Help me out here

[mtnman1100]

So my furnace quit working on me. I have a 10 year old Bryant 355MAV. It sequences fine, the hot surface ignitor glows and gas valve opens but the gas does not ignite. What is up with that?

[jeff]

replace ignitor not getting hot enought to light gas

[OkieBill]

Is the gas turned on:p

Do you hear the gas or just the click of the valve...

[mtnman1100]

replace ignitor not getting hot enought to light gas
Thanks Jeff, I wasn't sure if that would do it but that is also the conclusion that I came to.
And yes the gas is on thank you Bill.

[OkieBill]

I have never run into an HSI that glows but will not light the gas flow.

I was just starting the troubleshooting at the beginning by asking about gas flow:)

[plumberscrack]

I have never run into an HSI that glows but will not light the gas flow.

I was just starting the troubleshooting at the beginning by asking about gas flow:)

Same here.

Check the voltage at the gas valve while the HSI is glowing.

[Ruudacguy]

I have never run into an HSI that glows but will not light the gas flow.

I have. Extremely rare though. Once, maybe twice I have seen this.

Andy

[jeff]

one way to prove it is with a long lighter as you here gas valve open lit it to bring on flame . I have seen it more than eought glow and not lit gas

[OkieBill]

one way to prove it is with a long lighter as you here gas valve open lit it to bring on flame . I have seen it more than eought glow and not lit gas

14 years in service work and I can't remember a HSI that glowed but would not ignite proper gas flow...

No way would the first thought be to "change out the HSI" That would be at the bottom of the list if I could see the glow.

Change out the HSI without more information is just parts swapping advice:rolleyes:


Rule out the simple first then get to the weird 1 in a million faults.


Mtman1100 will let us know how his issue works out...

[Ruudacguy]

The first thing I would check for on that particular furnace is a blocked combustion air inlet. You can have fuel and ignitor but if you dont have air you wont get fire. My money is still on the HSI though.

Andy

[rjm78]

I have. Extremely rare though. Once, maybe twice I have seen this.

Andy
It's probably placement more than it was temp.

[rjm78]

I agree with the venting being an issue on that furnace. Try it with the burner box door off. If still nothing, try it quick, with the exhaust boot loose. If still no, check gas flow or at least if you smell it. Slightly bending ignitors twords the burner crossover and tword the center of the main opening might help. Also, especially if the intake is drawing from the basement, or drawing outside near a source of moisture, rust on the burners may stop it from catching. This furnace's ignition is very finicky.
Don't forget the $1500.00 to upgrade it to 95%. The venting is already there.....if properly sized. Might be worth thinking about this, or next year.

[OkieBill]

I agree with the venting being an issue on that furnace. Try it with the burner box door off. If still nothing, try it quick, with the exhaust boot loose. If still no, check gas flow or at least if you smell it. Slightly bending ignitors twords the burner crossover and tword the center of the main opening might help. Also, especially if the intake is drawing from the basement, or drawing outside near a source of moisture, rust on the burners may stop it from catching. This furnace's ignition is very finicky.
Don't forget the $1500.00 to upgrade it to 95%. The venting is already there.....if properly sized. Might be worth thinking about this, or next year.


OK, so are we talking about a spark ignition system or an HSI??? :confused: I know for sure an HSI will not bend...

[Ruudacguy]

The first thing I would check for on that particular furnace is a blocked combustion air inlet. You can have fuel and ignitor but if you dont have air you wont get fire. My money is still on the HSI though.

Man I gotta quit posting so early in the morning after a long night at the bar. If venting was the issue more than likely the pressure switch wouldnt close, which wouldnt send power to the ignitor or gas valve.


It's probably placement more than it was temp.

Ran across a few where placement was the issue. The ones Im referring to had zero adjustment on the placement.

Andy

[rjm78]

OK, so are we talking about a spark ignition system or an HSI??? :confused: I know for sure an HSI will not bend...

Ok, good point. I refer to the ignitors bracket. Ruudguy made me remember that yea, it may be a zero adjustment set up, I can't remember. Still, that often works on yorks for example where placement is the most criticle I've seen.

[breid1903]

jeff could be right. my personal furnace would not light. hsi was red. put on jumpers , still wouldn't light. torched it and it fired. called tech people. they said red hsi would not fire it. hsi needed to be white. new hsi all is well. hew hsi didn't get totally white but tip sure did. i'm not embarrassed to call tech, call em. breid..............:party-on:

[rjm78]

White!!!!!!!!!!!!! :eek: That's news to me. :eek:

[shock1964]

tech support should be able to tell you what voltage to expect from the board into the hsi, and also what value to check for when you ohm the hsi you currently have.
If you are not sure you are getting gas the only proper way to check is check for manifold pressure during startup sequence, do not use a torch.

[gassyplumber]

OK, so are we talking about a spark ignition system or an HSI??? :confused: I know for sure an HSI will not bend...


Interesting ... good call I have heard of an hsi glowing but not hot enough, maybe urban legend I haven't had this happen to me yet

[rjm78]

tech support should be able to tell you what voltage to expect from the board into the hsi, and also what value to check for when you ohm the hsi you currently have.
If you are not sure you are getting gas the only proper way to check is check for manifold pressure during startup sequence, do not use a torch.
Input voltage will always be line voltage on that type of ignitor, carbide (41-409)
Lennox and I'm sure newer others step thier voltage down as low as 90vac but thats a nitride ignitor.
As far as the ohm value, it varies too much on it's temp. Room temp may be 15-20 ohms but if it's within 15 min of it lighting it may be way different.

[desertmule57]

I've been in HVAC for 35 years and have only seen an HSI fail to light but still glowabout 4 times. If there is gas then the Ignitor is not hot enough. You can check amp draw on the ignitor. Many are up to 5.0. They do glow and fail to light. Sometimes I overlook the simple and get too complicated. I would also check voltage to the ignitor. I've seen a lot of boards lose voltage to the blower because of failed relays on the boards themselves.

[mtnman1100]

OOPS, sorry I haven't checked back.
So the exhaust discharge was great, lots of volume and I checked out the 3"PVC for anything, nothing was in there.
Checked out the intake and burner box, found three mouse carcasses, removed them and still no fire.
With burner box cover off, I lit the gas with a match and it would fire for a full cycle. But putting the box back together I would get a glow from the HSI and gas valve would open but no fire.
So I did replace the ignitor and I bent it towards the first burner and that did it, it finally lit up. I am not curious enough to put the old HSI back in and bend it over. So thanks guys, it's working now.

[rjm78]

Well good, I'm glad that helped. If anything, it's not bad to replace the ignitor just because but I think you'd realize it was just a slight weakening/dirt/position issue. You covered all you bases.
BTW Don't be tempted to cover the intake or exhaust. It'll possibly freeze in the very cold winter days.
Glad you checked back with us, I was wondering.