RM7800 - Code 28 problems

tim from Reed Wright

Try a new Ignition lead and a new Pilot solenoid

Dale_3

RM7800 - Code 28 problems

We've got a small boiler with a 7800 series controller on it and we have all of a sudden had quite a few nuciance "I can't spell" lock out problems. For the first couple of years it ran fine. We then began having code 28 "pilot flame failure" lock out problems occuring more often. Upon reseting the control it would fire up fine get a strong and constant 5v flame signal and run fine. We have checked everything we can think of and run down the list of checks in the serv liturature. It still happens too often. The next step is replacing the relay. Has anyone had a code 28 lock out end up in replacing the entire relay? Thanks for the help. Dale

jeff_25

is this boiler have a power burner is check air settings clean pilot check gap of spark open little more than spec. also replace spark lead i like to use rubber boots like on a car also use dioelct grease also what type of sensor if peeper check down shight tube on lite up to see if you see good pilot may need to adjust pilot but a good cleaning first if it a rect. replace wire with boots and grease also clean all ground surfaces and mounting screws also clean pilot and check flame lift off

Dale_3

We have ensured the ground on the ig trans is grounded better. "We were getting interference, now we are not" I believe the sensor is a C2027 ??. It has been cleaned. WE have been data logging the volt to the pilot sol and it is proper without fail. We have never been on site and seen a bad pilot flame "checked gas press and the like" EVERY time we have reset the control it has fired back up with a good pilot and a STRONG "non wavering" 5v pilot signal. There seems to be no ryhme or reason for the lock out. Thanks for all the responses. Dale

[Deleted User]

If it is a

Webster, change the electrode. The flat tip on the J1 & J2's burn down fast. 1/16th" will kill you.

If you have a tall stack, check the overfire draft or pressure. Tall stacks & cold temperatures have been killing us this year. Most fixes involved reducing low fire air, setting the pilot gas pressure to the 3.5" most call for, opening barometrics, closing dampers, or all of the above.

We also have replaced many 6K transformers. If we can't get over 90% of voltage needed, it's history. Careful. Some burner mfgs. have gone to 10K's on some burners.

Last. Have you locked the 7800 in Test & run the pilot for a long trial. Sometimes that will show you what is happening. In particular, look for the flame to drop down below scanner view just before main flame normally lights.

Good luck.

jeff_25

check vent lines on all regulators poss. pluged or regulator is sticking

Steve_13

7800 code 28

assume you have annunciation on the 7800- actual pilot failure time is annunciated time less the timing of amplifier-it may be failing prior to where you think it is