Espar Hydronic 10 Diesel Heater System Design

[Bellinghamster]

As other have said, I see no reason to have individual water pumps for each radiator in small (under 60ft) boat installation.

I'm currently preparing to installing a hydronic heater: Espar S3 D5E (5kw/17,000 btu) with 3 radiators (with with low-current 12V computer style 130mm tubaxial fans controlled by the thermostats in each zone) all in series via PEX tubing.

I'm going to run caliorifier output from the engine throught a "brazed plate" heat exchanger (this one: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1) (316ss, and UL recognized) to keep engine and heater antifreeze separate. This heat exchanger will be located at the cool/input side of hydronic heater so the heater will throttle down or turn off if there is sufficient engine heat being added to the heating loop. Polypropylene Glycol in the hydronic loop as other mentioned, to reduce the risk if it leaks into the hot water heater.

The "loop" starts and ends with an expansion tank, mounted higher than everything so any air will purge out there. The water pump (mounted lower than everything) draws from the expansion tank (so it won't every air-lock), pushes through the plate heat exchanger -> hydronic heater -> hot water tank heat-exchanger. (note: the pump drawing from the expansion tank also puts it at the "coolest" point in the loop, which will hopefully extend it's life)

In summertime, the flow can then be valved back to the expansion tank for another trip through the pump-> the plate heat exchanger-> hydronic heater-> water tank -> expansion tank.
In wintertime, instead of looping back after the hot water tank it'll be valved to the heating circuit flowing through all water-to-air heat exchangers in series, then back to the expansion tank.
I plan to only use 1 circulation pump, controlled automatically by the heater (on when the heater is running) OR via a manual switch (to get hot water or cabin heat if the engine is running and the heater is OFF).

The downside of runnning through the hot water heater before the heating loop is that the water tank has to heat up first before the cabin heaters start putting out appreciable heat (I calculated about 20 minutes for everything in the heating circuit, including the contents of the 6 gallon hot water heater to reach 130F from 50F)

I *might* try the water tank on the other end of the heating loop (after the water pump, before the plate heat exchanger) which will make it act as a "thermal battery" so that heat can be pulled out of it for a short while before the hydronic heater relights, possibly reducing ignition cycles. (The Espar S3 5DE throttles between about 5kW and 1.3kW as necessary to maintain water temperature, and turns the fire off if the temperature continues to climb due to low heat withdrawl from the loop. It continues to run the water pump, so any zone that wants it can blow heat simply by turning on the fan) None of the recommended installation diagrams I've seen show it that way, but I think they all assume you want domestic hot water as a priority.

Be sure to let us know how it turns out... and we like pictures!

[calmissile]

Bellinghamster,

Thanks for the details. This is the kind of stuff that makes the forums so worthwhile.
I will draw out a schematic from your text so I have an idea of the configuration. That heat exchanger is quite something. I thought it would be way to small, but looking at the specs it seems like the real deal. I might order one.

Since I am 17 hours away from the boat, I am going to gather all the stuff I need to complete the installation when I next go to the boat. Should be relatively easy to complete this part of the project with everything in hand.

Thanks again,
Doug

[calmissile]

Using Belinghamster's description, I threw together a block diagram of how I think I can make this work. Open for comments on the design.

https://imgur.com/a/YrMUNtF

Some comments about the layout....
1. All of the radiators and fans are already installed.
2. The cockpit radiator is the highest point of the system.
3. The current expansion tank is installed next to the heater and is located on the starboard side of the salon (saloon?). The tank and heater are about 4-5 ft below the cockpit radiator.
4. This layout moves the expansion tank up to the cockpit locker adjacent to the cockpit radiator.
5. The cockpit would be the most difficult to heat in cold weather even though it is fully enclosed (when desired). That is why I routed the hot water line to the cockpit first.
6. The order of routing is what I expect to be the easiest path throughout the boat.
7. The diverter valve is to implement the "summer mode" as Bellinghamster described in his design. It simply bypasses the radiators but allows the engine to heat the fresh water when the heater is not turned on.
8. The only concern I have (at first blush) is the optional pump which is necessary to have hot water and heating from the engine only (diesel heater turned off). The flow rate of the Espar Hydronic 10 is spec'd at 370 Gal/Hr. It seems to me that any restriction in the flow caused by this optional pump (when not running) might create some unnecessary load on the pump in the heater unit.
9. The heater unit does not appear to have connections to allow the internal pump to be powered externally. Since the heater operation is fully automated I am hesitant to break into the circuit to force the pump to operate when the heater is turned off.
10. If the flow rates of the heater pump and the optional pump were fairly well matched, I think I could use a switch and wire it so that the aux blower line coming from the heater would power the aux pump when the heater is on, and when it is off the switch could be thrown to manually power the pump when in Engine Only heating mode. Will have to give it some more thought.

Comments?

[bcboomer]

Originally Posted by calmissile

Using Belinghamster's description, I threw together a block diagram of how I think I can make this work. Open for comments on the design.



Some comments about the layout....

8. The only concern I have (at first blush) is the optional pump which is necessary to have hot water and heating from the engine only (diesel heater turned off). The flow rate of the Espar Hydronic 10 is spec'd at 370 Gal/Hr. It seems to me that any restriction in the flow caused by this optional pump (when not running) might create some unnecessary load on the pump in the heater unit.


Comments?

We have a 2nd pump in line for when the furnace is off and it doesn't restrict the flow.
I agree with not cutting into the Espar wiring. Their controller is hyper sensitive and any voltage change could shut it down.
We just switch the auxillary pump on when the engine is running.

[Cgstock]

Originally Posted by Bellinghamster

I'm currently preparing to installing a hydronic heater: Espar S3 D5E (5kw/17,000 btu) with 3 radiators (with with low-current 12V computer style 130mm tubaxial fans controlled by the thermostats in each zone) all in series via PEX tubing.

What size boat is this going on? I'm currently debating between a S3 D5 or the M12. I have a 38ft sailboat and seem to be right in the middle of what each is rated for. But I hear a number of people say the S3 D5E puts out plenty of heat for this size sailboat. Keep in mind I will be sailing in northern areas, but I'm insulating the hull everywhere I can. Interested to hear your thoughts. Chris

[bcboomer]

Depending on how far north and for how long be aware it has an expected service life of 3000 hours. You may need to carry a spare as they are not easy to work on.
Here in the Georgia Strait my Espar D5E didn't last a year without breaking down and took weeks to get a warranty repair.
On our boat it is enough heat down to about 5 degrees C.
we seldom leave the marina when it is that cold so it is enough heat.
Take a look at Planar. In my experience they are more reliable and they are definitely easier to repair.

[Bellinghamster]

Originally Posted by Cgstock

What size boat is this going on? I'm currently debating between a S3 D5 or the M12. I have a 38ft sailboat and seem to be right in the middle of what each is rated for. But I hear a number of people say the S3 D5E puts out plenty of heat for this size sailboat. Keep in mind I will be sailing in northern areas, but I'm insulating the hull everywhere I can. Interested to hear your thoughts. Chris

It's going on our 50ft Gulfstar ketch. I know it seems small (you can literally hold it in the palm of one hand!), but we're just looking to take the chill off and extend the seasons in the PNW and be able to make hot water without running the engine, not aiming for toasty warm when it's below freezing.

We're not (currently) living aboard, and won't likely go out if it's below freezing.

I actually have, and *almost* installed, a Hurricane 45 (about 38000 BTU heat output), but after much internal debate decided it was too much capacity, would take up too much precious space in the engine room, use too much power and make more noise compared to the little 5kw/17000 BTU Eber. I'm basing my estimate of needed capacity on the fact that two 1500W electric space heaters (on shore power) make the boat fairly comfortable with outside temps in the low to mid 40's (F). An additional 2kw above that should be adequate to warm up a cold boat and keep it comfortable, plus using waste heat from the engine to help get things warm when motoring out of the marina will help... I'll know for sure in a couple weeks!

After some additional thought and reading comments here, I like the idea of a second water pump to be able to circulate engine heat with the heater off... simpler wiring and some redundancy, also could be used to boost flow if needed during peak heating.

[Bellinghamster]

calmissile - nice diagram! My only concern with your layout is the potential to airlock the water pump. If you get a bubble in the line through the heaters, when it makes it was to the pump intake it'll likely cause the pump to airlock and stop circulating. Maybe having the two pumps in series mitigates that risk, since the other pump will push the air bubble through the locked pump. I get why you're doing it that way and the height challenge.

I am also considering adding another radiator/fan blowing into the cockpit, debating whether to mount the radiator high, or just duct the air up from a low-mounted radiator so I can keep the expansion tank low enough in the engine room to easily check and fill it and still have it serve as the bubble collection point.

[Cgstock]

Originally Posted by Bellinghamster

After some additional thought and reading comments here, I like the idea of a second water pump to be able to circulate engine heat with the heater off... simpler wiring and some redundancy, also could be used to boost flow if needed during peak heating.

Ahh, okay. I'm looking to heat my boat to live on it. I'm in Philadelphia now but will be going north to the Nordic Countries in a few years, so I want heat. I do plan on having a second pump to use the engine to heat the water for the radiators, but when sailing I obviously hope to not be using the engine as much as possible.

[bcboomer]

Originally Posted by Cgstock

Ahh, okay. I'm looking to heat my boat to live on it. I'm in Philadelphia now but will be going north to the Nordic Countries in a few years, so I want heat. I do plan on having a second pump to use the engine to heat the water for the radiators, but when sailing I obviously hope to not be using the engine as much as possible.

You will definitely want the bigger heater. Even sailing you will probably motor enough anchoring to heat the hot water tank and warm up the system.
Take a look at the Russian made Planar Hydronic Heater 14TC-Mini-PU27
In my experience a better buy and more durable.
Do a search of Espar and Webasto heaters on the forum and you will find lots of cruisers who have to go to a lot of work to keep them running.

[calmissile]

Originally Posted by Bellinghamster

calmissile - nice diagram! My only concern with your layout is the potential to airlock the water pump. If you get a bubble in the line through the heaters, when it makes it was to the pump intake it'll likely cause the pump to airlock and stop circulating. Maybe having the two pumps in series mitigates that risk, since the other pump will push the air bubble through the locked pump. I get why you're doing it that way and the height challenge.

I am also considering adding another radiator/fan blowing into the cockpit, debating whether to mount the radiator high, or just duct the air up from a low-mounted radiator so I can keep the expansion tank low enough in the engine room to easily check and fill it and still have it serve as the bubble collection point.

Thanks for the comments. I am not too worried about the air bubbles. I should be able to purge the system but will keep your comment in mind in case I have any issues.

The diesel heater was not on my priority list when I was in Portland working on the boat. My main issues were to get the engine and exhaust as well as the generator and exhaust installed. Also, to get the steering system sorted out and the autopilot installed.

Unfortunately, among the 100's of photos I took of every nook and cranny (I thought), I did not take photos of the partial diesel heater system. Only a couple photos of one or two of the radiator installations. The previous owner indicated that he could not get 12V components for the heater system and had purchased and installed 12V - 24V converters. As best as I can tell from the photos, I think that the converters are only used for the fans. On one of the pumps I can read the label and it indicates it is 12V so I am assuming that all the pumps he installed at each radiator are 12V.

I don't have the wiring harness for the Espar heater, so will have to order one. Since the heater is not installed, I am not certain if he bought the 12V or 24 version of the heater. Even though I have the S/N of the heater, Espar has not been able to tell me what model number or configuration I have.

I had a friendly boater next to my slip go aboard and take some photos of the heater. Hopefully, it will be enough info for Espar to define what configuration I have as well as quote me a price on the wiring harness and controller. The manual covers many different models of the basic unit and the wiring harnesses and controllers are different for each of them. Perhaps you can look at your model number and see if it matches what is in the photo. The model number on the tag in the photo does not match the numbers in the manuals.

I might look into getting rid of the 24V fans and converters and simply swap them out for 12V fans.

BTW, I caught an error on my diagram. The return line from the cockpit went to the wrong side of the aux pump. Have since corrected the diagram.

https://i.imgur.com/xhrWjlu.jpg

https://i.imgur.com/2oIDfJN.jpg

Doug

[Cgstock]

Originally Posted by bcboomer

You will definitely want the bigger heater. Even sailing you will probably motor enough anchoring to heat the hot water tank and warm up the system.
Take a look at the Russian made Planar Hydronic Heater 14TC-Mini-PU27
In my experience a better buy and more durable.
Do a search of Espar and Webasto heaters on the forum and you will find lots of cruisers who have to go to a lot of work to keep them running.

I'm starting to look into them, I was set on a Webasto, but then read about Espar and now hearing that those two have maintenance issues. Planar is now on the list. I don't mind cleaning out once a season to maintain it, it just want it to work and be able to get parts.

[Wood]

I have the Planar 14TC and currently installing a 4 zone system. Planar has been rebranded Autoterm and has been selected by Winnebago USA for their motorhome installations.

[Jammer]

Hello calmissile


I have designed and installed a handful of land-based hydronic systems and may be able to help. A few comments:


1) The practice of having a separate pump per "zone" -- in your case per radiator -- is not uncommon on land based systems where power is abundant and it works fine. Typically the "zone" pumps are controlled by a thermostat that senses room air temperature. It does seem like a questionable use of electricity on a boat where electrical power is at a premium but otherwise should work fine.


Old-time practice was to plumb the pumps in parallel as you describe and wire the boiler controls so that the boiler would operate whenever at least one of the pumps was on. Often the pumps would have integral check valves otherwise a separate check and balancing valve would be installed for each zone. In the last 10 years or so practices have shifted to there being a separate pump also for the boiler (much as in your situation) but with the boiler supply and return being connected by close Ts, like this (the forum software deletes white space so disregard the .s I have added to make the ascii art line up):


. . . . . . . . +-------+------zone 1 pump and radiator->---+
. . . . . . . . ^ . . . | . . . . . . . . . . . . . . . . . |
Boiler supply---+ . . . +------zone 2 pump and radiator->---+
Boiler return---+ . . . | . . . . . . . . . . . . . . . . . |
. . . . . . . . ^ . . . +------zone 3 pump and radiator->---+
. . . . . . . . | . . . . . . . . . . . . . . . . . . . . . |
. . . . . . . . +-------------------------------------------+


That allows there to be a constant flow of fluid through the boiler regardless of what the zone pumps are doing, which newer boilers require.


Regarding the fan-forced radiators, those are fine and it is common to have the fans controlled by an aquastat that senses temperature in the water returning from the radiator. Again, ordinarily the zone pumps would be controlled by the room thermostat, and that was probably the intent in your case.


A manual bleed on the top of the cockpit radiator is all you really need given your small installation, especially if you are using a diaphragm-type expansion tank that does not expose the hydronic fluid to air. After been bled a few times you will have most of the air out and no air coming in.


Victron among others have inexpensive 12v to 24v converters that are very efficient and that may be a good alternative to replacing motors.



Hope this helps. Good luck..

[calmissile]

Jammer,

Thanks for the comments. The radiator units already have the 24V fans and the converters installed, so no problem with that to leave as is. I blew up one of the photos of the Webasto pumps and I am pretty sure the label says 24V. My guess is that all of the pumps and fans are 24V. The 12/24V converters are labeled Step 10.

In looking at photos of a couple of the radiator units it appears to me that the 4 radiators in the cabin are plumbed in series. That is to say in series with all the other pumps and radiators. They do not appear to connect to a return line; but rather to the next radiator unit.

My initial reaction to what I believe to be the configuration is whether the resistance to flow through all the pumps and radiators in series would be more than the (heater) circulation pump could handle (especially if none of the series pumps were turned on).

When I re-read the previous owners notes, I discovered that he intended that the cockpit heater was to be a standalone unit that would run off the engine (calorifier). In thinking this through, I do not like the idea of having to have the engine running just to get cabin heat in the cockpit. That is why I want to include it in the diesel heater hydronic circuit. If I were under sail and it was cold, why would I need to run the engine?

From what I have read on the forums, diesels don't like to be run at low RPM for extended periods and in addition, my reasoning goes something like.... why put hours on the engine which is expensive compared to putting the same hours on a diesel heater that is less expensive? Maybe my reasoning is not valid but that was my initial reaction.

Your comment about bladder type expansion tanks interests me. I was not aware they made them this way. If in fact that is what is installed, then your comment about only needing to vent the cockpit heater unit would be valid. It would save me the trouble of having to relocate the tank. It presently sits at approximately the same level as the heater. Unfortunately, I will probably have to wait for my next trip to the boat to determine the model. In my earlier post I referenced two photos. One of them barely shows the top of the expansion tank. It is the round, white item to the right of the heater. Any chance you recognize it by the photo?