Mdshunk, Try This: RPJ2 Gas Furnace Similar Ignitor Prob

tpope

This is a follow-on of my previous post about the RPJ2 trouble.

With the initial error code of "pressure switch contacts stuck closed" and an observed crack in the evacuator housing, I replaced the evacuator and the pressure switch - only to still get the "pressure switch contacts stuck closed" error. Ran checks as per advice on this message service and replaced the control board (White Rogers, 50A58, if memory serves on the model number). All should be fine now.. but no!!!! Now the themo calls for heat, the evacuator kicks on, then the ignitor comes on... but only for about 1 second! Of course, it dies not light. On its own, the system then cycles and tries again, the ignitor now comes on for 4 seconds or so and the top 2 of 6 burners get to ignite before the controller shuts it down... on the third cycle of the system all burners ignite! Then I go about other tasks and find the furnace eventually errors out with "too many tries" on the next heating cycle. I'm running out of parts to replace!!! mdshunk, I may put a new ignitor in given your last post - just as a shot in the dark.
Ideas? Anyone?

hf05

I think i know the furnace your on. and got stuck myself ended up being the valve sticking.would try for ignition ,no gas or a little delay then shutting off on flame rectification...the valve was a w/r 36e??-201.If the pressure switch that u changed was a bigger odd shaped metal 1 than this is the same unit.. good luck

mdshunk

Ignitor comes on for varying amounts of time? One second one time, 4 seconds another time.....

Sounds like probably one of two problems. A limit (or pressure switch) kicking out for a split second, starting the cycle all over again. Or, the board is hosed up somehow. I'm slow to blame a board until all else has proven true or not. Seems you've already replaced the board, so that rules that out.

"Pressure switch stuck closed" and broken evac housing are two different matters. A broken evac housing would never permit the pressure switch to close. If it was stuck closed, it's shot. Even if it appears to be working now, you're just limping along. I go for replacing the pressure switch right now, since it was stuck closed at one point in time.

If the system does occasionally fire up, but for only a short period of time... and only certain burners, that's an easy fix. Take out all the burners and wash them in a tub of soapy water. They get spider webs and crud on them. Also, clean (to bare metal) or replace the flame sensor rod, and the connector where the "sense" wire plugs onto it.

ATS

I'm too lasy to read the prior thread but I'll put in my 2 cents anyway. Check the hose to the pressure switch, is it a straight run from the inducer to the switch or does it sag? If it sags then the condensation in the hose may be blocking the switch from turning off, the hose could be forming a P-trap, for lack of a better explanation. If so, trim back the hose and your problem will be solved.

tpope

OK. Here is the latest.
Pressure switch is now new - and functioning.
Evac fan is new as of a couple days ago.
Ignitor and flame sensor are both less than a season old.
Hose between Press/Sw and Evac is new, non-kinked, proper length.
Control board is new (White-Rog 50A55-843 universal).
I took off all 6 burners and blasted 120 PSI air through them carefully blasting out the sides where the gas is supposed to lap up to catch the flame from the burner above upon ignition. Visually, they seem clean.
While the burners were off, I used a small drill bit and carefully (by hand) inserted it into the gas jets that feed the burner, it was not apparent that any of them were clogged - but if any were, they are not now.

After reassembly I plugged it in and called for heat. Same scenario resulted. The heat call properly triggered the evacuator, pressure switch and eventually the ignitor. First burner ignited, 2nd ignited, 3rd hesitated and ignited late, causing the system to cease trying before the ignition reached the 6th and final burner where the flame sensor is located. There is some variability in the ignition, and I have witnessed the system actually get all 6 burners lit in time.

If the darn control board could be calibrated I could give the ignition sequence 2 more seconds to ignite and all would be fine. Is this something that an increase in gas pressure would fix? Should I get new burners?

mdshunk

What is the measured gas pressure, by your manometer, on the test port on the manifold side of the gas valve? What does the dataplate say the manifold pressure is to be? What is the differential between the two?

So far, it sounds like somebody is throwing an aweful lot of parts at this thing without doing proper logical troubleshooting. I hate to see that.

POOLMANinCT

im leaning toward mdshunk view, sounds like alot of swapping is going on, im only commenting b/c on a commercial nat gas unit, i had similar
symptoms... the culprit was "lack of drip leg" on gas line i'e restricted fuel... i opened line down stream of regulator between control valve & reg. control valve screen/filter caked... put down my pipe wrenches & got gas supplier to install drip leg... its been 2 yrs, & no probs

ray

hf05

gas valve

POOLMANinCT

cant condemn a valve w/o qualifying fuel source

FemaleAstarCO

One cheap thing to try I didnt see what furnace you are on but I know that Rheem and someone else had problems with the port from the hose to the inducer. Not the hose itself but the port try cleaning it out.

Magnettica

So what happened here?

I'm currently taking a course on the electrical interior end of heating and cooling equipment so I'm interested to know.

hf05

well????????????

AIRON

New here but thread caught my eye.

Igniter number dont think it exists but if robertshaw universal make sure any jumpers properly set and the trial for ignition should not vary. A 1 second TFI is normal.
The pressure swithches seem to be doing what they should be, saving your life. I am sure you installed a meter across switches to verify open and closure.
I suspect one of 2 things going on from your stating the way burners light off. 1st clean flame sensor and check exhaust venting,

2nd close the blower door you may be pulling the flame off the sensor and away from the pilot ribbon. check for backdraft through burners.

Just a thought.