Ultra SX90 main burners
 

Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?

Ultra SX90 main burners
 

On Wednesday, February 3, 2021 at 11:01:12 AM UTC-5, Jeff Gramza wrote:
Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?

Are you sure they are not lighting or are they lighting, then going out? If it;s
the latter, could be a bad flame sensor. If it won't light at all, what is the lighting
method? Pilot light? Hot surface igniter? Is it high efficiency with a blower for
combustion? Could be a pressure switch, blocked vent to the outside.

Ultra SX90 main burners
 

On Wed, 3 Feb 2021 08:01:08 -0800 (PST), Jeff Gramza
wrote:

Furnace is around 20 years old.
Sometimes the main burners light and sometimes they don't.


Elon Musk's rockets are having the same ignite problems !

https://youtu.be/klT3YcrG7K4

John T.

Ultra SX90 main burners
 

On Wednesday, February 3, 2021 at 10:44:39 AM UTC-6, trader_4 wrote:
On Wednesday, February 3, 2021 at 11:01:12 AM UTC-5, Jeff Gramza wrote:
Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?
Are you sure they are not lighting or are they lighting, then going out? If it;s
the latter, could be a bad flame sensor. If it won't light at all, what is the lighting
method? Pilot light? Hot surface igniter? Is it high efficiency with a blower for
combustion? Could be a pressure switch, blocked vent to the outside.
It seems odd that the blower motor is actually running. (figure of speech?) The motors on the few furnaces I've had were started by some sort of heat sensor. So maybe the burners light, the motor starts, and..............................?

Ultra SX90 main burners
 

On Wed, 3 Feb 2021 09:07:21 -0800 (PST), Dean Hoffman
wrote:

On Wednesday, February 3, 2021 at 10:44:39 AM UTC-6, trader_4 wrote:
On Wednesday, February 3, 2021 at 11:01:12 AM UTC-5, Jeff Gramza wrote:
Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?
Are you sure they are not lighting or are they lighting, then going out? If it;s
the latter, could be a bad flame sensor. If it won't light at all, what is the lighting
method? Pilot light? Hot surface igniter? Is it high efficiency with a blower for
combustion? Could be a pressure switch, blocked vent to the outside.
It seems odd that the blower motor is actually running. (figure of speech?) The motors on the few furnaces I've had were started by some sort of heat sensor. So maybe the burners light, the motor starts, and.............................?
My blower motor runs constantly (at low speed) and just ramps up to
higher speed when the furnace lights and the plenum temperature comes
up.

Ultra SX90 main burners
 

On Wed, 3 Feb 2021 09:07:21 -0800 (PST), Dean Hoffman
wrote:

On Wednesday, February 3, 2021 at 10:44:39 AM UTC-6, trader_4 wrote:
On Wednesday, February 3, 2021 at 11:01:12 AM UTC-5, Jeff Gramza wrote:
Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?
Are you sure they are not lighting or are they lighting, then going out? If it;s
the latter, could be a bad flame sensor. If it won't light at all, what is the lighting
method? Pilot light? Hot surface igniter? Is it high efficiency with a blower for
combustion? Could be a pressure switch, blocked vent to the outside.
It seems odd that the blower motor is actually running. (figure of speech?) The motors on the few furnaces I've had were started by some sort of heat sensor. So maybe the burners light, the motor starts, and.............................?
I suspect your problem is the same as on the neighbor's Tempstar -
the hose from the inducer motor gets condensation in it and eventually
the port itfice in the blower housing restricts to the point the
vacuum/pressure switches don't get the proper signal any more. Try
blowing through the hoses that connect to the inducer blower- if you
can't blow into the blower you will need to ream out the fitting -
sometimes a paper clip will do it - sometimes you need a drill.

Ultra SX90 main burners
 

In alt.home.repair, on Wed, 03 Feb 2021 11:55:30 -0500,
wrote:

On Wed, 3 Feb 2021 08:01:08 -0800 (PST), Jeff Gramza
wrote:

Furnace is around 20 years old.
Sometimes the main burners light and sometimes they don't.


Elon Musk's rockets are having the same ignite problems !

https://youtu.be/klT3YcrG7K4

He did so well until the end. I woudln't pay to ride on one of those.
You'd have to pay me.

John T.

Ultra SX90 main burners
 

On 2/3/2021 10:16 PM, micky wrote:
In alt.home.repair, on Wed, 03 Feb 2021 11:55:30 -0500,
wrote:

On Wed, 3 Feb 2021 08:01:08 -0800 (PST), Jeff Gramza
wrote:

Furnace is around 20 years old.
Sometimes the main burners light and sometimes they don't.


Elon Musk's rockets are having the same ignite problems !

https://youtu.be/klT3YcrG7K4

He did so well until the end. I woudln't pay to ride on one of those.
You'd have to pay me.

How much?

Ultra SX90 main burners
 

On Wed, 03 Feb 2021 14:17:04 -0500, Clare Snyder posted for all of us to
digest...


On Wed, 3 Feb 2021 09:07:21 -0800 (PST), Dean Hoffman
wrote:

On Wednesday, February 3, 2021 at 10:44:39 AM UTC-6, trader_4 wrote:
On Wednesday, February 3, 2021 at 11:01:12 AM UTC-5, Jeff Gramza wrote:
Furnace is around 20 years old. Sometimes the main burners light and sometimes they don't. When they don't, I go downstairs, turn the blower motor off and flip the black switch to 'off' on the little beige box (smart valve?). Wait 30 seconds, reverse the process and the main burners come on. They may come on the next few times but when it starts to get cold in the house, I go downstairs and see the main
burners haven't fired up. Doesn't appear the plastic hoses are clogged. Any suggestions where to start looking?
Are you sure they are not lighting or are they lighting, then going out? If it;s
the latter, could be a bad flame sensor. If it won't light at all, what is the lighting
method? Pilot light? Hot surface igniter? Is it high efficiency with a blower for
combustion? Could be a pressure switch, blocked vent to the outside.
It seems odd that the blower motor is actually running. (figure of speech?) The motors on the few furnaces I've had were started by some sort of heat sensor. So maybe the burners light, the motor starts, and.............................?
I suspect your problem is the same as on the neighbor's Tempstar -
the hose from the inducer motor gets condensation in it and eventually
the port itfice in the blower housing restricts to the point the
vacuum/pressure switches don't get the proper signal any more. Try
blowing through the hoses that connect to the inducer blower- if you
can't blow into the blower you will need to ream out the fitting -
sometimes a paper clip will do it - sometimes you need a drill.

Bingo! Small drill bit, not surgery, just to clear the orifice.

--
Tekkie

Ultra SX90 main burners
 

On Thu, 4 Feb 2021 11:28:46 -0800, Bob F posted for all of us to digest...


On 2/3/2021 10:16 PM, micky wrote:
In alt.home.repair, on Wed, 03 Feb 2021 11:55:30 -0500,
wrote:

On Wed, 3 Feb 2021 08:01:08 -0800 (PST), Jeff Gramza
wrote:

Furnace is around 20 years old.
Sometimes the main burners light and sometimes they don't.


Elon Musk's rockets are having the same ignite problems !

https://youtu.be/klT3YcrG7K4

He did so well until the end. I woudln't pay to ride on one of those.
You'd have to pay me.

How much?

Good one!

--
Tekkie

Ultra SX90 main burners
 

In alt.home.repair, on Thu, 4 Feb 2021 11:28:46 -0800, Bob F
wrote:

On 2/3/2021 10:16 PM, micky wrote:
In alt.home.repair, on Wed, 03 Feb 2021 11:55:30 -0500,
wrote:

On Wed, 3 Feb 2021 08:01:08 -0800 (PST), Jeff Gramza
wrote:

Furnace is around 20 years old.
Sometimes the main burners light and sometimes they don't.


Elon Musk's rockets are having the same ignite problems !

https://youtu.be/klT3YcrG7K4

He did so well until the end. I woudln't pay to ride on one of those.
You'd have to pay me.

How much?

Good question. Unless I get very sick or want to buy a chateau in
Europe, I have enough money to live on for the rest of my life. In fact
I can't stop economizing even though I want to. I probably need a new
laptop and I seem to have a $400 limit, for no particular reason. I'm
sure everyone else here spent more than that. (and knowing me, I'll
probably fix the old one or spend less than 400.) So why would I risk
my life for money? For the view? For the excitement? Those would be
nice if there were not such a high chance of dying. (yes, I know, the
death rate hasn't been that high, but I think the last 50 years have
been beginner's luck.)