11:25 AM 01/13/2013
Thanks so much to the community for helping with my last question. I have one more! I had to pressurize the hot water heating system (96,000 BTU Burnham boiler in the basement) for a 3rd-4th floor duplex (about 2000 sq foot with a total of 6 baseboard units) to a baseline of around 25PSI just to get the water circulating well... It appears that in when it fires up it hits around 35PSI and blows off the pressure reducing valve and leaks water ... The MAWP is 50.... I was under the impression that you need about 5PSI per floor. Are there any tricks to getting the water up to these high floors without simply increasing the pressure in the system?
you are setting the pressure too high...15-17 lbs is the standard for a hydronic system. it sounds like your expansion tank is blown, probably undersized as well.If your system is set up properly, you should be able to power purge the air out ,but at very least, bleed all the air out of the system ay the highest point, which should have at least a manual vent
12:23 PM 01/13/2013 | 0 Votes
It takes 1 psi of static fill pressure for every 2.31 feet, or ~28 inches of height, from the boiler to the highest radiator.
Eman is right in that your expansion tank is probably ruptured and will need to be replaced.
1:38 PM 01/13/2013 | 0 Votes