[Shop-talk] was tankless/instant water heater now slow hot water to fixture

[Bob Spidell]

Got a question: Where does the (heating) water being shunted from the 
hot water line to the cold water line by a pump go? I'm on a well, with 
a 500g storage tank that sits at about 50psi, and I suspect municipal 
water is at a similar pressure. Mine would go back to the tank--if the 
pump can overcome the pressure--but where would municipal water go?


On 1/25/2022 6:00 PM, Brian Kemp wrote:
> I've been looking at this.  We have a guest shower that takes about 3 
> minutes to get hot water.  Here is a sample product designed 
> specifically to be mounted at the far destination, like under a sink.  
> Push the button and the pump runs, pushing hot water into the cold 
> pipe until the pump senses the water is hot.
>
> https://chilipeppersales.com/collections/frontpage/products/chilipepper-on-demand-hot-water-recirculating-pump-model-cp9000-b-version-wireless-wired 
>
> https://www.homedepot.com/p/Rheem-1-25-HP-Hot-Water-Recirculating-Pump-with-Under-Sink-Kit-RH18537/301852244 
>
>
> Here is a sample video:
> https://www.youtube.com/watch?v=AQC_shrv8KA
>
> I have not used any of these products.  I hear the Chilipepper one is 
> loud.
>
> Brian
>
> On 1/25/2022 8:45 AM, Pat Horne wrote:
>> This is off target from the OP.
>>
>> I’ve seen homes/shops where it can take minutes for hot water to 
>> reach a fixture. One DIY fix for wasting water I ran across was to 
>> add a small pump, check valve & a bit of control circuitry at the 
>> fixture. Plumb the pump & check valve between the hot & cold lines so 
>> that when the pump runs it will transfer water from the hot line to 
>> the cold line with the check valve keeping the cold water from 
>> getting into the hot line.
>>
>> Add a push button near the fixture that turns the pump on for either 
>> a preset time or monitor the hot line & turn off the pump when hot 
>> water is present.
>>
>> It still takes the same amount of time but it doesn’t waste water.
>>
>> Peace,
>> Pat
>>
>> Pat Horne
>> We support Habitat for Humanity
>>
>>
>> On Jan 25, 2022, at 9:38 AM, Jim Stone <1789alpine at gmail.com> wrote:
>>
>> It is plumbed to the hot water line.  These heaters have two 
>> potential uses: as a sole source of hot water (e.g., for a sink where 
>> there isn’t another hot water source) or as supplemental heat for 
>> situations like mine.  For us, it is really just for hand washing and 
>> dish washing and not to have to waste so much water waiting for the 
>> main heater to kick in.  I don’t notice a drop off after extended 
>> use, so I assume 7 gallons is enough to allow the main hot water to 
>> come through.  The installation instructions cover both methods and 
>> do warn you not to set the heat on the main unit too high; as I 
>> recall, the max for incoming water was something like 140º.
>>
>> Jim