Adding Hotstart block heaters & Hydronic heater...

I was planning on switching out my current block heaters (Kat freeze plug style, screws into the block). Not a fan of their short life cycles and when they go out, the block basically needs to be drained and refilled to put the new ones in (big mess)...
That being said, I was thinking the HotStart TPS style might be a better option. I could add shut-off valves to allow for easy replacement when the time comes. I was also looking at the different wattage options. I am in the PNW (Washington) so temps don't get too ridiculous here... So, I was hoping to use a MUCH smaller wattage option then the recommended chart (1,800w). Currently I have a single 750 watt option on/IN each engine. I have them hooked up to temp switches that go on/off to regulate the temps to keep them right at about the mid-80's. If I just let them run, the temps can easily get up to about ~100° (or higher). Those single units keep the engines right about 82°-87° which in turn, also keeps the ambient temp in the boat sitting at about 55°-60° (which was a nice added benefit).
Would dropping the HotStart down to the 500w model/option still work in this scenario to keep everything at a decent block temp?
When I do the switchover, I was also wanting to add a hydronic heater to the mix. I am guess-timating about a 4'-5' rise from the top of the HotStart to the hydronic inlet. Where I am starting to second guess things is the coolant flow and how that might not work properly. The Hydronic heater would be above the coolant recovery tank, so wouldn't this cause the in/out flow to the tank to be off, due to the differing elevations? Or am I completely off since this is a pressure push/pull system???
Below is a ROUGH idea of what I was going to do...
Appreciate any thoughts or insight!!!

lol, anyone with any thoughts?

A lot to unpack here, what temps are you dealing with?, I am not familiar with your climate. Thermodynamics is pretty complex but when you really break it down, if you know how heat you are generating, it is just a matter of figuring out how much heat goes to your destination versus loses and how much heat is lost through the hull, windows, deck. My in-block style hot start runs at 1kw with no thermostat, in temps in the 30's, the boat stays above 50 with the engine room open in a pretty small trawler. Transmitting the heat to a bus heater will help heat reach your cabin versus soaked through the hull in the engine room but ultimately you will be limited to 1kw of heat with 2 500w units.

I can't speak to the details you are looking for, but I have 500w Hotstarts. I had them on Detroits and now on Cummins. I'm also am in the PNW. I run mine on timers, 2 hours off and on, alternating between engines during cold weather, as we are going to have in the coming week. I don't the temps, but the engine that's on is warm to the touch. This method keeps the ER about 20 degrees above ambient. I didn't answer your questions but maybe some side information will help you.

with regards to the heater elevation, i have a pretty large bus heater about 30 inches above my recovery tank. there's a set of valves so i can isolate and bypass it for system maintenance. i didn't plan or install it, it came with the boat. works really well with the engine heating it. with the block heaters powering it it might feel a little anemic.

So let me answer a few questions...
1. I am in Seattle, so outside temps generally never get much colder than 25°F.
2. I am not really concerned with the ambient temps getting warmer due to the block heaters (just a nice added benefit).

Ken- do you have the in-block ones or the TPS style (external)? I THINK the 500w option would work just fine, just wasn't sure about the external TPS version and it's ability to actually circulate the water well enough.

Bmarler- appreciate the info, that's one of my main concerns is the hyrdonic heater and it's interaction with the recovery tank...

Scott, I installed mine some years ago but as I recall they are simply a heating element like in a hot water tank. They screw into a port in the side of the block tapped with pipe threads. On b series Cummins, it's on the stbd side of the block. Easy installation. You will of course drain the block first and then refill.

Is your goal easier starting, freeze protection or warm salon area ?

Am not certain if my question is not the same but don't many of us have a hot weater that uses engine coolant to heat water while under way? Thinking out loud, why not reverse the process? Rig a simple pump such that cold coolant is run through an operating hot water heater's internal loop coil. Glitch? Would the engine thermostat block the flow? If it could work it would benefit only one engine. I am thinking in-the-water winterizing. Even with twins, a single warm block (140 degree water heater) would keep the entire engine room quite warm.

Benthic2-
Actually, lol, none of those reasons. My main reason is to eliminate the rather thick cloud of smoke when it's cold started from around Oct-May-ish here in WA.
The smoke generally goes away to almost nothing after a few mins. But once I added the heaters, I now have pretty much nothing at start, even on the coldest days...
Both my engines start within <1/2 second. Being in the lake here in WA keeps the ambient temp of the boat well above freezing, so also not really an issue. Warmer cabin was just a nice benefit I hadn't considered when I first installed the in-block style heaters.
Attached pic is one installed, one not. It wasn't particularly cold on the day of install, but still shows a very drastic difference between port/stbd sides...

Based on your graph, the existing Cat 750W immersion heaters with the temp set at 89º F. run at about a 50% duty cycle. You can expect a 500W immersion heater to run at about a 67% duty cycle. Over time you will use the same amount of metered electrical energy if you want to keep things max'd at 89º F, as there is no free lunch.

The Hotstart TPS system will likely run a little more due to the fact that it itself, is not in the engine block.

WRT trying to have a Hotstart TSP 500W element drive a Hydronic air coil with only it's thermosiphonic flow (ie, no pump) I doubt that you will get any significant heat to the engine and whatever heat you get out of the air coil first, will be disappointing. 500W is not very good for space heating.

If you go with the Hotstarts I would not return the coolant to the recovery tank unless you want to fill the bilge with coolant as at rest, the recovery tank is isolated from the engine block by the "Rad. Cap." Be safe and return the coolant too, from where it came from, the block.

Luna-
1. Not concerned with duty cycle or power consumption...
2. Not trying to use the TPS to do anything other than warm the block.
3. The hydronic heater questions were more about the flow of the coolant through the TPS and hydronic heater and it's ability to actually circulate through the block as intended.
4. The recovery tank question was about where it's located (elevation) and if the hydronic heater being located higher would have any adverse effects on the functionality of the recovery tank.

Hope that clarifies a bit more...

Unless your dock mates are complaining, I'm not sure I would do anything. It seems like a big effort to solve a small problem.

Use an external oil pan heater. Install to the bottom of the oil sump. They even have internal thermostats. 250 w leave on all the time (ones with stats self cycle) and it will take care of the problem you are having.

1 will reduce smoke
2 keep engine room condensation away.
3 low power consumption
4 your not messing with the antifreeze system

see pic and chart

Greg-
I've seen a lot of mixed reviews on these types. I will say it was mostly from people using them on vehicles/farm equipment and not boats...
I do like the simplicity of them and the even lower power draw is nice...
I was under the impression these mostly just heat the lower 1/3-ish of the block. And obviously, nothing would be circulating either, not that that is a deal killer...

Benthic-
I already have them (in-block style) and one of them has ran it's life expectancy. So that's getting replaced soon anyway. I was looking for other options, like the TPS version. Something that doesn't require drain/refill each time they need to be replaced... I like the no-smoke start-ups, as well as everything else that comes along w/ the heaters.

Have used the pad heaters for years. They heat the entire block and keep the ER warm . Takes time to work so they are on all the time.

The Zerostart installation instructions are pretty clear about removing paint from the oilpan for an install direct to metal. Has anyone installed directly to a painted surface? Any ill effects on performance?

If you read the spec sheet I posted you will see they range in temperature 200-300 deg. I'm sure its not a transition of heat issue, rather a failing of the paint and the unit falls off.

Scottwb96 said:

lol, anyone with any thoughts?

Click to expand...

What sort of lifespan we're you getting out of the in-block style? Just curious.

Greg QS said:

If you read the spec sheet I posted you will see they range in temperature 200-300 deg. I'm sure its not a transition of heat issue, rather a failing of the paint and the unit falls off.

Click to expand...

I have about two inches below the pan and stringers on either side. Installation alone will be a challenge never mind removal of paint. Wondering if anyone has had success with mounting to a painted surface.

Gdavid-
Right about ~2 years, which is what their tech at Kat's said I could expect. Obviously longer life would be nice, but they are relatively low cost to replace. Just not a fan of the mess of drain/fill of the blocks each time. External option (TPS style) would allow for shutoff valves to be placed in between.
While looking for an option to buy, I found this one at Napa. Had a 25% discount for black friday. Figure I will give it a shot and see what happens...

https://www.napaonline.com/en/p/KAT13080?impressionRank=8

Scottwb96 said:

Gdavid-

Right about ~2 years, which is what their tech at Kat's said I could expect. Obviously longer life would be nice, but they are relatively low cost to replace. Just not a fan of the mess of drain/fill of the blocks each time. External option (TPS style) would allow for shutoff valves to be placed in between.

While looking for an option to buy, I found this one at Napa. Had a 25% discount for black friday. Figure I will give it a shot and see what happens...



https://www.napaonline.com/en/p/KAT13080?impressionRank=8

Click to expand...

In Post #9, I posed a question (no responses) about maybe using a hot water heater equipped with an engine coolant loop and a pump as sort of a reverse cycle engine heater. I was concerned that the engine thermostat would impede the flow. Apparently not because this product does much the same. Available at Tractor Supply for $54.99. It draws 1,500 watts.

I'm surprised the block heater fails so quickly. I would expect it to last for at least 10 years, if not the life of the engine.


What sort of life span do others get from block heaters?

catalinajack said:

In Post #9, I posed a question (no responses) about maybe using a hot water heater equipped with an engine coolant loop and a pump as sort of a reverse cycle engine heater. I was concerned that the engine thermostat would impede the flow. Apparently not because this product does much the same. Available at Tractor Supply for $54.99. It draws 1,500 watts.

Click to expand...

I am sure it would work, my water heater is tied into the coolant loop but located back in n the lazarette, there is at least 8' of uninsulated heater hose that feeds it. Even without a pump circulating the coolant, the water in my water heater was still hot enough to scald due to my block heater (in block style, no pump). When I winterized my potable water system, I was surprised just how effective it was warming it, the temps were in the low 30's and my lazarette is not insulated in any way but the water temps were still above 50 degrees).

This looks like a good option for block heaters.

https://phillipsandtemro.com/wp-content/uploads/2016/09/LIT0018P_Thermostat-Immersion-Guide_LR.pdf

https://phillipsandtemro.com/soluti...ctric-immersion-heaters/engine-block-heaters/

Pocoron said:

I have about two inches below the pan and stringers on either side. Installation alone will be a challenge never mind removal of paint. Wondering if anyone has had success with mounting to a painted surface.

Click to expand...

Use a mini grinder with a wire wheel to remove the paint. The units heat up to 300 deg and can melt the paint and it falls off.

Scottwb96 said:

Gdavid-
Right about ~2 years, which is what their tech at Kat's said I could expect. Obviously longer life would be nice, but they are relatively low cost to replace. Just not a fan of the mess of drain/fill of the blocks each time. External option (TPS style) would allow for shutoff valves to be placed in between.
While looking for an option to buy, I found this one at Napa. Had a 25% discount for black friday. Figure I will give it a shot and see what happens...

https://www.napaonline.com/en/p/KAT13080?impressionRank=8

Click to expand...

That seems odd. Had internal block heaters in my last Boat for 12 years and still working when I sold it.

if you have a air compressor you can rent a cooling evacuation tool from most auto parts stores that will hold the cooling system under a vacuum while you can quickly change out a sensor or block heater, I used to use them on semis with 10 gal. system capacity with no problem i would think it would work on a closed loop marine system as well.

Heated dipsticks might be another option.

https://www.amazon.com/Kats-Dipstic...mzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840