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    knightpitt's Avatar
    knightpitt Posts: 17, Reputation: 1
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    #1

    Oct 27, 2005, 10:07 AM
    Bleeding radiators -> high pressure in furnace
    Hey Everyone (and Tom!)

    Okay, new house to my wife and I... we've had it less than a month and two days ago it was time to turn the heat on. This is an old hot water system, no pump (works by gravity) in a three story house.

    The radiator in the master bathroom wasn't full, so I tried to bleed it. Just a little air came out, and it didn't fill. The bottom half of the radiator was warm so the radiator shutoff isn't stuck closed. Off to the basement I went. The auto-refill on the system comes from the main water line, is "stepped down" to 12psi through a reducer and then has a 30psi relief valve going directly to a drain. I have two boilers run in parallel (one coal - unused, one gas), and each has an "Altitude" gauge on it with no units listed (is it psi or 'feet' of water?). They both have red needles set at "25", and had black needles (the actual measuring ones, and neither are stuck) reading at "25" on the gas and "20" on the coal. These things are 75 years old or so, so I don't expect them to be 100% accurate.

    Anyhow, I pulled a little handle on the 12 psi "step down", hoping that it would help me auto-refill (I have no idea if the handle is lets the water pressure get to 12 psi or if it bypasses the 12psi and lets the full "line" water pressure through). My wife sat upstairs bleeding the radiator. Pressure gauges on the boilers go up, 2nd floor radiator is bled. Yay.

    On to the 3rd floor. All of these radiators are almost empty. They all have brand new valves on them, so I guess they were drained for the valve installation. Unfortunately, the guy who owned the place before us passed away, so I couldn't even ask him. So, same thing as before, I pull the handle on the pressure reducer, wife bleeds the radiators. Well, this time I stop early and say "uncle". The altitude gauges on the boilers read "32" and "27", and I decide to call it a night before I screw something up.

    I know that it should only take about 15psi to fill up the water system (guess that the top of the topmost radiator is 35' (max) above the pressure gauges... 35'/(28"/psi)-> 15psi). Sooo... what's going on? Are my "altitude" gauges on my boilers measuring "vertical feet of water" or psi? Am in endangering my system/boilers by pulling that handle on the pressure step down in an attempt to fill my radiators?

    Actually, I guess the real question is: These " or psi? Am in endangering my system/boilers by pulling that handle on the pressure step down in an attempt to fill my radiators?

    Actually, I guess the real question is: These " gauges have no units listed on them. Is it normal for these gauges to measure "height of water column" or is it typically psi?

    Thanks in advance!!
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
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    #2

    Oct 27, 2005, 03:29 PM
    Your asking a Florida boy about a heating problem? Down here we heat with reverse air or electric strips. Labman, Rick, Fred or one of those other "Yankees" will have to field this one. How about it guys
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #3

    Oct 27, 2005, 03:58 PM
    Dud, that's right. There is a good reason why you don't help much in the heating area. Sorry.
    star393's Avatar
    star393 Posts: 12, Reputation: 1
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    #4

    Oct 27, 2005, 05:15 PM
    Just maybe
    Hopefully somewere in a closet in the top of the house is a exspanion tank to help bleed out the air or a bleed vent there must be a bleed vent at the top of the system look for it 15 20 psi shoild be enough to reach 30 feet my house is 25 feet low pressure hot water also so I have some exp. With low pressure hot water, you say no pump on your system so that means you have a newer old low pressure steam system in the boiler there is a chamber that creates steam pressure low pressure that is used to push the water nice thing about that is when the power goes out you still have heat who's the boiler made by sears?? It needs all the ait out, look for bleeder at the top of the highest part of system or expansion tank. That handle on the 12psi valve is for letting in city pressure bypassing the 12 psi couldbe 50 60 psi it will blow the 30 psi valve is overfilled , no biggee just let the pressure out until its back down to 15 psi. you can bring the pressure up if you like to do the air bleeding but return it to 15 psi or by a few pounds. The gauge reads psi related to the height of the column of water and what it takes in pressure to reach that height in psi be aware when the system is heated up pressure will rise by itself to maybe 25 psi cold it will be 15 psi that's OK. This is why you want to start at 15 psi pressure can build to 30 psi and at that point the 30psi pressure relief will open if it doesn't the expansion tank will blow that's the reason it's there to protect the exspansion tank and piping make sure it works. Some systems have a small expansion tank with a diaphram above the tank built in with a tire valve at the top (newer part) and or can be added on anywere you fill it at the top with a tire pump to a pressure level and leave it. See if you have a expansion tank somewere. Expanison tanks older ones have a special valve on it and a valve to close it from the system you close the tank off and then drain out the water that's in the tank from the bottom and close that valve and then open the outer valve again and the air in the tank allows for water expansion as the system gets hot every year before heating season you should do this. There will be a small screw with a tag that you must remove to let air in while draining water out.

    Hope this helps Douglas
    knightpitt's Avatar
    knightpitt Posts: 17, Reputation: 1
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    #5

    Oct 28, 2005, 04:50 AM
    Quote Originally Posted by star393
    hopefully somewere in a closet in the top of the house is a exspanion tank to help bleed out the air or a bleed vent there must be a bleed vent at the top of the system look for it
    Actually the only expansion tank is just above the boiler in the basement.

    Quote Originally Posted by star393
    15 20 psi shoild be enough to reach 30 feet my house is 25 feet low pressure hot water also so I have some exp. With low pressure hot water, you say no pump on your system so that means you have a newer old low pressure steam system in the boiler there is a chamber that creates steam pressure low pressure that is used to push the water nice thing about that is when the power goes out you still have heat who's the boiler made by sears?? It needs all the ait out, look for bleeder at the top of the highest part of system or expansion tank.
    It's a dinosaur of a hot water system. I don't recall the boiler manufacturer's name now, but it's not Sears. This thing is low-tech. I wish that I'd have heat if the power went out, but my sincere bet is that the gas cutoff switch (it's actuated by the temperature of the pipes coming out of the boiler) will "fail safe", meaning that if power is disconnected to it, it'll cut the gas. Hopefully I never get into a situation where I'm thinking about how to bypass it. :)

    Quote Originally Posted by star393
    That handle on the 12psi valve is for letting in city pressure bypassing the 12 psi couldbe 50 60 psi it will blow the 30 psi valve is overfilled , no biggee just let the pressure out until its back down to 15 psi. you can bring the pressure up if you like to do the air bleeding but return it to 15 psi or by a few pounds. The gauge reads psi related to the height of the column of water and what it takes in pressure to reach that height in psi be aware when the system is heated up pressure will rise by itself to maybe 25 psi cold it will be 15 psi that's OK. This is why you want to start at 15 psi pressure can build to 30 psi and at that point the 30psi pressure relief will open if it doesn't the expansion tank will blow that's the reason it's there to protect the exspansion tank and piping make sure it works.
    This is great information to know!! I bought a pressure test-type gauge yesterday from my local plumber's supply store and hooked it to the boiler drain just to see what the pressure actually was. It was reading around 13-14 psi, which is a good thing. With another little bit of pressure, I'll be able to fill my 3rd floor radiators, so I'll pull that handle just slightly to get more pressure and fill up those 3rd floor radiators.

    Hope this helps Douglas
    Absolutely! Thanks for the info!! :)
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #6

    Oct 28, 2005, 06:32 AM
    Quote Originally Posted by knightpitt
    snip....

    It's a dinosaur of a hot water system. I don't recall the boiler manufacturer's name now, but it's not Sears. This thing is low-tech. I wish that I'd have heat if the power went out, but my sincere bet is that the gas cutoff switch (it's actuated by the temperature of the pipes coming out of the boiler) will "fail safe", meaning that if power is disconnected to it, it'll cut the gas. Hopefully I never get into a situation where I'm thinking about how to bypass it. :)


    snip....
    Power? Does the system use electricity at all? Usually the gas shut off safety is self contained, shutting the gas off if the pilot goes out.
    star393's Avatar
    star393 Posts: 12, Reputation: 1
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    #7

    Oct 28, 2005, 06:35 AM
    Quote Originally Posted by knightpitt
    Actually the only expansion tank is just above the boiler in the basement.


    It's a dinosaur of a hot water system. I don't recall the boiler manufacturer's name now, but it's not Sears. This thing is low-tech. I wish that I'd have heat if the power went out, but my sincere bet is that the gas cutoff switch (it's actuated by the temperature of the pipes coming out of the boiler) will "fail safe", meaning that if power is disconnected to it, it'll cut the gas. Hopefully I never get into a situation where I'm thinking about how to bypass it. :)


    This is great information to know!!! I bought a pressure test-type gauge yesterday from my local plumber's supply store and hooked it to the boiler drain just to see what the pressure actually was. It was reading around 13-14 psi, which is a good thing. With another little bit of pressure, I'll be able to fill my 3rd floor radiators, so I'll pull that handle just slightly to get more pressure and fill up those 3rd floor radiators.



    Absolutely! Thanks for the info!!! :)
    Them old systems work just fine better then the new ones that's why its still there! The 12 psi valve has a adjustment under the lever or at the bottom it increase the pressure slightly if needed. The cutoff switch is normal and will only turn off the gas when to hot there maybe a manual knob on gas valve itself if it hasn't already been changed and say manual mode on it that is what you turn when the electric goes out . Depending on your winter and building insulation setting the main burner temp cut out to about 170 or 190 if needed that works in conjunction with your expansion tank if its full of water with no air the pressure will rise above 25 psi when the tank is half full of air the temp will be 190 and psi will be stable. Gravity doesn't move the water, pressure does so you must have that low pressure steam pump built into the boiler. Make sure that the filter on the cold water inlet side is always clean the system relies on that to keep it full when it gets dirty and plugs up and no water inlet the system will not work and people become prey to the salemen for a new boiler all because of the filter. If you ever have problems with the pilot light getting sucked off by the updraft and has to be relited then install a relite ign. Kit from granger or others easy to intall like a spark plug will relite the pilot automaticlly if it goes out within 15 seconds of safety turning off,also keep a extra thermo coupler on hand for hot water tank and boiler you'll be glad you did at midnight.
    Douglas

    PS coal hu man now that's old a dying art to run that baby someday you'll be glad you have that , burn all your advertizments junk and get free heat ha ha .
    knightpitt's Avatar
    knightpitt Posts: 17, Reputation: 1
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    #8

    Oct 28, 2005, 07:59 AM
    Quote Originally Posted by labman
    Power? Does the system use electricity at all? Usually the gas shut off safety is self contained, shutting the gas off if the pilot goes out.
    There is some sort of power connection between the temperature gauge on the pipe (set to 180 by the way) and the gas shutoff for the boiler. In fact, there's a transformer/rectifier to take the 120VAC down to 20VDC, and I guess that 20VDC is what runs the shutoff. I am guess in that when electricity goes off, the 20V will go away and the gas valve will close as a safety precaution. I'm not positive about that, however. I've just been looking at the hydraulic stuff thus far. ;)
    knightpitt's Avatar
    knightpitt Posts: 17, Reputation: 1
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    #9

    Oct 28, 2005, 08:10 AM
    Quote Originally Posted by star393
    Them old systems work just fine better then the new ones thats why its still there! the 12 psi valve has a adjustment under the lever or at the bottom it increase the pressure slightly if needed. The cutoff switch is normal and will only turn off the gas when to hot there maybe a manual knob on gas valve itself if it hasnt already been changed and say manual mode on it that is what you turn when the electric goes out .
    I'll have to see if there is a manual knob on there. I checked last night on the electric cutoff on temperature, and when I turned the temperature down low enough, the gas to the main burners cut off, which is what I expected.

    Quote Originally Posted by star393
    depending on your winter and building insulation setting the main burner temp cut out to about 170 or 190 if needed that works in conjunction with your expansion tank if its full of water with no air the pressure will rise above 25 psi when the tank is half full of air the temp will be 190 and psi will be stable.
    The pressure does go up somewhat considerably (maybe from 15 to 20 psi), and the temperature only got to maybe 140 or so. Is this a sign, then, that I should drain the expansion tank?

    Quote Originally Posted by star393
    gravity doesnt move the water, pressure does so you must have that low pressure steam pump built into the boiler. Make sure that the filter on the cold water inlet side is alway clean the system relies on that to keep it full when it gets dirty and plugs up and no water inlet the system will not work and people become prey to the salemen for a new boiler all because of the filter.
    I have no idea about the internals of the boiler. I looked in there once and saw lots of asbestos and thought to myself, "I really hope nothing breaks in there." :) My home inspector told me that it was "gravity", I believe, but I could be wrong about that. The 2 hot water supplies are on top of the boiler, and the two cold water returns are on the bottom, if that makes any difference.

    Quote Originally Posted by star393
    If you ever have problems with the pilot light getting sucked off by the updraft and has to be relited then install a relite ign. kit from granger or others easy to intall like a spark plug will relite the pilot automaticlly if it goes out within 15 seconds of saftey turning off,also keep a extra thermo coupler on hand for hot water tank and boiler youll be glad you did at midnight.
    Douglas
    Thanks Douglas, I've been lucky enough that the pilot has stayed on thus far. I'll have to look into thermocouples for the boiler as well!

    Quote Originally Posted by star393
    PS coal hu man now thats old a dying art to run that baby someday youll be glad you have that , burn all your advertizments junk and get free heat ha ha .
    I know... I've been looking forward to trying out burning some stuff in there, but I've been worried that the flu/chimney may be blocked (I don't know if it is or not)... that's something that I may be saving for next winter -- I have a lot of projects on the house already
    ;) :D
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #10

    Oct 28, 2005, 09:42 AM
    I have a book, specifically the Readers' Digest Complete Do It Yourself Manual (C) 1973. It says there were systems using gravity to circulate hot water. Likely over the years there were all sorts of systems, some of which, few of us here have seen. I seldom do any research to answer questions here. There are more questions I can help with without it, than I should spend time answering.

    From the book, ''water leaves the boiler usually about 180 degrees, the return temperature is about 140... The closed gravity system has an expansion tank installed near the boiler. The tank has no overflow pipe, but is completely air tight. When the water expands, it compresses the air in the tank and puts the water in the system under pressure, making it possible to maintain a higher water temperature. There is a limit to how much pressure the system can sustain; a relief valve in the supply line will relieve excess pressure should the need arise.'' Something like present auto radiators.

    It says nothing about any electrical components.

    This thread has brought up some past memories. 30 years ago I was managing a small vinyl compounding plant. We had vertical tanks we stored the liquid materials in including di octyl phthalate. They had leaky old sight glasses. I could have chosen to repair the sight glasses. Instead I fitted them with precision pressure pressure gages, 0-10 psi. Psi. times the cross section gave me a direct reading in the pounds we bought and used the material in. The sight glasses gave gallons needing lbs/gal corrections which varied for the different materials, plus were distorted by temperature changes.

    It also brings back Rheem hydronic water heat commercials from the early days of TV. Hydronic refers to new at that time technology using a pump to circulate the water.
    star393's Avatar
    star393 Posts: 12, Reputation: 1
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    #11

    Oct 28, 2005, 09:52 AM
    $$$ in heat out
    Also check with your gas company they may supply a service that checks the flue temp and give you a perspective on how well your old boiler is doing 80 % isn't to bad .
    knightpitt's Avatar
    knightpitt Posts: 17, Reputation: 1
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    #12

    Oct 28, 2005, 12:07 PM
    Quote Originally Posted by labman
    I have a book, specifically the Readers' Digest Complete Do It Yourself Manual (C) 1973. It says there were systems using gravity to circulate hot water. I seldom do any research to answer questions here. There are more questions I can help with without it, than I should spend time answering.

    From the book, ''water leaves the boiler usually about 180 degrees, the return temperature is about 140.... The closed gravity system has an expansion tank installed near the boiler. The tank has no overflow pipe, but is completely air tight. When the water expands, it compresses the air in the tank and puts the water in the system under pressure, making it possible to maintain a higher water temperature. There is a limit to how much pressure the system can sustain; a relief valve in the supply line will relieve excess pressure should the need arise.'' Something like present auto radiators.

    It says nothing about any electrical components.
    That sounds just about right... pretty accurate description of the system. The only electrical component that I can determine is the gas cutoff, which isn't a direct thermocouple... it looks to be a later add on (and a bit of a hack job at that) to cut the gas to the boiler if the outgoing temperature was too high. Perhaps there was initially a mechanical system to do this.. hmmm...

    Quote Originally Posted by labman
    This thread has brought up some past memories. 30 years ago I was managing a small vinyl compounding plant. We had vertical tanks we stored the liquid materials in including di octyl phthalate. They had leaky old sight glasses. I could have chosen to repair the sight glasses. Instead I fitted them with precision pressure pressure gages, 0-10 psi. Psi. times the cross section gave me a direct reading in the pounds we bought and used the material in. The sight glasses gave gallons needing lbs/gal corrections which varied for the different materials, plus were distorted by temperature changes.

    It also brings back Rheem hydronic water heat commercials from the early days of TV. Hydronic refers to new at that time technology using a pump to circulate the water.
    Wow... those are some memories... "the early days of TV"... and you were managing a vinyl compounding plant 30 years ago. Just to put this in perspective, my parents were newlyweds 30 years ago. :) I give you much, much respect for you being willing to come online and spend time out of your day sharing your wisdom and experience with so many people, helping them dianose and fix their house problems. Know that it is very much appreciated. My hat's off to you, sir! :)
    star393's Avatar
    star393 Posts: 12, Reputation: 1
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    #13

    Oct 28, 2005, 07:56 PM
    Early Days of TV
    You mean when radio was going strong and the TV was a round tube with a magnifier in front of it . More like 40 years ago ha ha only the shadow knowssssssssssssssssssssssssssssss

    Douglas

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