One of the interesting things about RVing is the availability of mobile service providers.  The mechanic who maintains our bus chassis, Joe Cannarozzi, travels all over the U. S. from his base in Chicago, Illinois.  Other vendors, many full time RVers themselves, travel the RV rally circuit providing on-site service.  We stopped by Phoenix Paint late in the morning to visit with Michele Henry, who painted our motorcoach in 2011/12, and met Darin Hathaway there.  Darin is an independent Elkhart-based factory trained/authorized Aqua-Hot service technician.  Our Aqua-Hot has not been running well the last few of times we have tried to use it, even failing to ignite once and producing copious amounts of white smoke for as long as five minutes if/when it did.  I described the symptoms we’ve experienced and what we have done to try and diagnose the situation.  Darin had time in his afternoon schedule to service our unit so we arranged to have him come over to Elkhart Campground to do the work there.

Darin arrived around 2:15 PM and performed the standard annual maintenance / tune up.  He let me watch and ask questions and I learned a bit more about the unit and how it functions.  He removed the burner and then removed the swirl chamber which had a buildup of carbon soot.  He removed the nozzle, flame sensor (photo eye), igniter electrodes, and the photo (mounting) disk.  He also noticed a small inline final fuel filter that needed to be replaced.  He clamped off the lines, removed it, and installed a new one.  I wanted a spare, but he only had the one with him so he said he would order one for me.

He disconnected the two main electrical harnesses, plugged in his service control box, and then installed a pressure gauge into the nozzle port.  He activated the fuel pump and the fuel pressure was just over 160 PSI.  It was supposed to be 145 PSI so he showed me the adjustment screw and backed it down to the proper level.

The photo disk was slightly wrapped which is not unusual, but could prevent it from sealing the combustion chamber, so he installed a new one showing me how to make sure it was loose enough that it could position itself correctly when the main blower/pump housing was re-installed.  I got a second disk to keep as a spare.  He installed a new nozzle and then reinstalled the two igniter electrodes and showed me how to set the spark gap.  He also pointed out that the cable clamp on top of the main blower/pump housing is the spark gap tool.  Nice touch.  He said the old nozzle was a bit loose which might have allowed a little fuel to get into the combustion chamber without going through the nozzle.  His tips for nozzle installation were to always use two wrenches and to tighten the nozzle, back it off, and tighten it a second time.  Apparently this helps the threads seat and seal.

He checked the four rubber grommets around the housing and said they were still in good shape and probably relatively new.  I got four for spares, two lefts and two rights.  I might as well get parts while I can.  He cleaned up the swirl chamber and re-installed it, seam side up.  Very important.  He checked the spark igniter and it worked and then failed.  He spent some extra time that was not part of the routine service diagnosing and fixing this issue.  He thought it might be a marginal or failed coil, but after tightening the wire connections and flexing the wires a bit, it seemed to work fine with repeated testing.  The coils are relatively expensive and decided not order one as a spare at this time.  Hopefully I don’t regret that decision somewhere done the road.

With critical components replaced, and everything cleaned and adjusted, Darin inspected the main combustion chamber for signs of fuel or coolant leakage but did not see anything out of the ordinary.  He secured the main blower/pump housing to the combustion chamber / “boiler” assembly using a short quarter-inch socket ratchet with a 12″ extension and suggested that I do the same.  Apparently it is very easy to over-torque these bolts and break the mounting tabs, which is a very bad thing to do.  A final test resulted in the unit starting up immediately with clean exhaust; no smoke, black or white.

We spent a few more minutes trying to determine which thermostats in the house (there are three) controlled which of the three circulating pumps, but did not figure it out.  The is important because the radiator for the water bay (where the Aqua-Hot is installed) is clearly part of one of the coolant circulation loops controlled by one of the thermostats in the house (the leftmost of the three at the top).  The radiator for the front bay is also part of one of the house loops but I do not know if it is tied in with the water bay radiator or with a different zone.  Darin said there was usually a separate thermostatically controlled zone for the bays, but I assured him that our coach was not configured that way.  Our unit does have a forth circulation pump that is tied in with the main engine coolant.  It can be used to pre-heat the engine or to provide heat from the engine to the coach.  Darin indicated that anytime the burner is lit one of the circulation pumps will be running, usually the middle one.  In our unit it seemed to be the engine pre-heat pump, but I later discovered that I had the pump turned on.

It was after 3:30 PM by the time Darin was finished and I had a 4:00 PM conference call meeting of the FMCA national education committee.  We turned the diesel burner on from its normal control switch and let it run for one complete cycle while he finished up the paperwork.  As the cycle finished I saw a little white smoke in the bay, which was still open.  I opened the door to the small compartment underneath the Aqua-Hot and it was full of white smoke.  I have the battery for the fuel polishing module installed in there but the compartment us otherwise empty save for a large diameter tube (5″?) that runs from the bottom of the Aqua-Hot through the compartment, and out the floor.  This tube provides fresh air to the combustion chamber and also provides a conduit for the exhaust pipe.  There was obviously a double problem:  1) exhaust gas was leaking from the exhaust pipe somewhere, and 2) the large outer tube was not sealed.  Add that to the project list.

I called in to the FMCA national education committee meeting at 4:00 PM and by 4:10 PM (EDT) we had enough members for a quorum.  Committee chair Gaye Young worked us through the agenda and we were done with our first meeting an hour after we started.  The committee is charged with looking at four topics, one of which is RVillage.

We had a quiet evening and had pan-grilled tofu with caramelized onions and bar-b-que sauce for dinner, followed by a final stroll around the campground.  We got online with the campground WiFi via our WiFi Ranger and took care of e-mail, RVillage, and WordPress tasks before turning in for the evening.