York GY9S100C20DH11K – runs for a minute and then drops flame.

[pecmsg]

https://youtu.be/9kD4zmYCtl0

[Push It]

Someone before him saw the gas pressure drop. That's why they put a larger gas whip on between the unit and gas run. They just never followed through with the call it looks likes. I love calls like this. So much can be learned.

I had a similar issue when I was younger. Was sent on a start up for about 8 Voyager RTUs. I started the heat one at a time. All was good. Then started as many as I could at once. After about the 4th unit some began to lock out. Found gas pressure dropped. Took a while to find out when the gas company drilled into the main for the tap to the building the piece of pipe did not come out. I was stuck in there restricting flow.

[ssterlingb]

My curiosity is getting the better of me, so I have a few questions regarding this.
Going back to the original complaint, this unit is horizontal with the bottom burner cutting out. This is the only unit locking out, not random with the other units. I assume, (yeah I know what that means) that you've verified the grounding on the unit is good. So, have you checked inside the manifold or the bottom orifice for debris or dead insects?

Yeah I know, stupid questions.

[Dan_G]

If this first floor unit is the only unit running, it will run reliably. It appears that the burner is clean. I could not remove it because there is no gas shut off at the unit. The unit is in a tough spot in the ceiling so inspecting everything is very tough – but it all appears clean. This combined with the fact that the unit will run perfectly fine if it’s the only unit running suggests that it’s a gas supply problem.

I was back there again briefly this week. A second floor furnace had a bad blower motor. We replaced that. As soon as that 100K BTU second floor unit fires – the first floor unit drops flame. We have observed that all burners are affected on some of these dropped flame events. For some reason the lowest burner seems the most sensitive but they can all drop flame. The lowest burner is also the burner that has the flame sensor. It could be that York put that flame sensor in that location on purpose.

The tenant has not yet had the gas regulator changed. Still waiting to see if that helps with this issue.

[Dan_G]

I do not know if the other units have problems. We are not getting complaints. It seems this unit has the most problems. This unit is physically the closest to the gas meter but it's possible the line goes up the wall to the attic and is routed to the second floor units first. This unit could be the last unit on the gas line - I have not had to trace out the gas line yet. After we change the regulator we will have to check all the units and make sure they can all run simultaneously.

[71CHOPS]

The flame sensor is on the last burner for this exact reason.

[berry42079]

OK, this post got me thinking. I was (emphasis on was) very disappointed in the York controller. I wanted to know what caused the controller to drop flame. I hear the relay click and the flame goes out – but I’m not 100% sure what sensor detected the problem. I just assumed that it was the flame sensor since I could see the flame current was not steady and momentarily drops to zero. I also ruled out the pressure switches. The HUM and EAC terminals are not used. I’m still pretty sure it’s the flame sensor dropping out as opposed to a brown out of the 24v supply – but I can’t really rule anything out just yet.

I found the docs for this controller. Sure enough, the controller actually tells you if the flame current is a problem. Here is what the docs say:

RAPID AMBER FLASH: Flame sense current is below 1.5 microamps. Check and clean flame sensor. Check for proper gas flow. Verify that current is greater than 1.5 microamps at flame current test pad.

So the controller was probably telling me all along what was going on – and I did not know it. I’m almost certain the controller was flashing rapid amber after the flame went out and while the unit was relighting.

I’ll be going back so if this problem comes up again, I’ll know what to look for.

Bad ground could be the issue. Proper flame sense relies on a proper ground.

[timebuilder]

Bad ground could be the issue. Proper flame sense relies on a proper ground.

Flame sense requires a complete circuit to the controller, and yes, that is usually through the cabinet and burner tubes.

However, when this is the only unit running, it's fine.

Ergo, a gas delivery issue.

[marchvac]

Easy way to tell to tell if its the piping or the meter and regulator from the gas company is to put your manometer just after the regulator to see if there is any pressure drop with all the equipment running. Then check the pressure drop at the furnace. We are not allowed more than 1" pressure drop at the inlet to the equipment when equipment is on high fire in our code book. You should have a minimum of 7" water column with everything off. So if the gas at the regulator drops more than 1" with all the equipment running then your gas meter or regulator is the problem.

[timebuilder]

All good points.

I'm hoping for some sort of conclusion. It is frustrating to view so many problems, through an internet, darkly.

[Dan_G]

It will probably be a while before I go back. I know they are working on getting the gas regulator changed. The tenant knows what to look for. After the regulator is changed, if the new regulator does not fix the problem then when the 2nd floor unit fires, the first floor unit will drop flame. On a cold day, the first floor unit will lock out within a few mins ... so they will surely call.

I do the maintenance there so I'll go back and test the whole system at some point.

[timebuilder]

It will probably be a while before I go back. I know they are working on getting the gas regulator changed. The tenant knows what to look for. After the regulator is changed, if the new regulator does not fix the problem then when the 2nd floor unit fires, the first floor unit will drop flame. On a cold day, the first floor unit will lock out within a few mins ... so they will surely call.

I do the maintenance there so I'll go back and test the whole system at some point.

The store I mentioned at the end of post #24 took about four months to get resolved, because it had to wend its way though two managements groups and the gas Co itself before the pressure was changed to service the small diameter piping that had been installed when the store space was being retrofitted. for the new occupant.