I recommend having a spare glow pin screen. These do plug easily and removal without damage is hard to do. As for gaskets it not a bad idea to have them but in the dozens of heaters I have taken apart the gaskets are reusable 90% of the time. Glow pin is not a bad idea, however these are ceramic and rarely burn out. You can clean them with a brass wire brush and I have scraped the carbon off with a pocket knife. But the up side is it comes with the socket needed to remove the glow pin so you can get to the glow pin screen.
Carbon build up is the biggest issue with the heater installed in your SMB. Reasons are the heater is over sized and it runs on low to much or high altitude without the high altitude kit.
The carbon is in the combustion tube and can be cleaned by soaking it in a good carbon remover, CSR makes a good one for this job. Sometimes if let go to long they cannot be cleaned and you will then need to replace it. Also read the TSB attached and you my be able to clean it that way too.
But the best way to keep the unit free from carbon is to wire it so it only runs on high. This is can be done by adding a bi-metal thermostat. You will still use the existing control to turn it on and off but what you would do it turn on the heater and adjust the knob for max and then adjust the thermostat to desired temperature. By doing it this way you still have the diagnostics and timer function available. If you have the mini controller you could just take it out and use the thermostat only. You can see a picture of the thermostat we use in the attachment below.
Another thing that would make the heater more reliable is change the fuel pickup. The last I was out to SMB west they were using the extra connection on the tank. This connection is really to big in diameter and does not go all the way top the bottom. With the pickup being to big it can cause you no starts if it looses prime or if you run below a 1/4 tank. The diameter is also big enough and the pump so small in volume that it can be hard for the pump to pump it up.
For better control if not using the extra thermostat you move the external temp sensor. The last I knew it was mounted up by the heater control. I recommend having enough wire on it so you can move it around the van to see where it controls the best.
One the floor plan that the heater is on the drivers side at the bottom of the closet, make sure it gets plenty of return air. At high altitude it has been reported that the heater will shutdown on over heat because of the lack of return air. This was over come by sliding the door open. I have also heard that a return air grill has been installed in later models but I cannot confirm this for sure.
These are all things that can make your Espar run better and have less trouble and maintenance. 90% of issues are normally installation related. We sell hundreds of these heaters every year and have hardly any issues at all. We have led the horse to water but have not been able to make him drink.
Many of the issues that you have with the Airtronic can apply to the Hydronic as well. As issues arise that have not been addressed in this post feel free to ask and we will do our best to help. If anyone has and issue they cannot get fixed your if you don't feel comfortable with doing the work yourself you can send us the heater. For heaters out of warranty its a flat rate of $75 plus parts and shipping back to you. For warranty repair its shipping only.
The file shows the spec for the auxiliary pumps we use.
Use the CM30 pump if you want and axillary pump to get heat right after you stop the motor. This will allow you to use the flat plate when the engine is warm without starting the hydronic unit.