Purchased Bosch 250SX 4 years ago to put in attic to free up space in laundry room for remodel.  I paid about $1000 for the unit and then another $500 in expensive stainless steel vent piping and rain cap.  Unit worked well at first until first big rain storm.  Poorly design of rain cap allowed rain to run down exhaust vent and fill up entire combustion chamber.  $250 in replacement parts to get it back on line.  Customer service's fix for problem was to buy additional vent drain to install in horizontal section of vent piping for $65.  Instead, I build a secondary rain cap that solved the rain intrusion problem for $15 worth of perforated SS sheeting.  However, the unit never worked correctly after being flooded.  Changed out igniter twice and unit continually has temperature fluctuation problems.  Currently, the control board throws out EA error messages about once a week and has to be reset to get it to work properly. The original control board was faulty and was redesigned and yet they refuse to acknowledge this or discount the purchase of a new one.

Bosch customer service is pathetic.  They won't admit that the 250SX was a very poor design and are unwilling to discount any replacement parts.   I am done with this POS and am looking into a Rinnai.

Recommended: No