I bought a Grundfos recircultion pump (model UP10-16BN5/ATLC) to reduce the time it takes to get hot water to the shower on the far side of the house. The plan was to install the pump in-line on the water heater outlet and the "confort valve kit under the sink in the bathroom.

What I just noticed is that the pump I bought has 1/2"NTP fittings and my water heater has 3/4 NTP inlet/outlets. The piping into and out of the water heater is about 24 inches of 3/4 copper transitioning to 3/4 " PB where it goes into the wall. I don't know where the 3/4 pipe ends in the wall and the 1/2 PB starts, but I have not seen 3/4 piping anywhere in the house. Regardless, I'm concerned about restricting the volumn of hot water if I install the pump in-line as designed.

My question is: 1) should I install the pump in-line in the 3/4" water heater outlet (which will/may reduce the flow) and not worry about it; or 2) should I try to return the pump (unlikely to get full refund) and buy a pump with 3/4" fittings; or 3) is there something else I can do?

Thanks