I am responsible for replacing a failing water heater at my work location - that is a pretty easy solution...take out the old State water heater and put in a new one. Simple & Done.
However, I was looking at the installation and there is a Grundfos pump (Model UP 15-18 SU) connected to an insulated pipe that "T's" into the cold water inlet. This is a hot water return line and comes from the ceiling above our 2 bathrooms that are about 20ft from the hot water heater. The pump is not wired up at all (never has been) - so it has never been used in 15 years...There is no expansion tank (the original building plans called for one), or a temp sensor in the pipe.
I have 1 Kitchen Sink and dishwasher that is 3 feet from the existing hot water heater location. This is a business location - Mon-Fri hours - so a timer or motion sensor in the bathrooms to trigger a recirculate pump would be the a nice thing. I don't want to spend a bunch of money updating this system, but want to see how I could get it running.
Any help would be appreciated! - Thanks
I have done the recirc both into the bottom of the water heater, removing the existing drain and installing a tee for the recirc,
And I have used the incoming cold for the recirc. Normally for the incoming cold, I would have a check valve to prevent the recirc from going upstream, and add an expansion tank.
Regardless, I use a spring check on the recirc line.
The Aqua Stat is a nice touch on the recirc. It shuts the pump off when the heated water has completeted the loop.