Hydronic diesel heater to yanmar 3gm30f and califor hot water tank?

[Mg451]

I'm looking to add a chinese hydronic diesel heater

Diesel Water Heater 5KW 12V, Diesel Parking Water Heater Complete Kit w/Remote Control and LCD Switch, Hydronic Heat Conduction Coolant Heating Engine for Trucks, Vans, RV Trailers, Cars, Motorhomes https://a.co/d/hNCCd7G

To my coolant loop in my yanmar 3gm30f. Currently my coolant loops off the coolant pump to my hot water heater for heating my domestic hot water. I'd like to run the tiny diesel heater to heat the hot water instead. This way save engine hours and less diesel fuel. I will have a way to isolate it in case of failure etc and I understand the chinese " junk " debate.

I'd also like to use it to circulate hot coolant through my engine in the winter tine so my engine will be preheated for start up , I'm not sure if my tstat will stop the coolant form getting to the engine block or not. I'm also concerned with short cycling due to the coolant not giving off enough of its heat before it returns to the heater, causing a shut down like this video.

https://youtu.be/Tr5hODbLKUA?si=ZAj3J83cG8Hs41qm


Has any one tried this?

[SailingHarmonie]

What problem are you trying to solve with this "creative" plumbing to your engine?

There is an awful lot that can go wrong with the modification you suggest, some of it subtle and installation specific. I see no value to it, especially since circulating hot water in the block will do little to warm the cold oil in the crankcase which is the REAL starting problem.

A block heater for an engine like yours becomes important only at temperatures below -10F (-20C)-- temperatures I am pretty sure you are not using your boat in. Using the right oil is far more important at boating temperatures. If your engine is hard starting at temperatures where the water around your boat is not frozen solid, there is something wrong with your engine.

If you really want to keep the engine warm, just add a hydronic heating zone to the engine room, or add a purpose built block heater instead of adding a lot of complexity combining two systems that were not designed to connect to each other.

But again, if you are not freezing your raw water circuit in the engine, you don't need to do this no matter how cool an idea you might think it is.

[Mg451]

It's pretty easy and cheap to add. They're designed to do just what I've mentioned and having hot domestic water with the added bennifit of warming the engine will make the engine last longer, and start easier. Working outside with various diesel equipment in the north east I know even at 40 degrees diesels are harder to start. The oil isn't the problem is the cold combustion chamber. These heaters are added in the coolant loop with a circulator pump to keep coolant circulating and warm. However my main use of it is to keep my domestic hot water ( which is already looped into my engine ) hot. Abs secondary bennefit would be to warm the yanmar up in colder weather for easier starts

[more]

Originally Posted by Mg451

It's pretty easy and cheap to add. They're designed to do just what I've mentioned and having hot domestic water with the added bennifit of warming the engine will make the engine last longer, and start easier. Working outside with various diesel equipment in the north east I know even at 40 degrees diesels are harder to start. The oil isn't the problem is the cold combustion chamber. These heaters are added in the coolant loop with a circulator pump to keep coolant circulating and warm. However my main use of it is to keep my domestic hot water ( which is already looped into my engine ) hot. Abs secondary bennefit would be to warm the yanmar up in colder weather for easier starts

also easy you can heat your boat ad in loop couple kalori https://www.heatso.com/kalori-kuba-v...er-3-25kw-12v/

[SailingHarmonie]

Originally Posted by Mg451

It's pretty easy and cheap to add.

So just go ahead and do it, but apparently it is not so easy you know how to do it..

Originally Posted by Mg451

Working outside with various diesel equipment in the north east I know even at 40 degrees diesels are harder to start.

But the engine in your boat is not outside. it is in the engine room, that is likely rarely--if ever going to be 40F--if you are heating the rest of the boat. If your little Yanmar is at all hard to start at an outside air temperature of 40F, I'd strongly suggest a compression test, and/or a battery check. Certainly my 10,000 hour Volvo TMD22 fires up without any issue at outside air temperatures of 40F, even without using the glow plugs.

But it is your boat. I am pointing out you are solving a problem that is not really a problem with boats. An awful lot of diesel cars and trucks seem to do just fine at 40F.

But it is your boat. If you decide that your engine needs this for some reason, you do not need to worry about your thermostat, assuming you connect to the right places in your engine cooling loop. You do not need to flow through the heat exchanger to preheat the engine.

You also need to be sure that when the engine is running, you do not have flow bypassing the heat exchanger, and there are no places where you can airlock the system, preventing you from filling it completely. No evaluation of these issues is possible with the details of your piping, and the two pieces of equipment involved.

There is no issue I see with the water heater, except making sure that the heating coil fills properly without air gaps.

[Mg451]

The problem I'm trying to solve is to heat my hot water with out running the engine or the inverter. PreHeating the engine was an aftert hought since every thing is pretty much in place to do so and I figure it would stop the heater from shortcycling due to it not giving off enough heat in the domestic exchanger loop.

[Bellinghamster]

I installed a system to do that on my boat. I have an Eberspacher 5kw hydronic "parking" heater along with my Yanmar (4JH4-TE) so that either one can heat a hydronic loop, which passes through the domestic water heater tank then through small hydronic "air handlers" (finned coil and a fan) in each cabin. Each air handler fan is controlled by a thermostat in that cabin, giving effective zone heating..

The hydronic system and engine coolant are separated but "thermally coupled" by a brazed-plate heat exchanger. The engine water pump circulates engine coolant through one side of the the heat exchanger via the "heater" ports on the engine anytime the engine is running The hydronic loop is circulated by the hydronic diesel heater water pump whenever the heater is running, or with a second in-line water circulation pump for when the engine is running and I want to heat the domestic hot water or the boat. I have a valve I can open to bypass most of the hydronic loop to it just goes through the domestic water heater and doesn't circulate around the boat (in case I ever go somewhere warm and don't want to add heat the boat while making hot water).

It doesn't specifically/intentionally preheat the engine block, but could probably be made to simply (albeit slowly) via thermosiphon (hot water rising) if the heat exchanger was oriented vertically, or by adding another 12V circulation pump in the engine heater hose to the plate heat exchanger.

I could have maybe used the parking heater water pump for both modes, powered either from the heater, or from a manual switch. I wasn't sure at the time of design whether it was a simple 12VDC pump (it has extra wires, maybe for sensing RPM).

The hydronic loop is 5/8 PEX tubing which conveniently has 3/4" OD so short lengths of 3/4" heater hose are used for connections, simply slipped over the pex and secured with hose clamps. I'm using propylene glycol (non-toxic) antifreeze in the hydronic loop for added safety.

It works fantastic. We joke that we can now take endless hot showers (until the water, battery or diesel runs out...). It extended our comfortable sailing season a couple months in spring and fall, heats the domestic hot water tank as fast as the engine did (15-20 minutes). The hydronic heater I have throttles back as the loop comes up to temperature and draws 3-4 amps (12v system) while running including a couple air handler fans. The only downside is the Eberspacher heater controller is a little finicky to use - you have to set a run time (in minutes) or set it up to it on a daily schedule, not as simple as just turning it on and off.

I highly recommend buying better quality exhaust hose and muffler than what comes with the cheap heaters (or even the Eberspacher / Webasto kits) since those are intended the be installed outside the living space in a vehicle and can leak exhaust (which can kill you). You want high quality stainless flex tube and a fully-welded muffler and proper through-deck fitting. It's expensive but necessary. Sure Marine in Seattle sells all the bits needed.

I got the heat exchanger from Amazon, search for "AB Plate Heat Exchanger, 3"x8" 20 Plates Water To Water Heat Exchanger, Copper/SS316L".

12V Circulation pump also from Amazon, "Johnson Pump 3/4 in. CM30P7-1 Centrifugal Pump 10-24489-03". Note: This probably has higher flow than necessary . I could have used a smaller/lower current pump like "Johnson Pumps 10-24487-03 CM10P7-1 5.0 GPM Circulation Pump with 3/4-Inch Port ", but plenty of 12V power is available when the engine is running so it doesn't really matter..

Peak SIERRA Full Strength Antifreeze + Coolant (Propylene Glycol with corrosion inhibitors)

[Dockhead]

Hydronic heaters on boats are not usually plumbed into the engine fresh water loop -- unlike the way it's done on trucks and cars.

Normally you want a separate loop for the hydronic heater. You can also space heat off this loop using radiators or fan coils.

Calorifiers with two separate coils are sold so that you can have a loop running with engine fresh water AND separately from your central heating loop. That's how my boat is set up.

If you don't have two loops in your calorifier and don't want to change it, then you could add a heat exchanger to transfer heat from the main engine coolant to your central heating loop.

[Mg451]

Thanks. Wasn't aware of the 2 heat exchanger califor or the a/b heat exchanger seperating engine and diesel heater loops. It's awful tempting to just plumb them together

[Bellinghamster]

I considered plumbing them together but was concerned about dissimilar metals, hydronic leak causing loss of engine coolant, potential difficulty bleeding air, etc. Also, you may want to make hot water without heating up your engine block (wasted energy/time). Also engine coolant runs ~180 degrees F, which is pretty hot for hydronic system. You could throttle the heat exchanger (with a thermostat in the return-to-engine heater hose) to reduce the loop temperature if desired. Separate systems with their own header / expansion tanks makes monitoring for leaks easier (or at least easier to narrow down). I have a (not so technically minded) friend who had a "common" coolant system on his boat - a slow hydronic leak caused low engine coolant alarm, so he'd top up with water. That practice over time eventually diluted his antifreeze ratio enough that his engine block froze and cracked in a cold snap + power outage. That said... If your system is simple, i.e. doesn't have hydronic boat heating loop, just engine + waterheater + parking heater, I'd be tempted to plumb them together as well with the parking heater installed in the loop to the water heater. downside is it'll delay water heating if your engine is cold.
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[Dockhead]

Originally Posted by Bellinghamster

I considered plumbing them together but was concerned about dissimilar metals, hydronic leak causing loss of engine coolant, potential difficulty bleeding air, etc. Also, you may want to make hot water without heating up your engine block (wasted energy/time). Also engine coolant runs ~180 degrees F, which is pretty hot for hydronic system. You could throttle the heat exchanger (with a thermostat in the return-to-engine heater hose) to reduce the loop temperature if desired. Separate systems with their own header / expansion tanks makes monitoring for leaks easier (or at least easier to narrow down). I have a (not so technically minded) friend who had a "common" coolant system on his boat - a slow hydronic leak caused low engine coolant alarm, so he'd top up with water. That practice over time eventually diluted his antifreeze ratio enough that his engine block froze and cracked in a cold snap + power outage. That said... If your system is simple, i.e. doesn't have hydronic boat heating loop, just engine + waterheater + parking heater, I'd be tempted to plumb them together as well with the parking heater installed in the loop to the water heater. downside is it'll delay water heating if your engine is cold.
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I generally agree with all this, and for all the reasons stated.

I would lean towards a separate loop, and add some radiators. Why not? You've already got everything else for a central heating system.

You may be delighted to find your season extended.

I sail all year round and in cold latitudes to boot, and the central heating system is mission critical and a real joy to have.

[Dockhead]

Originally Posted by Mg451

Thanks. Wasn't aware of the 2 heat exchanger califor or the a/b heat exchanger seperating engine and diesel heater loops. It's awful tempting to just plumb them together

As Bellinghamster said, you can just plumb them together if you're not going to do space heating with the system, and you're willing to accept the (many drawbacks).


But you're 90% of the way to have central heat on board -- why not go the last 10%?

[Bellinghamster]

I had to look up my heater model: Eberspacher S3 D5E. The $200 one you linked looks very similar and is about 1/4 what I paid.. cheap enough to carry a spare rather than worry about spare parts!

Mine throttles back as the loop temperature rises, then if temperature keeps rising it shuts down but keeps the water pump running. When the loop cools down a bit (don't remember the temperature thresholds, but something like 20F below the shutdown temp) it fires back up. This only happens on my boat if it's been running for a few hours, water tank is fully hot, all cabin thermostats are satisfied their rooms are warm and so turn off the fans. One additional comment: it runs ignition glowplugs during startup and shutdown which draws around 12A for maybe 30 seconds. Make sure to size wiring appropriately.

[Mg451]

Does it have a loud ticking fuel pump like the air heaters? I think I'm gonna add radiators and remove my domestic hot water from the engine add it tonthe diesel heater loop with 2 radiators. Ill go back and add the a/b plate exchanger to the diesel heater loop to capture heat from running the motor. to remove any type of room for all the mishaps described.

[Mg451]

I really did like the idea of keeping my yanmar warm and toasty.����.