RM7895 BURNER CONTROL PROBLEMS

[coolerinfrederick]

I'VE GOT ONE ON ORDER FOR A MUA UNIT, THE PROBLEM WAS THAT IT WOULD NOT INITIATE HEAT OPERATION WITH A CONSTANT 115V TO TERM. 5 AND 7 , TERM. 7 IS A INTERLOCK FOR YOUR LIMITS, AIRFLOW ETC. , PRETTY STRAIGHT FORWARD, I NOTICED AFTER ABOUT 2MIN.S OF POWER TO CONTROLLER THAT THE GREEN LED POWER LIGHT WOULD SLOWLY DIM AWAY, ANYONE EVER SEE THAT?

[nyrb]

Do you have a 7800 Display plugged in to see what is going on? You can enter into diagnostics and see if the burner control is seeing all the input signals. I seem to remember the greed LED going on/off in standby.

[HvAckid82]

green light stays on during stand by. Has this controller been in opperation for awhile?

[coolerinfrederick]

not too long maybe 7 yrs. , yeah that light should stay on as long as there's power to it

[nyrb]

Check out page 8 under Safety Provisions, Internal Hardware Monitoring. Addtionally I believe you need power to terminals 5 and 6 to initiate an ignition cycle, terminal 6 is the operating / limits and terminal 7 is the Air proving switch (of course sometimes they're jumped together depending on the control arrangement).

http://customer.honeywell.com/techlit/pdf/PackedLit/65-0205.pdf

[coolerinfrederick]

thanks for the info., yeah they were jumpered

[coolerinfrederick]

that article says it blinks every 4 sec.s, the power led would just go completely out though, replaced the controller today and unit is up and runnin, the rm7800 series have always been so reliable, shoot i think this is my second in 10 yrs. so i just have a hard time replacing one

[nyrb]

I have to agree with you there, I've seen my share of 7800's and rarely have I lost one due to an internal issue. I have a couple on oversized boilers that reached 99,999 cycles 2 years ago and just keep on going. Glad you figured it out. I don't know if have one, but the display window is the handiest tool for troubleshooting problems when they do occur.

[ascj]

I find the Honeywell 7800 series the most reliable primaries. It would be a cool discussion to find out what everyone thought were the most problematic primaries.

I would say Fireye TFM-2.

[freonrick]

I had 3 of them last year that was bad on start up. other than that they are hard to beat.

[coolerinfrederick]

totally agree with you ascj