Fireye controller fail.

donaldmc

Unusual mag relay (amp modules) burnout on a fireye controller. The story is best told by the home owner, so I'm posting his well written story here.


Fireye MC120 – Beware Tests Result Which Falsely Confirm Defective Unit is Working Fine

My boiler consists of the following:
· Weil McLain 78 (model 478) gas/light oil boiler (mine burns gas)
· Powerflame blower and flame rod
· Honeywell water pressure controls
· Honeywell R845A thermometer relay
· Honeywell V4943B1019 main gas valve
· Fireye MC120 controller, with two cards: a Mart1 MP230 flame rod amplifier and a programmer/LED.

The MC120 and cards look like this:




My gas line architecture is as follows:
→ the gas line travels from the ceiling to the floor and turns 90 degrees;
→ a ball valve opens and shuts the line;
→ a curled tube after the ball valve branches off to the pilot;
→ the gas line continues to the main gas valve;
→ from there, the line makes two 90 degree turns and feeds into the blower.

In other words, once the ball valve is opened and the electric switch turned on, the pilot lights first, then the main gas valve opens, and then the lit pilot lights the burner.

The boiler stopped working. Power goes into a junction box with BX cables out to the relay, water pressure controls, and Fireye MC120 faceplate. Voltmeter put on the Fireye chassis and got no reading. Voltmeter put on the junction box leads to the Fireye chassis got no reading. From this, it was determined the R845A relay was bad. New one purchased and installed it, and full power restored to the Fireye chassis.

The Fireye MC120 has five red LEDs as follows:
· Operate Ctrl (power)
· Air Flow (blower on)
· PTFI (pilot trial for ignition, i.e., the sparker to light the pilot)
· Flame
· Alarm (shuts down system if no gas, no flame or no blower)

Upon flipping the electric switch, the Operate Ctrl and Air Flow LEDs lit up immediately; after about 8-10 seconds, the PTFI sparked, and almost immediately, the Flame LED lit up; and a moment later, the PTFI LED turned off.

But the system was not fixed. The pilot lit and stayed lit, but there was no main gas burn at all. Voltmeter on the main gas valve leads showed no electricity to that valve. Confirmed all connections were sound.

The Fireye technician in New Hampshire insisted “these units almost never fail” and that Fireye distributors have testers and testing is free. Went to one distributor and had MC120 tested. Told it was working fine. Specifically asked if the 5 circuit was working, as it was not energizing to open the main gas valve. Distributor confirmed the 5 circuit was working. However, as he hadn’t tested a Fireye in some time, he suggested that, to be certain, the MC120 be tested again at another shop. Unit tested again at second shop and confirmed as working, including the 5 circuit.

Called the Fireye technician and reported the test results. He insisted that, if Flame LED came on and all circuits tested and confirmed as working, not once but twice, the problem is the main gas valve, not the MC120. Hence, a new main gas valve purchased and installed, and system fired up. As before, the pilot lit but not the burner. The MC120 still was not opening the main gas valve.

Tested the Fireye circuits with the voltmeter -- got 117 volts at the 3 circuit, but only 0.2 volts at the 5 circuit. Fireye removed from faceplate, and put on bench, Amplifier and programmer/LED cards removed, and chassis circuitry inspected. There are several amp modules soldered into the chassis. These are shielded by clear plastic covers. There was smoke damage on the amp module connected to the etched lines leading to the 5 circuit. MC120 reassembled and put it on the faceplate, and system switched on. As expected, the pilot lit, but not the main gas valve. Using 14 gauge copper wire, the 7 power circuit was hotwired to the 5 main gas valve circuit. Voila – the main gas valve opened immediately and boiler fired up. This proved the 5 circuit for the main gas valve was not energizing, despite two tests which showed it was working.

Took MC120 chassis to a third distributor. Unit tested as working fine, including the 5 circuit. Voltmeter put on the 3 circuit (pilot) and read 120 volts, but when voltmeter put on the 5 circuit (main gas), there was no reading, even though the tester light showed it was working. Amplifier and programmer/LED cards removed and put into a new MC120 chassis and voltmeter then showed 120 volts at both 3 and 5 circuits.

New chassis purchased and installed, and boiler now working fine.

In other words, the MC120 was tested three times at three different shops. The results were the same: nothing wrong with the unit, including the 5 circuit for the main gas valve. Only that was a false reading. In fact, the 5 circuit was shot, probably from a surge or current fluctuation caused by the failing R845A relay.

Bottom line: don’t rely on Fireye testing (at least not for the MC 120) at distributors, nor claims by Fireye technicians that favorable test results means the unit is working. Instead, always test each circuit independently with a voltmeter, and inspect the circuitry on the chassis for shorts, smoke damage to amp modules, etc.

Below is Mr Abady's link to his well formatted article, which I am not skilled enough to post here.

https://www.wetransfer.com/downloads/88b88d5ad8a1db0582e4fc4471c0759720151122053139/dca490

Jamie Hall

There's a different bottom line to this one, too: it is possible (all too possible) for a circuit -- such as the one in the tale above -- to show a correct, or nearly correct, voltage when there is no load on it (such as when one probes with a multimeter or megger) but to fail when there is a load, such as when it is plugged into a circuit. Surprising how often that happens.

The tipoff in this case was the smoke damage. Something had overheated and damaged the board, but there was still a high resistance connection in there.