How do I get air out of a down feed monoflo tee system

intelligentspace

This is in my own house, the boiler serves the second floor, 11/4" risers loop around in the third floor and 1/2" branches serve all second floor radiators.
Two radiators have been removed in previous renovations and I sissoect they capped the supplies and returns in the wall.... Any suggestions as to how to remove all air from the system

Eric_32

You shouldn't just cap off a monoflo tee when removing a radiator, it reduces the size of the main line since the water is dead ended in the branch of the tee. The tee should either be removed or the two tees piped in together so they will continue to flow thru them.

I've never seen a monoflow system where the main line is installed in the 3rd floor and the branches are all piped down to the radiators. The radiator coin vents should be the highest points in the system, piping should never be in a way that air could be trapped as in, a pipe runs up, then elbow back down, then back up again to the radiator. You will not be able to bleed the air from the radiator vent. The branches off the main line, should be pitched slightly up to each radiator.

Bleeding the radiators will also bleed the main lines in the basement, when all the radiators are bled everything below it is full of water.

icesailor

When you try to vent the air out of the second floor radiators, do you get a flow of air and then it stops? You go to the next radiator, it rushes air and then stops? If so, you don't have enough pressure in the system to push the water up high enough to push the air out of the radiators.

Although it is considered bad practice to cap off radiators at the source in Mono-Flow systems, it has been done often without significant problems. Low system pressure is a bigger problem.

If you vent a first floor radiator and water squirts out of the vent, and a radiator(s) in the floors above vent air and then stop venting air and no water or air, the system pressure is too low. If the system has an old fill valve/ Pressure reducing Valve that doesn't have a fast fill feature, replace it. Its probably not working properly. If you try to adjust it to get more pressure in the system, the valve will usually fail and start overfilling the4 system slowly with excess water. So, watch the pressure and shut off the cold water feed until you replace the valve,

IMO&E

intelligentspace

This is helpful information from both of you thanks, there is not an auto fill on the cold water coming in right now, and there IS, in a closet upstairs, an automatic vent off a 3/8" copper line that is there to help with venting. There is also a boiler drain and a ball valve in the near boiler piping as if it was a baseboard system or radiant system to help purge, I will try adding more pressure first, and hope it burps out of the high vent.
I must remember... 'Water is dumb' I am smarter than water. Thanks again

ProblemSolver

With a main running up to the 3rd floor and then feeding down to the radiators; this reminds me of a gravity flow Hydronic system. But originally, a gravity flow Hydronic system would have a holding tank in the attic. Off the holding tank, a 3/4 inch pipe would run down to the basement in the boiler room and end at a floor drain. The system would get filled until water runs out of the 3/4 inch pipe. That would explain why you don't have a PR Valve. But what doesn't fit in this type of system is the Monoflow tees. Was the system re-piped at some point? I came across a similar problem. I had nothing to do with the re-piping of the system, but was the one who did all the piping and control wiring in the boiler room. Two of the zones would not bleed or move water. This is when I studied the system and learned it was originally a "gravity flow" system. Two of the zones were pumping into themselves. So I had to go back and change the system piping.

Paul48

Could you tell us why you are suspecting air, and the events that lead up to this conclusion?

intelligentspace

This is the house I live in. I moved into a nightmare of a hearing situation, there are three boilers one for each floor, we sleep on the second floor and the rads are loud when the circ is pushing the water around, also one rad at the loose key air vent would show that it was full of water yet it didn't get warm at all. I already put a larger expansion tank on (from a 15 to a 30..) I don't know how long it has been 3 systems, I guess I could see when the boilers went in,

intelligentspace

This is the house I live in. I moved into a nightmare of a hearing situation, there are three boilers one for each floor, we sleep on the second floor and the rads are loud when the circ is pushing the water around, also one rad at the loose key air vent would show that it was full of water yet it didn't get warm at all. I already put a larger expansion tank on (from a 15 to a 30..) I don't know how long it has been 3 systems, I guess I could see when the boilers went in,

icesailor

You need to post some photos of this interesting dilemma.

Especially the boiler and the gauges on it. I think that you really need an automatic fill valve.to maintain some amount of pressure in the system.

ProblemSolver

What you really need is an experienced tech. There are so many possibilities, and most of them require some type of correction. My guess is the piping layout, but you got to know what your looking for. So stop talking about this and gather some pictures and post them.