Shower Hot Water booster

[FloridaCliff]

OK,  one last question...

If I put this block heater (1500 watt) on the HW tank input and since the  HW tank has a single 1500 watt element, would this appx half my HW recovery time up to the 120 cutoff of the BH?

That is when no demand for HW exists...

Cliff

[Sean]

OK,  one last question...

If I put this block heater (1500 watt) on the HW tank input and since the  HW tank has a single 1500 watt element, would this appx half my HW recovery time up to the 120 cutoff of the BH?

That is when no demand for HW exists...

No, at least not unless you add some kind of recirculating plumbing.

That's because this will heat the incoming cold water (a little bit, as discussed above) only while it is flowing.  Once the flow stops, because there is no demand, the little slug of water in the unit will quickly heat to the 120° cut-out on the unit, and then the heating will stop.  Unless the input on your HWH is at the bottom (unusual), there is not really a way for any of that heat to convect up into the tank, so it will just stay there.

If you do add recirculating plumbing that works by convection, as this unit would in a looped coolant system as per its design, then you'd need to be careful that you don't convect the normal HWH heat right out of the unit.

-Sean
http://OurOdyssey.BlogSpot.com