Hydronic and Espar Heat

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Last year we modified our Winnebago View to be able to use the motorhome (full water, showers, dump tanks, without Propane) throughout the Wisconsin winters. I thought I'd share the writeup that I did on the Winnebago View Owners site. The following are the posts that may give someone some ideas on winter heating.

By the way - we still LOVE the hydronic heating setup and the Espar heating.

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Testing results:

Ran the Espar last night while boondocked.

Outside temperature 35 degrees

Thermostat set at 60 degrees for sleeping

Only ran one Cozy heat exchanger, no dash fans, no water heater hydronics

Amps per hour usage according to battery monitor - 1.86 Espar 2.56 when thermostat turns on heat exchanger fans

Water heater water temperature in the morning - 137 degrees

Batteries state of charge went down 10% in 9 hours

Diesel fuel used - less then a gallon

Propane used - None

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Water Heater Hydronic Heat Steps:

-- Added check value between the hot and cold water piping located under the kitchen sink.

-- Added (2) Solar DC Circulation Pump Topsflo TS5 15PV to the output of the water heater. Wired these pumps to a switch on the control wall (one/both/off).

-- Added Heat Exchanger - Cozy III - EXE-103-0EX? to under the dinette and another one in the bathroom (located in the water pump compartment). Wire the fans to switches on the control wall (high/low/off). The Cozy III Heat Exchangers are plumbed into the hot water piping of the coach. The hot water exits the water heater and goes to the dinette Cozy III and then to the bathroom Cozy III and then onto the rest of the coach's plumbing.

-- Created a smaller loop in the water piping by adding a Water Solenoid Electric Valve - 12v Dc 1/2" Normally Closed in the water pump compartment. This valve will open when the coach's thermostat calls for heat. This shortens the loop that the hot water needs to travel to get back to the hot water heater those keeping the water warmer longer.

-- Added ATWOOD MOBILE PRODUCTS 93105 Adjustable Electronic Thermostat. This allows me to set the hot water heater's temperature to 150+ degrees (my electronic thermostat controller showed 180 degrees). The greater the water temperature, the easier to heat.

-- Wired the coach's thermostat Heat Pump option to the control wall to control all the switches.

Steps to run Water Heater Hydronic Heat:


-- The Water Heater Hydronic heat can be used with Propane, Electric, and/or Espar heating the water. All 3 can be run at the same time or individually.

-- Set the electric temperature controller to 175 degrees (this will ensure that the cycles of the Atwood water heater will be controlled by the controller and not the water heater).

-- Set the coach's thermostat to Heat Pump option.

-- The Cozy III heat exchanger fans and the circulating pumps are automatically controlled by the coach's thermostat.


When the thermostat calls for heat, the circulating pump(s) will turn on and pump the water through the Cozy III heat exchangers and through all the coach's piping. The thermostat will cycle the circulating pump(s) and Cozy III's fans on and off based on the temperature.

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Here is a write up for our Hydronic Heating modifications. Note that all original functions that our View came with from the factory are still in place and functional (Furnace/water heater/etc).

I really did two different modifications to produce heat - Water Heater Hydronic Heat and Espar Hydronic Heat.

I'll do the write up in two posts.

Espar Hydronic Heat Steps:

-- Completed the modification to allow the Espar heater to run without the engine being on and for an unlimited amount of time. http://sprinter-source.com/forum/showthread.php?t=668&highlight=espar+relay

-- Modified the Espar wiring to be run from the Coach's batteries. Tip: you need to modify both the "espar mod" battery connections and the fuse under the drivers seat (25 amp).

-- Added switch (Aquahot switch panel - ELE-ASM-506) to the control wall in order to control the Espar (on/off) which is also controlled by the electronic thermostat controller (will use this feature to heat the water heater in spring/fall/etc). Ran wiring back to control wall from dash to control Espar and another wire to control the dash fans (on/off - controlled by thermostat).

-- Ran Goodyear 5/8 Hi-miler heater hose from the output of the Espar (used a 1" x 1" x 3/4" pex T) under the chassis to the water heater's motor aide connections and back to the engine with the connection right below the dash heater valve (used a 1" x 1" x 3/4" pex T).

-- Installed a Cozy III (EXE-103-0EX?) heat exchanger under the pantry and ran the heater hose to this heat exchanger.

-- Tapped into the thermostat's heat pump wiring and added relay to control the switches on the control wall.

-- Added switch to the control wall to control the Cozy III (high/low/off) and to control the dash fans (on/off).


Steps to run Espar Hydronic Heat:

-- Ensure that the electronic thermostat controller is set to above 160 degrees before it will turn off. The Espar will run continuously as it takes too long to "reheat" the engine if you had the Espar turn off/on with the coach's thermostat. The Espar only uses .07 gph on low speed.

-- Turn on the Espar switch on the control wall.

-- Turn on the coach's thermostat to the Heat Pump option. The bonus with using the Heat Pump option is that if for some reason the Espar Hydronic Heat can not keep up with the demand, the thermostat will automatically turn on the LP Furnace if the thermostat's temp setting and the actual temperature is 4 degrees or more different.

-- The Cozy III heat exchanger fans will be controlled by the coach's thermostat.

-- If cold enough, turn on the Dash fans via the switch on the control wall (controlled by the coach's thermostat).

The Espar will heat the engine to 180 degrees and then it will go to a low speed or idle state. The engines electric coolant pump will circulate the coolant back to the Cozy III and the water heaters heat exchanger. The heat exchanger will produce great heat and the water heater will slowly heat up.

The Cozy III fans and the dash fans will cycle on/off via the control of the thermostat. When the thermostat calls for heat, the fans will turn on (blow through Cozy III heat exchangers) and when the coach has reached the proper temperature the fans will turn off. The Espar will continue to run and the water heater will continue to be heated via the Espar.

The Espar will slowly heat the water heater. That water is then circulated through a loop in the hot and cold water piping in the coach. There is a check valve under the kitchen sink to allow for this loop. This feature will keep the pipes from freezing. The pipes will also be protected via the cold air return that is below the shower. The Cozy III's will draw air through that vent, under shower, piping in rear of coach, and to the water pump area.

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Today I installed the Cozy III heat exchanger right under the pantry door. This Cozy I plumbed into the Motor Aide connection before it goes to the water heater's "heat exchanger". This works great and will certainly take care of any heating situation that we will need. In the short testing that I did running the Espar, the Cozy goes to about 160 degrees and holds that temperature with the Cozy fans both on.

I also completed the wiring to control each of the Cozy III's high/low fans, both circulating pumps, and control of the dash heater fans. All the switches are controlled by the thermostat. So, now I'll be able to test each function as the weather gets colder. Plus depending on the temperature I can conserve battery usage by turning stuff low/off/etc.

The last piece of my project that I need to install is the Temperature Controller that will run the circulating pump if it detects that the pipe temperature in the rear of the coach is too low. This circulation happens automatically when the "water heater" hydronic heat is going but if I just run the Espar - then I need this as a backup.

I need to have some colder weather to test - once I feel confident that I'm done, I'll post some pictures and info on what I added. Don't want to mis-lead until I know it works as designed.

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Update:

The weather has been a bit too warm to do any serious testing, but I have completed a few items.

---- The last time we had boondocked with the Espar running all night, the chassis battery went dead. So, I worked on moving the Espar from the starting battery to the coach batteries. That took a bit of trial and error to figure it all out but I now have the Espar running completely from the coach batteries.

---- I decided to try and shorten the circulating pump loop when the thermostat calls for heat. I found a "normally closed" solenoid valve on Amazon for $17. Now when the thermostat calls for heat, the solenoid valve opens and helps create a smaller loop. Hard to test right now because of the warmer temps, but I'm guessing this will keep the water heater water temp higher for a longer period of time.

---- I ordered another Cozy III heat exchanger. After testing the Espar and the hydronic heat from the water heater, I "somewhat" determined that the motor aide heat exchanger may not be able to keep up with heating the water as the hydronic loop cools it down to heat the coach. By adding a Cozy III heat exchanger that will be plumbed into the motor aide connection - I'm almost 100% sure that it will keep the coach warm in any temperature. The motor aide connection has shown 157 degrees on my last test. I should have that installed tomorrow.

I still have a few items to complete, but I really need some cold nights to see were I'm at. Fun project, so far.

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Now I'm starting to clean up the pieces and parts and continue to test everything out. Today I worked on the noise that was coming from the water heater when I had the circulating pumps on. The solar pumps do not make any real noise but there was a buzzing sound from the water heater. After some false fixes, I found that the check valve on the cold water inlet was making the noise. I removed it (ordered new one) and that took care of the noise.

Now the system is very very quiet - just the slight sounds of the computer fans that blow thru the heat exchangers.

Really waiting for some real cold weather to do some more testing.

So far, it has turned out great. Once I get it all set, I'll post some pictures and document some of the items that I added - just in case someone is researching this in the future. All the original equipment for our 06VH is still in place and working, we just have another option.

Hopefully I'll run the Espar all night Thursday (28 degrees) to see if my changes fixed the water temps slowly getting colder thru the night.

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Interesting fact on the Espar:

According to the manual the Espar burns .16 gph on high speed and .08 gph on low speed. Probably can go all night on a gallon of diesel.

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Update on Espar hydronic:

After doing some more research, I found that I had plumbed the motoraide connections into the engine in the wrong spot. I changed it to send the coolant to the water heater and the dash heat directly from thee output of the Espar.

I also noticed that the coolant pump seemed to be pulsating. Tapped it with a hammer a few times and it freed up sand ran correctly. That would be at least part of the issue with the water heater not being fully heated overnight. During the night we could hear the Espar go high speed then slow down then back tho high speed and on and on. That would make sense if the coolant was not being circulated correct by the pump. The Espar would reach the temp limit when it shouldn't have. Now the Espar stays very consistent in its noise output and the engine temps reach 180 like it should. The other morning it was only 110 degrees after running all night.

So, I believe I have the problem with the water heat sliding overnight. Tomorrow night should be down to 30 degrees, so I can test it then. I also installed a 5watt solar pump in the coolant loop right before the water heater.

Looking forward to testing this out again.

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Last night they called for temps in the low 20s, but checking this morning it only got down to the mid 30s. We ran the Espar all night and had no problems keeping the coach warm. The system would cycle on for about a minute and then turn off.

Still have the problem keeping the hot water heater hot via the Espar. I checked the engine temp when I awoke and it was only 105 degrees. I'll have to read more on how the Espar works - I expected that it would keep the engine at 180. So, this may be my problem. The water heater temp went from around 130 down to 85 this morning.

The other issue we had is that the chassis battery was dead (used battery booster to get started, no big deal). I wired everything to the house batteries, but must have missed something. The house batteries went from a State of Charge of 75% when we went to bed to 63% when we woke. That'll work, pleased to see that it doesn't use much battery.

Used NO propane (and very little diesel) and the Espar kept up with the thermostat with no problems.

Few more items to test out.

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Tonight will be a good test, low of 20 degrees as we boondock at a casino parking lot in Wisconsin Dells. We'll run on the Espar the entire night.

Noticed on the way up here (about a hour drive), that the motoraide heated the water heater to 135 degrees. But while sitting with just the Espar on, the water heater temp goes down. I'm guessing I need another circulating pump to get more of that heat to the water heater.

Trail and error, but making progress. At least I have a full propane tank and a good working furnace if needed.

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Last night we slept in the motorhome with the Espar/Hydronic heating the coach. The outside temps were 35 degrees. I have a switch for the Espar that will run the Espar but the dash fans only come on via the thermostat. When the thermostat would call for heat, the dash fans along with the hydronic heaters would turn on. Within probably a minute or so, the coach would be at temperature and the thermostat would turn off the dash fans and hydronic system.

I have great confidence that the Espar heat will provide all the heat we will need even when temps are close to zero.

The part I didn't like was the fact that the motoraide connection only heated the water heater to 95 degrees. While this will work in keeping the pipes from freezing, I would expect to get more heat from the engine. Today I'm going to try and install a second solar water pump (5watts) right before the water heater in the motoraide Hose. We'll see if this helps. Also, I need to review my motoraide hose routing.

Espar was great last night, giving me the confidence that it'll handle the real cold.

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Last night I ran the hydronic heat using the 110v electricity to heat the hot
water heater. I set the thermostat to 69 degrees with the night temperature
going down to 36 degrees.

I checked this morning and the coach temp was 69 degrees. The only issue that I
could see is that the water heater temperature was down to around 118 degrees
when it is normally 140 degrees. This was concerning, thinking that the
hydronic heating loop was cooling the water faster then the water heater could
catch up.

Well, after doing some research I found that the Atwood water heaters are set to
max temp of 140 degrees then will cycle down to 115 degrees before heating the
110v element again. This was a relief finding this info. I ordered an
adjustable temperature thermostat for the Atwood water heater - this hopefully
will cycle more often.

Tonight I'm running the Espar engine pre heater only (no 110v or no LP). The
overnight temperature will be around 30 degrees. It is around 40 degrees right
now and there is little doubt that the Espar will take care of the heat as it
cycles on for just a few minutes and heats it up to 70 degrees without effort.
I have the dash fans controlled by the thermostat along with the hydronic
heating.

Because the hydronic heating uses the hot and cold water pipes as the loop, all
the water pipes are warm and will not freeze.

Getting closer to having it ready for our Calgary trip over Xmas.

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Today I wired everything together and let the thermostat control the hydronic heating. So far, it is working great. It is quick to heat the coach and is fairly quiet. I checked the amp hours usage on our monitor and it was 1.9amp hrs with everything running- very pleased with that. Right now it is in the 50's and when the hydronic heat turns on, it heats up quickly and it takes some time for the thermostat to demand heat again. Might have something to do with the residual heat in the registers.

Right now I'm running on shore power with the water heater on 110v. I have it setup so that I can run off 110v, gas, and/or Espar. This weekend we are to have temps below freezing, so that will help out my testing. I'm anxious to try running it off the Espar alone.

Next I plan to add a small register in the outside water compartment. With the setup, the hot water circulates thru the cold water pipes keeping everything warm. I'm hoping this will also provide heat for the drains.

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Update:

After a few days trying different ideas and testing out our hydronic heating solution, I think I have it going in the right direction. When I first installed the 2gpm 5watt solar circulating, the pump would not keep the heat register hot enough. I then ordered a 3gpm 15watt solar circulating pump and this worked. Now the heat loss from the beginning of the loop to the end is under 8 degrees without the heat register fans on and 12 degrees with the fans on. This works.

I then installed a second heat register under the rear dinette seat. Now with both registers on and the circulating pump on, I'm getting consistent hot heat from both registers when I'm heating the hot water via shore power. Now, I need to do some testing to see how it works in much colder weather and with the Espar heating the water. Now that I have it functioning, I can do the testing.

Next, I'll wire everything into the coach thermostat and switches to control the pieces and parts.

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Today I installed the first Aquahot heat exchanger. I installed this one in the bathroom. The unit sits in the space where the water pump is located and comes out into the bathroom on the floor below the closet door. I don't have the circulating pump hooked up yet, but just for a test I ran the hot water out the bathroom faucet for about 30 seconds or so and connected the fans on the unit to a battery. Just in that short time, the heater was putting out quite a bit of heat and was very quite (almost not noticeable).

Now waiting on the circulating pump.