Bosch Thermotechnology Tronic 4000 Electric Tankless Water Heater, 3.5 kW, 13 x 8.5 x 4.5", 3500 watts, White

The water warms up in less than 10 seconds. The slower the flow to hotter the water.

Update: this unit started leaking inside the unit. I attached a photo of the leak location. This is 3 months after installation. Do not recommend this unit at all.This water heater doesn’t heat quickly for some reason when you turn off the water, it completely starts over and takes about 30 seconds to start heating again. So if you leave the water on, it’s fine, but if you turn the water on and off and on again, you waste many gallons of water, waiting for it to reheat again.

This was pretty difficult to get installed. It also seems to have a typo on the heater ring, so we had to try to figure out which was actually low medium high and off. Only two of the positions actually work. This was replacing an earlier model which was the same brand that died after only 2 or 3 years. Not thrilled about it, but seems to be working okay.

I wanted to use an economically-priced electric solution, from a name I trusted, to preserve my propane supply for emergency back-up. I tried a used one, for a great price, but sadly, it mysteriously stopped making hot water a week after I installed it. I decided to just take a refund, since I wasn't willing to buy new right now.

works like a charm

The water takes longer to heat and does not get as hot as the previous Bosch heater that I had. This unit has a larger kilowatt rating, but it does respond as the previous heated. Sometimes it will not heat at all, and I shut the water off and turn it back on to make the water heat - luke warm. I was wondering if I can get a replacement or a different brand. I currently have 3 other Bosch heaters and they work fine but this newer replacement heater is not as good. Wayne Welle

This unit is efficient for a point of use sink or something small. It is 6.5kw and is 240V. it requires a dual pole 30 amp breaker and 10g wiring. Two 40V breakers are required so you might be spending $200+ to get this unit installed if the area is not already set up for a tankless. It's a point of use tank at its size so it's ideal for a sink. You could maybe run a single shower off it in a pinch, but I honestly feel it's too small. Its max will do a 35 degree temp rise at 1.26 gal per min. Minimum water flow to activate is .55 gal per min. Installing yourself requires some electric and plumbing knowledge, but if you are familiar with those basics, diy installation should be possible. One thing to keep in mind is that water quality is important. Poor water quality can decrease life of the parts of the heater over time. The tank has a360 degree orientation mounting which is convenient. However, it suggests leaving a clearance around it (recommends 6 in on front and sides and 12 in on top and bottom) so there is room to service the unit if issues arise. I recommend putting a shut off valve right before it so if it ever leaks it can be shut off easily directly by unit. Overall, this is a very nice option for a point of use tankless water heater, but installation requires basic electrical/plumbing knowledge and extra parts will likely be needed for install.

The unit started to leak water after 8 months. I reached out to Bosch customer service and they told me they would send me a reimbursement check. (The unit is still under warranty). No check arrived. After two weeks I followed up (email) and Bosch's customer service team became unresponsive. Wow, I can't believe a quality Brand like Bosch is treating customers like that. Makes me really think twice about buying this brand again.Update: I finally got a response when I called the customer support line. Looks like they had some internal communication issue. The Customer Service person I talked to was very competent and figured out the issue. Looks like a reimbursement check is on it's way.