Monitor's FCX oil fired condensing boiler?

Kal Row

thanks, national is only 50blocks from me

Nick_12

FCX Facts (from someone who has spent intimate time with them)

The FCX is a phenomenal energy saver. Any compentant burner technician can work on one, clean it, etc. That being said, here are some caveats:

No post purge is set up. It's not wired for it, but can be. This is the reason the nozzles go bad quickly. The Danfoss AS nozzle seems to hold up best to re-radiation. Riello is the only burner I know of that has the nozzle set back in the burner tube to protect against re-radiation, and thus does not necessarily require a post purge. The HeatWise burner that comes on the FCX, and the possible Becket NX do not have this protection. Re-radiation will quickly cook a low GPH nozzle, and varnish will build up inside, causing nozzle problems. I suggest wire for post purge, if a Riello is not available. (Of course, you would think the manufacturers would figure this out, it would be interesting to know how it's wired in France, and what kind of burner design is used)

Initially, the condenser cover seal was split, instead of one piece. It would shrink, and obviously leak, causing a dangerous condition. They did correct this... but be aware of old ones out there, get the new cover seal.

They do not package a condensate trap with the unit, and the discharge pipe is an odd size... so the installer is left to imagine the proper trap seal.

They package the relief valve inside, where the tridicator should be (and where it is on the French units). This should be packaged as a kit to install on the exterior back, with the rest of the piping.

The primary heat exchanger is essentially a steel barrel with heat baffles and then an insulating baffle at the top. This is a fine set-up, but the baffles do need replacement every 2-5 years as they degrade with heat. Also be careful not to disturb the insulation in the top baffle.. if you do, replace it. I've heard they are trying to come up with a better baffle that will take the heat. It's important to know that this design requires that the primary boiler never operate below a 150F supply temperature. They do not want any condensation in the primary, it must all take place in the secondary (of course). But I say this to any of you control "freaks" :-) out there that want to run this on full outdoor reset like a gas condensing boiler. Don't do it. It's not necessary anyway. You'll find it always runs 93%-98% on the combustion analyzer anyway. You can reset between 150F and up supply temp.

The boiler tunes in easily with zero smoke, and must always run with zero smoke. These boilers run ultra and impressively clean during steady state... however, ANY soot is a problem for the condenser. Soot that coats the bottom of the condenser will act as a sponge, absorbing and concentrating the sulfuric acid... and will eat out the best of heat exchangers. When servicing, check the bottom of the secondary heat exchanger, and the rear exhaust tee. You can also stick your analyzer into the fresh air.. if you get any flue gasses reregistering, then you probably have a corroded exhasut tee (this tee separate the combustion air and flue into a concetric vent). Of course, having no post purge, is again a problem, as this when soot will build up. You'll have zero smoke very easily when operating; but when the burner shuts down, you will get smoke, and not even know it. This is the reason Beckett came out with the "clean-cut" fuel pump. This is also a Riello claim to fame, as it shuts down smoke free. This is why "plain vanilla" burners with typical solonoid shut-offs need a post purge, especially with a condensing boiler. As far as I know, the burner option on the FCX does not include either of these "clean-cut" burners, or a post purge. When cleaning, be critical to cleaning all soot out of the bottom of the secondary and also where the plastic flue inserts into the exhaust tee. (Maybe they'll start making these parts in a high grade plastic someday? Or stainless coated in PEX or PP ? (Hmmm)

The boiler is conspicuously missing the controls available in Europe, and the actuator for the built in three way mixing valve... sure would be nice to have.

The boiler goes a long way: it has two temperature circuits pre-piped... very cool. It has an expansion tank piped in... very nice. It has the primary circulator piped in and wired... nice. Built in switches and relays, high limits, etc. It's ultra quiet and has an appliance finish. All good. But it stops short, missing a pressure guage, missing the condensate trap, missing the mixing valve actuator, missing the controls intended to be built in on it, missing a built in high quality oil filter, missing post purge on the burner... this could be an awesome boiler, but stops short.

The Heatwise burner, while very good, lacks quality control and is inconsistent from burner to burner.

They initially had trouble with the CAD cell seeing properly... causing intermitant shut downs that were false. The fix was cable tieing a new CAD cell bracket closer to the retention head.

Other then that, you will see very impressive fuel savings.

All for now!