Originally Posted by hankenstein
There is a valve on each line hot and cold, as well as one in between.
Lost track of this thread for awhile, but I looked at your pic. Seems the inlet and outlet of the HW heater are closed and the hot to cold water bypass is open?? Thats fine, we're not filling the heater. I also see the pump and on the left side there is a small white capped filter or strainer. I cannot see however where that hose goes connected to the filter. That is where the suction hose will be connected in a tee format with valves blocking the tank suction and blocking the open ended hose probably with a plug. Question is, does the tee exist? If it does is it lined up to take suction from a jug or bucket? I'm attaching a picture of an aftermarket winter suction kit. In your unit it will be heavy 1/2" reinforced clear hose. It sure sounds like the pump is sucking air, you're showing water level in the tank correct. If this short suction does exist, make sure its valve is closed and the tank hose is open. Last option is pump is defective or we've seen it installed back wards! The filter is suction side of pump, its connection should lead to the FW tank, the other side will lead to pressure connections.
As I look at the pic again, could be your pump is in back wards. I see soft hose on the discharge pressure side and cannot see the suction side, however I see the hard tubing heading that way. The blue piping is normally higher pressure than the white/clear hose. Check that and see if the hard stuff is connecting at the filter. Shurflow the pump mfgr. show this on the inlet side of the pump, cannot verify till you confirm that detail, there is also a arrow on the case. If true close valves and turn pump around.
Only dumb question is that never asked. Anyway some things to check.