5059 Pilot Relite Contol Issue

REKBDR

On my old Utica boiler the pilot lighting control is working only intermittently. My suspicion is that the electrode at the pilot light is caked with carbon and other junk so as to insulate it from reliably making a spark to ground. When the main burner is on, the electrode is engulfed in flame continuously (is this right?). Can I pull out the electrode cable and clean that?

Alternatively, the grounding screw from the White Rodgers 5059 to the chassis might no longer be making a good connection. When I wiggle the booted cable connection (thinking that this could be the bad connection), it works, but maybe I am really wiggling the screw ground connection. Is this a common problem?

Thoughts and advice will be most welcome.

Tim McElwain

You need to pull the pilot and clean the orifice. That is a Mercury Pilot and it needs to have a sharp flame so the tip of the mercury sensor glows cherry red. Try that first and plug it back in and see if it works.

Steamhead

What @Tim McElwain said. He's the best. I'll add that those pilot assemblies are probably not made anymore, depending on which model you have, so be real careful with it. I've seen cases where the spark cable was shorting to ground at the pilot assembly, which would cause the problem you're having.

EdTheHeaterMan

The 5059 relight control has a flame sensing circuit built into the electronics. The pilot flame is part of an electric circuit called Flame Rectification. The flame rectification circuit includes the high voltage wire connected to the high voltage spark terminal. the circuit continues to the electrode then thru the flame and then from the flame to the ground of the pilot burner hood. the last leg of the electrical circuit is the return path from the metal grounding of the pilot burner hood to the grounding screw on the 5059 control.

The parts that can fail are
1. The ground connection can get loose or corroded.
2. The High voltage cable may be able to send the high voltage spark but unable to conduct the micro voltage of the flame sensor circuit.
3. The distance between the electrode and the pilot burner hood. (known as the spark gap)
4. or the actual control itself.

Start with cleaning the electrode then cleaning all the ground connections. In the past, I have even added a wire direct from the ground of the control to a mounting screw on the pilot burner. This will bypass all the rusted and loose nuts and bolts that hold the old burner together.
If you still have the problem, then replace the orange high voltage wire.

Tim McElwain

This 5059 system is NOT flame rectification. The mercury plug in is a SPDT mercury filled sensor which when it gets Cherry REd will boil the mercury causing the switch to walk over and energize the gas valve. The module is simply a relight control and once the flame is established simply shorts to ground and shuts of the spark, there are no microamps involved at all.

JUGHNE

I know from personal bad experience how fragile the tiny capillary tube between the gas valve and mercury bulb are.
Once it broke, the simplest replacement was a new gas valve with standing pilot. Keeps the boiler warm year around if you leave it on. If you have a motorized damper the standing piolet may not be usable.

The screws holding the module in place are crucial to establish the proper ground path for operation. They must be tight.

REKBDR

Good advice, but I am not sure about the debate as to flame rectification. My set up is 36C84 gas valve, equipped with a 3098 flame sensor. The 5059 spark module has what looks like the top of a spark plug (no 1/4” spade connector), but I am not sure if this is a 5059-23 (probably, as distinct from the spike version, 5059-134).

After cleaning and even sanding bare the contacts between the chassis and the back of the 5059, I tested and found this:

Upon rotating the zone valve wheel to call for heat, there is a single spark but it stops before gas has time to come out of the pilot. By jiggling at the 5059 or even disconnecting and replugging, I can get more sparks and the pilot lights (and the burners thereafter).

Does this seem like a problem in the cable or the 5059 itself? The parts are pretty pricey, cable at $75 and module at $100.

JUGHNE

The screws on the module are tight then?

Can you post pictures of the gas valve and pilot assembly.
We all may be talking about different systems.

REKBDR

Here are pictures. Wiggling at the cable boot seems to make it spark. Beginning to conclude that the cable isn’t carrying the low voltage signal. I'd be up for trying to replace just that except it seems that the new cables are connected with 1/4” spade connectors.

Tim McElwain

If you folks believe this is flame rectification then take some microamp readings???????

The flame rod/pilot picture looks like the rod is distorted.

They make adapters by the way to go from a "rajah" to a spade clip fitting.

Steamhead

Sounds like the 5059 is going bad. The metal stud that the spark cable connects to is threaded onto a stud in the 5059, so you can move it to a new one if needed.

REKBDR

Good to know about unscrewing the male spark plug adapter from the stud inside it. More wiggling seems to indicate the the problem is at the cable inside the boot. The female part of the connector is just a crimp-on fitting with apparently prongs that piece the silicone to make contact with the HV wire at the core (bad design?). I've got some slack in the cable, so what if I chop off the connector, strip back the sheath a bit , and put it directly on the stud with a correctly sized nut?

Tim McElwain

The system you are working on uses Flame Conductivity not Flame Rectification to shut the spark off once the pilot is lit. The flame simply "shorts" out the spark signal through the flame.

Any repairs you can do to the spark cable would be okay.

EdTheHeaterMan

Tim McElwain said:

This 5059 system is NOT flame rectification. The mercury plug in is a SPDT mercury filled sensor which when it gets Cherry REd will boil the mercury causing the switch to walk over and energize the gas valve. The module is simply a relight control and once the flame is established simply shorts to ground and shuts of the spark, there are no microamps involved at all.

I disagree with "NOT flame rectification"



I don't disagree with the mercury flame sensor.


The 5059 needs FC to sense when to stop sparking whether it is used on this gas valve or on a standing pilot.

The Mercury Flame Sensor only starts operating after the pilot is lit and allows the main flame portion of the valve to open.

Please get your facts correct if you are going to give advice. Grounding is important for the WR-5059 to operate properly.

Tim McElwain

My facts are correct (50 years in the gas business) that system does not use Flame Rectification it use Flame Conductivity. If it is Flame Rectification tell me how to check microamps??????

EdTheHeaterMan

If you want to replace the 5059 and the orange cable and the spark electrode. You should be able to use this kit made by Robertshaw. The price is reasonable.
https://www.supplyhouse.com/Robertshaw-785-001-24-120-VAC-Automatic-Pilot-Relight-Kit

mattmia2

Is the core of that spark cable solid wire or is it the composite resistance wire they use in RFI suppressing spark plug wires? The resistance wire type could be more difficult to connect to if you try to connect to something other than the crimp on terminals.

Take a good look at the wire itself and make sure it doesn't have any cracks or burned spots where it is grounding.(at this point I would just replace all of it with the robertshaw kit above).

EdTheHeaterMan

@REKBDR Your description of the failure leads me to believe the WR-5059 or the 24V signal is the culprit. When you "jiggle" the orange wire, you are also jiggling the PC boars inside the plastic cover. Any loose connection will be affected. You may be able to check the 24 V signal to the 5059 with a multi-meter when the spark is supposed to be lighting the pilot.

On a call for heat (when the boiler is cold and not off by the limit control), there should be 24V to the gas valve and to the 5059. This should open the pilot valve on the gas valve and also make the 5059 spark until the pilot is lit. If you have 24V to the gas valve and you have 24V to the 5059 and there is no spark and the pilot valve is open (you may smell gas near the pilot or you can light the pilot with a match. CAUTION there may be enough pilot gas to make a small flashback. Use match on a long handle or a lighter with a long handle) and you have no spark. then the 5059 is defective. Replace it.

Tim McElwain

One of the things that these systems had problems with was pressure switches attached to the valve.

JUGHNE

I would say that the pilot relight might use FR.
But flame rectification is not instrumental in shutting down the main GV in the event of a flame out.
The expanded Mercury has to cool for about 20 seconds to shut switch down the gas valve. Heat sensitive safety as is the old thermocouple.
The mercury switch was not around for very long IIRC.

REKBDR

Thanks. The discussion has been very helpful.

I put a meter on the leads going into the 5059, and I do get 24+ V when the igniter is supposed to be sparking. So, the problem is definitely in the 5059 or cable.

I will try tomorrow morning to hook up a makeshift HV cable and see if the 5059 properly sparks over a gap that I set up directly to the outside of the boiler housing.

If that confirms that the 5059 is working, I will then cobble together a better connection between the unit and the cable and post my results.

REKBDR

To test the 5059 I hooked up a white wire to ground as shown in this photo:


When I triggered a call for heat, there were regularly intermittent sparks across the gap, as I had hoped. After about five seconds I shut it down because gas was supposedly coming out of the pilot. I then positioned the high voltage cable to likewise exhibit a spark, as shown here:


Again, there were regular sparks until I turned off the power. I reran the test and checked for sparks at the pilot as well as at my makeshift gap, and there were sparks at both places. I noticed, however, that after the pilot flame came on, the sparks at the gap at the 5059 continued until I cut the power (the main burners came on and I didn’t want to heat up the boiler while working around the pilot light area). I could not tell if the cable probe was still sparking through the pilot flame.

Not knowing enough about flame rectification, I am wondering why the 5059 didn’t stop sparking. Is there some time delay built into the system and I simply did not let the sparking continue long enough before it would have stopped? Or did my spark gap at the 5959 disrupt the direct current detection circuit in some way?

In any event, my initial problem was that I was not getting a spark to ignite the pilot, not that the spark would not turn off. I am now running through normal operations to see if that problem is still present. Maybe all my jiggling has cured the problem, but not reliably. Seems like I might just replace the cable.

mattmia2

The flame ionizes the air and makes it conductive. The relight control senses that the flame is present by that conductivity. That gap at the control does not become conductive when the pilot lights so it fails to prove flame in your test setup.

You might want to look very carefully at where the electrode passes through the pilot bracket and make sure it isnt shorting out there, but a crack or abrasion of the Hv cable could cause it to ground out the spark there too.

mattmia2

Is this not a total shutoff system, is the pilot on whenever there is a call for heat regardless of if it has proven flame?

REKBDR

From what I can observe, the pilot comes on when there is a call for heat and the boiler water is cool. The burner then comes on after the 3098 heats up to confirm that there is a pilot flame. The pilot stays on while the burner is on. When boiler water reaches max temp, or when the call for heat ends, the burner and pilot both shut off. I have not observed the pilot flame staying on while the water cools if the call for heat continues. I assume that if the water temperature falls to the min while the call for heat continues, the pilot would be reignited and the cycle would repeat. Does that sound right?

JUGHNE

I believe the pilot valve is energized with a call for heat, even without a flame.
If flame is proven by the mercury switch then the main valve is switched on. The pilot is held on by a gas pressure switch once the switch flips over to main valve.

There must be at least 5" WC gas pressure, input to the gas valve for the gas switch to function.
The manifold pressure should be 3.5" WC.

Also it is stressed that there must be at least 15 volts to the gas valve and 5059. (at least a 30 VA transformer required, large for the day, 40 VA were not the standard yet).

For LP applications an additional module was required for 100% lockout.

This is from Ruud Learning Center training books of the early 80's. (This is the first time I studied this section of the book BTW.)

retiredguy

WOW, I have never seen so much back and forth on a question as to how this system works. I worked on systems similar to this and can say without a doubt that @Tim McElwain is correct about the mercury pilot sensor and the pilot igniter, That igniter is there to only light the pilot on a call for heat and that is all. Oh ya, there is no flame rectification or is there a need for one. Once a pilot flame is established the flame allows the voltage imposed on the electrode to flow to the pilot ground extinguishing the spark. The voltage is still there but there is no longer any spark. Once the mercury bulb heats up the mercury expands and closes the contact in that control. The mercury bulb and control act similar to how a thermocouple or powerpile system would work proving that the pilot is lit and allowing the gas valve to open. That control should be replaced along with the high voltage (spark) lead. I used these pilot re-lite controls on any atmospheric boiler that had a standing pilot that would be blow out occasionally.

JUGHNE

The only one of these I have seen was in a FAF I installed in the early 80's.
I recall some initial problems with it and Ruud/Rheem had a
"fix it" part that was a resister plate to put between the switch and the valve. Not sure what it did.
The system worked until the cap tube snapped off the valve and then was changed to standing pilot.
The pilot burner would accept a thermocouple where the mercury sensor was installed......all still working.

Tim McElwain

That resistor was to solve the pressure switch problem they had with those White Rodgers gas valves. It actually acted like a delay before allowing the system to come on.

REKBDR

Okay, guys, in hopes of getting some consensus, I pulled everything out and took this picture:



First, I think everyone agrees that the probe on the right is the bulb for the 3098. The function of this component is to open the main gas valve when the pilot flame heats it sufficiently (if the flame goes out, the main valve shuts). That seems to be working fine and not part of my problem with ignition failure.

The probe on the left is at the end of the HV cable from the 5059. Its function is to spark for ignition when the pilot valve is opened. Both the 5059 and the gas valve are wired in parallel from 24 VAC from the controller. Upon startup both the 5059 and the pilot solenoid are energized, and the probe starts sparking while the pilot valve opens to let gas flow to the pilot light. When the main valve opens, a pressure switch inside the gas valve takes over to hold the pilot valve open. Burner is running.

At that point something inside the 5059 has turned off its power output, even though there is still 24 VAC running to it. When I disconnect the cable from it, pull back the boot, and try to put the connectors close together to make a spark gap, there is no spark—even though in my earlier experiment I could get a spark there and at the pilot simultaneously when there was no flame. (So, can we rule out there being a current that continues to flow but is simply going to ground through the flame?)

This seems to have triggered a debate about Flame Rectification (part of this system or not?) vs. Flame Connectivity [and Google turns up nothing quickly related to HVAC involving this term]. From what I can tell FR and FC may be related: a flame may be conductive because it’s ions can carry a charge, but only in one direction, so it rectifies AC to DC, and the 5059 may be looking for a small DC circuit flow to trigger its internal relay circuitry to cut off the high voltage output.

I dunno. I know even less about electricity than I do about my boiler. However, it's very interesting to learn how all this works—or is supposed to, and if you guys can decide, I’m all ears.

Nonetheless, I got into all this because my boiler isn’t coming on, and it’s getting cold outside. I was hoping to find a simple solution like cleaning this connection or that one, and save myself nearly 200 bucks in replacement parts. All I can tell for sure from my wiggle tests is that I have a bad connection somewhere near the cable connection, and that could in the cable or in the circuit board inside the 5059. Before replacing both, I’m going to chop the cable and hardwire it to the 5059 to see if that works. I'll let you know.

EdTheHeaterMan

mattmia2 said:

Is this not a total shutoff system, is the pilot on whenever there is a call for heat regardless of if it has proven flame?

Yes, the pilot gas is always on as long as there is 24V to the gas valve. Not the best design, With a modern standing pilot, the gas is terminated to the pilot valve if the thermocouple does not sense a flame. In the year before that design, there was a manual pilot valve that let pilot gas flow indefinitely even if the pilot was not lit. Just as it was on old kitchen gas ranges and ovens. If the pilot blew out, overnight, you would wake up to the smell of gas in the kitchen. That smell would remind you to relight the pilot(s) on the gas burners.

It is considered "SAFE" for pilot gas to be released without burning. That small amount of natural gas would dissipate in the normal home of the 1930s.

On larger appliances like the home heating boiler or furnace, there was a BASO switch that would detect the pilot flame. No pilot flame... No main burner... but the pilot gas would keep being released until someone would relight the pilot or shut off the pilot manual valve. AGAIN, not the safest design but it passed the minimum safety requirements of the day.

But we also thought Asbestos was our friend back then.

Merry Christmas
Ed

EdTheHeaterMan

REKBDR said:

From what I can observe, the pilot comes on when there is a call for heat and the boiler water is cool. The burner then comes on after the 3098 heats up to confirm that there is a pilot flame. The pilot stays on while the burner is on. When boiler water reaches max temp, or when the call for heat ends, the burner and pilot both shut off. I have not observed the pilot flame staying on while the water cools if the call for heat continues. I assume that if the water temperature falls to the min while the call for heat continues, the pilot would be reignited and the cycle would repeat. Does that sound right?

This is exactly correct. This FR or FC that everyone is debating is not part of your problem. The test I suggested on Dec 11 is this.
Operate normally with a meter connected to the 24V black wires attached to the terminals with an alligator clip type leads so you do not need to hold them on with your hands.

This way the meter is ready the next time you experience a failure.

Once you have the failure you can turn on the meter without touching the 5059. Now you can see if the 5059 is receiving a 24V signal to power up the 5059 and the gas valve. (since they are both on the same wire terminal). During that time you will see the 24V signal at the 5059 and you will be able to observe if there is a spark at the pilot burner.

If there is 24V. and no spark, then touch the 5059 and the orange wire and jiggle it to see if there is a spark. If the spark happens and the pilot flame ignites, then you can be sure the 5059 is definitely the problem.

If there is no 24 V to the 5059, then the problem is elsewhere. You need to find the reason there is no 24v signal.

I still believe the 5059 uses FR or FC however the FR or FC is not used to prove flame for the main burner in the way it does on newer controls. (i believe this is where the discussion started) The pilot flame is proven by the mercury switch to open the main valve for main burner operation.

All this discussion of FR v. FC is not resolving your problem. The test I have outlined will prove or rule out the dependability of the 5059 spark module.

The Robertshaw relight kit is your best value in procuring the replacement part. It is not necessary to get the same brand and exact part number. The module from either company (WR or Robertshaw) has the same specification as relating to how it is used on your boiler. I believe they are the only 2 manufacturers of that component.

The reason you want to verify the condition of the 5059 module is one of my pet peeves. I would ask a question of the mechanics that worked for me when asking for authorization for purchasing a new control from the supply house
"After you replace that part and it does the same thing again, what will you check next."
90% of the time the thing they checked next was a lot less expensive and often solved the problem.

REKBDR

Thanks everyone! I hard wired the cable to the 5059 to rule out a bad connection there and got mixed results. Without a cable connection to wiggle anymore, I wiggled the unit and was able to get sparks. Nonetheless, I ordered the Robertshaw kit, as recommended, and it should arrive tomorrow. In the meantime I wedged the 5059 body cockeyed on the boiler housing and it seems to be working regularly. Maybe there is a loose connection on the PC board inside, or maybe bad grounding connection on the back side. I may never know, but it seems clear the everything in the system up to the 5059 is working fine. Hope to install the new unit tomorrow night.

Tim McElwain

More on the 5059 control also what is the number of the Robertshaw Kit?

PILOT RELITE CONTROL - TYPE 5059: Ignition
control generates spark pulses to ignite pilot gas.
Controls are usually 24 VAC input. with two 1/4" male
spade terminals for power. The high voltage
connection can be either a 1/4" male spade, or a spark
or spike plug connector. The Relite control is normally
wired in parallel with the pilot solenoid valve, so that on
a call for heat. both devices are energized at the same
time. The Relite control generates sparks
(approximately 10.000 volts ) until a pilot flame is sensed between the ignition electrode and ground. The Relite control detects a flame through "flame conduction" (ability of a flame to conduct a current in one direction). When flame current is sensed between the electrode and pilot burner ground. the Relite control stops sparking. If the flame is extinguished during the heat call. the Relite control will begin sparking the instant the flame goes out.

REKBDR

Installed the Robertshaw unit. Works like a charm!

Thanks to everyone!

EdTheHeaterMan

Tim McElwain said:

More on the 5059 control also what is the number of the Robertshaw Kit?

PILOT RELITE CONTROL - TYPE 5059: Ignition
control generates spark pulses to ignite pilot gas.
Controls are usually 24 VAC input. with two 1/4" male
spade terminals for power. The high voltage
connection can be either a 1/4" male spade, or a spark
or spike plug connector. The Relite control is normally
wired in parallel with the pilot solenoid valve, so that on
a call for heat. both devices are energized at the same
time. The Relite control generates sparks
(approximately 10.000 6000 volts ) until a pilot flame is sensed between the ignition electrode and ground. The Relite control detects a flame through "flame conduction" (ability of a flame to conduct a current in one direction). When flame current is sensed between the electrode and pilot burner ground. the Relite control stops sparking. If the flame is extinguished during the heat call. the Relite control will begin sparking the instant the flame goes out.

Good information that helps. I don't know how it helps, but I'm sure it helps. Can you tell us what time it is or do you need to tell us how to build the clock? FR or FC is the same difference in this case. Proper grounding is important in canceling the spark. I brought it up to stress how the ground is important to the operation of the control, not to start a discussion on the difference. If the OP wanted to understand it better he could Google it and get a better explanation from FR than if he Googled FC. @Tim McElwain did do a good job of actually solving the problem with all his input ...Maybe ...or not

Replacing the part was the right thing to do.

JUGHNE

In Tim's defense I would like to point out that we have all seen systems where the spark will continue, sometimes by design, even after the pilot flame is established. This is with FR systems.
The spark is not snuffed out with the flame established, rather by a time controller or the FR proving flame and disconnecting the ignition circuit.

FC systems are probably rare today, IDK.
I am glad to have read all this discussion for the FC system.
Learned a lot, but may not see another in the wild again.

unclejohn

This thread is way to long for a out dated no longer produced control. Replace it with the manufactures recommend parts.

JUGHNE

Long, yes, but the homeowner learned a lot and got his problem resolved. He is also aware of the obsolete gas valve and the options for replacement in the future.

And as Ed pointed out, the 5059 was used for troublesome standing pilots. Another, probably forgotten, simple fix.

I would also guess a few young pros here learned a little.
This is like studying history, if you don't know what you are looking at you cannot make a good decision of how this should work.
If the 5059 is the only problem, easy fix.
If the HG gas valve is defective, then replace with standing pilot.

Would some say the gas valve is not available and you must replace the boiler??
Maybe it is time for a replacement, but can everyone afford it?
ROI would probably be a long way out.

EdTheHeaterMan

Thanks @JUGHNE for your comments, especially the one about replacing the boiler wor a bad gas valve. There are more ways to replace a part than trying to find the OEM obsolete part.

I just had a discussion on the phone today with a mechanic that worked for 2 different plumbers in my area. The old boss would find out if you had $10.00 then make the repair cost $12.00. Profit Profit Profit.

The other wanted to just get the best job for the customer and charge a fair price. He can quote a price on a job and if the job got done at less time or less material needed, the customer got the lower price. He said that would never happen with the old boss.

He is much happier with the new company.

I grew up in a business where we took old oil burners from the 1930s to the 1950s out of converted coal heaters from the late 1800s to the 1930s There was no OEM oil burner or control or thermostat. The OEM that operated that heater was a shovel.

I was taught how to engineer a high-efficiency flame-retention oil burner into that old coal heater and reduce the fuel bill.

mattmia2

So i think i learned something else here. i have a cooktop that automatically lights/relights the burners. i assumed it sensed the flame through flame rectification, but i think it is exactly the circuit of this control. it is just some sor of a cap circuit that puts a pulse in a coil when the cap charges. that causes a spark if there is no flame. if the flame is there, it provides a path for the secondary to discharge to ground before it reaches a voltage that would spark. If the flame is out, that conductive path is gone and the spark happens again. This sort of explains the intermittent sparking with a really low flame.

Thinking further as i write this, more conventional ranges with a "light" position on the switch and a module that lights 2 burners would need to locate the electrode where the flame can't short out the spark.