Armstrong GUK075D14-3A Gas Furnace

Schnidly

Can someone here give me detailed instructions on how to remove the burner cover to access the flame rod and the igniter? I dont want to have to remove the gas valve if I dont have to. Pictures would help if someone would have a service manual for this furnace? PLEASE HELP.

DZoro

can you post some pictures of the furnace

HVACNUT

Unless you have the right tools, you might have to pull the gas train.
I certainly dont recommend it if your not an HVAC tech.
Is it a HSI or spark?
What's happening?
No ignition, flame loss?
24v to the gas valve?
Gas pressures?

Schnidly

Inducer Fan starts, pressure switch closes sending 24v to the gas valve, I hear a click, the igniter lights up and the pilot comes on, sometimes briefly, then after a short time it stays on longer and eventually after a few restarts(inducer fan stays on during all these restarts) the furnaces main burners light. I checked and I have 24volts on the igniter, and the 4 pin connector. The resistance through the igniter is 3.4 ohms which from what I read is good. The gas valve is 2 years old.

JUGHNE

Sounds like the flame rod/sensor would be the place to start.
Could you post pictures of this burner compartment?
It doesn't seem practical that the FS/rod would be that difficult to access, IMO.

Schnidly

Schnidly

Schnidly

JUGHNE

I see this is your second posting for the same problem.
I'm sorry, but if you feel challenged by removing that front burner cover, perhaps you need to call a pro. IMO

Schnidly

I honestly am not intimitaded by taking some screws out, I just wanted a second opinion.

JUGHNE

Then go for it, the 6 screws on the perimeter of the front cover.
Perhaps you need to remove the screws on the right hand side as it did not look like there was a seam on the RH, rather a bend of the box cover.

Look for what was described in your first posting that I replied to.

Schnidly

The four screws in the front middle area of the box I think are just screwed to the burner tubes? I do appreciate your help and input, thanks.

Schnidly

Of course I would have to disconnect the pilot tube at the smart valve.

ratio

You might (But I wouldn't pry too hard on it!) be able to take the window off & peek inside to see if the four screws in the middle must come out to remove the cover. Also, I've had problems with the connector of the flame rod & igniter on the smart valve. unplugging & plugging it back in a few times got it working for another season. Still ended up replacing it though.

DZoro

Just have to remove the cover, replace the igniter pilot assembly, or igniter and clean out the pilot orifice. Make sure burners are clean and pilot tube connections are tight and leak free.

Schnidly

Is there some place on line that has service manuals available?

Schnidly

What kind of reading should I get from the flame sensor as far as voltage goes from the connector while plugged in on gas valve to ground since there is only one wire from the gas valve to the flame sensor? Maybe ground does not xount on the flame sensor?

ratio

You're looking for microamps on the flame rod.

According to this, you're looking for a minimum of 0.12 to 1.3 µA depending on which valve you have.

Schnidly

I would have to cut the black flame sensor wire to run my meter in series sibce there are the two blue igniter wires in the same molex connector?

Tim McElwain

What is the model number of the gas valve?

Schnidly

It is SV9502 H2522

JUGHNE

If you can unclip the HSI/FS unit, remove it and clean the FS rod.
Or the simplest thing it to replace the component.
HSI ignitors have a limited life/cycles.
If this is the original you have got good service out of it.

That 1/4" AL pilot tube looks a little funky.
IIRC, the ones I have seen have the pilot with the ignitor wires passing through that hole with a sealed grommet.
Just so the AL tube does not rub a hole in itself.....it is easy to cut.

I would guess someone had the cover off previously.

DZoro

Agree the pilot tube looks like it has been changed. There should be a grommet in that hole and any other holes. I have seen burner issues when some of these holes are left open. Really just need to change the pilot, and igniter, just normal maintenance. If that doesn't do the trick then, let us know.

Tim McElwain

This is a Generation II SmartValve system from Honeywell. The two blue wires going to the igniter assembly are the 24 volts needed to get the Silicone Nitride igniter to glow. The black wire is the microamp wire back to the electronics in the gas valve the minimum microamps on that is 1.3 as already mentioned.

The gas valve is a slow opening valve. The typical timed trial for the pilot is 90 seconds. The pilot is typically using either a unshielded Q3400A-1024 harness or the shielded version which is Q3400A-1115. The two blue wires should ohm out at 10 ohms or less 3 to 4 is normal.

To test the microamps you need a test harness Honeywell Part number 395466. DO NOT CUT INTO THE BLACK WIRE TO TEST FOR MICROAMPS.

To remove the front panel remove the six screws and that should get you inside.

Schnidly

Thank you for all the information. What I am noticing is that my intermittent pilot flame is weak at times, then eventually it comes on stronger and heats the flame rod sensor and main burner ignition happens. I turned the pilot flame adjustment to max and it still is weak at times. Eventually the main burners do light and everything is good. Please advise further.

Schnidly

Tim, there are two screws on each side of the burner cover that I believe that have to be removed also. If you look at the pics you can see these two screws on each side. If I remove the 10 screws will I be removing the entire burner tubes and pilot ignition also? I mean, the main burner tubes will come out with the front cover which is split on the bottom and top halves. I would be just removing the center part with the main burner tubes.

DZoro

Will need to clean out the pilot orifice/or replace it. A very small broach (hair thickness) will be needed to clean the orifice. Suggest like earlier changing the entire pilot assembly. If you are on Propane make sure the pilot orifice is for propane.

Tim McElwain

I really can't say for sure but gently remove the six screws and see what will come with it. I went looking through Google for info on that furnace and there really is not much that I can find.

DZoro

If my memory serves me right, 2 of the middle screws hold a air deflector, other 2 center screws are attached to the internal housing. Remove the screws and see.

Schnidly

Had a hvac service man over today to tuneup the furnace. He just removed the bottom of the burner box and then had access to pilot assembly. Just for anyone else having the same difficulty as I was trying to get the burner box off.

Schnidly

He cleaned my flame rod and pilot tube orifice and that solved my problem.

rerun123

i was wondering if anyone knew the orfice size on this model 75000 btu natural gas would be thank full any help trying to convert from propane to natural gas

Carltaddeo

How many BTU's is Armstrong Ultra SX90 Model GUKO75D14-3 A Serial number S8499B36831

ratio

Guessing from the model number, 75k.