Hot water recirculation bridge valve

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Mart

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I recently installed a Grundfos Comfort 10-16 DT PM BU/LC hot water recirculating pump and a single Grundfos Comfort 00595926 thermal bridge valve (I.E. retrofit application, using cold water line for return, no dedicated return pipe) that is installed at the furthest sink (kitchen) from my hot water tank, powered as need be via an Eve smart plug. It works properly, in terms of the hot/cold water flow and valve shutoff, but it still takes an inordinately long time for the hot water to initially arrive when the pump is switched on. I’m considering installing a second bypass valve on another faucet to potentially reduce that initial h w wait-time. But I’m unsure as to if that would, in fact, help, or how our hot/cold water line(s) are plumbed in our two-story house with basement and hot water taps on all floors, or as such, where to install that second valve for maximum benefit.

Might it help to add one or more additional bypass valves? And if so, should I install it on the faucet that takes the second longest (after the kitchen) for hot water to arrive, with and without the pump on (which in my case is a bathroom tap, same floor and quite close to the kitchen tap with installed bridge valve)? Or should I install it on an upstairs tap or basement tap, even though all of those hot water taps all have much speedier hot water flow even with the pump off? Grundfos offers no help on this issue, far as I could determine, so I’d appreciate any advice/info, thanks.
 

John Gayewski

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I recently installed a Grundfos Comfort 10-16 DT PM BU/LC hot water recirculating pump and a single Grundfos Comfort 00595926 thermal bridge valve (I.E. retrofit application, using cold water line for return, no dedicated return pipe) that is installed at the furthest sink (kitchen) from my hot water tank, powered as need be via an Eve smart plug. It works properly, in terms of the hot/cold water flow and valve shutoff, but it still takes an inordinately long time for the hot water to initially arrive when the pump is switched on. I’m considering installing a second bypass valve on another faucet to potentially reduce that initial h w wait-time. But I’m unsure as to if that would, in fact, help, or how our hot/cold water line(s) are plumbed in our two-story house with basement and hot water taps on all floors, or as such, where to install that second valve for maximum benefit.

Might it help to add one or more additional bypass valves? And if so, should I install it on the faucet that takes the second longest (after the kitchen) for hot water to arrive, with and without the pump on (which in my case is a bathroom tap, same floor and quite close to the kitchen tap with installed bridge valve)? Or should I install it on an upstairs tap or basement tap, even though all of those hot water taps all have much speedier hot water flow even with the pump off? Grundfos offers no help on this issue, far as I could determine, so I’d appreciate any advice/info, thanks.
This is about run time. Your saying it's functioning good, but then saying it's not working. So your pump isn't running long enough to get the water hot enough or your temperature setting is too low. With the pump running there should be no wait time. If your using a timer you'll have to wait some amount of time to circulate the water once it kicks on after that there should be no wait. Those pumps are tiny and only move water very slow. Adding another won't help.
 

Mart

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This is about run time. Your saying it's functioning good, but then saying it's not working. So your pump isn't running long enough to get the water hot enough or your temperature setting is too low. With the pump running there should be no wait time. If your using a timer you'll have to wait some amount of time to circulate the water once it kicks on after that there should be no wait. Those pumps are tiny and only move water very slow. Adding another won't help.
Thanks, John. I probably should have more accurately said that the valve seems to open and close properly when hot water finally reaches it with the hot water faucet open, with the pump on or off. That is, with the cold water angle stop off and the cold water tap open, the water does slow to a trickle but not quite full stop whether or not the pump is on. And the pump was installed correctly, far as I can tell. But I’m guessing the Comfort model I’ve got simply isn’t powerful enough to actually do its job.

Even after it is on and running at the “100%” setting for 2-3 hours, the valve is still cold and the cold water does not get pushed through until the hot water faucet is opened and hot water is delivered, which initially takes about the same time when the pump is on or off. Also, even if the pump has been on for hours, hot water is not readily delivered if the tap/hot water has been off for several minutes. Instead, I only get luke-warm water when the hot water faucet is opened until the hot water eventually flows through, which takes only marginally less time than when the pump is off altogether. When the cold is turned on, it is also initially luke-warm for a bit, as one would expect, if the hot water has been recently running and the valve is working properly. But even with the pump on, if the hot water has been off for at least 20-30 minutes, the cold water returns to fully cold (i.e. not initially luke-warm), again indicating the pump isn’t delivering much if any hot water. As such, as you said, my specific Grundfos Comfort model is not only “tiny” like all such pumps, but perhaps altogether inadequate for our house in terms of its total head space, flow rate, etc. Pretty much useless, as things stand.
 

Mart

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Do you have a tankless heater?
No, it’s an electric Rheem 60g. And I’ve only now discovered that the Grundfos Comfort model 10-16 DT PM DU/LC I was sold and had installed is apparently much less powerful than the Comfort System model. Maybe that’s the problem. The unit I’ve got is evidently rated at a max flow of 2 gpm with a 4’ head max and designed for “application with a footprint of up to a 2,000 sq ft” (however relevant that is for our 3,100 sq ft, two-story w basement house). As opposed to the Comfort System unit, which is rated at 6 US gpm and 5’ head max, with no sq ft qualification indicated on the Grundfos website that I could find. In short, my unit’s perhaps simply undersized for our particular application?
 

John Gayewski

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4' of head is only enough head to get through 66' of pipe at speed. Do you have more than 66' of pipe?
 
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