Im not aware of any. What I did is drilled and tapped a hole in the pump housing between the water inlet and the pulley and screwed in a valve with a 90 degree angle with 3/8 pipe threads on one side and a hose barb on the other and connected the heater return there. Been working for 15 yrs. I carry a spare pump thats also been drilled for that side just in case of a pump failure on the road.