Espar Hydronic 10 Diesel Heater System Design

[calmissile]

I am having to reverse engineer a partially installed Hydronic 10 heating system. In order to complete the installation I need to understand the system level design of these systems.

The Espar manual covers the diesel water heater quite well, but does not have much in the way of integrating it with remote radiators which is a product you must buy from other parties.

I am looking for specific answers to some technical questions and hope someone on the forum has designed and integrated this system.

The previous owner installed the heater and exhaust. I still have to install the diesel fuel system and do not see a problem with that. The heater has a circulation pump and the startup, operation and shutdown sequence is fully automated.

It appears that the hot water output line is connected in series with 4 heating stations. Each station has a Webasto circulation pump in series with the hot water hose prior to going into the radiator. The other side of the radiator appears to go to a common return water line. I am not near the boat at the moment so don't have the exact part number of the Webasto pumps but they appear to be this one...
https://www.heatso.com/flowtronic-wa...-d9w-d10w-12v/

My first question/concern is that the hot water line is in series with all of the pumps. If any one of the pumps are not turned on, will the circulation pump in the heater still circulate water throughout the system? Is there a chance of stalling or overloading the circulation pump in the heater under these conditions?

I have not found any diagrams or descriptions on line that suggests that this is a common way to configure the heaters. The owner has installed Aquastats in line with each station so that the fan (and maybe the pump) will not turn on until the water is hot. There are no flow controls anywhere in the system. Each station has the hot water going through the Aquastat, then to the pump, then through the radiator to a common return line.

I guess one of my questions deals with what happens when all 3 or 4 pumps are running at the same time? Will it cause a partial vacuum in the hot water line if the heater circulation pump cannot keep up with the flow rate? I can't find any technical info on the Webasto pumps to know if when they are off, will the hot water flow through them without restriction?

I also have some decisions to make concerning other options for the heating system and sources. I have seen some examples where the califorier (heater hoses from engine) are run through the diesel heater as well as the fresh water heater. I have the fresh water system working fine for both hot and cold water. The water heater is using only the 120 VAC heater element for testing and it all works fine. The water heater also has a heat exchanger that allows you to connect the calorifier connections from the engine to heat the fresh water when the engine is running as well as can be used to pre-heat the engine.

In analyzing the pros and cons of using this connection I come up with the following argument...
I will have hot water only if the engine is running. If I were on a passage or a cruise without the engine, I would not have hot water since the power consumption off the batteries (for the inverter and heater element) would be prohibitive.

I am also a little nervous about having the engine coolant running around the boat in hoses that could potentially leak or burst, overheating the engine. Since I would not have hot water without the engine running, I had another idea and would appreciate comments from the pros about adopting it....

If I were to connect the existing diesel heater hot water circuit and run it through the fresh water heater (rather than using the calorifier lines), then I could have hot water by only running the diesel heater which is pretty skimpy on diesel usage compared with running the engine. Of course I would need to bypass the heater radiator cores if the weather were already warm outside. What are your opinions?

[goboatingnow]

I’ve only seen one single circulating pump used on hydronic systems so I’m bemused at the multiple ones.

I wouldn’t run my engine coolant through the whole hydronic system , there is too much risk of leakage

[sv_pelagia]

Originally Posted by goboatingnow

I wouldn’t run my engine coolant through the whole hydronic system , there is too much risk of leakage

We have our engine coolant separated fron the Espar heating by passing it through a heat exchanger. This allows the engine to heat the heating system without the worry of leakage somewhere in the hydronic system. When not running the Espar but running the engine, a separate pump circulates the hydronic fluid for heating. (The hydronic network also heats water tank; thus when motoring, the engine coolant heats hydronic system via heat exchanger, which then heats both boat and water tank or water tank only if switched to "summer".)

[calmissile]

Originally Posted by goboatingnow

I’ve only seen one single circulating pump used on hydronic systems so I’m bemused at the multiple ones.

I wouldn’t run my engine coolant through the whole hydronic system , there is too much risk of leakage

My thinking also.
I am still puzzled by the multiple pumps. Waiting for some comments on that topic.

[calmissile]

Originally Posted by sv_pelagia

We have our engine coolant separated fron the Espar heating by passing it through a heat exchanger. This allows the engine to heat the heating system without the worry of leakage somewhere in the hydronic system. When not running the Espar but running the engine, a separate pump circulates the hydronic fluid for heating. (The hydronic network also heats water tank; thus when motoring, the engine coolant heats hydronic system via heat exchanger, which then heats both boat and water tank or water tank only if switched to "summer".)

Sounds like something I would consider. Do you have a schematic or drawing of your system you could send me?

Also, what did you use for the additional heat exchanger to isolate the engine coolant system from the hydronic system fluids? Is it close to the engine? Did you use the typical calorifier (heater hoses) to tap into the engine coolant system?

[bcboomer]

Originally Posted by sv_pelagia

We have our engine coolant separated fron the Espar heating by passing it through a heat exchanger. This allows the engine to heat the heating system without the worry of leakage somewhere in the hydronic system. When not running the Espar but running the engine, a separate pump circulates the hydronic fluid for heating. (The hydronic network also heats water tank; thus when motoring, the engine coolant heats hydronic system via heat exchanger, which then heats both boat and water tank or water tank only if switched to "summer".)

Same

I can't imagine why separate pumps were installed. Waste of electricity.
From experience make sure the pump is low enough on the system that a small leak won't result in no circulation.
Heat exchangers are cheap.

[Tugwit]

Originally Posted by sv_pelagia

We have our engine coolant separated fron the Espar heating by passing it through a heat exchanger. This allows the engine to heat the heating system without the worry of leakage somewhere in the hydronic system. When not running the Espar but running the engine, a separate pump circulates the hydronic fluid for heating. (The hydronic network also heats water tank; thus when motoring, the engine coolant heats hydronic system via heat exchanger, which then heats both boat and water tank or water tank only if switched to "summer".)

Ditto-this is similar to the system on my vessel. A couple of notes:

• I use a Webasto 906-089 mag drive pump as the "auxiliary" circulation pump when the engine is running. When it is not energized, it has little or no effect on the fluid circulation from the (internal) Espar pump, i.e. it does not block the flow. This pump has a flow rate of 400 liters/hour at 1.4 bar which is less than that of my internal (D5WS) Espar pump which is ~900 l/h at 1.0 bar (your Hydronic 10 appears to have a higher flow rate of 1,400 l/hr at 1.4 bar ). Still, with the engine is running, this inefficiency is not noticeable since the engine puts out so much heat. And, when the furnace is off, my internal Espar pump does not seem to impede the flow of fluid, either .
• I use a mixture of a Propylene Glycol antifreeze and water as the hydronic fluid for the Espar. It is much less toxic than Ethylene Glycol, and should it somehow contaminate the potable water in the water heater, it won't likely kill you (or your pets). That said, I wouldn't voluntarily drink either.
• The system has a "summer" valve (mentioned by Pelagia) which can be switched to divert the hydronic fluid flow back to the furnace (yet through the hot potable water tank) and avoid circulating it through the radiators. Thus, in the "summer", you can have hot water while keeping the cabin cool.
• I also use an Aquastat to switch ON the fans behind the radiators only when the circulating fluid is hot enough. Works well.

I can't imagine why your PO installed all of those extra pumps. If you follow Pelagia's design, you could likely use one of them as an "auxiliary" pump to circulate fluid heated by the heat exchanger during engine operation. Also, if you have a particularly lengthy hose circuit, an auxiliary pump may be useful to overcome friction and sustain flow (in which case you could simply run the internal Espar pump and the "auxiliary" pump simultaneously). My circuit is 65 feet in length, and a single pump seems to work fine.

That said, at nearly $400/each on the link you cited, you could sell a couple of them on eBay and buy a lot of project lubricant.

[sv_pelagia]

Originally Posted by calmissile

Sounds like something I would consider. Do you have a schematic or drawing of your system you could send me?

Also, what did you use for the additional heat exchanger to isolate the engine coolant system from the hydronic system fluids? Is it close to the engine? Did you use the typical calorifier (heater hoses) to tap into the engine coolant system?

Sorry, do not have a schematic (though I could sketch one up).

Yes, the additional heat exchanger is there to isolate the engine coolant from the hydronic system fluids. The normal heater hoses from/to the engine go to/from only to this heat exchanger. The hydronic system goes hot water tank heat exchanger and (when not in "summer mode") to radiators.

The heat exchanger is probably about 1-1.5 metres away from engine.

The extra pump is required to circulate the hydronic fluids through the system (including the engine-hydronic heat exchanger) when the Espar is off. When Espar not running, there is no fluid circulation without the extra pump.

[calmissile]

Thanks to all for the responses and comments. I just discovered an old thread that has a lot of info on this topic.

https://www.cruisersforum.com/forums...er-149641.html

Perhaps a MOD can take this thread and add it to the end of the existing thread. I must have not used a good search term when I was searching for answers on this topic.

Still a couple of current questions....

Do your systems have a "T" in the hot water line to go to each radiator (parallel connected) , or are all the radiators connected in series (the water goes through one radiator before going to the next one)?

SV_Pelagoa, or others.... What is a good heat exchanger to use to isolate the engine cooling system from the hydronic system?

Thanks
Doug

[Lepke]

Depending on the size of the system, usually each heater has a valve that is opened by a thermostat. A single circulation pump moves the coolant. When I set them up I use a common supply and return. Both insulated so you aren't unnecessarily reheating coolant. On a big boat the supply and return run almost the full length. Each heating station has a solenoid valve that opens the supply to that heater. On long boats I also put solenoid valves in the common supply, so only the part of the system calling for heat gets heated water. That way a heater close to the boiler/Espar only circulates water thru a short section of the commons. Insulation and breaking the supply line into sections can save a lot of fuel. In my boat, in cold weather, it saves a couple gallons/day. On my 83' boat, heating the boiler deck and upper deck, one circulation pump is enough.

Houses with multiple zones and usually 2 stories or more have a pump for each zone in order to have enough push to reach higher levels. Usually the controller keeps all of the pumps from running at once. Otherwise they are limited by the supply pipe size. Vacuum shouldn't be an issue. Circulation pumps used in hydronic systems are high volume/low pressure.

[Tugwit]

Originally Posted by calmissile

...Still a couple of current questions....

Do your systems have a "T" in the hot water line to go to each radiator (parallel connected) , or are all the radiators connected in series (the water goes through one radiator before going to the next one)?

SV_Pelagoa, or others.... What is a good heat exchanger to use to isolate the engine cooling system from the hydronic system?

Thanks
Doug

On my (small) 36' boat all the radiators are connected in series. On a larger vessel (e.g. Lepke) divided into "zones", a parallel system with solenoid valve control for each zone is likely a worthwhile complexity.

I used a 2" x 19" heat exchanger from MSR Marine (model 005-222), but it no longer appears on their website. However, I'm sure that either SeaKamp Engineering or Orca Marine (both in Bellingham, WA) could whomp up whatever you might need....e.g. Cabin Heat On Orca Marine Cooling Systems

[calmissile]

Thanks Lepke for the comments. I like the idea of the solenoid valves for each radiator. Will have to take that into account and search for them if I decide to use them.

The consensus seems to be that there is no need for pumps at each radiator. The Aquastats are already installed, so no need to remove them.

I have pretty much ruled out using the calorifier hoses from the engine to tie into the hydronic system unless I can find a suitable heat exchanger to run the engine coolant through first (near the engine).

I do like the idea of the hydronic diesel heater being tied into the fresh water heater to provide hot water when sailing without the engine running.

A lot of good comments from those that have actually designed and used the systems.

[calmissile]

Originally Posted by Tugwit

On my (small) 36' boat all the radiators are connected in series. On a larger vessel (e.g. Lepke) divided into "zones", a parallel system with solenoid valve control for each zone is likely a worthwhile complexity.

I used a 2" x 19" heat exchanger from MSR Marine (model 005-222), but it no longer appears on their website. However, I'm sure that either SeaKamp Engineering or Orca Marine (both in Bellingham, WA) could whomp up whatever you might need....e.g. Cabin Heat On Orca Marine Cooling Systems

Thanks for the link. It appears they make a large selection of heat exchangers and mounting brackets.

[Lepke]

My twin main engines are tied into my hydronic system by valves. Coolant is the same and shared. The advantage is that when cruising, the mains supply the heat. Also before stating the engines, I circulate the hot coolant thru the engines to preheat in cold weather for easier starts and don't have to use the block heaters. The one circulation pump on the boiler is enough.

[calmissile]

Originally Posted by Lepke

My twin main engines are tied into my hydronic system by valves. Coolant is the same and shared. The advantage is that when cruising, the mains supply the heat. Also before stating the engines, I circulate the hot coolant thru the engines to preheat in cold weather for easier starts and don't have to use the block heaters. The one circulation pump on the boiler is enough.

I understand your configuration. I remember block heaters from the times when I lived in Montana and North Dakota. As I recall, we used tank heaters which were inline with the heater hoses. No pump was required.

If I configure the system as we have described so far, it would appear to me that by starting the diesel heater it might well heat the block even without any pumps, just like the tank heaters did in the cars.