Hi, I'm replacing a recirc pump while also installing a new water heater. It's a Taco 1/2" model and I'm concerned about how quickly it heats up and how hot it gets; concerned enough that I've not actually run it for more than 10 minutes for fear of damaging it.

It gets almost too hot to touch, uncomfortable at least, even before the return water is hot (it takes about 5 minutes starting from cold until the return water is hot) am I correct in being alarmed?

I know it is not pumping air because a) I have a clear pex section after it and could see bubbles and b) I have an air trap on the supply side.

The pump is located on the return end of a loop that is almost 100 ft in length. It flows through a T, both lines have a check valve installed (yes, in the correct direction); one flows to the water heater supply line, the other to a tempering valve. Have I made an error here?

Thanks much,

Sam

Hi Sam,
You have to bleed the lines after pump is installed. You have air lock in hot water system. Connect all pipes, activate pump. Go to all faucets in the house and run hot water for few minutes. Make sure the shut off valves are all in open position and that pump is not installed backwards. Remember, regular hot water recirculating pump is pulling water towards the heater, not pushing away from the heater. If installed properly, pump should be running very quietly and w/o vibration.

Hi Milo,

Well I already did do all of those things so at least you've confirmed I'm thinking along the right lines. But based on your response I'm thinking there must somehow still be air in the system, but since the house has been active for a week and all hot water lines opened, where can it be hiding? The air trap before the recirc pump is not something I purchased; perhaps I installed wrong: it was empty before I installed, is that correct?

I'll try the drain operation again anyway, thanks!

Bleed the pump itself. There should be Bleed Screw . Open it and let it run until it drips w/o any air coming out. Also, you probably have trapped air in the return line. So open faucets won't have any effect on it. You should have installed Auto-Air-Release valve, like Watts ( see the first photo ).

The pictures help, thanks. I didn't realize the system supported it or I would have provided one. I'm configured as in the second diagram, except that the Taco cartridge recirculator does not have a bleed valve. Did I buy incorrect pump for the application?

Appreciate your help very much Milo.