No water pressure in one zone

Hello all,
I have a Dunkirk boiler that I installed in the mid 90's. Everything has been fine up till last year. I had to replace the expansion tank and boiler fill valve. I have 3 loops. One is for the sidearm hot water heater. One is for the first floor. The last is for the second floor. Each loop has it's own circulator. First floor loop has all the mechanics, fill valve, pressure relief, expansion tank and such. The second floor loop has a air vent at the high point.
After the work last year I had air in the system on the second floor loop. This year the air is still there. Mainly can hear it when the circulator first comes on.
My main concern is I change the air vent earlier this year and there was no pressure when I took the old vent off. In the past there has been water skirting out when I had to replace this. The new one is a maidomist valve. I can press on the Schrader valve when the is on and air and or water will skirt out. But when the circulator is off the is no pressure on the loop. The boiler is holding 12 to 14 lbs of pressure. There is another gauge on the first floor loop and that is also holding at 12 to 14 lbs.
Anyone know why there is no pressure on the second floor.
I plan on putting a boiler drain on the second floor loop so I can purge that line better.
Thank you for any help.
ljc2tall

 

Welcome to the forums.

I'm not the boiler pro but what I've done to purge an upper floor system is to shut the other zones off and raise the boiler pressure up to 20-25 psi to help get the water to the second floor.
After I get the air out I let water back out of the boiler.

The other guys will stop by an add their opinions to the mix.

 

Never install automatic air vents out in the system, replace with a manual air vent. Automatic vents can admit air when system pressure drops.
The zone pump should be enough to move air in the system to the air separator.

Is this what you did.
Close automatic air vents, or they get plugged up.
Fill system -- all pumps OFF.
Open automatic air vent on boiler/ air separator.
Isolate system from water supply.
Monitor for pressure loss.

Without pictures etc I can only guess, but: See Drawing 2C [Page 22 of PDF] For correct component placement.
All pumps should be on the supply side and pumping out into the system.
Expansion tank, reducing valve, air separator, all located on the suction side of pumps.
Air separator must be located in the primary system flow.

 

I wonder if your pressure gauge is accurate. There's a sticky at the top about checking your gauge. Also, did you check the air charge in the new expansion tank when you replaced it? Good luck, Steve

 

Thank you for your responses. A little background on the system. Back in 1988 when I installed the system, it was an electric thermal system (OPUS). It came with all the piping and plumbing fixtures all put together. All I had to do was connect one end to the water tank and the other to the household baseboard heat. About 7 years later I replaced the water tank with a boiler. Everything was fine up till last year when I replaced the fill valve and expansion tank.
I never had problems with the automatic vent before. Actually had a plumber tell me to put one in back in 1988, to get rid of air in the second floor loop.
I believe that air is going back in the system from the automatic vent from the fact that there is no pressure in the line when the system is not circulating. I will close that vent off to see if it helps.
As I stated before I have 2 pressure gauges in the system (came pre-plumbed that way) one in the piping and one on the boiler. They both read the same , so I don't think the gauges are off.
I am just curious as to why there would be no pressure on the second story loop when there is pressure on the first floor loop.

 

Because:
CounterPoint How Hydronic System Components Really Work [pdf]
[page 7, pdf] Water has weight!

And if you pump into the point of no pressure change the pressure out in the system drops.
[page 33, pdf] The Point of No Pressure Change.

 

very interesting read, thank you for that info. I will have to make sure everything is in it's proper order.

 

In the pdf you supplied it stated that the water supply should be turned off once the system pressure has been established.
So I turned off the supply valve today with 12 to 14 #'s of pressure in the system. The pressure remained the same all day. Thermostat called for heat later in the day. As the temperature rose the pressure rose to 24#'s. Out of curiosity I opened the supply valve and the pressure dropped immediately to 19#'s.

 

At this point pictures of the system and what that valve is connected to would help.

 

Appears to be a lot of conflicting information out there. The pdf that I just read on here says the fill valve should be turned off after pressure is reached. The info on the taco fill valve I installed last year says it must be open all the time.
Other info has the air scoop in one place and the next info puts in another place. Same with circulator positions.

All I know is that my system worked fine until last year. Now I have air in the lines and can't seem to get rid of it.
Ground hog says we are going to have an early spring. So I may live with it for now and dig further into this spring.

 

What is confusing?
Did I post something confusing?

Air scoop is not a synonym for air separator, this is a Taco Inc AIR SCOOP [pdf] See Diagram on far right for proper installation of scoop. Inlet:18" minimum of straight pipe, full size of port, flow velocity should be 4 ft/sec. or less, and should see all of the system flow.

 

I said conflicting, I did not say confusing. I did not state you said anything confusing.

 

Conflicting information about what exactly?

 

You have provided some good information. And I thank you for that. This is the conflicting information as I posted earlier

"Appears to be a lot of conflicting information out there. The pdf that I just read on here says the fill valve should be turned off after pressure is reached. The info on the taco fill valve I installed last year says it must be open all the time."

 

hi guys –

I’m not an expert, just know what I picked up on this forum. From what I remember it seems like there is no consensus out there from the pros about whether make-up water should be always ON or always OFF. I think I remember one point: if you have a leak and the water is always ON the leak is masked. But if you have a leak and the water is always OFF the boiler can overheat, the pressure rise, etc. I think there are other points also.

If I remember correctly, NJT on of the real experts here, doesn’t come down one way or the other. I can’t remember what the other experts here think. I haven’t looked but there may be some old threads here addressing that issue - if you can find them. My make-up water is always OFF and I have to admit it makes me a little nervous so I usually check my boiler pressure several times a day.

 

In any closed heated hydro electric system with a leak the loss of water will cause a rise in temperature which will cause a corresponding rise in pressure. The leak needs to be fixed as it will only get worse but until then keep the water on.

 

David –

But I thought the problem with leaving the water always ON is that you won’t know you HAVE a leak that

For example if the leak is inside how would you know?

 

How long has Bell & Gossett been doing reducing valves, etc?

Training Manuals - Xylem Applied Water Systems

[page 6, pdf] Pressure-Reducing or “Feed” Valve
[page 11, pdf] Something you may not know...

CounterPoint How Hydronic System Components Really Work [pdf]
TECHNICAL BROCHURE FHD-501A

 

Taco's literature said leave it open.

 

Voice of experience -- Furd post #2 http://www.doityourself.com/forum/bo...ml#post2501714 or hurried manual author.