[RE-wrenches] On Demand Heaters for SDHW

[Peter Parrish]

We have a SDHW client that wants to replace his old water heater with a new
tankless water heater. We do a SDHW system about once a year, and only for
clients that are getting a PV system from us to begin with. So this is not a
big business line for us and we are behind the curve in terms of
understanding the latest technologies.

As I remember from an excellent workshop that I took about four years ago:
when used in conjunction with a SDWH system, the tankless heater should 

(1) Modulate heat input based on INPUT water temperature
(2) Be able to modulate down to ZERO BTU/hr 

The only unit I knew of back then was the Bosch 125BS (I believe). Today I
can't find any bigger units that fit the above requirements.

Short of using two Bosch 125BS units in parallel, does anyone have a
solution?

- Peter
 
Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com  
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885