I have a closed loop forced hot water heating system with four zones. The 2nd floor zone keeps getting cold and I have to purge the air out of the zone over again each day to keep it heating. I just installed 3 days ago in the highest point a SpiroTop air purge valve, it seems to work, I do hear the air releasing, the reason I installed this valve is to get rid of the waterfall sound in the pipes when heat is circulating. It was working ok before I installed this Spirotop, there are no leaks, my system is ok on the other zones. I have to purge the air from the Thrush Co. purge valve in the cellar which is above the circulators, the circs ae on the return line, it seems to always get air pockets ! I installed last year on the same zone near the boiler a Spirotherm air eliminator but it never seemed to work, it was a used one from a neighbors heating system, and I never heard anything purge or hiss from this inline Spirotherm valve. My Boiler pressure is around 20 lbs, its a Weil Mclain 468 with the old style ceilng expansion tank, I give up !!! I had the hardest time to purge the air out and get circulation in the zone. I manually filled the system to 25 psi and it seemed to purge after that, I filled the system after purging to 25 psi to see if that helps, maybe I needed more water in the system, but it happened again today, and the expansion tank is more active than before, so I guess there is ore water than it needs.

I have a gas boiler and hot water radiator system. I am getting virtually no heat from the second floor radiators. As I am apparently not allowed to post photos for some reason, I'll describe in as much detail as possible. At a friend's suggestion, last Saturday I drained the whole system (including the expansion tank) and refilled it--yet, still no water to the second floor. Yesterday, after cranking the boiler all day (set thermostat to 85* to keep it going to the max) water temp maxed about 150* and pressure never got above about 12 psi. From reading this forum, I believe the system should have about 15 psi [B]cold[/B] in order to reach the second floor. From reading this forum, it seems like the most likely culprits for the low pressure are (1) faulty PRV, or (2) waterlogged expansion tank. So, a few observations on those things: 1. [U]PRV[/U]. The fresh water feed from the house main goes through a dedicated ball valve (yes, it's turned on), through what must be an ancient pressure regulator or water feed controller (for lack of a better term, I'll call this the "[B]PRV[/B]"), into the cast iron return line to the boiler. The return line connects to a circulating pump right at the boiler. The pump switches on normally and appears to be working. Wish I could post a pic of the PRV--the thing is ancient, made of cast iron, about 8" wide from input to output, 6" high and 3" deep; originally fitted to about 1" iron pipe, now stepped down to 1/2" copper for the newish feed line. It appears that fresh water is flowing through the PRV. I can hear the water running, and the copper pipe is cold on either side of the PRV, until the feed hits the warm return line. I can't tell how much water is getting through, however, so it's possible that there is not sufficient pressure from the feed to get the boiler up to 15 psi. Should I replace the PRV to find out? 2. [U]Expansion tank[/U]. As noted, I drained the expansion tank along with the boiler. I have no way of knowing if it somehow got "re-waterlogged" or is otherwise not working properly since the refill. To the extent it matters, let me describe the tank: It looks like a smaller version of an oil drum, probably holding about 20-25 gallons, mounted horizontally to the ceiling of the basement. It has what looks to be a fairly ordinary hose bib at one end for the drain. 3. [U]Water Temp[/U]. As noted above, yesterday the water temp only got up to about 150* even after cranking the boiler for several hours. Despite that, I don't think the problem is with the boiler itself. The burners are all lit and appear to be working properly, and Saturday (when first filling the boiler after draining the system) the temp was up to around 170*. I assume yesterday's relatively low temp was because of the constant feed of cold water. But, I could be wrong of course, so if you have other suggestions, go right ahead! While I don't want to do something unnecessary just to be doing something, it looks to me like the "PRV" (or whatever it is) is the most likely culprit. Is it worth my while to replace this thing with a modern PRV (which would seem to serve the same purpose of regulating water flow from the feed line)? Or is that just shooting in the dark? I appreciate any suggestions! Thanks, Jim