the problem sounds like you can not close off the piping for the original house. this would force water only thru the pex of the new addition. Water pressure should not be an issue. It's hard to say without seeing the setup if your boiler guys aren't doing something right or what. There should be some type of air vent or air eliminator installed near the boiler to help remove the leftover air from the system.

Without a doubt a bleed valve on the top floor would help. One should have been installed there from day one. There should also be some isolation valves in the loop too.

Thanks for the responses. There are shut-offs for all the zones, and they shut all of them, only opening one at a time for a purge of each - old and new. There is an air-vent, and I pressed the valve down to see if water would come out as I saw suggested in another thread. Can air from the top floor really make its way down to the vent at the boiler and escape? I would have thought that once the air is at the top, it would stay there. If so, if I just wait long enough (more than the two weeks I originally waited before calling the install guys back) will it find its way out?

Thanks guys

Hi oldmacdonald, I wrote the thread "Air Bubbles In Baseboard Water Heater Pipes". I'm not a plumber, but am learning as I go. Being retired and having to pay for service calls hurt, so I try to do it myself. The people on this forum are great and can really help you solve your problems. Have you followed all the replys to my thread? When you pressed the valve down on the air vent, did water come out? You didn't mention that. If not, you probably have the same problem that I had. I changed the air vent to a Taco 400 and it appears the problem is solved. Maybe I should not talk so soon, but I am tickled about how quiet it is now. When you purged the system, did you open the pressure on the pressure regulator to force the water thru. That helps force the air out! That is why I put the other end of the hose in a bucket outside, then I can see all the air bubbles coming out. When the bubbles stop, I stop! Hope this helps, only my .02!

air will typically collect at the highest point. When you purge the loops individually you push enough water through to loop to carry the air down to the basement. Usually you will have a garden hose hooked up to drain the water/air mixture. The air vent is used to remove the small amount of air that is left in the system. You can try to close the valves to the original house again and hopefully provide enough velocity to get the remaining air pockets down to the air vent.

Whenever I had to purge mine, I did it as described above, but instead of putting the garden hose into a bucket, I put the end of the hose outside the second floor window, above the highest radiator and left it purge until all the air was out. The air vent will take care of the rest. The air has never come back.

If you are getting air into your system, something is wrong. A pressurized system should push out water at all joints, not take air in. Are you sure you don't have a leak somewhere and your make-up valve is feeding in fresh oxygenated water? There are leaks that are never seen, because the water evaporates from the heated steel/iron as soon as it leaks.

Fresh water added to a steel boiler because of a leak is the fastest way to ruin the boiler. If I suspected a leak, I would shut off the make-up valve and check the pressure every few hours for a few days to see what is going on. Then I would make sure to open the valve again.

I also have the EK System 2000 and same problem with air since installation in March 2009. I am wondering if the OP found a solution to his problem?