When I first installed my 140 degree danfoss valve which requires the throttling valve on the bypass circuit I drilled two small 1/8 holes in the thermostat to allow for some flow when the system was cold to prevent freezing. Probably wasn't the best idea but that's what I did. I have been running this system for 3 years and when my 500 gallons of remote storage gets below 140 top and 100 bottom it seems difficult to get the temp back up. Boiler pump is set to come on at 170 and it cycles on and off lots of times before return water gets up to temp. Recently I was reading on the forums and decided to try a 160 degree stant thermostat from an auto Parts store. I immediately noticed positive benefits when starting the boiler with storage cold. The boiler pump kicks in and stays on for much Longer and temp of boiler will climb and hold at 175ish. Before with the 140 stat the pump would kick in and the temp of boiler would slowly fall to 150 ish and gasification was slow. The best benefit with the 160 stat is I get hot water in top of my tank way faster to start using which is great with my WAHX. Now for the big negative. The boiler idles with return water at 130 degrees for 10 minutes and then kicks back in and it takes forever to get bottom of tank hot. I did not have this problem before. I currently have 1 1/4 thermopex with taco 00r three speed pump. I had a taco 0011 but switched it out for the smaller pump as I was over pumping. So the question is do I install the larger pump or lower the element to 140 without the holes or maybe a 150 stat if I can find one.