A heating question

I

Irish Mist

Well-known member
Joined
Apr 25, 2012
Messages
1,175
Fluid Motion Model
C-288 C
Hull Identification Number
FMLT2922K011
Ok here is one to think about .. I know there are a lot of smart tuggers out there so I want to get your input..spending time in the cold gets me thinking about ways to heat.. I think I have a reasonably good idea.. But looking for flaws in my thinking .
What if I hook a circulating pump into the cooling system, If I have the water heater on would it not heat the coolant that normally makes hotwater when the engine is running? This would allow me to use the built in heater.. And keep the engine toasty , as I have the water heater on most of the time.. It just seems too easy . That is why I'm asking for your thoughts
Thanks
Mark
 
A great question with what I think..and its a big I think..it comes down to efficiency. The hot water heater is very inefficient ie. draws quite a bit of constant current with a constant water change in the tank. I am assuming 120VAC or generator is being used to supply current to the water heater. A simple electric cabin heater will be much more efficient and fewer moving parts.
 
On shore power and water heater is always on ... This is a live aboard in winter at dock thing
 
Irish Mist":307l4xqo said:
Ok here is one to think about .. I know there are a lot of smart tuggers out there so I want to get your input..spending time in the cold gets me thinking about ways to heat.. I think I have a reasonably good idea.. But looking for flaws in my thinking .
What if I hook a circulating pump into the cooling system, If I have the water heater on would it not heat the coolant that normally makes hotwater when the engine is running? This would allow me to use the built in heater.. And keep the engine toasty , as I have the water heater on most of the time.. It just seems too easy . That is why I'm asking for your thoughts
Thanks
Mark
Click to expand...

Here are my thoughts to challenge your question:

a) The pump would have to be very low volume so that it will allow the coolant fluid enough time to warm up.

b) The initial circulation may be an issue. The engine thermostat will be closed because the engine is cold. So I can't see how the coolant will pass through the heat exchanger portion of the engine to form a complete loop through the engine and warm it up. I am assuming that the lines that come off the engine to heat the domestic hot water are not in series with the loop but are parallel therefore the hot coolant water naturally circulates off of the system in and is just a loop off of the coolant system. If the hoses or coils that provide the heat for the domestic hot water and the fan blower were to get clogged you would loose domestic hot water and the cabin heat from the blower, but the engine coolant would still be able to pass through the heat exchanger and cool the engine. Therefore, I think you would only be heating up the coolant to the extent that it is circulating around your water heater through the blower and back again, but never actually passing the warmed coolant through the engine block because it will be blocked by a closed thermostat.

c) If my assumptions are correct in (b) then adding a heater/blower in the engine compartment off of the coolant heater/hot water domestic loop may heat your engine compartment.

d) Is all the work to modify things worth it? A small electric ceramic heater in the engine compartment is probably all that is needed.

So what do others think? :idea:
 
Heating the engine is not really the intent but a possible by product... I actually think if I move forward I would by pass the engine.. Just loop water heater and heater.. No question the portable heater is easier..just the thought of the water heater sitting there on all the time full of a heat source.. I guess my biggest question is would the heat move from the water heater to the coil from the engine as well as it goes the other way .. Thanks for the heads up with the thermostat.. Good point But there should be a bypass for that..
 
Not sure how your system is set up but my r27 has a cabin heating system that is driven by the engin when running. So there is some piping in place already. My understanding is also that this heating loop also passes the water heater and a heat exchanger. I assume there is some form of pump in this loop which could be a blockage if engine is not running.

On another note, a few years ago I bought a webasto based diesel heater that uses water to circulate heat. According to installation information it was suggested that it could also be used to loop thru engines for preheating of the block. Considering the comment above and earlier posts I also would question how a closed thermostat would affect this. At the time I was not planning to extend heating to the engines and never installed the unit as it turned out to be difficult on my catamaran. Now, that I have the tug, I will have to revisit the use of that unit as it is more feasible.

On a second other note, I have read about the following system setup for home use. As you know, when open hot water faucet in a home may deliver cold water for some time until the lines have been flushed of the cold water. Somehow you can connect the cold and hot at the faucet and use a pump to circulate the from the hot line to the cold line assuming those are terminating in an unrestricted connection between cold and the water heater thus circulating hot water for instant hot water at the faucet. It would be thinkable to add a heat exchanger there with a blower to facilitate cabin hating.

However a simple electric heater would do the same job without rue Goldberg approaches as it was mentioned before 🙂
 
Mark:
Here goes.
I think you would end up being colder in the cabin than you are now. Your engine heater plan appears to have a lot of parasitic loss built into it. If your goal is to heat the cabin then I think your best bet is to apply your available kw. to heating only the cabin. I am assuming that you are talking about the best available use of shore power at 30 amps.
Assuming that your boat is sitting at the dock and you are not running the engine or generator, all power use, 12 volt and 120 volts will have to be provided by the available shore power. The parasitic loads as I see them are. The running of a circulation pump, the water heater element running continually (normally off and on depending on hot water use) the radiant loss of heat from the heater plumbing to and from the engine, The battery charger trying to keep up to the power use of the heater fan and also the loss of btu's that are heating the engine and the continual loss of radiated heat from the engine.
Not knowing the amp. / btu. draw of the above I can only guess that you are fast using up your available shore power.
Other thoughts I have are-------
The installation of a pump in the heater supply line may inter-fear with its operation when the engine is running.
The engine thermostat may not allow coolant flow to or from the water heater and cabin heater unless the engine is up to operating temperature.
I don't know that the water heater element could provide the heat to the heater that the running engine would.
I believe that you would shorten the life of the water heater element, The heater fan, and perhaps the battery charger.
I have not taken into consideration any freeze protection needed.
Any thoughts for or against are welcome.
Regards Don
 
Thanks everyone. Not sure if I will try it. If I can get a pump for not a lot of $ I might give it a go as I can always put it back to original if it is a failure. I will report back my findings 🙂
 
I can see that being on your boat in the PNW has your brain going into overdrive. You won't have those issues in Florida. :lol:
 
I won't lie we miss being south , but it is also pretty nice here. And our dollar is at par here 🙂
 
Irish Mist":26218vpx said:
I won't lie we miss being south , but it is also pretty nice here. And our dollar is at par here 🙂
Click to expand...

hehe... and our dollar, which isn't based on a false economy will be worth something in the future... the sequel will be coming to a theatre near you, soon. 🙂
 
Hi Mark,

You are onto a good thought. If you are serious about winter cruising in NW waters warm and dry is key. We cruise as much or more in the winter months - few people, lots of wildlife, and interesting weather. Hydronic heating is the best and most comfortable way to stay warm on a boat. We installed this system on our Nordic Tug 26'.

http://www.suremarineservice.com/PriceLists/TSL17.pdf

The heat exchanger off the engine worked great underway to heat all areas of the boat. Would prefer this system to the hot air factory installation on our R31. Besides the steady warmth we always had hot water when on the hook.

Good luck.

Bill Sibbers
R31 Sea Natural
 
Bill,
Did you install this system yourself or, did you have someone else install it? If you installed it, what would you rate the degree of difficulty (1-10) to install?

Thank you,
David
 
I looked at the hydronic system. I would like having the hot water on the hook, but in the end I thought there were a lot more moving parts. I can not see it being too hard an install , just accessing the heater locations. The hardest for me installing the forced air heater was the first hole I cut , after that it went easy 🙂 Look at Plannar heaters. Have been really happy with mine, and they make Hydronic heaters as well .
 
I assisted withe some prep work. I would install next time my self. Probably rate at a 7 or 8 for difficulty.
 
The hose routing, sequence, and zoning as well as the heat exchanger location for the engine are critical to successful system design. After that, it's a pretty straightforward install.
 
Right now, I am considering just purchasing the components needed to produce hot water. With a 1,000 amp hours in the house batteries, there is no need for a generator to produce power. We use forced air diesel heat to warm Destiny in the cooler months. So, the only reason we would have to purchase a generator would be to produce hot water when hanging on the hook. Right now we use our Honda Generator for this purpose.

We have checked into purchasing an Onan 5kw Generator. With installation we are looking at $13k. Seems a bit spendy to make hot water.

So, the idea of having the boiler to heat the water looks much better. We already have fuel lines in place for the generator so that is one issue solved. Currently we heat water via 120v and when underway. For a simple fix, I could use the lines that come off of the engine cooling system running to the water heater attaching them to the boiler. A more complex method would be to put in the heat exchanger. This would allow us to heat water while underway without firing up the boiler.

Thanks Bill for your input!

David
 
I appreciate your thinking David. The heat exchanger adds a degree of safety and separation from your engine cooling system. I would not proceed without this "firewall" to insure the engine will cool regardless of the accessories. We don't want a generator and have no gas onboard. We added two solar panels identical to the factory installation and have a Torqueedo electric motor for our Portland Pudgy dinghy. Very happy with the results. Now looking for an engine mounted AC generator to maximize utilization of our diesel main.
 
check out the Espar diesel heater and the PlatCat propane heaters while you are at it. either may be an easier install.
 
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