Plumbing Espar Hydronic D5

[B350]

I don't have a rear HVAC and do not plan on plumbing into the van's coolant loop at all. The main reason for the Espar D5 is for hot shower and sink water.

Espar NA replied today stating that the coolant capacity should be at least 2.5 gals. Being the current design only holds about and estimated 2 to 3L max I would need to add considerable capacity with a tank that could allow coolant flow through it.

Maybe I should consider a Webasto Dual Top Evo? Does anyone have experience with one of these here in the US?

 

[Joe917]

Tying into the vehicles cooling system will give you free domestic hot water any time you drive. It will give you the required volume of coolant and gives the option of preheating the engine. It will cut your heater running time way down. We almost never run our Webasto to heat water, our engine produces plenty of excess heat! What are you using as a hot water tank. We got a great price on an Isotemp Spa from Defender Marine. The original heater was an Isotemp and it went 23yrs before failing.

 

[B350]

After being adamant about not wanting to tie into the van's cooling circuit I've realized this is indeed the easiest way to get the coolant capacity that is needed for the Espar D5. I guess you guys have told me to do that all along. I'll stop being stubborn now...

Also, the Webasto Dual Top Evo is not available to the consumer in North America. It is sold to certified installers only. These installers are typically RV manufacturers that do not sell to the public and don't dabble in home builds. Not that I want to pay someone for the install anyway. If you were to buy one online from a Canadian source or elsewhere Webasto will not uphold the warranty on the heater. A real shame because it really is the cat's meow when it comes to one easy solution for air and water heat.

And now on to laying out the plumbing with the addition of a heater core and fan combo.

 

[B350]

Coolant System Tie-In

My van has no rear HVAC system so I have to plumb off the engine.

Where, on a Ford E350 7.3L engine block, do I place both a coolant inlet an a coolant return for the Espar?

If anyone can share pictures and necessary parts I'd greatly appreciate it.

This is the new plumbing diagram. Anyone see any issues?

 

[Joe917]

The new diagram is incorrect.the Espar needs to be plumbed across the coolant loop with "T" fittings so the engine can be bypassed from the system. One shut off between the Espar and the engine is all that is needed to stop coolant moving through the entire circuit.
With the valve open , Espar on, engine off = engine preheat and heating domestic water.
With the valve open, Espar off, engine on = engine heating domestic water, coolant bypassing Espar.
With valve closed, Espar on, engine off = heating domestic water only, no wasted heat through engine.

 

[javajoe79]

Am I reading your description correctly? Seems like bypassing the Espar would require a 2nd valve and a bypass. Also is bypassing the Espar when it's not running necessary? Seems like coolant can just flow through it

 

[dwh]

Sure coolant would run though it with the engine running.

But if the engine is off, and you want to heat water, but not heat the engine...

 

[javajoe79]

He mentioned bypassing the Espar when it's off.

 

[dwh]

He mentioned bypassing the Espar when it's off.

Oh, I see what you're saying.

Um, I think he goofed in the second case he described. With the valve open, the Espar isn't bypassed.

The Espar thermostat would keep it turned off though. Maybe that's what he was thinking.

 

[Joe917]

You need to jump across from the coolant line returning to the engine to the coolant line heading to the camper.the Espar is installed on this jumper.
Valves are not needed on the jumper. You need a valve between the engine and where the jumper joins the loop, either side, supply or return it does not matter. with the valve closed the Espar will not heat the engine.
With the valve open and engine on, the engine's water pump will push the water around the camper's heating loop. The coolant will not run through the Espar just as a matter of course.

Your diagram does not allow you to cut the engine out of the circuit which means the Espar will have to heat the camper and the engine block at all times, a huge waste of heat.

The set up I describe is the way my Webasto is installed, the system works perfectly. Espar must have an installation guide.

 

[javajoe79]

You need to jump across from the coolant line returning to the engine to the coolant line heading to the camper.the Espar is installed on this jumper.
Valves are not needed on the jumper. You need a valve between the engine and where the jumper joins the loop, either side, supply or return it does not matter. with the valve closed the Espar will not heat the engine.
With the valve open and engine on, the engine's water pump will push the water around the camper's heating loop. The coolant will not run through the Espar just as a matter of course.

Your diagram does not allow you to cut the engine out of the circuit which means the Espar will have to heat the camper and the engine block at all times, a huge waste of heat.

The set up I describe is the way my Webasto is installed, the system works perfectly. Espar must have an installation guide.

Ahhh... ok. Done that way, when the valve is open and espar running, that puts the engine in parallel with the camper's heating loop. Or do you put a valve on the camper loop too and use the espar to only heat one circuit at a time? I suppose you could heat both loops at the same time but that cuts flow in half.

 

[Joe917]

Now you have it. The valve is not needed on the camper loop. You will always want hot coolant heating the domestic water if it is available. You control heat in the camper at the camper heater, radiators or whatever.
Having a valve on both loops would also introduce the possibility of running the Espar with no coolant flow, not sure what damage, if any that would cause.

 

[B350]

Guys, it seems my plumbing diagram would still work taking the following into consideration:

1. The Espar Hydronic D5 requires a minimum of 2.5 gals of coolant (about 10 liters). If there is less coolant, the heater will cycle up and down too often resulting in much shorter heater life. I will not be using a hot water tank and the capacity of coolant in just the hoses run from the back of the van to the front will not be enough. That is why I will tie into the van's coolant system- more specifically the block if possible. The reason for tying into the block being that it will keep heat better than if tied into the radiator or heater core.

2. The option to cut the Espar out of the coolant circulation loop will not be necessary. That is unless it needs to be removed for service and for that reason there are valves incorporated right after the block. The other valves at the heat exchanger/flat plate are also for service purposes and will likely include a drain valve. The additional valves at the hydronic heater are there to cut it out of the loop when camper heat is not needed.

So, other than the valves to the hydronic heater, all other valves would stay open enabling hot water through the heat exchanger/flat plate. Coolant will always flow through the Espar, the heat exchanger/flat plate and the engine block. This is necessary to achieve the capacity needed for proper cycling of the Espar and will have the added benefit of preheating the coolant in the block. This makes sense right?

 

[Joe917]

If coolant volume is your issue you would be far better to add a coolant reservoir in the camper. If you try to heat the camper in below freezing temperatures by running through the cold block the Espar will never shut off .
The Spa hot water tank has a built in temperature mixer.

 

[javajoe79]

Seems like using a plate exchanger for your hot water will require the espar to be running for you to have hot water. If you use a marine hot water tank, you can run the espar once and have hot water for a day or two. A simple reservoir in line before the espar will add enough capacity.