Diesel Coolant heater sizing question

[kbeefy]

I'm building my next campervan and I'm incorporating a diesel coolant heating/hydronic heating system. (van is diesel E350).

I don't have any experience with diesel heaters aside from a toyotomi cabin (air) heater that I had in my last van.

Most Diesel Coolant/water heaters seem to be 5kw heat output. I don't really know what that relates to, or how it would perform in real life. It looks like I can get a 12k heater for not much more money.

Does anyone have any reasons I shouldn't get the bigger version, or how the 5kw would work for heating 15 gallons of coolant and domestic hot water?

Also, anyone have any real life experience with a diesel coolant/parking heater? Any recommendations? I'm not looking to buy a $2000 Webasto or Eberspacher... a knockoff version is OK with me.

 

[kbeefy]

I guess typing the question out convinced me that I should get bigger than 5k.
Still interested in others opinions and experience.

Thanks!

 

[llamalander]

I recently picked-up a well reviewed 5kw Espar copy (for about 1/8th of the price).
I'll be using for hot water and heat when the engine isn't running. Shipped fine, tested well on the bench and came with a guarantee, which is unusual for diesel heaters.

www.banggood.com/12V-5KW-Plumbing-Water-Heater-Kit-for-Truck-SUV-Bus-RV-Boats-p-1614469.html

Going on another member's recommendation, I reduced the size of my domestic hot water tank from 5gal to 2.8gal because either the engine/heater is quick to get it to 180º, which then gets mixed-down to something comfortable. Smaller, lighter and less expensive all appealed to me.

I have yet to install it or build the radiators I intend to use, but 5kw of forced air is likely too much for my little pop-top, so I'm not too concerned about having enough heat. I am excited at the possibility of throttling back the fan/flow through them to modulate the heat to a degree not possible with the forced-air units.

I also like that the unit is outside, and coolant is all that has to be brought into the living space, smaller holes and much easier to design for.

 

[kbeefy]

I recently picked-up a well reviewed 5kw Espar copy (for about 1/8th of the price).
I'll be using for hot water and heat when the engine isn't running. Shipped fine, tested well on the bench and came with a guarantee, which is unusual for diesel heaters.

www.banggood.com/12V-5KW-Plumbing-Water-Heater-Kit-for-Truck-SUV-Bus-RV-Boats-p-1614469.html

Thanks for the link!
Thats cheap enough I might just try it. I could even add a second one if needed and still be under budget.

I already have a Kuuma 6g marine water heater, so thats what I'll be using. I got it for $305 shipped, I don't think I could have found a smaller one cheaper.

 

[llamalander]

Great deal! your rig can probably handle the weight--
I've included a second pump to circulate coolant when the engine is running but the heater is not, and I like the redundancy. I may put it on a timer once I see how long it takes to heat the water tank, so I don't risk loosing any hot water from the safety valve it it gets too hot.

I also found an X-shaped heater-bypass valve on the river of things site that simplifies the engine-side connections considerably. It is much more clean and light than anything I could put together. I think it's important to be able to isolate the house system from the engine if a problem arises.

Looking forward to hearing what you build. If my system actually works, I'll post details too.

 

[kbeefy]

What's the river of things? I still need to sort out the heater line interface, I was planning on using some 3/4 electric ball valves I found.

I'm planning on doing a big loop, basically engine - coolant heater - domestic HWH - heat exchangers - engine. With bypass plumbing and a circulating pump to isolate just the engine and/or any of the 'zones' so I can heat the cabin and water without heating the entire engine coolant circuit or use the coolant heater as an engine pre-heater.

Does that coolant heater have a circulating pump? I have no experience with them.
Based on another install I saw I was considering using an auxiliary vw coolant pump.

 

[kbeefy]

I also found an X-shaped heater-bypass valve on the river of things site that simplifies the engine-side connections considerably.

Something like this?

 

[llamalander]

Exactly the valve--you found the river!
The heater I linked comes with a 12v. pump and a harness that can tie into the cabin fan to preheat the cabin along with the engine... probably not going to install that myself.

I'm not counting on the engine pump to run the whole circuit when the diesel heater is off, so i've added a 12v. Bosch pump to run from the cab when I'm driving.

This is the thread where I got a bunch of good info from Peter'n Margret in Oz, who have built and tested something similar-

Engine-heated (Hydronic) hot water?

Hi, planning to build my pop-up with a small, insulated hot water tank for cleaning and bathing, principally heated with the engine coolant or a diesel engine pre-heater, & possibly 110v &/or 12v from my solar. Before I start I want to make a long-winded post to try and keep warm. I'm gathering...

forum.expeditionportal.com

 

[Peter_n_Margaret]

5kW is a lot of heat in a small space.
I am currently building another expedition rig. I chose the hydronic heater on the basis of how low it could be turned down without cycling on and off.
Not that either are an issue, but starting up uses the most power and creates the most noise.

My first unit was built with 5/8"/16mm hose and fittings. With all the bits in series (including the motor) the new build will use 3/4"/20mm hose and fittings.

Cheers,
Peter
OKA196 motorhome

 

[kbeefy]

Oh.... That river. Got it.

Good point on circulation with the heater off. Will you install the pump in parallel with some check valves, or inline?

This is the pump I was going to use... I see it's Bosch as you mentioned. river link

I was going to use some of these valves... River of things linky they will require a bit more plumbing than the x setup, but will be controllable from in cab while driving or camping. My van has ALOT of coolant so I would like it to get up to temp before trying to heat the camper side.

 

[kbeefy]

5kW is a lot of heat in a small space.
I am currently building another expedition rig. I chose the hydronic heater on the basis of how low it could be turned down without cycling on and off.
Not that either are an issue, but starting up uses the most power and creates the most noise.

My first unit was built with 5/8"/16mm hose and fittings. With all the bits in series (including the motor) the new build will use 3/4"/20mm hose and fittings.

Cheers,
Peter
OKA196 motorhome

Hey, thanks for chiming in Peter! I was just headed off to read your thread @llamalander posted above.

It will probably be covered in your thread, but did you coolant lines start at 5/8? I had contemplated running 3/4 but was thinking 5/8 would do. Your feedback might sway me towards 3/4 but where I'm taping into the engine coolant is 5/8.

Cheers!

 

[kbeefy]

5kW is a lot of heat in a small space.
I am currently building another expedition rig. I chose the hydronic heater on the basis of how low it could be turned down without cycling on and off.
Not that either are an issue, but starting up uses the most power and creates the most noise.

My first unit was built with 5/8"/16mm hose and fittings. With all the bits in series (including the motor) the new build will use 3/4"/20mm hose and fittings.

Cheers,
Peter
OKA196 motorhome

Oops... I see now that it's @llamalander s thread, not Peters.

 

[Peter_n_Margaret]

The difference between 5/8" and 3/4" dose not sound like much but it is actually a 50% increase in cross sectional area and that makes a big difference to flow rate and pressure drop.
There are a few calculators available to plug some numbers into.
So while 5/8 might do, increasing flow rate makes for a package that will simply perform better and likely not need an auxiliary pump to run all the time, or maybe at all.
Cheers,
Peter
OKA196 motorhome

 

[kbeefy]

The difference between 5/8" and 3/4" dose not sound like much but it is actually a 50% increase in cross sectional area

Copy. I'll plan on 3/4 just because.

 

[llamalander]

The motorized valves you linked are excellent, no power consumption except when changing states (decide if you want normally open or closed). I plan to use one to isolate the hot water tank once it's up to temp, but likely hand valves elsewhere-