Espar D5 for Cabin Heat & Hot Water Heat

bsqr

Active member
I am currently in the pre-build stage of a Sprinter conversion. I am considering going with an Espar D5 hydronic system for both cabin heat and hot water heat and was hoping some you more experienced builders might be able to answer a few questions for me.

If I go with the hydronic diesel heater, I'll probably go with two or perhaps three supply diffusers and pipe a supply/return loop with glycol or similar to heat exchanger fan units at each diffuser location. My current thought is that for simplicity I'll omit the interconnection with the engine coolant. I'm a little baffled in that with a hydronic system, fan units with heat exchangers such as these should be mandatory for cabin heat, but I've only been able to find one manufacturer. The manufacturer is Kalori (which Eberspaecher now owns). I guess I wouldn't have any issues with using a unit similar to this https://kalori.com/us/products/heating-us/water-heater-us/silencio-fai/
I'm just wondering if anyone on the forum has used a cabin heat setup like this and can provide any insight regarding the do's and don'ts as well comment on the general performance. What would be a reasonable way to integrate a thermostat into the system, given the manual fan level settings on the Kalori units and knowing the hydronic loop would also include an exchanger in the hot water heater?

As far as using the hydronic loop to heat hot water goes, I was planning on using the isotemp Slim Square heater the built in heat exchanger. I would also utilize the 115v 750W heating element as backup. Can anyone provide a guess as to how capable the D5 hydronic loop is at heating hot water in this scenario? My thinking is that I would go with the "factory" controls for the electric heating element and generally use the hydronic and electric concurrently. I could wire a switch into the electrical connection so I could go with hydronic heat only if desired. Again, I'll need to figure out a reasonable way to integrate HW specific controls for turning the D5 on and off as well as a hydronic bypass for when cabin heat is needed, but HW is already at temperature. Any effective, but easy to implement ideas to accomplish this would be appreciated. Similarly, what would be the simplest way to do a hydronic bypass for the cabin heat exchanger fan units so I don't have cabin heat fan units acting like convectors when it's summer time when I still want the hydronic loop going for HW only?

The D5-E version appears to have a boost mode and generally lower power consumption compared to the S and SC models. Are there any benefits associated with the S and SC models that I should consider? The manufacturers data that I've found so far is very limited and it's difficult to determine what the differences are between models.

I'm trying to keep things simple and depending on how complicated things become I could end up just going with the D2 for cabin heat and electric only HW heat. Right now my biggest concern is controlling everything without getting too complicated. I'm pretty decent with electrical stuff and pretty terrible with plumbing stuff. My preference would be to go with hydronic, but unfortunately my tolerance for complexity in that category isn't quite what it should be.
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
I am currently in the pre-build stage of a Sprinter conversion. I am considering going with an Espar D5 hydronic system for both cabin heat and hot water heat and was hoping some you more experienced builders might be able to answer a few questions for me.

If I go with the hydronic diesel heater, I'll probably go with two or perhaps three supply diffusers and pipe a supply/return loop with glycol or similar to heat exchanger fan units at each diffuser location. My current thought is that for simplicity I'll omit the interconnection with the engine coolant. I'm a little baffled in that with a hydronic system, fan units with heat exchangers such as these should be mandatory for cabin heat, but I've only been able to find one manufacturer. The manufacturer is Kalori (which Eberspaecher now owns). I guess I wouldn't have any issues with using a unit similar to this https://kalori.com/us/products/heating-us/water-heater-us/silencio-fai/
I'm just wondering if anyone on the forum has used a cabin heat setup like this and can provide any insight regarding the do's and don'ts as well comment on the general performance. What would be a reasonable way to integrate a thermostat into the system, given the manual fan level settings on the Kalori units and knowing the hydronic loop would also include an exchanger in the hot water heater?

As far as using the hydronic loop to heat hot water goes, I was planning on using the isotemp Slim Square heater the built in heat exchanger. I would also utilize the 115v 750W heating element as backup. Can anyone provide a guess as to how capable the D5 hydronic loop is at heating hot water in this scenario? My thinking is that I would go with the "factory" controls for the electric heating element and generally use the hydronic and electric concurrently. I could wire a switch into the electrical connection so I could go with hydronic heat only if desired. Again, I'll need to figure out a reasonable way to integrate HW specific controls for turning the D5 on and off as well as a hydronic bypass for when cabin heat is needed, but HW is already at temperature. Any effective, but easy to implement ideas to accomplish this would be appreciated. Similarly, what would be the simplest way to do a hydronic bypass for the cabin heat exchanger fan units so I don't have cabin heat fan units acting like convectors when it's summer time when I still want the hydronic loop going for HW only?

The D5-E version appears to have a boost mode and generally lower power consumption compared to the S and SC models. Are there any benefits associated with the S and SC models that I should consider? The manufacturers data that I've found so far is very limited and it's difficult to determine what the differences are between models.

I'm trying to keep things simple and depending on how complicated things become I could end up just going with the D2 for cabin heat and electric only HW heat. Right now my biggest concern is controlling everything without getting too complicated. I'm pretty decent with electrical stuff and pretty terrible with plumbing stuff. My preference would be to go with hydronic, but unfortunately my tolerance for complexity in that category isn't quite what it should be.
I designed my space/water heating a while back. Evaluated Rixen, Webasto Dual Top but decided to do my own. I had forced air coolant heat exchanger on my boat and didn’t like its noise.

I decided to separate water heating from space heating, combining these functions into one D5 seems simple, until digging deeper.

For space heating I chose Airtronics D2, best RV heater I ever head and the newer model (mine is 2013) is even better. Very quick, very quiet due to its variable speed. Once desire temperature is reached heater runs on 1st or 2nd level. It fits nicely under the passenger seat.

For water heating I use Isotemp with Hydronic D5 not connected to engine coolant. The heater has winterizing loop for grey tank and is plumbed for fresh water tank winterizing loop.

Both units are controlled by one Eberspacher EasyStart Timer
https://sprinter-source.com/forum/showpost.php?p=719131&postcount=1027 See this thread for more info.

If I do it again I would:
1. Reevaluate Webasto Dual TOP.
2. Evaluate new on NA market Truma dual function units.
3. Repeat the same system. I used D5 with integrated pump which resulted with air purging pain, next time I would just use separate pump with D5. I would consider Rixen overflow tank without electric heater instead of my own design.
 

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bsqr

Active member
Wrinkledpants - You may be right. I know generally about the Risen system, but the couple of times I looked at their website I always found it somewhat cryptic and never delved further to try and determine the specifics. This time I read through some of the installation instructions they reference and find their system is very similar to what I was thinking.

GeorgeRa - Thank you for all of the useful info. Having two units (D2 & D5) as you have described does seem to simplify things (at least for me anyways). I did notice the coolant exchanger fan units that Kalori makes run at 48db. Not sure how loud that is, but it doesn't sound quiet and is a concern. At this point I'm leaning towards a system similar to yours with the D2 for cabin heat & D5 for HW only or perhaps just the D2 cabin heater only and use electric only for HW.

I looked at the Webasto Dual Top some time ago, but the operation modes for winter use scared me off. I would like to be able use the van for ski trips so cold weather use and freeze protection are a priority. Speaking of freeze protection, GeorgeRa - could you point me in the right direction to find more info on your winterizing loop configuration to keep all your tanks, pumps and water lines from freezing?
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
See the current state of my almost finished D5 installation. Grey water tank is heated by ¾” rubber hose loop, could be improved by running copper tubes instead of rubber. For fresh water tank I am planning to attach copper tube to the surface of the tank with a copper tape. Both my tanks are custom built from stainless steel.

To finish fresh water tank winterizing tube I am considering adding a passive radiator mounted on ½” copper tube at the rear door but final decision is still in the air. Having longer van like 170WB would sway me toward this passive radiator heater like this one https://www.amazon.com/FABTEK-CLR-2-Hydronic-Baseboard-Additional/dp/B00GHUSRSY
 

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mntnmanga

Member
I may be able to provide some useful information on this subject. I have an Espar hydronic heater for my van heating system. My system consists of a heated floor system, hot water heating tank, and water to air coil heat exchanger. My whole system is separate from the engine cooling system. I did this to avoid creating any additional failure points in the engine cooling system....although now I am debating adding engine pre-heat with a heat exchanger.

My system runs off a standard household thermostat with some relay logic. The thermostat enables the hydronic heater and turns on the fans on the coil system.

My heated floor system has a separate arduino based controller that I programmed which turns on an auxiliary circulating pump to circulate water through the floor loop based on a floor temperature probe.


Looking at your design...I would personally circulate the hot water though your heating coil at your rear doors all the time and control the heat output by turning a fan on and off to move air over the heating coil. This would avoid any complexities of balancing the system by restricting flow to the hot water heater in order to force water through the heating coil. Simplicity is key in a system like this so that you can set it and forget it.
 
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bsqr

Active member
Looking at your design...I would personally circulate the hot water though your heating coil at your rear doors all the time and control the heat output by turning a fan on and off to move air over the heating coil. This would avoid any complexities of balancing the system by restricting flow to the hot water heater in order to force water through the heating coil. Simplicity is key in a system like this so that you can set it and forget it.
Yes, I think I have agree with this. My initial thought was that it would be necessary to isolate the two types of heat exchangers in the hydronic loop (cabin fan units & HW heater) when only one of them needed to operate at a given time. As near as I can tell Rixen doesn't provide any kind of bypass or isolation in their hydronic loops either. I did see one diagram where they add a mixing valve between the return & supply of an added underfloor heat loop to provide some control of the coolant temperature for the the floor loop.

However, there are two issues that are not 100% clear to me when running coolant through exchangers when it's not needed. 1) Can the domestic hot water get too hot when the hydronic loop continues to flow and heat above the HW temp setpoint? I.e. - cabin heat needed when domestic HW is already at temp. I do understand that a mixing valve of some sort would be needed to provide the desired HW temp at the faucet. and 2) Will the cabin fan heat exchangers act like radiators and expell unwanted heat into the cabin when the hot water heater requires hydronic flow and cabin temp is at or above setpoint?
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
Since I dived into designing my own conversion of the Camper Van, I noticed 3 schools of thoughts to use diesel furnace(s) to heat water and space:

1. Hydronic D5 for water and space with Rixen being the lead in NA
2. Hydronic D5 with a marine water heater (marine water heater is called calorifier in British) or flat plate heat exchanger for water and Airtronics D2 for space heating (my choice)
3. Airtronics D2 for space and water heating, well done experiments were documented on this site and one German company sells small water heater fed by hot air, I think there is a distributor now in NA.

Having experience from using D5/Isotemp/D2 for a while now here are my findings:

1. Love the D2. Inside - very quiet on lower levels. Outside - loud during starting and low at steady state.
2. Isotemp marine water heater keeps water hot for at least 12 hours giving instant hot water. Very convenient on shore power.
3. D5 - heats water in Isotemp in just over 10 min. Inside - I can hear the coolant pump running, perhaps being integrated into the D5 allows noise to transfer through the D5 mount. Outside - it is very loud outside and noise is reduced after about a minute but still loud.
 

mntnmanga

Member
I should probably include that I use the MII-12 heater. This heater is much larger than the D-5 but it has continuously variable heat output from 41,000 BTU/hr down to 4100. That means I get very fast warm-ups and the heater can turn down quite a bit to run on low if needed.

I ended up fabricating an intake silencer as well as an additional muffler to quiet the heater down. It is difficult to hear when standing 10ft away from the van now which is nice for other campers in some camp grounds.

The MII-12 heater is an expensive option but at the time, I was building my van to live in the mountains in the winter time. I wouldn't go back and do it differently though.
 

wquek

Work in progress
I designed my space/water heating a while back. Evaluated Rixen, Webasto Dual Top but decided to do my own. I had forced air coolant heat exchanger on my boat and didn’t like its noise.



I decided to separate water heating from space heating, combining these functions into one D5 seems simple, until digging deeper.



For space heating I chose Airtronics D2, best RV heater I ever head and the newer model (mine is 2013) is even better. Very quick, very quiet due to its variable speed. Once desire temperature is reached heater runs on 1st or 2nd level. It fits nicely under the passenger seat.



For water heating I use Isotemp with Hydronic D5 not connected to engine coolant. The heater has winterizing loop for grey tank and is plumbed for fresh water tank winterizing loop.



Both units are controlled by one Eberspacher EasyStart Timer

https://sprinter-source.com/forum/showpost.php?p=719131&postcount=1027 See this thread for more info.



If I do it again I would:

1.Reevaluate Webasto Dual TOP.

2.Evaluate new on NA market Truma dual function units.

3.Repeat the same system. I used D5 with integrated pump which resulted with air purging pain, next time I would just use separate pump with D5. I would consider Rixen overflow tank without electric heater instead of my own design.


Hi George, regarding the Dual Top, where do you think would be a good place to locate the unit in a 144?


Sent from my iPhone using Tapatalk
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
Hi George, regarding the Dual Top, where do you think would be a good place to locate the unit in a 144?


Sent from my iPhone using Tapatalk
Under the van spare tire space is the only one which wouldn't reduce road clearance, or inside the van.
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
…………………
Looking at your design...I would personally circulate the hot water though your heating coil at your rear doors all the time and control the heat output by turning a fan on and off to move air over the heating coil. This would avoid any complexities of balancing the system by restricting flow to the hot water heater in order to force water through the heating coil. Simplicity is key in a system like this so that you can set it and forget it.
My rear heater and fresh water tank winterizing loop design is still in the drawing phase so many changes are possible. The rear door heater would be a passive radiator, no electric fan so I will need to be able to shut it off in summer times.
 
I may be able to provide some useful information on this subject. I have an Espar hydronic heater for my van heating system. My system consists of a heated floor system, hot water heating tank, and water to air coil heat exchanger. My whole system is separate from the engine cooling system. I did this to avoid creating any additional failure points in the engine cooling system....although now I am debating adding engine pre-heat with a heat exchanger.

My system runs off a standard household thermostat with some relay logic. The thermostat enables the hydronic heater and turns on the fans on the coil system.

My heated floor system has a separate arduino based controller that I programmed which turns on an auxiliary circulating pump to circulate water through the floor loop based on a floor temperature probe.


Looking at your design...I would personally circulate the hot water though your heating coil at your rear doors all the time and control the heat output by turning a fan on and off to move air over the heating coil. This would avoid any complexities of balancing the system by restricting flow to the hot water heater in order to force water through the heating coil. Simplicity is key in a system like this so that you can set it and forget it.
I am in the design phase of adding a heated floor to my van. Would you mind elaborating on your setup, if you can add a parts list and ruff sketch of your system than I would be forever in your debt!
 

mntnmanga

Member
I can probably put a quick sketch together of my pipe routing to give you a concept of what I am doing. Be back in touch shortly.
 

joyfulvans

New member
YES PLEASE! I would love that :) I've installed an espar heater, but I may want to add hot water and heated floors. No idea really where to start so any help would be amazing!
 

avanti

2022 Ford Transit 3500
My Great West Vans Legend has a Rixen's system. The exact setup they used was later adopted by ARV when they spun-out of Great West. As far as I know, they are still using it, so they are another place you can look for ideas. In particular, note that they use the coolant loop to heat the tanks and exposed piping in order to achieve 4-season operation. I stole this idea from them and reworked my system along the same lines. Reported here:
https://sprinter-source.com/forum/showthread.php?p=405931&highlight=season+upgrade#post405931

The Rixen's setup uses a flash-plate heat exchanger for instant hot-water--no hot water tank included or needed. It works extremely well. You are correct that there is danger of getting excessively hot DHW. You have to include a thermostatic tempering valve, which solves the problem. I really recommend this approach. Simple, compact, and inexpensive. From a cold start, I can take a shower in about 5-7 minutes--the D5 puts out a LOT of BTUs. The value-add of the Rixen's system is a logic board to decide when to fire the D5. You could duplicate it with an Arduino.

I, too, was annoyed by the noise of the water/air heat exchanger. It had two speeds "high" and "higher". I solved this problem by adding a PWM fan motor controller with a knob that lets me set the speed. This completely solved the problem. I find that unless it is extremely cold, I can set the fan speed such that I can barely hear it, and it still works great.

So, to summarize my system: It is a simple loop of four devices in series: An expansion tank (with integral aux electric heater coil); the D5, the DHW water/water exchanger, and the cabin heater water/air exchanger. After that, the glycol loop continues throughout the van, bundled with the exposed plumbing (wrapped in insulation) on its way back to the to expansion tank. This system works extremely well. I really wouldn't change it in any way. I doubt that you need more than one water/air exchanger and I wouldn't bother with under-floor hydronics. The single hot-air unit works just fine throughout the van.
 
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kcshoots

VanTripping.com
I built my system based upon What GeorgeRa did and Rixen and modified it. I have an IsoTemp Slim, D5 and two Aqua-Hot fan coils (one Cozy and one Whisper 4000). In summary the water can be heated by the engine if hot and desired, or from my heating D5, and each fan coil has independent fan speed control for heat location preference. One fan coil is in the front and one in the rear. If doing again, I would add a third for faster warm up when cold.

I have a supply and return line from factory D5/radiator running to isolation valves, then into a thermostatic Espar valve, which allows the engine coolant to pass to my heating loop if above ~150F. My installed heating D5 is also connected at this valve, so if it's on or the engine water temp is hot, either proceeds to the Isotemp heat exchanger and heats up the water inside. Otherwise they loop until hot enough to pass. I then have a 12vdc control valve wired to a switch inside the van that powers my heating system, which means fan coils, supplementary heating water pump and fan coil fans (all 12vdc powered). If the switch is on, the valve opens and allows the hot water to pass from the IsoTemp heat exchanger up into the van to the fan coil loop. Otherwise this hot water stays below the van. When the switch is on, it also powers a small 12vdc coolant pump to further help circulate the hot water thru the fan coils and their plumbing loop from IsoTemp thru them and back down. This pump is inside the van and likely unnecessary since the heating D5 has a likely adequately sized pump but I add this supplementary one since I could not find any specs of how much head the D5 pump could push against. The switch then powers the two fan speed controllers for each of the fan coils. I also have temp sensors and monitor on my supply and return from D5/engine, as well as heating loop and domestic hot water supply so I can see all four of these temps in addition to exterior and interior temp sensor/monitors.

Yesterday morning at NorCal Sprinter camp out it was 28F outside, van 50F inside and I warmed it up to 71F in about 45 mins with just the heater D5. Today it was about the same outside and 49 inside when I awoke and I ran the heater D5 for about 20 mins and warmed up interior to 64F before turning on the van to both charge batteries but also to run the factory D5 for first time this year and to see how much additional heat it provides. With just heater D5 my hot water supply went up to about 105f and heating loop into the low 90's. With factory D5 running, supply temp went to about 112 and heating loop 101 with engine temp only up to 140f (my factory D5 only runs when below 39f outside and with engine running). Factory D5 would be hotter and since very near my heating loop providing heat into it. It's now 76f inside my van so beyond cozy. The hot water loop will remain above 90 for about 20-30 mins after shutting down off either D5 and leaving my heating loop on (fan coil fans on and heating valve open and loop pump on). I left it running today for about 10 mins until interior temp reached 78 which was hot enough.

As a note, because my heating system is connected to the engine coolant loop, I installed a coolant specific check valve on my supply from engine to my heating loop to provide some restriction of my heating loop heat to the engine yet to also allow only my higher pressure heating loop water to pass but to limit the return and hence flow thru so I am not heating my engine block except when my system is really hot and only minimally to keep most or all of the heating D5 for space & potable water heating. The heating thermostatic valve also prevents engine water from returning if below 150. However, this configuration allows expanding water to reach the van coolant expansion tank and while the engine or factory D5 are running, to purge the system of air and equalize the pressure of the two systems. This provides for my heating system expansion tank. I also installed a coolant system air release valve at the high point in my heating loop to purge any air in the system (much like on radiators in boiler heated apartments of the east). This valve releases air but not water. This worked well during first start up to purge the air in the system since all of my plumbing lines and fan coils are within cabinets. Accessible but not easily while my air release valve is very accessible when a purge is needed. A benefit of this is that I only have the factory coolant expansion tank to manage water level and coolant ratio. The same water/coolant for the engine is used in my heating loop. This is simpler with little to no maintenance but does add some cautions. I ensured that all fittings, tubing and other parts of my heating system are rated to at least 250f and for coolant. My UltraGuage shows that my engine coolant temp reaches a peak of 230f on hot days when climbing hills with AC on so I feel that 250f rating is sufficient. I have thermally scanned my heating lines and connections when the engine coolant is hot and they are well below 250f, mostly in the 160-180f range.

If I were to redo this, I would add a third fan coil or replace the Aqua-Hot Cozy with a 4000 or slightly larger fancoil to get a little more heat out to heat up the cabin faster. The included fans with these fan coils while fairly quiet and do put out a reasonable air flow but I would prefer more air flow and more heat, so larger fan coils, higher temps or fans that move more air would be nice. However, it's all a trade of noice, energy use and speed to comfortable temps. I optimized my system more for noise comfort, space and energy. My cabinetry has intentional perforated panels for air return to the fan coils as well as for fridge/freezer compressor heat venting.

I have taken the van into the dealer many times and they are aware of my heating system, and when they replaced the coolant, they closed my isolation valves to my heating system so only a little air gets into it. It's simple to reach under the van to close or open them. This is just another option, with like any pros and cons. I've been very happy with this system but caution anyone connecting into the van's coolant system to use materials that are rated for the hot coolant and ensure that you have a leak-free system. Mine has been and was installed over two years ago. Additionally all of these lines and other system components are above the bottom sill or frame members and reasonably protected from errant bushes, snow, rocks, etc, to protect them against a trail or road damage. While still possible, it's a safety precaution.
 

avanti

2022 Ford Transit 3500
The other option if you wish to connect to the van's coolant system is to use a water/water heat exchanger to keep the systems isolated. I think that this the safer option. Rixen's sells an exchanger intended for this purpose.
 

Graphite Dave

Dave Orton
I use a back seat heating pad under the sleeping bag to stay warm at night. Let van interior get cold. Very quiet and also reduces the time refrigerator operates. In morning use the optional Transit remote start to start engine for dash heat and heat from a 750 watt electric heater powered by a vehicle powered inverter. Start engine before getting out of bed.

For shower water I use a Sous Vide water heater in a 14 quart Igloo cooler. Takes 45 minutes to heat 3 gallons of water to 100 degrees. All water at same temperature so no hot/cold water mixing or plumbing. No hot water at the sink.

Not at all like the systems discussed here but it is simple for my use in my climate. Not equivalent to a complicated system but it can work depending on your application.
 

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