try shutting downstair rads and see if it can heat them up? i would think that upstairs rads would be the easier to heat allowing for heat rising even allowing for having eight rads,you can then adjust flow rates to individual rads (shut down on opposite side of thermostatic valve) remove small cover and turn down takes a while to get this right slow flow to rads that are hotter than others and go from there,best of luck
avs
February 2010
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