CARLIN EZ PRO gas conversion burner question - firing problem.

Dirtcrasher

Since the end of the last heating season I would hear my atmospheric boiler with hydronic heating and the Carlin conversion burner fire, but only for about 6 seconds. Then it would shut off, as if the flame is not sensing a flame (similar to how a dirty sensing eye would act on an oil fired boiler). This will happen 3 or 4 times, but then it will start and run until the aquastat or tstat are satisfied for 10 minutes or so. And those same events are now duplicated nearly every call for heat or hot water (aquastat). I assumed I needed a flame sensing rod, but I've read that it should lockout after a few attempts, and that hasn't happen. Nor do I have to hit the reset or reset the service switch. Bear in mind I still have the original controller, not the digital newer style, so I don't get any type of message and that could be why this unit does not lock out?? After that 4th attempt, the burner runs without a sputter. The firebox is clean, the heat exchanger is clean, it is vented from C pipe to B vent (which is also clear) and it has a damper that moves freely and opens slightly while running, there is no CO detected in the immediate area. How do I figure out what part I need when all I can think of is the flame sensor or swapping out the controller? I'm unsure if the flame sensor can be tested. I do have the new (diagnostic) control box with the troubleshooting screen, but I try not to be a "parts changer". Although, I'd be willing to replace the flame sensor if some others felt that could be the issue seeing that it has the original controller which may not lock out. Thanks for any help.

HVACNUT

It needs to be set up properly with a combustion analyzer. Its likely excess air.

archibald tuttle

Funny, I just mentioned the flame rod in another thread and how difficult it is to reinsert correctly in A and B style heads. However, as @HVACNUT has pointed out, the condition you report is often the result of a combustion problem and in your case with no sooting it is reasonalbe to suspect it is excess air although similar flame rod results can arise with too little air. (exception being you talk about sputtering during operation. I don't know if you had been carefully familiar with the sound of operation before you noticed these restarts or if you have acquired that first hand knowledge during these drop outs such that you might not realize there can be a mildly wave like form to the sound of operation which isn't really sputtering. If this is really sputtering you've got the kind of problem where you ought to shut it down. I don't know if the gas valve could be fluttering. In some installations you might be able to observe the flame if there was an observation port. I sometimes make an observation port by drilling the door or plate where the unit is installed and adding a piece of quartz glass or equivalent but it is very unusual or would mean a crapload of excess air that the process is blowing itself out or marginally igniting and these are intermittent ignition so you wouldn't get a full 10 minute cycle as you describe if the flame were actually going out.)

and if the relay picks up within its retry limit, it won't lock out and it sounds like that is what is happening.

do you have the old 60200FR relay or the newer 60200FRS that has a display. that display allows you to push the up arrow (which if you can read the fine print on it has a microamp symbol) and that will display the microamps generated by the flame rod throughout the light and running process. (I wish it did not automatically return to regularly scheduled programming as quickly as it does as sometimes you are watching through a pure or repurge and just as the boiler fires it disappears and if you aren't quick you won't hit it again in time to see the reading the resulted in a drop out, if one occurs.). these days carlin tech doesn't really even want to talk to you about maginal flame rod pickup if you have the old relay. And, to be fair, despit the $150 you gotta throw for a new relay, it is so much easier to diagnose flame rod output compare to trying to meter it that I keep these relays on hand and replace them anytime I service a unit that has the old realy.

you are looking for something around 2.2 microamps but the control will run with maybe 1 (carlin doesn't tell me that number, only that that 1 is too low even though it may prove flame at that level).

slightly complicating to your post is that this cannot be an atmospheric boiler. the ezgas is used to convert a boiler that took an oil power burner, i.e. forced draft from the burner end, with a gas alternative. but the setup was never atmospheric. (at least I can't imagine how it could have been-maybe some clever macguyver has an atmospheric boiler they could eliminate the draft collar and find enough room to low mount the power burner and kind of seal the base of the combustion area. now you've got me thinking about trying this sometime in the shop for the fun of it, but I don't this you have atmospheric boiler.

IIRC the desired combustion set points are 3-6% oxygen and 8 to 11% CO2 which are fairly typical so I try to get within the range and then monitor CO and flame rod microamps with an eye towards less of the former and more of the later but balancing them to hit the desired 2 and change microamps and usually the range to accomplish that doesn't allow me a lot of luxury to play with efficiency numbers, they just end of being whatever they are.

so the question I posted (Aside from asking for tips on inserting the assembly back into the head), was also how you really assess if the microamps produced reflects any degradation in the rod itself and I haven't had that question answered yet. I will be putting it to my carlin connections when I see them at AHREpxo later this heating season. Because literally every flame rod issue I have encountered with an EXGas I have solved by checking the combustion set, but maybe there is some kind of degradation in the rod that means I am compromising either CO emissions (still well within nominal 400ppm limit although I would prefer below 100ppm and can't always quite make that) or efficiency in order to get the flame rod response I need to satisfy the primary safety control. it may be that it isn't a rod problem and I could consider downfiring the given burner. the setups are not easy for changing the firing rate, which is too bad. I have taken in later installations to adding a union on the downstream side of the gas valve to make it easier to change the orifice (one of the carlin techs told me when I mentioned that that that is how they set up for testing so they can change easily. I think they ought to ship 'em to be set up like that, bit I digress).

Steamhead

https://forum.heatinghelp.com/discussion/comment/1869447#Comment_1869447

THIS!

Where are you located? We might know someone who can help……………

Dirtcrasher

Thanks for the replies. I did mention that I have to old style controller, no digital display. But I also have the new one with a digital readout in stock, but I didn't want to be a "parts changer" as I was taught not to throw parts at things without properly diagnosing them; but, the new controller can't hurt. And I don't have any sputtering, at any portion of when the unit cuts off, that was my point as to why I was unsure why it would drop out. I was an HVAC service tech for a few years and thrown into things I had never seen before. I'm actually more used to the dealing with big RTU's and large air handlers as well as the 90% air handlers we would install.

Today I paid a bit more attention to the cycles. many times it would run about 12 seconds, sometimes 30 seconds and a other times a full cycle of 3 minutes because it's not that cold here yet. I can probably borrow a combustion analyzer from my old boss and I have a chart for the parameters. It just didn't make sense that some times it would run for 12 seconds, and other times the complete cycle.

Dirtcrasher

This is my personal 2 zone boiler for a 2 bedroom Cape. It never had a draft hood, not when it was originally oil nor after the conversion burner was installed. I have not checked the micro amps, I'd have to get another meter, IDT any of mine deal with micro amps. Any service man I've called around here in my life (prior to going to HVACR school) just throws parts at things. They don't test, they just change things until your unit runs and send you a bill. I wasn't like that as a tech, because I could not handle overcharging older people for parts they did not need. I told my boss I would no longer fill out the invoices if he wanted me to change gas valves when we were not 100% certain it was a gas valve. In one instance, the burner on a hot water tank was plugged (a 5 minute repair). And I was told to charge them 2 service calls for 2 men, plus mileage, plus a 250$ gas valve they didn't need because another tech made a bad diagnosis. I couldn't do it. Now I've own rental properties.

mattmia2

the combustion is going to change depending on if the boiler and the vent are warm or cold and the ambient air temp and humidity so it may be less off at some times vs others when it tries to fire.

if you don't know why it doesn't have a draft hood with a power burner then you definitely should call someone that knows combustion.