Heater Core installation for cockpit heat

A

AllTideUp

Member
May 6, 2013
198
Northern Virginia
Boat Info
2003 SeaRay 380 Sundancer
Engines
8.1s - 370HP
I've seen this on a boat I looked at years ago but didn't get the details of the install.

I was curious if anyone installed/added a heater core to one of their main engines to add heat to the cockpit for cooler weather running. I was looking at a 28k BTU heater install.

In the cooler weather we usually just run a 1500w electric heater in the cockpit but thats ~5k BTU and doesn't well really underway.

I was looking at this https://www.jegs.com/i/JEGS/555/70601/10002/-1

It looks like it will do the job but wondering how to "T" off the coolant as I doubt it would offer sufficent flow to take all the coolant through it and probably just need a small amount.

Thoughts?
 
Do you have a hot water heater that is fed from the engine? Not sure how much flow you would need (at a given temp) to achieve a specific BTU.

Dual engines - one for hot water, one for a warm cockpit?
 
Used to be a member (Nehalennia?) that, as best I remember, installed some sort of heater in his cockpit. You might try searching his posts to see what he used.
 
Windjammer said:
Used to be a member (Nehalennia?) that, as best I remember, installed some sort of heater in his cockpit. You might try searching his posts to see what he used.
Click to expand...
Your spelling is about what mine looked like. Yes, he did add a hydronic heater to his 260 Sundancer, basically an old school heater box with core and fan and some ducting. Big issue is the cold air source. It can’t be pulled from engine compartment because of CO contamination risk.

The other solution is to do what is done in the pilot house of our boat, two AC units that have reverse cycle capability. Of course this also requires a genset if you want to use it while underway.
 
I don't see why it wouldn't work ...

I had older British cars that were set up to draw in outside air and the fan would push it across the heater core, but that wasn't even hooked up anymore and it worked fine. Essentially it's just a 1/2" heater hose loop to and from the engine, a heater core in a box with a flap on it, and a basic fan. My Minis had a valve on the engine (controlled by a dash knob) so you could shut off the flow to the heater core if you want to. THat's probably because the heater box was under the dash and exposed. So if you are out running the boat and it's hot outside, now you've got this extra heat source that is being fed hot water or coolant as long as the engine is running.

On a 380 you've got a much bigger cockpit than the size of the interior on the average car but I'm sure it would provide some heat.

On my setup, the stbd engine feeds the hot water heater when it's running so that leaves the port engine available. If it were me, I'd mount the heater box aft closer to the bilge to keep the length of hose to a minimum. I guess if you've got the space in the bilge, and the fan is ignition-protected since you're on gas, you could mount that in the bilge and run insulated ducting up to vents in the cockpit. Now I want to do this :)
 
markrsimon said:
Do you have a hot water heater that is fed from the engine? Not sure how much flow you would need (at a given temp) to achieve a specific BTU.

Dual engines - one for hot water, one for a warm cockpit?
Click to expand...


Unfortunately in the 380 the water heater is located under the aft birth and SR did not extend the coolant lines from the engine to heat the water, so hot water is electric only.
 
Henry Boyd said:
Your spelling is about what mine looked like. Yes, he did add a hydronic heater to his 260 Sundancer, basically an old school heater box with core and fan and some ducting. Big issue is the cold air source. It can’t be pulled from engine compartment because of CO contamination risk.

The other solution is to do what is done in the pilot house of our boat, two AC units that have reverse cycle capability. Of course this also requires a genset if you want to use it while underway.
Click to expand...


Thanks, I'll try looking them up. I'm trying to stay away from having to always run the gen and use this for booze cruising and just later in the year. No real need for it right now as summer is coming but I'm thinking for fall. I'd also look to put it either behind the bar on the port side as there is alot space back there or under the forward bench as I could put ducts to the helm floor and aft.
 
Phil S said:
I don't see why it wouldn't work ...

I had older British cars that were set up to draw in outside air and the fan would push it across the heater core, but that wasn't even hooked up anymore and it worked fine. Essentially it's just a 1/2" heater hose loop to and from the engine, a heater core in a box with a flap on it, and a basic fan. My Minis had a valve on the engine (controlled by a dash knob) so you could shut off the flow to the heater core if you want to. THat's probably because the heater box was under the dash and exposed. So if you are out running the boat and it's hot outside, now you've got this extra heat source that is being fed hot water or coolant as long as the engine is running.

On a 380 you've got a much bigger cockpit than the size of the interior on the average car but I'm sure it would provide some heat.

On my setup, the stbd engine feeds the hot water heater when it's running so that leaves the port engine available. If it were me, I'd mount the heater box aft closer to the bilge to keep the length of hose to a minimum. I guess if you've got the space in the bilge, and the fan is ignition-protected since you're on gas, you could mount that in the bilge and run insulated ducting up to vents in the cockpit. Now I want to do this :)
Click to expand...

I'm pretty sure the small heater cores that I'm finding the UTV ones from JEGS would work nicely, I just need to figure out if I can T off the coolant line and join it back down the line as the lines on those heater cores are smaller than the main ones on the main.
 
My '95 220 OV Sig Select came with the cockpit heat setup. Just uses two hoses off engine water system, a blower box with some outlets off of it and fan speed switch at the helm.

The provisions for the water lines are on the the engine already (one on the circ pump and one on the elbow / stat housing) and just need to remove the plugs and install barb fittings for the hoses.

Kinda rudimentary, as one regulates the temp by opening and closing a ball valve located under the Port side trim panel next to the seat.
 
You might also have plugs on the top of the engine (the 5.0 does). Then you could install 5/8 barbs and run a loop to the heater core. I think the ones going to the HW heater are 1/2" but you should be able to get 5/8"

Or as Bill said use the other ones -- anything that's tied in before the thermostat so you get heat right away.
 
I think the only downside would be if your engines run on the cooler side (mine are 160), you won't get as much heat as a modern car/truck running 190-200F.

Summit seems to have a lot more options -- including a 40,000 Btu one for a few bucks more.
 
Last edited:
Phil S said:
You might also have plugs on the top of the engine (the 5.0 does). Then you could install 5/8 barbs and run a loop to the heater core. I think the ones going to the HW heater are 1/2" but you should be able to get 5/8"

Or as Bill said use the other ones -- anything that's tied in before the thermostat so you get heat right away.
Click to expand...


Interesting, I have Merc 8.1s so I'll have to see if I there is something already on the motor I can use vs adding a "T" on one of the lines.
 
Phil S said:
I think the only downside would be if your engines run on the cooler side (mine are 160), you won't get as much heat as a modern car/truck running 190-200F.

Summit seems to have a lot more options -- including a 40,000 Btu one for a few bucks more.
Click to expand...

I think even if the motor was 160 that would be plenty to heat up the cockpit for a cruise with the enclosure up. I'm not looking for it to be 90 degrees in there but if it could reach 70 that would be outstanding for spring and fall comfort.
 
They put the hydronic ones in ski boats all the time. You can connect them to the engine to circulate hot water/coolant and the fan is 12v. I had one factory in my 95 300DA and it worked great. Had a vent on the dash brow to defog the windshield. I have a friend that has several of those models they sell on Jegs in his warehouse that he would let go of for less than retail if you are interested.
 
Cocktail Time said:
They put the hydronic ones in ski boats all the time. You can connect them to the engine to circulate hot water/coolant and the fan is 12v. I had one factory in my 95 300DA and it worked great. Had a vent on the dash brow to defog the windshield. I have a friend that has several of those models they sell on Jegs in his warehouse that he would let go of for less than retail if you are interested.
Click to expand...

Interesting, why would ski boats want a heater like this? cold water when they get out? When you say hydronic ones, your meaning the ones like I'm talking about on Jegs? I saw a few different makers but are there better ones than the Jegs? the size of them seemed to fit what I'm looking for which is why I called them out specifically.

I have to pass this idea by the admiral before I execute it. I haven't really gotten far in my planning yet as I've really only thought about it for a day lol.
 
AllTideUp said:
Interesting, why would ski boats want a heater like this? cold water when they get out? When you say hydronic ones, your meaning the ones like I'm talking about on Jegs? I saw a few different makers but are there better ones than the Jegs? the size of them seemed to fit what I'm looking for which is why I called them out specifically.

I have to pass this idea by the admiral before I execute it. I haven't really gotten far in my planning yet as I've really only thought about it for a day lol.
Click to expand...
Ski boats like them because there are retractable hoses that can connect to stick into a wetsuit to warm people up. I asked the same thing. Hydronic just refers to how the air is heated. Instead of electric heating Hydronic uses hot water or coolant passing over a radiator to provide heated air and a 12v fan blows the hot air out. The Jegs ones are exactly what I was talking about. A buddy had an online store that he has shutdown and has some still in the box in his warehouse.
 
Our 245 came with a bus heater under the step when entering the cabin. It is set up to just recirculate the cabin air and not try to pull the cool outside air in. We live in the north and heat is nice when trying to extend the season so it was used whenever we could. It was free heat while the main engine is running, but that's it. In my opinion, if you are going to the efforts and expense of installing a heater, pick one that doesn't require the main engine running at operating temperature.
We installed a cheep Chinese copy of a Wabasto from amazon a couple seasons ago for the same price as a bus heater. It hasn't skipped a beat. Pretty much instant heat. Push a button and select your temp, push it again to power off. The whole system with exhaust through hull and multiple duct/vents was about $400 CAD. Haven't used the bus heater this year in the 10 days we have been out. The little forced air diesel heater has been on for all of but a few warmer afternoons on those trips.
Something else to think about if you haven't.
 
Thornton69 said:
Our 245 came with a bus heater under the step when entering the cabin. It is set up to just recirculate the cabin air and not try to pull the cool outside air in. We live in the north and heat is nice when trying to extend the season so it was used whenever we could. It was free heat while the main engine is running, but that's it. In my opinion, if you are going to the efforts and expense of installing a heater, pick one that doesn't require the main engine running at operating temperature.
We installed a cheep Chinese copy of a Wabasto from amazon a couple seasons ago for the same price as a bus heater. It hasn't skipped a beat. Pretty much instant heat. Push a button and select your temp, push it again to power off. The whole system with exhaust through hull and multiple duct/vents was about $400 CAD. Haven't used the bus heater this year in the 10 days we have been out. The little forced air diesel heater has been on for all of but a few warmer afternoons on those trips.
Something else to think about if you haven't.
Click to expand...


I've looked at the diesel heaters as well but I'm really just looking to add heat while we are actually moving from the dock. Our boat has 2 built in heater already but to use them when I'm away from the dock means I'd have to run the generator which I'm just looking at alternatives to. When I'm at the dock I'll just plug in and use the existing system and add a small electric heater to the cockpit but when underway I could use the "free" (and I use the term loosely lol) heat from the engine to make the ride comfortable and spare the gen hours and fuel.
 
Heater connections at engine. This pic is for closed coolling, but you get the idea

Mercruiser specific engine manuals have this, too.
 

Attachments

  • SBC cooling-system.jpg
    SBC cooling-system.jpg
    46.4 KB · Views: 288
You must log in or register to reply here.

Forum statistics

Threads
113,095
Messages
1,425,825
Members
61,017
Latest member
IslandGirls1020
Back
Top