Hey guys. A little help please. I have let the fire go out in the boiler for a few days now. The water is still circulating but obviously the temp is way way down. So my question is, am I safe to just turn my furnace fan on to circulate air? You can see in the pic it says bypass valve - open in summer. Is it safe to close the valve with water still circulating? Is there anything else I should be doing? Do you guys circulate the water all summer?