It seemed to be simple to connect the Miljødusj to the shower, but it turned out to be a bit of a struggle. Removing the lower skirt of the cabinet and pushing it into place was the easy part.
Prior to buying the unit I had measured the height clearance to be almost 10cm ( 4 ") so I knew the heat exchanger would fit. If the space had not been there I could have bought some rubber stand offs to increase the clearance underneath the shower cabinet.
I bought the cheapest flexible water pipes I could find (http://www.clasohlson.no/) which felt more rigid than flexible. Fighting with them underneath the shower cabinet I realized that the 3/4" connection did not fit. As can be seen on the picture, the center metal piece of the connection has a slightly larger diameter than the inner hole diameter of the no 2 connection on the Miljødusj. I had to buy a small 3/4-3/4" nipple pipe to fix this problem. Installing it with 20 rounds of sealing tape made it leak prof (1o rounds was not enough). They might have increased the size of the inner diameter on newer versions of the Miljødusj. Make sure to check this, or buy the flexible pipes they sell with the product.
This next picture shows the installed heat exchanger underneath the shower cabinet. The closest pipe is the drain water from the shower entering the heat exchanger. The pipe behind is the, now somewhat cooler, drain water exiting away and down the house drain. It turned out that it is important to have these pipes at a continuous incline to ease the drain water flow. Originally one of them was twisted upwards to the bottom of the cabinet, and it made the drain water flow too slowly out of the cabinet. If your shower uses a lot of water pr minute, it will be a good idea to make the drain pipes as short as possible. Using solid drain pipes, instead of the flexible ones in the pictures, will increase flow as they are smooth on the inside. On the cold water connections in the back of the picture you can see some red rubber bands. These I used to strap my temperature sensors to the pipes to get the facts on the temperature gain of the incoming cold water.
Continue reading here: 5.Mesuring the cold water temperature increase of Miljødusj