Camus 399 modcon Natural gas to PL conversion questions

Mark Eatherton

Anyone got any tricks or tips they'd care to share?



No conversion kit (orifi) included.



Thanks



ME

Mark Eatherton

The final results....

This boiler is essentially a Gianonni condensing fire box with the EBM Pabst blower coupled to a Honeywell negative pressure gas valve. I was called in as a hydronics consultant to guide the installer for a good and proper set up for the boiler, DHW tank and space heating interface. As a part of my services, I was to commission the boiler.



After the contractor made the requested piping changes, I attempted to fire the boiler. It would not catch. In speaking with the factory, they guided me through the process of actually turning the high speed flame adjustment screw while the boiler was trying to ignite (5 second trial). I finally got it to light, but as the boiler would ramp up, the CO and CO2 was off the charts (actually locked up my detector). I had a manometer connected to the inlet fuel tapping. Pressure started out at 13" WC, but as the boiler would ramp up, the pressure would drop to 6" WC. Factory wanted to see no less than 11" WC, so, naturally, I suspected a fuel supply issue.



The 3/4" 2# LP CSST line should have been capable of carrying the load, but the drop of pressure at the boiler inlet, after the 2# to 14" regulator indicated otherwise, so we up sized the fuel supply line from 3/4" to 1".



When I went to try and fire with the new fuel line, the exact same problem occurred again, significant drop in fuel pressure. The CO was still off the charts, and the CO2 was at 13.9% and O2 was ZERO. Nothing made any sense. We replaced the negative pressure gas valve, to no avail. Same problem.



As adjustments were made on the high speed screw, just as the CO2 was coming down, the boiler burner would start chugging. chug, chug, chug chug, with the flexible intake hose lurching in unison with the chugging and eventually, the burner would lose flame confirmation signal and drop out and retry for ignition, but would not catch. Fuel mixture too rich? EXTREMELY frustrating...



The supply fuel pressure was ALL over the place. No stability at all, and it too was bouncing along with the flexible combustion air hose, and the chugging burner...



In desperation, I pulled the 2" flexible combustion air inlet pipe off of the intake venturri, and the boilers flue gas cleaned right up....



On the Knight Lochinvar boilers I work on, granted they use a different (Dungs) gas valve, but the same principles apply, they have a 1/4" relief hole drilled in the intake pipe. They also use rigid 2" PVC piping to connect to the venturri intake horn.



I poked a hole in the flexible 2" intake, and reconnected the flexible pipe, and saw a slight increase in CO2 (from 10% to 11%) which the factory tech said was OK.



Things are working quite well at this point in time. Fuel pressures stable, NO CO in the flue gas stream, nice easy light off and smooth transitions from low to high burn and back.



My advice to the factory would be to modify your I&O manual as follows; In the Fuel Supply section, put a clause in there about keeping a minimum of 20' of separation between any upstream pressure regulators, and the negative pressure regulator on the boiler.



Secondly, get rid of the piece of crap flexible connector hose, replacing it with rigid PVC that can not flex, and drill a 1/4" relief hole in the bottom of the pipe, right before it enters the venturri horn of the boiler.



Lastly, Include in your I&O manual, the process of continuous adjustment of the high speed fuel screw during the ignition process when setting the burner up for use with LP fuels. Also, your requirements of 11" WC pressure during high and low burn are virtually impossible to achieve. In my 36 years of doing this, I have never seen a fuel supply system that was that well installed and controlled. You need to get out of the lab and into the field to see what it is that your equipment is doing...



We wasted a CONSIDERABLE amount of time, money and effort, all because of your silly flexible hose.



The appliance is very well built, and one of the prettiest appliances I have seen in my many years of service, but you need to pay attention to critical details before someone gets hurt, or worse.



ME