Section of Baseboard not Hot

[jtfoxman]

I have a gas furnace w/expansion tank and 1 zone. 1 hot water heat supply pipe goes to the downstairs and 1 goes to the upstairs. Both get returned and converge into a single line before returning to the furnace.

Here's my problem in the Master bedroom on the 2nd floor the baseboard is only getting lukewarm. The rest of the 2nd floor pipes are hot. There is a small container that sits at the highest point of the baseboard pipes with a red cap ( size of a valve stem cap) on top of it. I turn this cap and air escapes. So I am thinking this is some sort or air arrestor or bleeder.

Should I drain and flush the system to see if this fixes the problem or does anyone think there is something else wrong. If I do drain it, is a straight forward process. Turn of water supply and open up drain valve. Turn on water supply while keeping drain valve open to flush. There is some dark sediment that comes out when I open the pressure relief valve. Then turn of drain valve to close the system up again. What about my expansion tank?

Thanks for your help.

[jtfoxman]

Now none of the 2nd floor baseboards are hot. The downstairs work great. The supply line going upstairs is hot but once it gets into the baseboards on the 2nd floor they are still cold. I set the thermostat all the way up to 72 and let it warm up that much and still no heat upstairs.

There is an Airtrol valve at the highest point right before the line comes downstairs, also one on the 1st floor and 1 in the basement. I took the red caps off of them and a little air escaped. Do you have to do anything else to these to bleed them? I also bled my one radiator in my kitchen and that is working good.

I am at a loss here. I guess the kids will be sleeping downstairs tonight.

Thanks

[HayZee518]

OK I'm thinking that this is a circulating hot water system. You feed boiler water to a manifold system and the return lines are taco zones valves. or in some cases boiler water goes to the zones valves first and the returns are common coming back to the boiler. In either case there is a recirculating pump in the line. water when heated expands a little and forces some air out of the liquid. so you got this air bubble in a closed system thats supposed to go to the expansion tank and get trapped, but it is not - so there's air bleeders at the highest point in the system where the air gets trapped and acts sort of like a plug in the pipe. continuous liquid flow, flows, if it meets an air bubble the flow stops so the air must be removed to keep the liquid flowing. pump cavitation will create air bubbles. try bleeding out air until liquid flows then shut off.

[jtfoxman]

I am trying to do that but there are no bleeders anywhere on the baseboard. I even took the panels off and checked, nothing. There is an Airtrol on the upstairs baseboard. Is this a bleeder? How would you bleed this? I took the red cap off and some air came out but I am thinking something alse has to be done with this bleeder

[jtfoxman]

You are right about the pump (Taco) being on the return side of system. Both returns enter into the basement, 1 for 1st fl., 1for 2nd fl.,, both have seperate shut off valves at this point, after they enter the basement they are tee'd into 1 line and return to the boiler. Supply is the same, 1 line, but it tee's into 2 lines before they leave the basement, with a shut off valve for the first floor supply.

I drained the system by shutting the valve right above the pump off and opening the spigot valve above it, this was after I turned off the water line into the bolier. I then refilled the system by turning the water line back on and leaving it run until what i could tell all the air was out. I then opened the valve above the pump back on. Still not upstairs heat.

I have 1 airtrol fitting on each floor, for a total of 3, including 1 in the basement. Air came out of these when i took the red caps off. I am thinking these were to tight and caused air to be trapped in the 2nd fl. line, since it is the highest point. A little water and air spit out of the 1 on the 1st floor when I turned the heat back on. Could this mean there is air in the system? I do not know how to bleed these manually. Do I press the mechanism down under the red cap to manually release air, is this the correct way? Or is the another way to do it?

Thanks for your help!

[HayZee518]

I never worked with an airtrol valve. I suppose you could try bleeding air until a steady flow of water came out. as you bleed off this air/water add some more water via the fill valve at the boiler or you'll just be introducing more air in the system. Hey I had a sister that had a condo around you in pa. honeoy lake??

[LazyPup]

Ideally there should be no air in a hydronic heating loop with the singular exception of the air chamber in the expansion tank.

In the configuration described above you have one circulator pump supplying circulating hot water to two floors therefore the water from the pump has two alternate paths that it may follow.

Air, by its very nature will collect at the highest point in the system and restrict the flow of water past that point. The result is that the water will now take the path of least resistance through the pipe on the lower floor by increasing the velocity of flow through this pipe. The end result is the upper floor is now starved for energy while the water on the lower floor is flowing faster than it can release its heat energy into the living space, which further reduces energy efficiency on the system.

Whenever a circulating hydronic system is drained, obviously air will enter the lines, which then must be manually bled out to insure all circulating lines are full of water. There is also a small percentage of air encapsulated in the makeup water that is used to fill the system initially. As the water is initially heated the encapulated air is released and will also form bubbles in the system which will collect at the high point.

To prevent air pockets in the system each loop should have a manual bleed valve at a high point where you can manuallly bleed the air off until you get a fulll flow of water.

The proper procedure when filling the sytem is to begin at the boiler level and open the bleeder to release any air on that level, then move to the next higher level and repeat the air bleeding process until you have reached the top level.

The boiler should have an automatic make up water control that will allow additional water into the system as the air is bled out.

When a system has been drained and refilled it is usually necessary to repeat the bleeding process within a few days of operation to remove any additional air that was generated by thermally releasing the encapsulated air in the water. After the suspended air has been released there should be no further need to bleed the system because there is no other source of air in a closed loop.

[jtfoxman]

That's the problem I have. There are no bleeders on the system besides for the airtrol fittings. Last night I had the baseboards hot all the way to the last room on the 2nd floor, after I drained and refilled, then the boiler shut down. Do boilers shut down when the water hits a certain temp? The temp was about 180 and the pressure was around 20psi. It was running for a long time though. The whole time I was hearing air come from the airtrol on the second floor, then nothing.

There is also another section of pipe that branches out from the downstairs line to run to our kitchen radiators. I bled the air from them also. Even downstairs I can hear the water and air going through the pipes.

I don't believe the airtrol fittings do a good enough job of removing air. The air comes out very slowly. Which is good for little pockets or air bubbles but not for what I'm experiencing. Now I think if I had bleeders it would make it a whole lot easier.

I am going to try to drain and fill one more time tonight and then I'm done. I will have to call someone to come in to look at it on Monday. The weekend is not supposed to be that cold, 50's and mid 30's at night, and I do still have heat downstairs and a kerosene heater. Plus the kids are at there grandmother's house.

Thanks for your help. I'm pretty good with the plumbing part but I am not that experienced in the heating department..... besides for bleeding radiators and installing thermostats.

HayZee, where is that lake located? I'm in the NE corner of PA in the Poconos. I'm a big fishermen and never heard of it. Is there actually a lake or is the town just called that?

[jtfoxman]

Well the plumber just left and he will be back to make the repairs. He said the water is having a hard time reaching up to the second story with the circulator pump on the return line, so he is going to switch it to the supply line. Makes sense but I am not sure. He is also going to install a bleeder in the upstairs bedroom right before the line returns to the basement since there is a lot of air in the system and there should be a few bleeders throughout the house.

What does everyone think?

I am also getting an estimate to make it in to a 2 zone system, which I have wanted but never did.

[HayZee518]

the place is off 903?? road number. down the road from albrightsville.

[jtfoxman]

I know where albrightsville. I will have to check my map.