m back to 2 heaters installed/working and will be installing a 3rd that I can use intermittently to boost bridge deck temperatures during very cold weather. The 3rd might also be quite handy for heating the boat from cold up to warm which takes unbearably long. I also have a 4th heater for parts now.

Only took about 15 minutes to fix since I didn’t need to do a reinstall of the heater. Just unhooked the malfunctioning one from the install and hooked the new one up in its place

Found a way to save a lot of power and heating fuel overnight at anchor. Wondering what people think of this from a condensation point of view. Instead of heating the whole boat with multiple heaters overnight, I’m instead, just heating my cabin a little bit and relying on my electric blanket if needed. This causes the refrigerator and chest freezer to cycle on much less and reduces the heater power and fuel consumption down to about 25% of heating the whole boat. Condensation wise, my cabin is slightly warmer, more damp air, but it is escaping to a huge, huge cooler area of the bridge deck that is drafty so the air changes a lot up there. I’m thinking this won’t cause any condensation. Thoughts?

I’ll keep the area outside the cabin warm enough that my plumbing doesn’t freeze in the deep winter when I’m asleep by using a seco heater as needed

Daytime I’ll heat everything to 65-70F

Note: considering anchoring out for the whole winter as well. The marina I was going to stay at filled up while I was waiting for the crane and stopped returning calls/emails. The backup marina appears to be full by visual inspection and didn’t really want me there due to my size. The backup to the backup is $5000 and not in a very good location. So, considering paying myself $5000 to anchor out all winter.

Just have to get some bibs (for snowboarding and dinghy rides). Anyone have experience with DryVent material as compared to Gore-tex? Considering some DryVent ones. Everything else, I have: waterproof Gore-Tex shell/removable thinsulate warm liner with hood, warm winter waterproof boots, waterproof mittens half way up forearm, hat, thermal underwear sets, wool socks.

[rslifkin]

Originally Posted by Chotu

Found a way to save a lot of power and heating fuel overnight at anchor. Wondering what people think of this from a condensation point of view. Instead of heating the whole boat with multiple heaters overnight, I’m instead, just heating my cabin a little bit and relying on my electric blanket if needed. This causes the refrigerator and chest freezer to cycle on much less and reduces the heater power and fuel consumption down to about 25% of heating the whole boat. Condensation wise, my cabin is slightly warmer, more damp air, but it is escaping to a huge, huge cooler area of the bridge deck that is drafty so the air changes a lot up there. I’m thinking this won’t cause any condensation. Thoughts?

I’ll keep the area outside the cabin warm enough that my plumbing doesn’t freeze in the deep winter when I’m asleep by using a seco heater as needed

That should be fine. Just monitor for condensation to see what the minimum temperature in the rest of the boat is before condensation happens. Then you can adjust temperature if needed.

[Cpt Mark]

Chotu, I haven't kept up on this thread. Yikes, you're going through the wringer.

Pumps. Yeah. I went through a bunch of them too and even got to the point where I was considering the $100 usd pump. Then I tried something. I installed the the plastic tank that came with the heater. Voila! I have never had a problem since. Can run it for weeks on low power only, no carbon build up. It works perfectly.

I had Teed into my engine fuel line after the Racor for my fuel supply with a ball valve. I would have though that was good enough but for whatever reason it just isn't. Maybe if I teed in before the racor.... Now I drilled a hole in the cap and stuck the fuel line from my Tee in there and pump it in that way. I have an electric priming pump on the engine, both engines.

Try the fuel tank. Mines mounted close by and gravity feeds the pump which then pumps up to the heater less than a meter.

[Chotu]

Always going through some wringer. Lol. I’m used to it.

I have the same set up you have. The big day tank gravity feeding.

As it turns out the pump was just fine. The heater is what went bad. The control board. When they sent me the new heater everything worked. I am using the old pump.

I have a 12 gallon day tank with 1ft head pressure to the pumps. They are the lowest point in the system. They are gravity fed. I have 30 gallons of Jerry jugs (all of them) loaded with diesel and will use those to ferry it.

I do have to add the third heater in also. But I will follow the same installation. I have also heard that mounting the pump more vertically is good for them. So I did that as well. They are not 45. They are a little steeper than that.

Only complaint with the new heater is it is running a bit hotter than it should or the fan is a bit lower or something. I got an overheat on #9 setting and it’s still putting out some burning candle type of smell. Hopefully that will go away soon. The other one did the same when I first got it. Odd behavior.

Today? It’s warm! Windows open, not much breeze. Nice to get some fresh air in

[rabbi]

Condensation ...

It will happen. You breath so you create damp air. If you keep your cabin door closed it will just be confined and easily visible in the morning.
If you open up to the bridgedeck the moist will condensate over a larger area and may not be so obvious. But actually it will be more due to lower hull temperatures in the colder sections.


I don't know your energy budget. Do you have 150~250Ah to spare per night? That should be enough to run a dehumidifier for most of the night. The Meaco DD8L runs on 300W to keep the air dry, and converts this energy into heat. Thats what I do when visiting our boat in winter storage

[Chotu]

Originally Posted by rabbi

Condensation ...

It will happen. You breath so you create damp air. If you keep your cabin door closed it will just be confined and easily visible in the morning.
If you open up to the bridgedeck the moist will condensate over a larger area and may not be so obvious. But actually it will be more due to lower hull temperatures in the colder sections.


I don't know your energy budget. Do you have 150~250Ah to spare per night? That should be enough to run a dehumidifier for most of the night. The Meaco DD8L runs on 300W to keep the air dry, and converts this energy into heat. Thats what I do when visiting our boat in winter storage

My stateroom cabin door is definitely not closed. It’s kind of hard to explain, but heat blows in at cabin sole level in there which warms it and flows out the cabin doorway into the salon/bridge deck area.

Not sure if you saw all of my samples of temperature and humidity? I don’t have a problem here with humidity. I don’t need a dehumidifier. It’s too dry, if anything. Currently at 55% humidity while typing this.

What I was asking about that Rslifkin answered about were the specific zones. Breathing in my stateroom and having that warmer, slightly more humid air escape out into the cooler remainder of the whole boat. If that was an issue.

The bridgedeck is pretty drafty so I think it’ll be ok. The bridge deck has a lot of air changes. It stays dry. It’s hard to picture just my breathing causing any changes in this 25 x 14 room (with 6+ft ceilings) that is my salon. Also, every part of the boat is open to every other part so the volume of air is much bigger than 25x14ft. But looking at my humidity in the attached pics, it’s not a dehumidifier I need.

Also, something a little different is my hull is R7. The bridge deck floor is R10. That keeps the surface at the same temperature as the interior of the boat. The big variables are the dagger board trunks and the windows-which already have insulation panels on them but are not sealed off properly yet.

First pic is diesel heaters running. Second pic is solar heating only.

[rabbi]

Originally Posted by Chotu

My stateroom cabin door is definitely not closed. It’s kind of hard to explain, but heat blows in at cabin sole level in there which warms it and flows out the cabin doorway into the salon/bridge deck area.

Not sure if you saw all of my samples of temperature and humidity? I don’t have a problem here with humidity. I don’t need a dehumidifier. It’s too dry, if anything. Currently at 55% humidity while typing this.

What I was asking about that Rslifkin answered about were the specific zones. Breathing in my stateroom and having that warmer, slightly more humid air escape out into the cooler remainder of the whole boat. If that was an issue.

The bridgedeck is pretty drafty so I think it’ll be ok. The bridge deck has a lot of air changes. It stays dry. It’s hard to picture just my breathing causing any changes in this 25 x 14 room (with 6+ft ceilings) that is my salon. Also, every part of the boat is open to every other part so the volume of air is much bigger than 25x14ft. But looking at my humidity in the attached pics, it’s not a dehumidifier I need.

Also, something a little different is my hull is R7. The bridge deck floor is R10. That keeps the surface at the same temperature as the interior of the boat. The big variables are the dagger board trunks and the windows-which already have insulation panels on them but are not sealed off properly yet.

First pic is diesel heaters running. Second pic is solar heating only.

Lets run some numbers...

You breath and you sweat. Roughly a liter per 24h at rest in moderate climate. Triple that if you work out a bit in hot climate.
Add maybe another liter if you shower & cook inside the boat.


To put that into prespective:
At your "solar heating" data point (30°C and 52%) the air contains 0.015 liter water per cubic meter. I don't know your boats's total volume but my guess is it holds a total of maybe 2-4 liter water.

So your personal emisions are relevant as you can easy double the water present in the air ;-)


Dewpoint for that solar heating measurement is 19 C / 66 F. Any surface below that temp will see condensation. Does the main bridgedeck stay above 19C at night?




Even with good insulation in the main areas condensation will still happen in smaller areas with less insulation. Like around hatches and fittings, behind lockers, ...

You wil have condensation issues to some degree. I prefer to close my cabin door to contain my added humidity and remove it with a dehumidifer near the source (me)

[Chotu]

Cool. I like running the numbers. It paints a good picture.

Ok. So 1 liter per 24 hours. That’s .3 liters in 8 hours of sleep. I don’t sweat and it’s certainly not warm. But let’s use the round numbers.

My interior vol is approximately 114 cubic meters. At 52% humidity we have 0.015 liters of water in each cubic meter for a total of 1.7 liters of water floating around in here.

My 0.3 liters of water sleeping added to the 1.7 liters of water puts it at an even 2 liters floating around.

But the only thing missing in the numbers is the air exchange. Cooking doesn’t raise my humidity. Boiling pasta doesn’t raise my humidity. Why? The outdoor air comes in and displaces the humidity. The humid air goes out cracks and vents.

The math is incomplete.

If I were to seal myself off in the state room, yes. The numbers would be accurate. But in the real world the numbers are not accurate because they don’t account for the air exchange.

The air exchange with the diesel heaters on in my first temperature data point is 40% humidity. That’s because of the air exchange. My boat is the same humidity as the outdoors pretty much, then when you heat that air up the relative humidity drops. It drops quite a bit as you see in the picture.

With Rslifkin I was talking about sealing off gaps and cracks to try to get the heaters working better. But I have been very resistant to that and decided to add more power rather than try to make the boat more efficient because I don’t want to lose that air exchange. Not only is it good for the humidity, it’s generally good for the breathing atmosphere in here. It’s one of the things I like most about my boat. It doesn’t get mold. It never has. It’s too airy for that.

I even have a whole stack of moldy books in here that got moldy in storage. Cruising guides and things like that. When I brought them in here? The mold progress stopped. It is all dormant. My dishes dry very very quickly also. And very thoroughly.

[rabbi]

Yea if you are pumping in fresh air then it will lower humidity.

Anyway if I where you I'd check surface temperature with an IR themometer, I have one made by Bosch that also takes humidity into account and gives dewpoint and warns if there is risk of condensation.

The fact that the boat has always been airy and dry over the summer doesn't mean there won't be condensation in winter when its really cold. Actually its unlikely to not have condensation if you have unheated sections.

As far as I understand you are measuring near your heater outlet. I'd suggest to measure in the unheated area in the cold morning hours and then calculate the dewpoint from that.

[rslifkin]

The unheated areas will still be warmer than the outside temperature, it's just a question of whether they stay warm enough to avoid condensation without a bit of additional heat in those areas.

[Chotu]

Ok. I have some colder weather coming up. I’ll measure the morning surface temperatures out there.

This better be good with you guys making me get out of bed to a cold boat before turning the rest of the heat on! Ha ha ha.

Usually I just turn on the heat by remote control from bed a couple hours before I get up.

I have an idea to have the majority of it at lower heat than my stateroom while sleeping only. There is no unheated section, although I am considering leaving the heat off when it’s above freezing outside when I’m sleeping and only heating my stateroom, which represents about 15% of the volume of the boat at most

[Chotu]

Everything I shot with the handheld thermometer was at 51.6F this morning when I got up. A warm night. Not good for evaluating condensation.

However, the triad is in effect!!

One for each hull and one for the bridge deck.

After trying these all winter, I’ll see how they do and do a permanent installation once I have more cabinetry and places to stash the heaters. I think they’ll stay outside and go under a table on deck. They are a diesely stinky bunch.

Currently (just barely) have all 3 exhausts going through an aluminum pipe section that I tapped into one of my cockpit drains. It’s so tight the ridges on the exhaust pipes cause you to have to pull all 3 exhaust hoses through at once because they interlock with each other once in the pipe section. But they did fit!

This should be quite a setup. Hopefully will get me through the harsh, snowy winter.

That’s 24kw (81,000BTU) on the labels, but it’s a true 15KW (51,000BTU) setup.

The bridge deck heater will be used mostly just as a booster. The other two will be the main heating. I will turn on the bridge deck heater when it needs to heat up quickly or when the temperature just plummets to like 10 or 5 or 0F. For this reason I am leaving the bridgedeck heater open to outdoor air. This will be my source of outdoor air. I will not recirculate that one unless it becomes necessary. The other two are recirculating indoor air.

Looks like an expensive heating bill and a lot of diesel hauling by jug. Fair amount of generator running as well to keep up with the power draw. Currently running new heater on 10 for a bit to burn off new heater stinks

[Chotu]

OK. Following up on the condensation part of the thread.

We have actual data. Not sure of the interpretation of it yet as I’m just waking up. It’s in the 30s right now. Just about freezing.

Last night I went with the plan of just heating the starboard hull and stateroom with one single diesel heater on the lowest setting possible. This keeps the stateroom warm enough - probably in the 50s. The heat runs through a completely uninsulated aluminum duct which is designed to give off a little bit of the heat as it travels and then ends up blowing toward the stateroom at the end.

Port hull and bridge deck were not heated at all.

Advantages are significantly less power consumption by the refrigerator and freezer which are my largest consumers. Significantly less power consumption by the diesel heaters and also of course less diesel consumption. Significantly less.

Disadvantage might be condensation or whatever out in the main area in the bridge deck salon and galley and everywhere outside the stateroom I’m in.

Data was taken at 7am after a whole night of me sleeping/breathing and just the one diesel heater on blowing toward/into stateroom.

NOTE: yesterday I cooked down some vegetables in an open frying pan and boiled water for noodles as well after dark for dinner

DATA:

I shot all surfaces in the salon and galley. They range between 39 and 41F surface temperature. 39 are my uncored/uninsulated dagger board trunks. 41 is everything else (hulls, furniture, bulkheads)

According to the thermometer out there, the air temperature on the bridge deck is 49F.

Relative humidity on bridgedeck is 63%.

Calculated dew point is 37F in the bridge deck/ salon.

Looks like I’m very close, but no condensation possible in these exact conditions.

I don’t trust the thermometer/hygrometer to be this accurate either. Maybe they are, maybe they aren’t.

So for now, no condensation possible.

Also: I have noticed the humidity inside depends greatly on the weather outside. If it is really humid outside, it certainly rises inside. If it is really dry outside, it drops inside.

Current outdoor humidity is 55% (I added 8% humidity to that in the boat from all sources)

Current outdoor dewpoint is 24F. I added 13F to that dew point inside the boat, which is more than I had expected

[rslifkin]

That sounds pretty good to me, and it also sounds like you're sitting at a decent balance between dry enough to avoid condensation, but not unpleasantly dry inside the boat. If you start to get some condensation on really cold nights, leaving the heater in the other hull running at its lowest setting should be plenty to get rid of it (and on a cold night I expect that will warm the boat some, but far from the temperature and fuel consumption of heating things fully).