Home hot water heat system pressure is too low?
Home hot water heat system pressure is too low?
(OP)
I've been browsing the advice found here regarding draining x-tank in order to prevent the overpressure valve from discharging. Found my tank was full, so followed the advice here and drained it. Before that, the pressure was varying from ~12 to 30 psi. (It vents at 30.) Now with mostly empty tank, the psi is between 5 to 10 per cycle. Doesn't seem to be any air in the rest of the system. But it does seem to heat more slowly now.
Questions are: For my split level home, is 5-10psi okay? If not, what should it be and how can I increase it?
Thanks in advance for any advice offered.
Questions are: For my split level home, is 5-10psi okay? If not, what should it be and how can I increase it?
Thanks in advance for any advice offered.





RE: Home hot water heat system pressure is too low?
Your system may be starving. Low flowrates result in low pressure drops and slow heating rates. But if the earlier pressure swing is between 12-30psi, you may be close to the required pressure(I assume it to be 12). You shouldn't totally drain the tank but should keep enough empty space for the expansion of water at the maximum operating temperature.
Specific volume of water corresponding to a saturation condition of 12psig(26.7 psia) pressure is 0.0169504ft3/lb and at 30psig(44.7psia) it is 0.0172053ft3/lb. This means for every lb of water in your system, you should have 0.0002549ft3 free space.
Regards,
RE: Home hot water heat system pressure is too low?
RE: Home hot water heat system pressure is too low?
RE: Home hot water heat system pressure is too low?
12-30 psi swing means your "x" tank aint "x"ing. You drained the thing and found the heat-up rate to be low. It means you shifted the bubble from the pressurizer to the reactor.
If you live anywhere near Three Mile Island, PA, please evacuate. Otherwise, get a new bladder tank.
RE: Home hot water heat system pressure is too low?
If there is a pressure regulating valve and the elevation from the expansion tank elevation to the highest point in the piping is 15', then the minimum fill pressure seting for the PRV & expansion tank in psig = (62.34/144) x (15+5) = 8.7 psig. Where 62.34 is lb water/cubic ft. The larger the pressure difference between the expansion tank fill pressure & the relief valve setting, the less the volume requirement for the expansion tank.
RE: Home hot water heat system pressure is too low?