We have a Espar 5 in our 43' boat here in Baltimore. The boat has ducting throughout for the heater. We use it as our only source of heat in the winter here as we live on the boat. This is our 3rd winter with the unit. We have been averaging 2000 hours run time per winter.
Now the problem. According to Espar, because of the "heavy use" and the US diesel fuel, we have to service it once a year to clean the coke out and replace O rings. Cost about $500. The unit is set up to run through 3 different speed cycles. As the interior of the boat reaches the set temp (we like 75 deg), the unit will cycle down to low speed and stay there until it needs to warm up some. The other option is like a traditional unit in a home. Comes on when needed at high. Runs on high until desired temp is reached and cycles off.
The problem with the latter in our set up is the layout of the boat creates hot and cold spots. So by constantly running the boat stays more consistent in temp throughout. However running on high, I have been told, reduces the heavy build up of coke. Ideally if a separate fuel tank with kerosene was used, there would be almost no coke issue.
We run the unit from about mid Nov to mid March. The boat stays dry with no condensation or mold issues that some other boats have running electric heat.
We use about 180 gallons of fuel per winter.
This year we turned it on before servicing. All was good until it shut down in the middle of the night (of course). I got it running briefly, but died again.
The tech came out and pulled some codes, took it back to the shop. Turns out the control module in the unit needed replacing along with the yearly service. Total bill $1256.
Since I broke my leg, we had to move off the boat because of all the steps into an Extended Stay hotel. Pretty nice and a fair price. $950 per month.
At this rate, it is less expensive to be in the hotel than it is to run the Espar. With the fuel, servicing and electric bill for staying on the boat in the winter.
Lesson learned: If I was to install another fuel type heater on a boat, it would be a hydronic. The installation is much more costly and complicated, but is much less to run overall. The unit I would use is a Hurricane heater. Service intervals range between 4 to 7 years dependent on hours used.
Another advantage in a boat installation, if the plumbing is run right to the remote cores, the flooring and compartments have heat from the plumbing.
Example: A neighbor at the Marina, has the plumbing run by each through hull fitting in the engine room. So nothing freezes so you don't have to winterize with antifreeze, just blow out with air. Plus the engine room stays about 55 deg. because of the heat radiant off of the plumbing. No need to hook up to the engines as in block heater, because of the 55 deg temp in the engine room. Another advantage is you can mount the remote radiators just about anywhere.
The disadvantages, but no big deal, is one, the water. Even though it is a closed loop system, there is water level loss. Some more than others. If tapping into engine coolant, to act as your supply tank, it is very important to check the antifreeze level on a regular basis. The other disadvantage is, depending on how many remote radiators you have, you will want to have a separate battery supply to run the fans of the remote radiators. The unit itself doesn't use much except for the electric fuel pump and glow plug.
The airtronic and hydronic both use a considerable amount or amps. More than what the specs say! If you were going to be sitting for 2 or 3 days at a time, I would certainly have an aux deep cycle group 31 105 AH battery, no less.
Mercedes in Germany for European models mounts the hydronic under the hood. They used to use Webasto, but now I believe they use Espar.
A note on installation for vehicles.
There is a valve on the exhaust elbow that looks like a tire valve. Some of the installation kits have been missing the drain coil that is supposed to be attached to that valve. Also fill the coil with water first before attaching. Make sure the coil drains to the outside of the vehicle otherwise you could have a wet floor. Some kits supply a cap and ball bearing fitting for that valve. That's ok along as the condensation can drain out of the exhaust pipe on its own.
If your mounting the unit inside the vehicle, it is important to have one of those two devices on that valve because if left undone hot exhaust will come out of that valve! It isn't a lot, but enough to scorch whatever is beneath it and create an exhaust oder.
Sorry for the babbling, but I am soooo bored! lol