Re-occurring air problem

joe amadio

About 2 yrs ago I was involved with a heating renovation in a home on Long Island. The home was heated using steam and there was a brand new Burnham gas steam boiler in use. My contract included converting the steam boiler to hot water, providing 2 new zones and running out a new feed and return to the 2 new fan coils. The fan coils, the blower units and all duct work was supplied and installed by the HVAC contractor.All that I was hired to do was the boiler conversion and the loop work. The boiler was converted using the Burnham factory recommended steam to hot water conversion kit. The two zones are set up using a 2tee manifold with a 007 IFC circulator on the supply side of each. The loop work is done in Wirsbo/Upunor pex tubing. The larger fan coil located in the attic is piped in 1" pex. The smaller unit is in the basement and piped using 3/4" pex. Originally each fan coil was supplied with taco 1/8" auto vents. They have since been removed and replaced with with manually operated coin vents. I have been back to this job at least 4 times in 2 years because the 2nd floor zone has become air bound. Each time I have tried to bleed the fan coil from its bleeder valve first and there seems to be no air in the coil itself. I have had to go down to the boiler and purge the loop from the purge valve on the return side. And each time I have removed a significant amount of air.The system has no visible leaks and I have even left the feeder off for two weeks with no pressure loss. Could there be a problem associated with either the IFC circulators or possibly the pex that is causing this re- occurring problem. On my last visit(this December) we installed a Taco "vari vent" style purge on the supply header. I am still not confidant that the problem is solved. Any thoughts ?

JaredM

Pressure

Assuming you are pumping away......I'd be looking at the boiler fill pressure.  Do you have enough for the difference in elevation between the boiler and the attic fan coil?

Gordo

Do You Have a Part Number and Other Information

for the "Burnham factory recommended steam to hot water conversion kit"?



Any pictures of the near boiler piping?



Are you "pumping away"?

joe amadio

Re-occurring air problem

Yes, we are pumping away. The boiler working pressure is about 18-20 lbs.

joe amadio

Re-occurring air problem

Do not have any pics at this time but we are currently doing some plumbing work at the residence as part of a finished basement project. I will be back there in a week or two and can take some pics then. We are pumping away. Do not a model # for the Burnham hot water conversion kit but it was purchaced through a reputale supply house that carries the Burnham line.

icesailor

Recurring Air Problem:

First, check the PEX tubing to be SURE that it is Heat Pex (HePEX) and not Aqua PEX. There IS a difference.

Next time you go there, and the system hasn't been running, take note of the system pressure. You say that it is 18-20# PSI (when cold?). Turn all thermostats up high and make the system go as high as you can get it. Up to the high limit setting. Note how high the system pressure rises to.

The Extrol tank may be undersized and be under pressurized. This has been an ongoing problem. The removal of the float vents and replacing them with coil vents was an attempt to solve a problem that they didn't understand. They probably leave the fill valve off and when the system gets cold and contracts, air is being drawn in. If the PEX is Aqua PEX, all bets are off. You will never resolve the issue caused by others.  

Steamhead

Bet they never had this problam

with the steam system....................

Al Corelli_2

Steamhead....

I was saying the same thing to myself while reading through it.



I'm going with the expansion tank being too small.