Just had a recirculating pump installed. I have only a trickle of hot water at the single handle control faucet where the return line is attached when I turn off the cold water supply. What could be the cause? Is the faucet bad or do we need some kind of valve? Cold water mixes at the faucet and sends cold down the return line no matter if pump is on or not.

  • "A trickle of hot water"; does this mean that a) you open the faucet all the way to hot and you only get a trickle, or b) you get a small burst of hot and then you get cold, or c) you only get hot if you open the faucet to a trickle; any more and it becomes cold? Apr 16, 2016 at 17:53
  • Open the faucet and I only get a trickle of hot. No burst of pressure. I turned the supply to the cold off so only hot going to the faucet. Apr 17, 2016 at 12:12
  • I thought about your question and am amending my answer. When the cold supply is on the faucet gets hot for a count of three then goes cold and stays that way no matter how long you run it and the water going down the return line turns cold as well. With the cold supply off everything is hot but you only get a little water out of the faucet. Seems like all the hot water is going down the return line and not into the faucet. Apr 17, 2016 at 12:30

1 Answer 1


"A trickle of hot with the cold turned off" is utterly normal for any modern fixture with a built-in anti-scald valve arrangement, which responds to low cold water pressure by blocking hot water flow.

If cold water is flowing from the faucet to the hot water circulating loop, it sounds like you need a check valve, or if you have one it's backwards, in the wrong location, or not working.

  • The only place cold water could mix with the hot at this faucet is at the faucet itself. Does that mean the faucet is malfunctioning? Is the "t" junction for the return line (installed at this faucet) malfunctioning? I can't seem to get the plumber who installed it to come and troubleshoot. I appreciate any help. Apr 17, 2016 at 17:30

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