Solved: Domestic boiler system, adding a new zone.

cooper185

Adding a new groundfloor 100 foot run through a 20 ft. baseboard radiator in a two story home. This will be zone 3 and all three zones have shutoffs on the supply side before their corresponding valves. The new zone is piped from the crawlspace. Must the entire system be drained and refilled with water when this new air filled zone is opened to the system? Valve manifold is pictured. The third zone isn't piped yet. Picture attached.

EdTheHeaterMan

No.

If you can valve off everything, then when you add the new zone and want to purge that zone, just close off the other 2 zones so that the air from the new zone does not find its way into one of the old zones. After you purge the new zone, it should have almost no air left in it. Then you can open the valves to the original zones and operate the boiler to see that all the zones work one at a time. Then let the place cool down.

In a few hours, see if they all they all work together. The return pipes should come back hot within 2 to 5 minutes of each other. If one zone takes longer than 5 minutes to return hot, then you may need some balancing in order to get the home balanced.

cooper185

Edward F Young,
Edtheheaterman, Thank you for your 'edited' post, which I didn't see until the job was done, and I'm following up with this post. I went ahead with only your first 'No'. At first, the water/air was flushed out a window through a faucet which was soldered into a second story radiator in an existing old zone. Water was supplied from the boiler system's make up. Lots of air from the new zone was visible through the clear hose hanging outside the second story window. After the subsequent boiler startup the two old zones had heat but the new zone remained cold. The first flush followed the path of least resistance through the two old zones, but only partially through the new zone, even though the new zone was less than half the run of either one of the two old zones. This indicated an air lock in the new zone. The second successful air/water flush isolated both the old zones along with the boiler. Water/air was flushed into a bucket from a faucet just before the new zone 's' zone valve, while raising the lever on the pressure regulated water system make up valve. Note that, after the flush, water pressure PSI in the system must be closely monitored since opening the lever to city water pressure must be taken down to normal system operating PSI by opening the flushing faucet to drain water. In my case I needed to drain water until I had 10 PSI in the boiler system. Note that it's very important to prevent a sizable air pocket from entering the boiler. Without water to absorb the heat, the boiler chamber will overheat very rapidly possiblity causing irreparable damage and thousands of dollars in replacement costs. Be wise when installing a new system and include many 1/4 turn shutoff ball valves.