I just bought this house and am noticing water on the floor by the downspout of the pressure relief valve. While watching a cycle of the boiler i notice that the pressure gets up to about 29 to 30 psi. When i watched one cycle on a semi cool day (45 degrees), the pressure went up to almost 30 but no water out of the PRV. I am figuring that under more of a load the pressure is going higher and releasing onto the floor. Anyhow, I know the previous homeowner installed the boiler himself and I am questioning the location of the expansion tank. The tank is brand new by the way. The boiler is piped on the hot water supply side to a horizontal header. The header has three vertical circulators for the three zones in the house. The expansion tank is after the circulator at the top of the rise on the main zone. Should this be before the circulators off the header? Would the circulator for the main zone hold back enough pressure for the PRV to release? And i also have a hot water coil in the boiler. I am wondering if the boiler fires for hot water and the heating circulators are not running for a heat call if that is why i am getting higher pressure? Also, the expansion tank is horizontal. Not sure if my theory is correct about the pressure building because the expansion tank is after the circulators on the supply side. Any help would be appreciated!!