Jet Well for Heat Pump loses Prime with Demand

[joeharley]

I am having some problems with my Well/System. Need some HELP!
System: Deep well, Jet Packer type with 1/2 hp Myers HR 500. Small blatter tank on top of pump(2 gal?)@ 28lbs. 30/50 pressure switch...This is used for my ground source heat pump. worked great for last 2 yrs.
1.The pump will prime easily. But, shut off from heatpump, it very slowly loses pressure to 30 lbs and pump kicks in until 50. This takes 25 minutes. I checked for leaks from well head to pump by digging up plumbing. NO leaks above ground.
2...valve is open for water flow to heat pump..The pump kicks on below 30lbs. But pressure keeps going down to '0' and pump loses prime.
ANY suggestions as to the problem(s) willbe appreciated. Thanks

 

[Patrick88]

Vertical pipe could be leaking, but I bet it's the foot valve.

 

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[joeharley]

Length of pipe between the foot valve and jet?

Patrick 88, How far down from Jet should foot valve be installed? Also, Thought just came to me, could this loss of prime indicated a low water table?