Julia, you have to take the case off. A knob on each side at the back. Note how the cover goes back on. The knob controls the water flow. The way I set mine up is turn the hot in the shower if that's the main focus or at the kitchen sink to full open. Turn the knob in the heater untill you have the temp set to the maximum you want at the outlet.
This way if your washing the dishes you shouldn't need to add cold, but you will in the shower or vise a versa.
In summer/winter you might need to adjust at the tap or unit. I'm in Perth and set mine i...Read more

Replaced my older Bosch unit with Bosch 13H and what an expensive mistake this is.
My water bill has sky rocketed, it takes so long for any hot water to make its way to the taps, and the unit is extremely close to the kitchen/bathrooms. The pilot turns off if you try to regulate the temperature to warm or if it’s placed on low pressure. I have been extremely frustrated with this product the day it was installed. Twice I’ve called Bosch and twice they have sent out the installers, basically all I get is that’s the way these new systems oper...Read more

Because of the layout of our house we installed 2 Bosch H13 water heaters - one for the main bedroom and living areas and the other for the two remote bedroom ensuites. In the 5 years since we have not had a decent shower except when we go on holidays.

Both units exhibit the same annoying problem with the water temperature constantly varying between hot and cold while showing. We even tried one with the tempering valve removed but the problem was still there. While my elderly father was staying with us for a few months after an operation we ...Read more

Used in our shed where we've lived full time for 7 months (3 years now and still no problems...), 100% reliable so far. Despite frosty, minus 3 temperatures at times, there has been enough water for a good and hot shower all Winter. Wife is happy. I installed myself, lagged pipes from rain-water pump to heater, used a large LPG regulator. As Winter hit and the tank water temperature dropped I had to adjust the flow rate down twice, but despite this, there is still more than enough water for a good shower. We don't have water-saving devices fitt...Read more

Avoid this unit like the plague that it is .
I have lived with one for these past twelve years, and paid for it to be repaired for the last time . Out the door on Monday and hopefully straight to the tip where it belongs . Seven service calls in total ; an average of more than one every two years . I have spent hundreds of dollars in keeping this unit going and received no joy, or reliable hot water in return .
I also have a Bosch 780 Water Wizard on the second bathroom, this has given sterling service over more than 25 years . It needed ...Read more

Another complaint to add to the list for these atrociously designed systems. I have plenty of flow to shows and taps as we have no restrictors (yes, we waste lots of water just to get this ridiculously poor system to run). Every time the hot tap is turned on the spark fires but the gas usually won't light. Typically it takes 5-6 goes to get the gas to light and the only easy way to know when this happens is go out but the system and open and close the main water valve, continually triggering a startup attempt until it lights. About 5% of the ti...Read more

Purchased machine brand new in late 2011 and how ironic just after warranty period lapses (2 year warranty) the unit plays up?!

The ignition module doesn't work hence no hot water.

Paying more than $400 out of pocket expenses on a hot water unit that cost me $710! No surprise year 2015 the same failure yet again??

I had called customer service back when the first issue occurred just after warranty only to be told, " you need to get out a plumber to fix the issues, do you want a list of plumbers in your area?"!

Bosch is living on passed merits!
...Read more

I have had a Bosch 13H since 2007. The plumber who installed/ sold it to me was not interested once out of warranty. It has been serviced several times by the SA agents since then. They say they can't find anything wrong with it (and charge me for that). The shower has temperature fluctuations - from cold to scalding with no warning. I've contacted the SA agent's office who have replied - saying straight away that it's not the heater and
"Winter example

(set temp. 37c) – (Cold water temp 15c) = (temp. rise 22c)

You would need...Read more

We live in QLD and have persevered with the Bosch 13 Hydropower for about 8 years now, But finally I have given up nursing it along and will be replacing it this week with a more reliable product from another supplier.

Our troubled journey started when a salesperson from a retailer advised my wife this was the perfect size for our 4 bedroom, 2 bathroom home with 2 adults and 4 kids to run on a rural property using tankwater where the pumps don't work when there is no electricity and we were using water saving shower heads. So for many reas...Read more

We moved into a property that already had the 13H unit installed. This is the most useless piece of junk I have ever come across. You waste enough water to fill a swimming pool to try and ignite the thing and even then it still won't ignite.

You can only have your shower during the day which is pointless because your at work. You cant heat water to wash dishes or use the dishwasher.

Each morning I am running to my parents house for a shower before work because our system just won't work.

By reading all the reviews on this site as wel...Read more