I seem to have a mystery in my hydronic heating system and wondered if you can advise and/or point me nearer a solution. I have a small, two story 1500sqft house with basement and use a small high efficiency condensing boiler. From the boiler I have Taco 0011 circulator (the only pump in the system) pushing hot water into a 5 outlet manifold of 1.25" pipe. Each of the 5 manifold outlets feeds a 3/4" copper pipe going to baseboard heat and a DHW heater. Each outlet has a control valve activated by the thermostat in each zone. Output end of the supply manifold is tied in to the return manifold (with a manual controlling valve) as recommended by the boiler manufacturer. Everything worked as expected (whichever zones called for heat, received heat) until I lowered the manifold from near the basement ceiling about 30" in an attempt not to have pipes and manifold hanging from the ceiling for better sound insulation to the rest of the house from the circulating water. Now the problem. Unless the second story is the only zone calling for heat and I restrict the circulation from the supply to the return manifold, no heat circulates to the second floor. I have flushed the system several times to be sure there no air in the system. I do not know what the pressure gradient across the manifold looks like but I am assuming that there is higher pressure in the supply manifold than in the return which should circulate the water. The only thought I have on the situation is whether of not the additional 30" of height that I introduced has created too much of additional head for the pressure differential to manage? The second floor baseboards are about 12feet above the circulator and supply manifold. What else should I consider? Many thanks for any advice. Dave

Hello I have a Weil-Mclain Gold Oil WGO-4 Boiler with a Carlin EZ-1 Burner. I have down fired the boiler from a 1.10 to a .85 Nozzle, same angle. Combustion test comes out fine but sometimes there will be a very loud humming noise (almost sounds like car bass) coming from the boiler. If I open the flame viewer the noise subsides, but the moment you close it again, the noise picks back up. It doesn't happen every time the boiler runs. Weirdest thing of all, the boiler seems to run better when its making the noise, carbon monoxide readings are lower, boiler efficiency is up about 2%. Again the noise will go away when you open the flame viewer. Draft above flame is good, draft at the breech is only around 4ish now. Any other information needed let me know!