Posted by GM on December 21, 2000 at 18:52:41:
I have a new house with a new base board hot water Burham Boiler with tankless hot water heater with a 40 gallon hot water storage tank. It has 4 zones in the system. I noticed that the hot water piping out of the boiler does not conform with the installation guide. Specifically, the install guide depicts a union, hose bib, shut off and cold water fill input on the pipe out of the boiler going towards the radiators. The plumber did not install it this was. He didn't include the union, hose bib nor shut off prior to the cold water fill. My question concerns filling and purging the zone lines. According to the install guide, you close the said shut off and open a zone valve and then add water from the cold water fill until clear water (no bubbles) drains out the hose bib just below the said shut off. The you open each zone valve repeating the process for each zone. Then you close the hose bib and continue to fill the system until the pressure gauge reads 12 psi ( the cold water feed has a pressure reducing valve so it should fill just to said 12 psi). then you close the hose bib and open the shut off just above the hose bib. It seems to me that in doing this, air is chased through the system and boiler and comes out of the system at the hose bib which would be just below the shut off (say 6-8" below the hose bib). When this process is finished it seem to me that there would be a short segement of pipe from the hose bib to the shut off that would be full of air. This air would then be travel up the supply line and be vented through the air vent above the diaphram tank. My plumber did install a drain cock on the return line just before the boiler. Without the hose bib and shut off how does one effectively purge the system. Apparently it can be done because the plumber did it. Can anyone advise me.