I have it in my head I want to install an Red Dot brand cabin heater in our 1986 E32-3 that uses engine coolant for the heat source. We motor a lot here in the Pacific NW and capturing some of that waste heat just seems like a good idea in these cold winter months. I have kind of looked at where the heater might be installed and how I might route the two heater hoses and see no real obvious perfect setup. Perhaps some of you could offer some suggestions on locating the heater and where to route the hoses (or air ducts?). I have bought nothing yet, but the local boat show is coming and ..... Thanks
Engine coolant cabin heater-install ideas ?
- Thread starter newgringo
- Start date
Heatercraft
We like our Heatercraft brand engine-coolant heater I mounted under the port settee, just in front of the nav table.
Note that mature mariners often call it a "Red Dot" in honor of that brand of transplanted painted-steel truck heater coils that were installed on a large bunch of boats in the 70's.
I plumbed ours in series with the 5/8" hose lines to the hot water heater tank internal coil. Works great and will put out a LOT of heat when our M25XP is under load. Luke warm output when idling. There is indeed a lot of "waste heat" available from a small (three cylinder) diesel under full load.
For less than $150, it will heat the whole interior, but of course only... when the engine is... running.
I have a few pics of the installed heating unit, but did not take any during the install. I have no audio of the cursing that accompanied the hose routing, either...
I confess to being somewhat proud of the panels I built to preserve some of the settee storage space around the heater unit. They are honeycomb board and epoxy.
Loren
Portland, OR
Olson 34 Fresh Air
We like our Heatercraft brand engine-coolant heater I mounted under the port settee, just in front of the nav table.
Note that mature mariners often call it a "Red Dot" in honor of that brand of transplanted painted-steel truck heater coils that were installed on a large bunch of boats in the 70's.
I plumbed ours in series with the 5/8" hose lines to the hot water heater tank internal coil. Works great and will put out a LOT of heat when our M25XP is under load. Luke warm output when idling. There is indeed a lot of "waste heat" available from a small (three cylinder) diesel under full load.
For less than $150, it will heat the whole interior, but of course only... when the engine is... running.
I have a few pics of the installed heating unit, but did not take any during the install. I have no audio of the cursing that accompanied the hose routing, either...
I confess to being somewhat proud of the panels I built to preserve some of the settee storage space around the heater unit. They are honeycomb board and epoxy.
Loren
Portland, OR
Olson 34 Fresh Air
Attachments
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Heater-FrontGrillView.jpg -
Heatercraft-in-settee-front.jpg -
HeaterFan-view.jpg
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What Loren said ...
Hey Jerry,
I would add that we enjoyed our engine-coolant Red Dot type heater until we decided change to a heat source that was usable on the hook. It kept our cabin toasty while underway. It was located under the starboard settee, pretty much in the center of the cabin fore-aft and had two fan speeds. I am not familiar with your interior so I can't advise on the location or hose routing.
We plan to extend our cruising season considerably after retirement, and once we get the cabin port leaks fixed. Maybe we'll see you at the Seattle boat show.
Hey Jerry,
I would add that we enjoyed our engine-coolant Red Dot type heater until we decided change to a heat source that was usable on the hook. It kept our cabin toasty while underway. It was located under the starboard settee, pretty much in the center of the cabin fore-aft and had two fan speeds. I am not familiar with your interior so I can't advise on the location or hose routing.
We plan to extend our cruising season considerably after retirement, and once we get the cabin port leaks fixed. Maybe we'll see you at the Seattle boat show.
It's Done
The Red Dot heater is installed and working. I ended up installing the model 254 heater in the port side storage compartment beside the table which is just aft of the port side water tank. With the help of my trusty sazall and a big hole saw it draws air from the bottom side of the chart table (out of sight) and blows out under the table. Routing the hoses was challenging. They go aft under the seating, under the chart table floor, just outside the battery compartment then around the outside of the fuel tank. I plumbed the heater is series with the hot water tank with the heater getting the hot water first. My only complaint with the Red Dot heater is they use a propeller style fan which is noisier than a squirrel cage type and needs a freer air flow path, read that more sazall work. The fan motor only draws about 1 1 /2 amps so wiring was easy (cabin lights circuit). My first observation using this heater is that it does not work with the engine at idle. The engine gets hot but the heater does not. At cruising rpm it works just fine (which makes me wonder about my Universal Diesel water pump. Humm. And that is after heroric efforts to get all the air out of the system, (I think). All in all this was a several day project which included all the head scratching. Would probably be a 2 day deal if I did it again on an E32-3. Oh, yes, it is nice to have a warm cabin after motoring in cold weather. Kind of for free too...
The Red Dot heater is installed and working. I ended up installing the model 254 heater in the port side storage compartment beside the table which is just aft of the port side water tank. With the help of my trusty sazall and a big hole saw it draws air from the bottom side of the chart table (out of sight) and blows out under the table. Routing the hoses was challenging. They go aft under the seating, under the chart table floor, just outside the battery compartment then around the outside of the fuel tank. I plumbed the heater is series with the hot water tank with the heater getting the hot water first. My only complaint with the Red Dot heater is they use a propeller style fan which is noisier than a squirrel cage type and needs a freer air flow path, read that more sazall work. The fan motor only draws about 1 1 /2 amps so wiring was easy (cabin lights circuit). My first observation using this heater is that it does not work with the engine at idle. The engine gets hot but the heater does not. At cruising rpm it works just fine (which makes me wonder about my Universal Diesel water pump. Humm.
And that is after heroric efforts to get all the air out of the system, (I think). All in all this was a several day project which included all the head scratching. Would probably be a 2 day deal if I did it again on an E32-3. Oh, yes, it is nice to have a warm cabin after motoring in cold weather. Kind of for free too...I'm wondering how much these engine coolant heat exchange cabin heaters helps to cool the engine. I'm thinking of installing one for the heat, but I'm also wondering if it might be helpful in an emergency? I mean, if the thru hull got plugged or the salt impeller failed, how much extra running time might this give you before the engine over heats? Has anyone tried running the Red Dot full blast with the thru hull closed to see how long it can keep the engine temperature down??
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Transferring Heat
The short answer is... a qualified maybe...
After all, similar to the main engine coolant-to-water heat exchanger, your cabin heater is also a coolant-to-air radiator.
Many many years ago i managed to drive 20 miles home in my old Civic on a 95 degree afternoon after the thermstat switch failed on my radiator fan --- by running the car's heater on high, at highest fan speed.
'Bout cooked the driver, even with all (2) windows open!
Temp guage would start heading for the Red Zone every time I stopped for a light, and receeded when I got 'er moving again...
At low speed or idle, your cabin heater might indeed be a get-home kinda engine cooler. Probably not....
YMMV.
Loren
The short answer is... a qualified maybe...
After all, similar to the main engine coolant-to-water heat exchanger, your cabin heater is also a coolant-to-air radiator.
Many many years ago i managed to drive 20 miles home in my old Civic on a 95 degree afternoon after the thermstat switch failed on my radiator fan --- by running the car's heater on high, at highest fan speed.
'Bout cooked the driver, even with all (2) windows open!
Temp guage would start heading for the Red Zone every time I stopped for a light, and receeded when I got 'er moving again...
At low speed or idle, your cabin heater might indeed be a get-home kinda engine cooler. Probably not....
YMMV.
Loren
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Brisdon,
Very good question. Now I am supposed to know the answer from my engineering background (or at least figure it out) , but maybe somebody has some real life experience that would be more usefull. I guess a good starting data point is that the 2 inch heat exchanger on my M25 is just barely able to meet coolant demand at full power.
And, testing by closing off the seawater coolant would not be a good idea. Would destroy the seawater pump impeller as well as overheat the exhaust system. And damage who knows what else.
Very good question. Now I am supposed to know the answer from my engineering background (or at least figure it out) , but maybe somebody has some real life experience that would be more usefull. I guess a good starting data point is that the 2 inch heat exchanger on my M25 is just barely able to meet coolant demand at full power.
And, testing by closing off the seawater coolant would not be a good idea. Would destroy the seawater pump impeller as well as overheat the exhaust system. And damage who knows what else.
That's a good point! You'd actually have to bypass the heat exchanger to test it without overheating the exhaust. But then I guess the second question is how long till the exhaust melts. Then again, if I didn't have salt water coming in and I were trying to run off a lee shore, I would rather melt my exhaust than cook my engine. Just wouldn't go down into the cabin while the exhaust is pouring from the hot cracked vernalift with the bare steel spiral clamped to it where the hose used to be. When I originally bought the boat ten years ago, that was the way I motored it home, so I know that trick works for at least two hours. (I had cooling water, it just went from the engine to the cushions, but that's another story.) I guess what I'll do is install the damned heater and then bypass the heat exchanger for a test and report back on how long it takes the engine temperature to climb. I'm suspecting that with my 20 horse, it will make some kind of a difference??
Heater Cooling Test
Brisdon,
That will be a very interesting test. A couple of points before you proceed.
1. These heaters all have some sort of capacity rating in BTU per unit of time. The bigger the better.
2. Most boats also have engine heated hot water tanks which will also help cool the engine, at least until they heat up and stop absorbing heat. So starting with a cold hot water tank will give you a longer test time till engine heatup.
3. The engine coolant load is a direct function of how hard the engine is working. Since the engine power output is a cube function of boat speed up to near hull speed, running a lower speeds/rpms also lowers the coolant load (and the exhaust temperature too) but;
4. Adequate coolant circulation thru the heater for good heat exchange means the engine needs to be turning up a respectable rpm (say 1500, still not sure on this). Some experimentation needs to preceed your test to find how many rpms will make the heater function "good enuf" for engine cooling.
That's all I can think of right now. Would be fun to watch you do this test. What part of country you in?
Brisdon,
That will be a very interesting test. A couple of points before you proceed.
1. These heaters all have some sort of capacity rating in BTU per unit of time. The bigger the better.
2. Most boats also have engine heated hot water tanks which will also help cool the engine, at least until they heat up and stop absorbing heat. So starting with a cold hot water tank will give you a longer test time till engine heatup.
3. The engine coolant load is a direct function of how hard the engine is working. Since the engine power output is a cube function of boat speed up to near hull speed, running a lower speeds/rpms also lowers the coolant load (and the exhaust temperature too) but;
4. Adequate coolant circulation thru the heater for good heat exchange means the engine needs to be turning up a respectable rpm (say 1500, still not sure on this). Some experimentation needs to preceed your test to find how many rpms will make the heater function "good enuf" for engine cooling.
That's all I can think of right now. Would be fun to watch you do this test. What part of country you in?
Well, the water tank is a small 5 gallons Isotherm, so it's insulated like George Bush. Probably won't supply much empathy to a hot engine, but I guess I should test it with a hot tank and cold tank, and see if I see a difference. That's a good point. Anyway, if I could do the math on the BTU's, then I could probably do the math on how much money I'm spending owning a boat, and that wouldn't serve me. I guess I'm just destined to do the physical test. We're down here in L.A. I'll check out the BTU's when I shop for the heater, and make sure that it can crank. Thanks for your ponderings Newgringo.
exoduse35
Sustaining Member
The long answer is that it is unlikely to make much if a difference! the engine has adequate cooling to survive producing maximum power (and it's byproduct- heat) under normal conditions. that translates to keeping the rise in temp of the raw water to under 150 degrees from intake to discharge. In an auto that has a thermostat of 190 degrees, and normally runs at 200 +or- with the heater off will still keep the thermostat open with it running full on. the area of the heater core is too small to make that big a difference. the boat is the same way the heat exchanger is vastly more efficient than the heater core and the volume of cooling air to remove heat. also, the overheating problem will come either from poor circulation meaning that the 'hot water' will stay in the engine and not get moved into the cooling core, Or from heat being generated into the coolant and overwhelming the system. This would typically come from the head gasket or a crack into the exhaust, both of which are above 500 degrees at the head, far, far beyond the 200 degrees that the heat exchanger can handle which is again far more efficient than the heater. The short answer is it probably won't help or not for long but in an emergency I'd try it if I needed to
Gary Peterson
Marine Guy
Your local engine selling distributor should be able to supply the BTU/hr information and the heater manufacturer the same. Your exhaust system would turn to mush pretty quickly as fiberglass doesn't like excessive heat much over 250 degrees.
The formula for determining BTU/hr content is: gph times delta T times a constant (8.33). It is necessary to use blocked open stats.
We had to do all of these heat rejection tests when we were developing marine cooling packages in the engine test cells. Very interesting work.
Radiated heat doesn't make much of a difference.
The formula for determining BTU/hr content is: gph times delta T times a constant (8.33). It is necessary to use blocked open stats.
We had to do all of these heat rejection tests when we were developing marine cooling packages in the engine test cells. Very interesting work.
Radiated heat doesn't make much of a difference.
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Update on E32-3 Heater Install
I originally post thet - "My first observation using this heater is that it does not work with the engine at idle. The engine gets hot but the heater does not. At cruising rpm it works just fine (which makes me wonder about my Universal Diesel water pump. Humm.". Now after the coolant system is fully purged of all air (the hoses go up, down and around) the heater does circulate and work fine at lower engine rpms. At 1200 it puts out heat just fine. My conclusion - A series plumbing with the hot water tank is a suitable arrangement.
I originally post thet - "My first observation using this heater is that it does not work with the engine at idle. The engine gets hot but the heater does not. At cruising rpm it works just fine (which makes me wonder about my Universal Diesel water pump. Humm.". Now after the coolant system is fully purged of all air (the hoses go up, down and around) the heater does circulate and work fine at lower engine rpms. At 1200 it puts out heat just fine. My conclusion - A series plumbing with the hot water tank is a suitable arrangement.