bleeding radiators

i start from the top floor working my way down to the second. 3 out of 5 upstairs are really hot but i get neither air or water from them. other 2 are luke warm - get some air but when air stops i get no water.
moving to main floor i get air from all 3 and are working fine. when the air stops i should get water flow from the valve(?). any ideas on this?
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On 1 Jan 2005 17:55:32 -0800, snipped-for-privacy@nf.sympatico.ca wrote:

Yes, You're doing it all wrong and you havent a clue. Call in a professional before you freeze to death. Bubba
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You probably don't have enough pressure in your boiler. Check your pressure gauge to see how much you have. Every pound of pressure is equal to 2.31 feet. So if your highest radiators are 30 feet above the boiler then you would need at least 13 pounds of pressure at the boiler just to raise the water that high. ----- Original Message -----
Newsgroups: alt.home.repair Sent: Saturday, January 01, 2005 8:55 PM Subject: bleeding radiators

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wrote:

While I agree with the above, I would add a couple points:
1. It is always a good idea to have a little extra pressure, so I recommend measuring the height of the system and dividing by 2. For a 30 foot system, I recommend setting the minimum pressure at 15 psi.
2. When the boiler is heating, the water expands, increasing the pressure. This extra pressure from expansion must be removed before measuring and adjusting the pressure. This can be accomplished by turning off the boiler and pump, then draining off water from the boiler until cold fill water starts feeding into the system. Close the boiler drain and wait. When the water stops feeding into the system, this is your minimum pressure.
Adjust if needed, then turn everything back on and bleed the system starting at the top.
If you do it right, you will probably never have to bleed the system again.
_______________
Gary R. Lloyd CMS HVACR Troubleshooting Books/Software Written by a veteran Service Technician
https://www.merchantamerica.com/tmethod /
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On Sun, 02 Jan 2005 12:50:27 GMT, snipped-for-privacy@gatecom.com (Gary R. Lloyd) wrote:

Why does the pressure increase and water expand if you have a properly opreating expansion tank?

Bleed the system starting at the top???????? Nope. Never

In theory, maybe, but not in the real world. Maybe we are on 2 different "pages" here? Fill me in..... Bubba

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wrote:

Water always expands when heated. That's just basic physics.
Without the expansion tank, the pressure would rise very rapidly because water cannot be compressed. With the expansion tank, the expanded water pushes up into the tank, compressing the air.
The pressure of both the water and the air are increased as a result of that compression. How much the pressure increases depends upon the amount of expansion and the size of the tank. There is always some increase in pressure.

Why not?

Generally there is some sort of automatic vent for the very tiny amount of air entering the system with the fill water. Usually, if a system needs repeat bleeding it is because there is insufficient fill pressure, resulting in a vacuum at the top of the system whenever the boiler is cold.
Note: When the water is pumped into the boiler rather than away from the boiler, there may (or may not) be a vacuum at the suction side of the pump, in which case additional fill pressure may be needed.
_______________
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https://www.merchantamerica.com/tmethod /
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On Sun, 02 Jan 2005 14:37:28 GMT, snipped-for-privacy@gatecom.com (Gary R. Lloyd) wrote:

Although, in theory, I would say there is an increase in pressure, again I am applying this to the everyday world and the everyday residential boiler. I do a lot of boilers and repairs. The boiler pressure gauge rarely moves during burner operation unless the expansion tank is water logged.

Why not, you ask? Im guessing you are just playin with me but I'll bite. My answer would be because if I start purging a system of air from the 2nd or 3rd floor and then work my way down to the first floor or even the basement, I am almost guaranteed that I will still have air in a 2nd or 3rd floor radiator. Im assuming you know that air is lighter than water :-) and that the air will make its way to the top floors while the water is constantly trying to settle down lower due to gravity? Now, although I like your thinking about purging air from the top down, I DONT believe my customers would like me to repeatedly purge the air from the system incorrectly at $150 hr! I would believe that they would like me to do it correctly and quickly the first time.

and many times there is not an auto vent. Hell, I even see tons of systems where someone was too stupid, too lazy or too cheap to install valves on both sides of the circulator, fill valve and boiler! Those valves save tremendous amounts of time and money in future repairs. Bubba

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wrote:

The largest increase in pressure would be in going from a cold boiler to full temperature. Once it is up to temperature, the normal operation will cause little movement in pressure because there is little movement in temperature and the pressure is already elevated. It is when the boiler is off for an extended period that air is most likely to enter the system as a result of insufficient cold fill pressure. In any case, expansion pressure needs to be removed in order to get the fill pressure right.

Okay, I'll buy that, based on your experience. I have not worked on any residential systems for several decades, and don't recall ever working on a residential boiler. Commercial boilers have such things as automatic vents at the tops of the risers. I have always vented from the top down without having any problems, but I accept that residential systems are not the same.

_______________
Gary R. Lloyd CMS HVACR Troubleshooting Books/Software Written by a veteran Service Technician
https://www.merchantamerica.com/tmethod /
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On Sun, 02 Jan 2005 18:28:10 GMT, snipped-for-privacy@gatecom.com (Gary R. Lloyd) wrote:

Damn Gary, you were starting to scare me there. :-) I thought you and I might be living on 2 different poles of the earth.........you know, like South America where the toilet water flushes down the bowl in the opposite direction as here in North America. I understand where your coming from. With bigger commercial boilers and piping, a little air isnt a huge problem. In residential though, a bubble of air 1/2" in diameter is enough to stop a radiator (baseboard) from heating. Bubba

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You call those baseboard heaters radiators too? I've been picturing the cast iron monsters that I have here. Also, do you use a single riser for multiple radiators? On different floors even? Ewwwww... Every radiator in my home has it's own riser ( 1" black iron pipe ).
--
"De inimico non loquaris sed cogites."

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Baseboard radiation. There, that better? Yes, single riser works bestes" , but Ive seen em all. Bubba
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Ummmm.... isn't that what the circulating pumps are for?

I imagine you're bleeding while the circulating pumps are not running. Try it when they are.
Since air moves upward, you should bleed the *lowest* radiators first. If you start at the top, you may have to go back and bleed the upper ones again after the air lower in the system finds its way up to the top.
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On Sun, 02 Jan 2005 14:19:15 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Nope, they are for circulating water in a full system. The pressure is increased on the discharge side and decreased on the suction side. At the midpoint of each loop, the effects cancel each other out.
And, if the pump suction is in a vacuum, it will suck air past the seal. It is also in danger of cavitating, which can destroy the pump.
_______________
Gary R. Lloyd CMS HVACR Troubleshooting Books/Software Written by a veteran Service Technician
https://www.merchantamerica.com/tmethod /
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it was the circulator pump. thanks for the help. it was covered under my furnace maintainance warrenty.
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Hi Doug, hope you are having a nice day
On 02-Jan-05 At About 09:19:15, Doug Miller wrote to All Subject: Re: Bleeding radiators
DM> From: snipped-for-privacy@milmac.com (Doug Miller)
DM> in your boiler. Check your pressure >gauge to see how much you have. DM> Every pound of pressure is equal to 2.31 >feet. So if your highest DM> radiators are 30 feet above the boiler then you DM> > would need at least 13 pounds of pressure at the boiler just to DM> raise the > water that high.
DM> Ummmm.... isn't that what the circulating pumps are for?
Nope, "circulators" are for "circulating" the water. they aren't designed to act as lift pumps.
-=> HvacTech2 <=-
.. "Hermits have no peer pressure." - s.w.
___ TagDude 0.92+[DM] +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ spam protection measure, Please remove the 33 to send e-mail
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If your radiators are bleeding, there is most likely a dead body under them. Call the police immediately and report a murder in your home. You will want those bodies removed quickly or the smell will drive you out.
wrote:

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snipped-for-privacy@bannet.net wrote:

under
you
radiators are bled from the inside using the valve. your attempt at humor leads me to beleive your momma dropped you on the floor as an infant.

pressure
2.31
you
raise the

out of

them.
water.
when
on
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