Bosch Thermotechnology Tronic 4000 Electric Tankless Water Heater, 10.5 kW, 13 x 8.5 x 4.5", White

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

I have installed this water heater little over 2 months. It replaced my previous heater Bosch AE12. My heater is located on the wall in boiler room and supply hot water into neighboring bathroom and kitchen. I had it installed by licensed plumber. In my case, the installation was not difficult. There are three settings for hot water temperature. It delivers sufficient amount of hot water. So far, so good. My previous Bosch unit lasted 8 years, hopefully this will be working for longer time too.Added June 6th 2025: Shortly after installation I noticed drop of water hanging down of connecting valve. Speed of dripping was negligible and I thought it's seeping from valve and eventually it stops. It did not and speed of dripping was increasing to making puddle of water on the floor. My plumber arrived, checked all connecting piping, removed the cover from heater and found the leak from inside of unit. He contacted Bosch, after few phone calls Bosch agreed to sending new unit. The new unit arrived, the plumber installed it and let's hope, this one will last longer then 2 1/2 month. Since installation requires licensed plumber, the cost for re-installing was skyrocketing.

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.

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.

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

We opened up the item and installed it per instructions and it did not work we in contacted Boch and they walked us through some troubleshooting issues and that did not resolve the problem so they sent us a slip to mail it back and evidently we were supposed to just mail the broken piece back but we didn't know that we mailed the entire unit back the entire unit came back to us along with a little part that we were supposed to install ourselves we did that on the phone with the technician from Boch, the unit still did not work we were supposed to get a full refund it's been 2 months and we still haven't seen any money and we've repeatedly contacted them. One hand doesn't know what the other one is doing and why they can't just send out a new unit was beyond us but now we just want our money so we can move on.

works like a charm