Ruud/Rheem 80 delayed ignition. New unit.

[Glennhvac]

New furnace and a/c installation. Ruud 80 DSI. So the first time I fired it up I had a second or 2 delay after the first burner lit off. I've had that in the past the first time I have fired up units after the gas line has been open. I didn't think much of it and fired it up a few more times and it lit off perfectly.

The unit ran all night and the next day while I had the vac pump on I fired up the heat to check the humidifier. Delayed ignition again. It would happen three or four times and then work perfectly for a few cycles and back again to delay. Note, this is with the blower off. One time two lit off and not the other two. I checked gas pressure with water manometer. I did not have the electronic with. Gas out_3.5. Gas in with water heater off was 6", water htr on was 5", both on 4.5".

I tried flipping the burner over and remounting the ignitor bracket and it was the same thing. They are sending a new burner but I am at a loss as to what else could be causing this. If during the short delay I light off the next burner manually they all fire perfectly. I am wondering if the two mounting brackets that are welded to the burners could be off and the orifices may be cocked at an angle. Naturally as soon as I hook up the manometer the thing fires up perfectly every time so it's hard to blame the gas meter side of things without seeing it. One thing I thought was a bit strange was the manifold had 4 yellow paint blobs on it opposite where the orifices are drilled out.

[BaldLoonie]

Some years back their burner maker put oil on the burners and didn't wash them off causing delayed ignition or no ignition. We had to go around and take the burners out and wash them in soapy water.

Only ignition problem we've had with a Rheem since the ribbon burner days.

[theoldscroll]

Run an orfice bit thru the orfices. Gas valve may be opening slower than it's susposed to. Said before production oil in crossovers is most likely.

[Glennhvac]

Sorry am not getting mails when a reply is made for some reason. I didn't notice any oil and for the life of me I could see nothing out of the ordinary with that burner. It would have been great if the darn thing didn't light off correctly just once while I had the manometer on it. Gas valve slow? Could be but I would think the first burner would not light off perfectly. I did not put a test light on the valve to see when it lit as compared to when the valve was powered. It seemed like it was lighting off about a second or two after the ignitor began sparking. I'll check mine later.

No thoughts on those orifices not being aligned in a perfectly straight shot into the burners?

[DavidDeBord]

Glenn,

Could the manifold possibly have some debris left over from the manufacturing in it? Have you thought about dropping it from the gas valve, pulling the last orifice, & blowing it out with compressed air? By pulling it out, you'd also get a better look at the orifices up close, & also see if they are all the same #.

What about rapid fluctuations in the low voltage to the gas valve?

[Glennhvac]

Glenn,

Could the manifold possibly have some debris left over from the manufacturing in it? Have you thought about dropping it from the gas valve, pulling the last orifice, & blowing it out with compressed air? By pulling it out, you'd also get a better look at the orifices up close, & also see if they are all the same #.

What about rapid fluctuations in the low voltage to the gas valve?

Yes I pulled the burner several times. I even flipped it over and remounted the spark bracket and it still delayed a couple times. I was even going to try and swap the spark to the left and sensor to the right just to see but there was not enough slack in the wire on one to do that. It fired fine the last ten times I tried it on Thursday and I am thinking it must be working all day Friday and today so far. I don't recall if there is a three hour delay before a try again on flame lockout so it's hard to say in this weather if they would even notice a lockout that resets after time.

If I do not hear from them prior I am going back when we get into the 80's to recheck the a/c anyway and I will have the new burner I can stealth replace at that time.

Still not convinced it may not be a cocked manifold.

[DavidDeBord]

What Brand/ Md# of Gas valve is that, I'm wondering if their Tech Service would have any input, matter of fact they might have been having a problem with the valve, but, it's not reached a recall level yet.

What's the Md.#/ Ser.# of the furnace?

[roaddog320]

I have had the same problem and it was the burner assembly.Also had a bad gas valve on start up with intermittent problem.

[Glennhvac]

I have had the same problem and it was the burner assembly.Also had a bad gas valve on start up with intermittent problem.

Good to hear on the burner I guess. The tech guy was in when I called about a replacement burner. I gave him my gas pressure readings and he thinks that's about all it can be. Naturally no matter what problem I ever have with any product made under the sun it's always the first time they heard of it.

I really have to rule out the gas valve. Even when it delayed I could light off the other burners with ease manually. It's carry over from the first burner and once or twice from the sec on burner.

[DavidDeBord]

"Even when it delayed I could light off the other burners with ease manually. It's carry over from the first burner and once or twice from the sec on burner. "

Are the "Carry-over"s warped? I think that I've got the wrong name for them, but a few years back, I had a furnace do this, & finally found out that the "wings" were to tightly crimped, & not allowing the flame to pass to the next burner. Matter of fact, I've found several that had corroded so badly, that they wouldn't allow the succeeding burner to ignite.

And, I'll add to that, I had a valve on another call that intermittently would open/ close just enough for the 1st burner to light, but not the others, for several seconds.

[theoldscroll]

I guess if burner don't fix it you might take along some 1/4" pipe nipples about 10" long to screw in place of the orfices in the manifold (removed of course). Its hard to look at an orfice to see if it's drilled crooked but with the pipe nipples in place the crooked hole will not let the pipes run strait with each other.

[Juan Madera]

Crossovers are pinched or have some detritus in them. Have had this issue on Ruud Rheem way back. Spiders?

[Cosmicmuffin]

I carry small air tank on truck,charge it at home. I blow out all inshot burners on services.In most cases no shop vac is required.A set of long feeler gauges helps with stubborn X-overs.

[DavidDeBord]

How'd it turn out Glenn?