What are you meaning by your question about warm water coming out of the cold faucet?? this often happens when a hot line is run too close and directlly under a cold, and also when a cold line is in a duct space for heating ..
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good to know about Grundfos, will highly consider this one, and Laing Autocirc. I was reading on Amazon with regards to Grundfos, Watts(looks just like Grundfos), Laing autocirc, Metlund, and that Chilipepper, all confusing.
A couple of reviewers commented on how when they turn on the cold water faucet the water is not cold but a bit warmer. It's Amazon, I forget which system it was, though. One reviewer wrote this about the Watts which I found interesting...but whether it's true or not I would leave it up to you pro plumbers to discern. He wrote "I installed the Watts recirculating pump November '07, along with under sink mix valve kit in the kitchen. I bought an extra valve kit for the master bathroom sink. The pump timer was set for the busiest times of day. There was a nearly immediate improvement in hot water at both faucets, which was glorious! The cold water side runs warmer, but so what? But the story gets more interesting:
Being an engineer I was always a bit curious why the pump was necessary, since a law of thermodynamics states that heat always flows toward cold. Theoretically, the mix valves under the sinks ought to function without the pump. Well, one day I unplugged the timer to see what would happen. You know what? The faucets produced hot water just as fast without the pump running! Now we leave the pump off all the time. My advice is to save yourselves money and just purchase the undersink valve kits (about $50 each). The pump can always be added later if you find it's still necessary. Maybe some water systems require the pump. Hope this helps!"
So, no pump? just the undersink valve kit
