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  1. #14
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    Quote Originally Posted by slctech View Post
    So what is that click noise you hear 30 seconds to a minute after initial ignition that coincides with the furnace glitching??? You say it is on the "controller". ...
    The click I was talking about is the relay letting go of the gas valve when the flame sensor detects a drop in flame. When the furnace first fires I hear the click of the indoor blower coming on after the blower delay. The furnace maintains flame past that point. We were able to force the unit to drop flame by calling for heat from the other furnaces in the building sharing the same gas line.

  2. #15
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    Quote Originally Posted by VTP99 View Post
    We don't use hi pressure systems where I'm located.
    So my question is, on the high pressure type systems does the pipe have to be welded ?
    No. the high pressure is only 2 psi. The largest piping I see on 2 psi systems is about 2", and that is conventional threaded pipe or the new "Mega Press" joint.

    Now, if you have a LOW pressure system, larger pipe is required to flow enough gas, and I believe the rule for that is 3" and larger must be welded.
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  3. #16
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    Quote Originally Posted by slctech View Post
    So what is that click noise you hear 30 seconds to a minute after initial ignition that coincides with the furnace glitching??? You say it is on the "controller".

    Does the furnace trip out EVERY SINGLE TIME you hear this click?? Or is it just every once in a while?? You make it sound like the click you hear has a direct relationship to the gas valve dropping out??

    I got a sneaking suspicion that the click you are hearing is the control board mounted blower relay turning on 35 seconds delay after ignition. If the gas valve is being affected every time after this relay is being energized, then I would assume there is a voltage drop dramatic enough to affect the either the gas valve's coil and cause it to drop out or affecting the board itself. The board is also energizing the EAC and Humidifier at the same time per the timing diagram I attached below.
    That's also a good idea. I was going by the click being the gas valve closing after flame loss on the sensor circuit.
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  4. #17
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    Quote Originally Posted by timebuilder View Post
    No. the high pressure is only 2 psi. The largest piping I see on 2 psi systems is about 2", and that is conventional threaded pipe or the new "Mega Press" joint.

    Now, if you have a LOW pressure system, larger pipe is required to flow enough gas, and I believe the rule for that is 3" and larger must be welded.
    Sounds right that's about the size pipe I see welded on the roofs over here. I wonder why its required on the larger size ?

  5. #18
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    Quote Originally Posted by VTP99 View Post
    Sounds right that's about the size pipe I see welded on the roofs over here. I wonder why its required on the larger size ?
    Because the stress on the threads increases with pipe size, along with required force to mate the surfaces for a leak free joint. The code was changed to help ensure a sealed piping system.
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  6. #19
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    Quote Originally Posted by timebuilder View Post
    Because the stress on the threads increases with pipe size, along with required force to mate the surfaces for a leak free joint. The code was changed to help ensure a sealed piping system.
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  7. #20
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    Quote Originally Posted by slctech View Post
    So what is that click noise you hear 30 seconds to a minute after initial ignition that coincides with the furnace glitching??? You say it is on the "controller".

    Does the furnace trip out EVERY SINGLE TIME you hear this click?? Or is it just every once in a while?? You make it sound like the click you hear has a direct relationship to the gas valve dropping out??

    I got a sneaking suspicion that the click you are hearing is the control board mounted blower relay turning on 35 seconds delay after ignition. If the gas valve is being affected every time after this relay is being energized, then I would assume there is a voltage drop dramatic enough to affect the either the gas valve's coil and cause it to drop out or affecting the board itself. The board is also energizing the EAC and Humidifier at the same time per the timing diagram I attached below.
    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.
    Last edited by Dan_G; 02-10-2019 at 09:43 AM.

  8. #21
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    In Canada, anything 2 1/2" and larger is required to be welded, for gas piping. Pressure is irrelevant.

    Gas pressure maximum is also depending on Canadian gas code, building usage and AHJ.

    2psi is becoming common. I have seen 5 psi in commercial buildings.
    Quote Originally Posted by VTP99 View Post
    We don't use hi pressure systems where I'm located.
    So my question is, on the high pressure type systems does the pipe have to be welded ?
    Sent from my SM-G965W using Tapatalk

  9. #22
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    Quote Originally Posted by BALloyd View Post
    In Canada, anything 2 1/2" and larger is required to be welded, for gas piping. Pressure is irrelevant.

    Gas pressure maximum is also depending on Canadian gas code, building usage and AHJ.

    2psi is becoming common. I have seen 5 psi in commercial buildings.

    Sent from my SM-G965W using Tapatalk

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  10. #23
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    Quote Originally Posted by timebuilder View Post
    Okay, let's step back for a moment.

    If you have one regulator...the gas Co regulator...for the entire building, it means the entire building is running low pressure gas service.

    SO...if you have piping that is too small, you cannot move enough gas to run all of the units, and that is why the unit is seeing a drop in pressure when the others fire.

    This is a MUCH bigger problem than an adjustment.


    I have a customer that had six new RTU's installed last April. It was a new store, and we had not yet been assigned as a service contractor.

    The installing contractor ran 1" piping all around the roof and down to the meter. Luckily, he installed a regulator at every unit. The gas had not been turned on, and so they called the Gas Co and had them come out and restore gas service.

    Turns out the gas service was only about 5"wc. Not enough to get gas to six units through 1" piping. There were two choices: upgrade the meter rack to 2 psi, or upgrade the piping to 3". Kind of a no brainer, yes?

    About three weeks ago, the client finally got the gas Co out to change the rack pressure to 2 psi, and that solved the issue.

    In your case, they "could" have their gas pressure changed, IF the main is not a low pressure main. Then, you guys can install regulators at every unit. That would solve your issue.

    BUT, be warned...if they plan to do this, you MUST install the regulators BEFORE the gas pressure is raised. Otherwise, you kill all of the gas valves.

    It is very difficult to coordinate a visit with a gas utility, and just turning off hand valves at units is not a solution, because someone else can turn them back on.


    Adjusting the gas Co regulator will probably not help.
    We have had the same problem with one Lennox RTU and we had the gas company come out. They said it was a gas volume problem.
    There is a difference between gas volume and gas pressure...so I hear.
    I would like to learn more about the two.
    Can you explain this to me?
    Thanks!

  11. #24
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    Quote Originally Posted by Lickety-Split View Post
    We have had the same problem with one Lennox RTU and we had the gas company come out. They said it was a gas volume problem.
    There is a difference between gas volume and gas pressure...so I hear.
    I would like to learn more about the two.
    Can you explain this to me?
    Thanks!

    Sure.

    In physics, liquids and gases (like atmospheric air) are considered "fluids." This is why explanations about electricity often use water an an analogy, because we can see it and touch it, where as we avoid events where we can "see" electricity, and we sure as heck do not want to touch any of it.

    I mention this because they are related to each other in the way they behave.

    So, let's use water to explain your gas question.

    Let's say I want to fill a bucket full of water using a hose.

    The water service to the house has a constant pressure of 40 psi.

    Now...if I use a garden hose to fill my bucket, I might take 45 seconds to get the job done. The 40 psi of pressure can only flow just so much water through the 1/2" opening in my garden hose. In fact, if I have a loooong garden hose, the friction inside it makes it take even longer to fill my bucket. Maybe it takes 90 seconds.

    Now...suppose I have a BIG hose...a section of fire hose connected to the hydrant and the same 40 psi of pressure in the main. Intuitively, you already can guess that the larger hose can move a LOT more water, and I can fill that bucket in maybe 4 seconds, and I might have a hard time controlling the bucket and the splashing as I try to fill it.

    Same 40 psi. Just a larger pipe.

    So...when you have low pressure gas service, you need to reduce the internal friction of the pipe to be able to flow enough gas to satisfy all of the gas valves that are opening in the various units. If there is enough resistance in the piping system, one or more units can be starved for gas. It's like using a garden hose. If I want to move enough gas at a low pressure, such as 7" WC, I will need to use a big pipe (3" welded) to make sure that I can flow enough volume of gas to get it to all of the units. Like using a fire hose.

    If I could raise the pressure in the water main from 40 psi to 160 psi, I could fill my bucket MUCH faster, and still use my garden hose to do it. The pressure (voltage) overcomes the friction (resistance) to increase the flow (current) through the hose (conductor). That is the "water analogy" of electricity.

    In your case, most gas mains have a higher pressure than customers can use, just like the voltage that feeds your house transformer out on the pole could be 1,000 to 14,000 volts on the primary side, and your house gets a nice, reliable 120 volts to neutral, or 240 volts hot to hot.

    Many gas mains ruin at 8 -12 psi, and the gas Co can select how much pressure goes to the meter by changing the regulator. In my area, low pressure mains have about 5"WC, and high pressure mains have about 10 psi. The high pressure mains allow the gas Co to provide either 12.2" WC, or 2psi to their meter, and therefore, to the customer.

    This allowed them to come out last month and fix the issue at the store which already had 1" piping, and regulators at all of the units. A simple changeout of the regulator at the meter allowed enough gas to be flowed through smaller pipe (garden hose) instead of changing the entire piping system to 3" welded pipe (fire hose).

    Questions?
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  12. #25
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    Just so we're clear and on the same page..... I'm not saying that this is definitely the problem you're experiencing because I'm not there to do the diagnostic. I'm giving you some insight as to what it sounds like based upon what I see on a computer screen.

    So at this point, you could theoretically add up the needed BTU capacity of all the units connected to that meter, and there are online calculators which will tell you at what pressure what size pipe is necessary in order to provide all of the gas heating units with the gas that is required, so that they can all run without losing gas pressure.
    [Avatar photo from a Florida training accident. Everyone walked away.]
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  13. #26
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    Quote Originally Posted by timebuilder View Post
    Sure.

    In physics, liquids and gases (like atmospheric air) are considered "fluids." This is why explanations about electricity often use water an an analogy, because we can see it and touch it, where as we avoid events where we can "see" electricity, and we sure as heck do not want to touch any of it.

    I mention this because they are related to each other in the way they behave.

    So, let's use water to explain your gas question.

    Let's say I want to fill a bucket full of water using a hose.

    The water service to the house has a constant pressure of 40 psi.

    Now...if I use a garden hose to fill my bucket, I might take 45 seconds to get the job done. The 40 psi of pressure can only flow just so much water through the 1/2" opening in my garden hose. In fact, if I have a loooong garden hose, the friction inside it makes it take even longer to fill my bucket. Maybe it takes 90 seconds.

    Now...suppose I have a BIG hose...a section of fire hose connected to the hydrant and the same 40 psi of pressure in the main. Intuitively, you already can guess that the larger hose can move a LOT more water, and I can fill that bucket in maybe 4 seconds, and I might have a hard time controlling the bucket and the splashing as I try to fill it.

    Same 40 psi. Just a larger pipe.

    So...when you have low pressure gas service, you need to reduce the internal friction of the pipe to be able to flow enough gas to satisfy all of the gas valves that are opening in the various units. If there is enough resistance in the piping system, one or more units can be starved for gas. It's like using a garden hose. If I want to move enough gas at a low pressure, such as 7" WC, I will need to use a big pipe (3" welded) to make sure that I can flow enough volume of gas to get it to all of the units. Like using a fire hose.

    If I could raise the pressure in the water main from 40 psi to 160 psi, I could fill my bucket MUCH faster, and still use my garden hose to do it. The pressure (voltage) overcomes the friction (resistance) to increase the flow (current) through the hose (conductor). That is the "water analogy" of electricity.

    In your case, most gas mains have a higher pressure than customers can use, just like the voltage that feeds your house transformer out on the pole could be 1,000 to 14,000 volts on the primary side, and your house gets a nice, reliable 120 volts to neutral, or 240 volts hot to hot.

    Many gas mains ruin at 8 -12 psi, and the gas Co can select how much pressure goes to the meter by changing the regulator. In my area, low pressure mains have about 5"WC, and high pressure mains have about 10 psi. The high pressure mains allow the gas Co to provide either 12.2" WC, or 2psi to their meter, and therefore, to the customer.

    This allowed them to come out last month and fix the issue at the store which already had 1" piping, and regulators at all of the units. A simple changeout of the regulator at the meter allowed enough gas to be flowed through smaller pipe (garden hose) instead of changing the entire piping system to 3" welded pipe (fire hose).

    Questions?
    Great explanation! Makes all sense. Thanks!

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