I appreciate you all being here. :cheers:
Long story short summary questions: Will running at about third (~32%) too much natural gas pressure above the label’s maximum be dangerous? (due to a “stuck” adjustment screw) The gas valve will be changed. Is it okay to run a furnace a few degrees over the the maximum rise when it is well below the maximum outlet temperature? Will it risk damaging the heat exchanger? Should I ask for a second call back from the same guy or should I not trust him now and find someone else to check the work?
I recently checked the temperature rise on a two stage 96% furnace and the difference seemed a bit low. I checked the fan speed dip switch settings and they were at the lowest for the furnace size. So I figured the gas pressure might be a bit low. To be safe, I called a licensed hvac contractor to check and set the gas. He set it and left. Right after he left, the furnace wouldn’t light so he had to do a call back and bump the gas up again. He said he set it to 1.7 and 3.8 wc.
I checked the rise again, since I noticed he didn’t do it for his call back. On low, the rise was 73.6F and 79.7F on high. This furnace says the specs are a low rise of 60F with 195F max and a high rise of 70F and a max of 165F.
At this point, I don’t want to deal with waiting for him on yet another callback for both our sakes, so I set the furnace fan speed to its maximum boost of +10% for a “comfort” setting and another setting for +17% fan speed. This dropped the temperature but not enough to be within the rise ranges on the label. It was still 69.6 of rise on the low setting and 71.8 and the high. All the vents were opened.
I usually don’t mess with gas but at this point I’m wondering what is going on here. So I plug a cheap manometer in that I don’t really trust for accurate readings. I zeroed it when the gas valve was closed. The gas pressure read 2.56wc on low and 4.48wc on high. The label says it should be max 1.7 on low and 3.8 on high.
So, I dialed the low side down to 1.7wc and checked the rise. It read 55.7F. Perfect
I go to dial down the high side counterclockwise and I notice something strange. The numbers don’t budge from 4.48wc. I’m turning it very slowly counterclockwise as the manual says and just did so without any issues on the low side.
So I look at the gas valve’s plastic adjustment screw. It’s not backing out. I know it should back out in 9 turns or so because I’ve seen it done on a White Rogers to change the springs with nat gas to lp conversions.
Is it possible the person who came to look at the unit somehow stripped the screw? Or is it something that likely happened from manufacturer? I don’t see how it’s possible he did it after looking at a diagram of the part. Unless I’m wrong, the screw looks like it should bottom out on metal or come out. I saw him working on the unit. I never noticed the adjustment screw coming out. How would you all deal with this kind of a situation? Have you seen this happen before?
What do you all think is going on? I called the manufacturer. They said to replace the gas valve and they don’t sell the plastic part.
The high stage doesn’t go over temperature on rise or max outlet temperature. Do you think it is fine to run at this gas pressure? Maybe the manometer is off? Is it okay to be a few degrees over the rise as long as you’re far below the maximum outlet temperature?
Thank you all a lot for your time help. It’s difficult to find reliable people these days.
Long story short summary questions: Will running at about third (~32%) too much natural gas pressure above the label’s maximum be dangerous? (due to a “stuck” adjustment screw) The gas valve will be changed. Is it okay to run a furnace a few degrees over the the maximum rise when it is well below the maximum outlet temperature? Will it risk damaging the heat exchanger? Should I ask for a second call back from the same guy or should I not trust him now and find someone else to check the work?
I recently checked the temperature rise on a two stage 96% furnace and the difference seemed a bit low. I checked the fan speed dip switch settings and they were at the lowest for the furnace size. So I figured the gas pressure might be a bit low. To be safe, I called a licensed hvac contractor to check and set the gas. He set it and left. Right after he left, the furnace wouldn’t light so he had to do a call back and bump the gas up again. He said he set it to 1.7 and 3.8 wc.
I checked the rise again, since I noticed he didn’t do it for his call back. On low, the rise was 73.6F and 79.7F on high. This furnace says the specs are a low rise of 60F with 195F max and a high rise of 70F and a max of 165F.
At this point, I don’t want to deal with waiting for him on yet another callback for both our sakes, so I set the furnace fan speed to its maximum boost of +10% for a “comfort” setting and another setting for +17% fan speed. This dropped the temperature but not enough to be within the rise ranges on the label. It was still 69.6 of rise on the low setting and 71.8 and the high. All the vents were opened.
I usually don’t mess with gas but at this point I’m wondering what is going on here. So I plug a cheap manometer in that I don’t really trust for accurate readings. I zeroed it when the gas valve was closed. The gas pressure read 2.56wc on low and 4.48wc on high. The label says it should be max 1.7 on low and 3.8 on high.
So, I dialed the low side down to 1.7wc and checked the rise. It read 55.7F. Perfect
I go to dial down the high side counterclockwise and I notice something strange. The numbers don’t budge from 4.48wc. I’m turning it very slowly counterclockwise as the manual says and just did so without any issues on the low side.
So I look at the gas valve’s plastic adjustment screw. It’s not backing out. I know it should back out in 9 turns or so because I’ve seen it done on a White Rogers to change the springs with nat gas to lp conversions.
Is it possible the person who came to look at the unit somehow stripped the screw? Or is it something that likely happened from manufacturer? I don’t see how it’s possible he did it after looking at a diagram of the part. Unless I’m wrong, the screw looks like it should bottom out on metal or come out. I saw him working on the unit. I never noticed the adjustment screw coming out. How would you all deal with this kind of a situation? Have you seen this happen before?
What do you all think is going on? I called the manufacturer. They said to replace the gas valve and they don’t sell the plastic part.
The high stage doesn’t go over temperature on rise or max outlet temperature. Do you think it is fine to run at this gas pressure? Maybe the manometer is off? Is it okay to be a few degrees over the rise as long as you’re far below the maximum outlet temperature?
Thank you all a lot for your time help. It’s difficult to find reliable people these days.
source https://hvac-talk.com/vbb/threads/2244090-White-Rogers-plastic-adjustment-screw-will-not-back-out-after-contractor-worked-on-it?goto=newpost
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