Valve on radiator shut off then probelm with heating


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Old 02-17-10, 08:47 AM
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Question Valve on radiator shut off then probelm with heating

Hello Gentleman,

If someone can please explain what is going on. My wife closed the valve of one of the radiators on the second floor of my house and we started having problems with the heat in one of the upstairs room. It's a hot water system that has no bypass and it has a steel compression tank and nothing to get the air out of the system automatically. The pressure at the boiler when I first checked was approximately 17 PSI. The first thing that came to mind was bleeding the air out of the system. I started at the 2nd floor radiators and worked my way down to the 1st floor. The room that was not heating had a lot of air in the radiator. I added more water to the boiler and continued to bleed the radiators. The pressure went down as I bled the radiators and I continued to supply water to the boiler until I got all the air out and got approximately 17 PSI @ the boiler again. I know the compression tank has some water in it, but when the water expands as it gets hotter it needs somewhere to go, but why did so much air get into the system and why was it fine before? Is it possible that I had the air in the system before and never noticed it until the valve was shut off?

Thanks in advance
 
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Old 02-17-10, 11:09 AM
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Red face

NJTrooper, Can you shed some light on this problem?
 
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Old 02-17-10, 03:33 PM
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Not without asking more questions...

Did you try opening the valve on the radiator again?

How is the system piped? Monoflo? Series? Home runs?

My only thought as to what happened is that perhaps when the radiator valve was closed, the velocity increased in that pipe run enough to push a small bubble down the line where it met up with another small bubble and formed a big bubble.

When you say radiators, what do you mean?
 
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Old 02-19-10, 12:04 PM
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Fair enough.

Yes, I opened the valve again and I still had the problem with the one room not warming up. I proceeded to the check the boiler and it had about 10psi @ 140 deg. I proceeded to bleed the system, beginning at the 2nd floor radiators. There was a lot of air in the 2nd floor radiators. I purged the air and supplied more water to the system. I had to do this a couple of times before I got all the air out. After all the air was out I was getting around 17psi @ 140 deg.

When I say radiator I mean cast iron radiators. Think they are in series.

I have been getting a little less heat at the room I had no heat before, but it's a big difference from the 68 deg. I was getting 73 before, now it's from 71-72. That's with the thermostat set to 69 and it's in the first floor. We can't set it back because we have a 6 month old, my wife is always cold and the room sits over a garage with no insulation in the garage ceiling.

The system takes forever to warm up since it has no bypass, no valves at all. None on the circulator or the any of the return or supply lines. I tried to help the system a little by installing an aquastat (L6006c) on the supply line, so it keeps the circulator off until the water temp at the boiler reaches around 165 and then cycles it on and off. I thought this was a good idea since condensation is a problem when there is a cold start. I don't know if this was a good idea but it has helped some.
 
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Old 02-19-10, 05:40 PM
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Sounds like you did the bleeding just right. I might suggest letting the system sit without the pump running for a few hours and then temporarily raising the pressure in the system as high as possible without the relief valve popping... say 25 PSI, and then bleed. Let them bubbles float up out of the water, and the extra pressure might give a little more 'oomph' to move that air.

After all the air was out I was getting around 17psi @ 140 deg.
That might be a tad on the high side... but as long as it doesn't get up to like 25 when the boiler is at 180, you should be OK.

I know the compression tank has some water in it
Sure it does, it should. What's important is that it doesn't have 'not enough air' to provide that expansion 'cushion' you talked about... Have you serviced the tank lately? i.e. draining it completely, and then re-pressurizing it. In normal operation, the tank will be at least 1/2 full of water at 12 PSI.

Think they are in series
Of course you know now that you can't close the valve on one series connected radiator and expect the others in series with it to still heat. But, they may be monoflo? Can you see the piping to/from the rads on the lower level at the ceiling in the basement? Can you describe how they are piped? Example: Is there one big pipe going around the perimeter with the in/out of each rad tee'd into the single big pipe? or does the pipe loop in and out of each rad (series), or, maybe there are two big pipes running around, with the in coming from one, and the out going to the other... what you see downstairs is _probably_ the same as upstairs.

the room sits over a garage with no insulation in the garage ceiling.
I'm sure you also know that insulating that ceiling will go a LONG way toward making that room more comfortable...

my wife is always cold
Where have I heard THAT before?

I think the 'stat on the circ is a good idea... one thing kinda bothers me though... if the system were cool... and called for heat, boiler fires, no circ... now the boiler is hot, and the pump kicks in and dumps a lot of cool water in a hot boiler...

How much differential you have set on that 'stat?

I might experiment with that stat setting a little... because the lower you can set it, the better for the boiler. Try knocking it down a few pegs... maybe mmmmm... 150 or so? Or have you already done the experiments? And if you can come up with an easy way to measure the return temps, that's what you need to keep an eye on. Of course a boiler bypass would be the way to go...

No valves anywhere? What were they thinking?
 
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Old 02-20-10, 05:47 AM
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Sounds like you did the bleeding just right. I might suggest letting the system sit without the pump running for a few hours and then temporarily raising the pressure in the system as high as possible without the relief valve popping... say 25 PSI, and then bleed. Let them bubbles float up out of the water, and the extra pressure might give a little more 'oomph' to move that air.
Thanks, I've been reading a lot of the posts here and I thought it was a good idea to do that before I posted. I will try the method you described as soon as I can.

That might be a tad on the high side... but as long as it doesn't get up to like 25 when the boiler is at 180, you should be OK.
I will check the pressure again. The boiler gets to 175 and I have the circulator set to kick on around that temp. I did make sure that the high limit is set to 180.

Sure it does, it should. What's important is that it doesn't have 'not enough air' to provide that expansion 'cushion' you talked about... Have you serviced the tank lately? i.e. draining it completely, and then re-pressurizing it. In normal operation, the tank will be at least 1/2 full of water at 12 PSI.
I've read about that and from what I remember it's called "waterlogged". No, it has not been serviced. We bought the house about a year ago and had someone come in and check the boiler and right off the bat what they recommended was giving the system a tune-up to the tune of $1500. Then they recommended a new system, which they thought was necessary after looking around a bit. They didn't seem to make up their minds on what would be best, so I never called them. All this and the system seemed to be heating the house properly. Back to the tank, with the system running and the temperature around 150 deg I can knock on the tank and it doesn't sound full, it's got some air in it, how much I don't know. How can I repressurize a steel tank?

Of course you know now that you can't close the valve on one series connected radiator and expect the others in series with it to still heat. But, they may be monoflo? Can you see the piping to/from the rads on the lower level at the ceiling in the basement? Can you describe how they are piped? Example: Is there one big pipe going around the perimeter with the in/out of each rad tee'd into the single big pipe? or does the pipe loop in and out of each rad (series), or, maybe there are two big pipes running around, with the in coming from one, and the out going to the other... what you see downstairs is _probably_ the same as upstairs.
I checked in the basement and from what I can see there are two big pipes running around, with the in coming from one, and the out going to the other.This would be considered in series?

I'm sure you also know that insulating that ceiling will go a LONG way toward making that room more comfortable...
Yes, we are going to work on that this spring/summer.

I think the 'stat on the circ is a good idea... one thing kinda bothers me though... if the system were cool... and called for heat, boiler fires, no circ... now the boiler is hot, and the pump kicks in and dumps a lot of cool water in a hot boiler...
Yeah, I thought of that when I read about thermal shock and condensation, but I don't know what was worse having the boiler fire and stay on for about two hours or longer circulating cool water for most of that time. I thought the stat on the pump was a good idea because at least the boiler could come up to temp and circulate a some hot water faster and when the 'stat detected the cooler water it would shut the circulator off and let the boiler heat the water that returned at lower temps.

How much differential you have set on that 'stat?
I have it set to 5 deg. I've experimented with different settings, but that is the only one that keeps the drop to 20-25 degrees. If I go higher than that then it drops even more. I've noticed that the L6006C is not to precise and I'm guessing it's because it's not submerged and it's on the pipe's surface.

I might experiment with that stat setting a little... because the lower you can set it, the better for the boiler. Try knocking it down a few pegs... maybe mmmmm... 150 or so? Or have you already done the experiments? And if you can come up with an easy way to measure the return temps, that's what you need to keep an eye on. Of course a boiler bypass would be the way to go...
What you're saying is have the 'stat controlling the circulator trip at 150? If so, the temperature drops to about 125 or so at the boiler and that brings condensation into play doesn't it? The only thing I have to measure the temps and I'm relying on is the boiler gauge. I know how much you distrust these temp/pressure gauges but that's all I have for now. I will try to get a infrared thermometer or is there anything else you can suggest.

No valves anywhere? What were they thinking?
I'm sorry, I said no valves, but there is one close to the compression tank in the ceiling, which looks pretty rusted,the drain valve at the back of the boiler on the return pipe, the pressure relief valve and the pressure reducing valve. none that will really help me balance out the system. If the pump goes bad I have no other choice than to drain the whole system.

thanks again Trooper!
 
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Old 02-20-10, 06:59 AM
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Originally Posted by ezra18042 View Post
I checked in the basement and from what I can see there are two big pipes running around, with the in coming from one, and the out going to the other.This would be considered in series?
So you have two main pipes and each radiator has one pipe going to one main and another pipe going to the other main? IF that is the case, then it is in parallel. Series would have the water flow through one radiator to get to the next radiator.
 
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Old 02-20-10, 08:45 AM
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what they recommended was giving the system a tune-up to the tune of $1500. Then they recommended a new system, which they thought was necessary after looking around a bit.
Typical... I'm glad you didn't bite... what make/model is the boiler? appx age? Why not post a few pics and we'll look them over and evaluate / make suggestions... know how to do the photobucket thing?

I'm not sure if you mentioned the fuel type either?

...from what I remember it's called "waterlogged"... I can knock on the tank and it doesn't sound full ... How can I repressurize a steel tank?
Yep, that's the term usually used. I'm not big on the 'tap test' to tell if it's waterlogged or not. You would kinda need an 'audio reference' to know the difference.

I'd like to see pics before you proceed, but you did mention that there is a valve in the line to the tank, with a drain valve on it? And that the valve is rusted... so let's have a look before you turn that valve... but basically, the procedure would be to isolate the tank from the system by closing that valve (if it's in the line to the tank?) and connecting a hose to the drain. It should be a hose that's only long enough to get to your drain point... it shouldn't be looped all around, because that won't allow air to travel back up the hose, and the end of the hose should be open, not submerged in a bucket, for the same reason.

You need to completely drain that tank. What happens most often is the 'drinking straw analogy'... finger on the end of the straw and the drink stays in the straw when you lift it out... same thing happens with those tanks. You open the drain, and gravity and pressure drain the tank until a 'suction' or 'vacuum' forms in the tank, and water stops draining. You need to break that suction by forcing some air into the hose.

Sometimes you can blow into the end of the hose, but think about the germs and whatnot ... I'm not a big fan of that method. If you have an air compressor, you can blow that into the end of the hose... sometimes just loosening the hose connection where it's connected to the drain will allow it to take a gulp of air... you may also have one of the 'specialty' drain valves that includes an air valve on it... pics will tell.

Once you are sure that the tank is empty (or full... of AIR), you would close the drain, and re-open the isolation valve. Water from the system will enter the tank, and it will fill to around 1/2 with water. That's normal... the air in the tank will compress to whatever pressure is on the system.

As the system heats and cools, the air 'bubble' will be compressed more or less depending on the system pressure.

Typically, you might expect say 8-10 PSI pressure change from a cold boiler to a high limit boiler. This is usually a better indicator of the status of the compression tank than tapping. If you have excessive swing in pressure it's a sure bet the tank is near waterlogged.

two big pipes running around, with the in coming from one, and the out going to the other.This would be considered in series?
Deputy Droopalong (I bet you guys are too young to remember that cartoon...) is correct. Called 'parallel' or simply 'two-pipe'. There is a variation of two pipe called 'reverse return' but that's not real important. With two pipe, you CAN close individual radiators to regulate the flow through them, because it won't change the flow through the others [much].

It is possible that the upstairs is in series though... look some more... it might be that the supply and return for each upstairs rad is piped down to the basement, and also tees into the same pipes that the downstairs do. It could also be set up with another pair of two pipes going upstairs, and around, and those rads tee'd in up there.

With a two pipe system, and functioning shut off valves on each radiator (don't force them! ) if you have a 'problem' radiator that seems to have an air blockage, you can increase the flow through the problem unit by closing the valves on some/all of the other radiators. This might help to move that air out... but this brings up another point.

That moved air has to go somewhere... and that somewhere should be back to the expansion tank. Ideally, with a compression tank, it would be connected to an 'air scoop' which would collect the air from the system as it is caught, and pass it up to the expansion tank. All the piping to the tank should be sloping uphill in order for the air to make it's way back in... this is another reason I'd like to see pics if possible.

Yes, we are going to work on that [floor insulation] this spring/summer.
If the ceiling in the garage is exposed, explore having it spray foamed... that stuff also acts as a vapor and infiltration barrier. (for a few hundred bucks, there are also DIY kits available, but know that BIG mistakes can be made, so if you decide to DIY with spray foam, do your homework!)

more later... chores...
 
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Old 02-20-10, 05:45 PM
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Thanks guys! I will post the pictures tomorrow and answer all your questions about the system.
 
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Old 02-20-10, 09:10 PM
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I know how much you distrust these temp/pressure gauges but that's all I have for now. I will try to get a infrared thermometer or is there anything else you can suggest.
You noticed that, eh?

If you do go with the infrared, pick up a small can of flat black paint. If you first paint all the points you intend to measure, you will get the best accuracy. Those thermometers are terribly inaccurate on copper pipe. Rusty old cast iron, reasonably accurate... anything shiny, not accurate. Flat black paint, about as good as yer gonna get (not perfect, but good) Google "EMISSIVITY" for more info on this.

I think your pump a'stat is the lesser of two evils. If you've done the experiments, and are happy with the settings, then leave it be. If you use some 'heat sink compound' between the pipe and the bulb, and INSULATE the bulb and pipe at least a foot in each direction, you will get better performance of the stat... but don't expect pinpoint precision on the dial calibration in any event.
 
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Old 02-21-10, 03:21 PM
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Hello again gentleman and the link below is for the pictures I said I would take. I hope it works!

Pictures by ezra18042 - Photobucket

Typical... I'm glad you didn't bite... what make/model is the boiler? appx age? Why not post a few pics and we'll look them over and evaluate / make suggestions... know how to do the photo bucket thing?

I'm not sure if you mentioned the fuel type either?
Yeah they thought we were easy prey, but the system was working fine, so we didn't think they were being too honest, but we did get someone in to do a cleaning of the boiler and they made some adjustments. I did a little research and found out that my boiler was actually an oil set up before and it was converted to gas. It is an H.B. Smith Series-8. From what I found out from the serial number it's like 20 years old, I think.

It is possible that the upstairs is in series though... look some more... it might be that the supply and return for each upstairs rad is piped down to the basement, and also tees into the same pipes that the downstairs do. It could also be set up with another pair of two pipes going upstairs, and around, and those rads tee'd in up there.
After looking at the pipes in the basement, I noticed that where the pipes branch off to supply the first floor radiators there is a single pipe that branches off and goes up and I can't really see where it goes. There are 2 pipes one off the supply and one off of the return. That would still make it a parallel branch wouldn't it?

With a two pipe system, and functioning shut off valves on each radiator (don't force them! ) if you have a 'problem' radiator that seems to have an air blockage, you can increase the flow through the problem unit by closing the valves on some/all of the other radiators. This might help to move that air out... but this brings up another point.
Don't worry about me forcing the valves; the only one that even budges is the one that was mistakenly closed. That one seems like it was replaced because it looks new, but the others won't move at all.

If the ceiling in the garage is exposed, explore having it spray foamed... that stuff also acts as a vapor and infiltration barrier. (for a few hundred bucks, there are also DIY kits available, but know that BIG mistakes can be made, so if you decide to DIY with spray foam, do your homework!)
I've read a lot about the spray foam and it sounds great. I've also checked into the DIY kits and they seem to be more of a headache than what they are worth. Usually the complaints are that the yield is low, expansion rate is not the same as what people see on the internet and problems with clogged nozzles. I think the DIY kits cannot be compared to a commercial system and people that actually do that stuff for a living. It's approximately a 15'x20' area, so I think it would take more than 1 kit if I want to get a decent R-value. I think it would probably be more expensive for me to do it.

You noticed that, eh?
Yup.

If you do go with the infrared, pick up a small can of flat black paint. If you first paint all the points you intend to measure, you will get the best accuracy. Those thermometers are terribly inaccurate on copper pipe. Rusty old cast iron, reasonably accurate... anything shiny, not accurate. Flat black paint, about as good as yer gonna get (not perfect, but good) Google "EMISSIVITY" for more info on this.
I will work on getting the thermometer and the paint. I actually have flat black paint that is used on grills. Is that any good?

I think your pump a stat is the lesser of two evils. If you've done the experiments, and are happy with the settings, then leave it be. If you use some 'heat sink compound' between the pipe and the bulb, and INSULATE the bulb and pipe at least a foot in each direction, you will get better performance of the stat... but don't expect pinpoint precision on the dial calibration in any event.
If you notice on one of the pictures the astat is mounted on the supply line off of the boiler. I tried to mount it on a couple of different places like on one of the return lines, but it took too long for the system to get hot enough to keep the circulator on. I figured I would place it on the supply line and I would set it to trip just before the boiler got to hi limit and it would help get warmer water through the system until eventually it would stay on longer. If you have a better way please let me know. I just tried to do the best I could with what I had.

Pete
 
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Old 02-21-10, 03:50 PM
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It is an H.B. Smith Series-8.
That's what the widder lady next door is running. Still burning oil though... I've cleaned it a few times for her, and it's not so easy to do with that boiler.

What's with the duct tape on the gas burner? That don't look right.

I am not sure about this, because I have zero experience with gas burner conversions, but I have to wonder if the baro damper maybe should have been replaced with an atmospheric hood... or maybe not, since the gas burner is pressure fired... anybody know?

That would still make it a parallel branch wouldn't it?
I would think so... but who knows when they get upstairs? With a supply up and a return down, they could still be in series, but I kinda doubt it. They probably would have followed suit.

I actually have flat black paint that is used on grills. Is that any good?
Yes, that's fine. Even black electrical tape, or duct tape will work... but the paint is probably better. If you paint every spot you intend to measure the same, you will get good 'relative' readings... absolute accuracy may not be top notch, but at least from point to point you will be comparing apples.

I just tried to do the best I could with what I had.
Looks fine... if it's insulated it might be more accurate, but if it's working as intended, then I wouldn't worry about it.

Ultimately though, a bypass would be the way to go...
 
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Old 02-21-10, 06:35 PM
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What's with the duct tape on the gas burner? That don't look right.
The guy that came in to clean the boiler had the same question, but when he performed an efficiency test or something like that, he decided that it was working fine and whoever put it there had there reasons so he decided to leave it alone. He said he has never seen anything like that before, but it was working fine so I didn't worry about it.

Ultimately though, a bypass would be the way to go...
Yes, that's what I was going to try and do, but a friend of a family member sold me a Smith Boiler, model GV100 at a very good price, which I would like to get installed in the spring or summer. I am trying to keep the old system running as good as possible, but ultimately if I have to invest money into a boiler that was really made to work with oil and has issues like no valves, no bypass and old inefficient burner then why not just start from scratch on a new boiler and try to do it right the first time. Besides the person that inspected the chimney said that when they converted the boiler to gas they did not line the chimney and the gas was taken it's toll, so I would have to get it lined anyway and that's 2 investments on an old system. The new boiler is a power vented unit, so that gets me around lining the chimney, which is very expensive and all I have to do is get someone to vent it. I would love to install the boiler myself, the challenge is very tempting.

Pete
 
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Old 02-23-10, 05:08 AM
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Trooper

After looking at the pictures do you think I can try the procedure you described for emptying the expansion tank?
 
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Old 02-23-10, 03:34 PM
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First let's make sure that it's needed...

If the tank is waterlogged, you will see large pressure swing from cold to hot. If the tank is OK, you probably wouldn't see more than 8-10 psi increase from C to H ... cold should be around 12 PSI or so. So first determine if you really need to drain the tank.

If you do need/want to drain, a few pointers will be helpful.

First, the valve... before you try to close that valve, take some fine emery paper, or a wire brush, or steel wool and clean the STEM... get all that gunk off there, because if you close the valve with that stuff on the stem, it may damage the 'packing' material that seals the stem.

That valve is a 'gate valve', and when you close it, you don't want to 'muscle' it closed. If you do, you may end up wedging the gate into the slot and not get it open again... so snug it reasonably tight, but not power tight.

Of course, before you do anything, you want to shut the boiler off, and maybe let it cool a bit before you start.

Hook a hose to the drain valve. Remember that AIR needs to travel up the hose to displace the water that is being drained. If you use a long hose, all looped and rolled around on the floor, the air won't get to the tank. In other words, the hose should only be long enough to reach the bucket, or floor drain, or laundry tub... and don't submerge the end of the hose in the bucket when you drain either, again, air needs to go up.

Even with all this about the hose, the tank will probably STILL get 'suction locked', just like when you put your finger over the end of a drinking straw and lift it from the drink... drink stays in the straw. You will need to break that vacuum that develops in the tank. If you have a small air compressor, you can blow that up the hose... or if you have good lungs and are not afraid of dirty nasty boiler water in your face, you can blow into the end of the hose... sometimes by loosening the hose at the drain fitting the tank will take a 'gulp' of air... but whatever you need to do to get ALL the water out of the tank is what you need to do. (of course, not every last drop, but enough that you know the tank is at atmospheric pressure.)

Close the drain, open the gate valve and the tank will refill under pressure from the boiler to about half way... that's normal. Check that the boiler has returned to 12-15 PSI and fire it up.
 
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Old 02-23-10, 04:01 PM
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The lowest temperature I get before the t'stat calls for heat is about 100 deg @ around a little above 10psi, if you trust the gauge, which I know you don't.
 
 

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