Friday, December 12, 2008

Add a new dimension to your Christmas light decoration

Over the years we have improved our Christmas decoration outside our house. Adding fun while cutting the need for energy.

It all started out many years ago with four chains of lights, each with twenty light bulbs. All our neighbours had nice decorations with white light bulbs, while ours where multicolored party lights. We put them in our only tree, a plum tree at our entrance. Neighbors where joking that they needed sunglasses to look at it. Next year I added a motion detector ( 36-1084). When people or cars pass by, the plum tree really lights up with its 80 x 5W of light bulbs. It gets even more attention than before. The motion detector has a built in timer and a light sensor. The timer is set to make the light go on for only 20 seconds, while the light sensor make sure the light goes on only when it is dark. This cut the daily energy use from a shocking 24h x 80 x 5W= 9.6kWh to an estimate of 0.5h x 80 x 5W=0.2kWh.

The year after when my wife was going to through away an old speaker, I got the next idea for the plum tree. Music! Christmas music! Together with the kids we compiled a CD with a mixture of traditional and crazy Christmas songs. This we put in an old CD Walkman, set on REPEAT ALL. This connects to an old amplifier that I bought used. Then comes the little trick with the speakers. Between the speaker and the amplifier there is a on/off switch controlled by the same outlet that turns on the plume tree light (a relay controlled by 230VAC, such as 36-1984 from Clas Ohlson, So when movement is detected the light comes on and the speaker is connected to the amplifier. Sparkling colors and Christmas music for 20 seconds or as long as there is movement outside our house. One year we had a mother and a small child visiting every day. The little boy wanted to hear the music and see the ligths. This reminded me that we should turn off the music at night when neighbor kids sleep with their windows slightly open, so I added a timer (32-3835 ) to the power line of the amplifier. The timer is set to be off between 11pm and 7 am. For a while I was worried that some people might dislike these lights, but I do believe they appreciate the fun and the surprise. Two days ago we had three teenage girls laughing loud outside. Walking back and forth a couple of times in some crazy disbelief of the musical-plume-Christmas-party-light-tree. This evening I left my cell phone video recoder on next to the tree for a while, and caught this comment from someone running by:

Perhaps you can adopt some of these ideas? If you already have some outdoor Christmas lights, please do go and get a timer to turn the lights off when most people are asleep and during the day time. Easy savings. Next time you add an outdoor outlet, have one made that is connected to a motion detector. Use it for your Christmas lighting, and perhaps you can come up with a fun use for Halloween too?

Monday, November 24, 2008

6.Can the washer machine benefit from the Miljødusj?

The Miljødusj is designed to heat the incoming cold water based on the drain water leaving the shower at the same time. It must be simultaneous to work efficient. I was first thinking of hooking up the washing machine together with the shower, but I was told it would not do much good. The washing machine does not drain anything until it is done with the washing cycle, and then the next water that flows inn would be for rinsing, which I believe is usually just cold water. But then I thought, what if I connect just the water inlet to the washing machine from the preheated outlet of the Miljødusj heat exchanger, and forget about the drain water going through it. Then I could start the washing machine right after my shower and harvest the left over energy. (Or possibly run it at the same time as I shower?) After my morning shower, I set the shower mixer to just cold water, and emptied 2 liter at the time while measuring the temperature. It gave be this table, that shows the energy value of the "leftovers" when I am done showering. I am not sure how much water our washing machine needs, but I would say it should be less than 8 liters. If so, it should be possible to squeeze out 85 Wh by also connecting the washer machine to the Miljødusj. Many ifs, and not a big potential saving. Based on this I decided not to connect our washer machine, at least not for now.

Wednesday, November 19, 2008

5.Mesuring the cold water temperature increase of Miljødusj

I used two digital thermometers to measure the in and out temperatures of the heat exchanger under the shower cabinet. Each thermometer was strapped with a rubber band to where the pressurized water is connected to the Miljødusj, one on connection 1 which is incoming cold water, and the other on connection 2 which is the preheated water going to the shower.

My initial test setup was performed by cooling it all down first. I let the cold water flow in the shower for 5 minutes, then I took a quick shower. The plot clearly shows how the temperature of the out pipe to the shower increases from 15 to 26 °C (59-80°F) . The lowest graph shows the temperature increase which is about 11 °C . (The increase after the 6 minute mark is after I stopped showering).

The day after I measured my own shower which is usually fast, followed by our oldest son, Simen, who takes longer showers. ( Yes, teenager..) Looking at the graph you can see that the temperature in the room, and then also of the initial water in the heat exchanger, is 22 °C. When I start to shower the red curve shows the temperature of the preheated cold water pipe going to the shower. It is increasing all the way along as we shower. The blue curve shows the temperature of the incoming cold water pipe. Looking at the second shower you can see that it bottoms out at 14 °C . After a shower it heats up due to the last drain water passing through the Miljødusj and also later from the room temperature. The lower curve is just the difference between the two upper ones, showing the temperature increase, which is really what we are looking for. The difference show 11 °C . But is this the real temperature increase of the water? No, it is the temperature increase measured on the outside of the connecting pipes. If you recall the pictures of the inside of the Miljødusj, the out pipe goes from the back of the box and above the drain water back to the pipe connection to the shower. I assume the pipe temperature here is close to the water temperature inside the pipe. Around 25 °C . The incoming cold water is out of the picture I managed to take, but it is most likely very close to all the parallel pipes and in contact with the drain water. To check for this I just measured the cold water coming out of the tap. It showed 11°C . So when I measure 14 °C outside the pipe, the inside water is really just 11 °C. I am confident that the real cold water temperature increase in our shower is close to 14 °C (57 °F) from 11 °C to 25 °C.
Continue reading here: 6.Can the washer machine benefit from the Miljødusj?

Monday, November 17, 2008

4.Conecting the small heat exchanger

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 ( 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

Sunday, November 16, 2008

3.Looking inside the heat exchanger

The first I did after receiving the Miljødusj or small heat exchanger for the shower, was to try to figure out how it was put together. Using my cell phone I manage to take some pictures showing the inside.
The cold water is entering in the left corner that we can not see in the picture, but the water can flow in the copper connection all the way up to the black arrow. From this connection there are 10 parallel copper pipes making the cold water (blue arrow) flow to the right. On the right side there is a similar pipe connection that extends all the way in to the bottom wall of the box. From this connection there is another set of ten pipes making the water flowing back to the second half of the first connection (yellow arrow). At the top of the picture you see the exit pipe (darker yellow) feeding the preheated cold water to the shower.
So there are a total of 20 pipes that looks like they have been pressed half flat and then soldered together to form one big copper area. The drain water from the shower will flow over this area.

The drain water from the shower enters the heat exchanger at the end of the big pipe on the right. I put a flash light in it so it can be more easily seen. The warm drain water will counter flow with the cold water coming in, which is the best way to do a heat exchange. The copper area is tilted 2 cm (about an inch) to make the drain water flow slowly over it all and exiting out the hole from where the picture has been taken. Since the cold water flows in parallel pipes, then there should be no problems with pressure drop in the cold water supply.
The next step was to connect it to the shower. Continue reading here: 4.Conecting the small heat exchanger

Saturday, November 15, 2008

2.The small bathroom heat exchanger - miljødusj

I thought I should give Norwegian websites a try in my urge for finding a small heat exchanger for our shower. To my surprise, a new product had just been introduced to the Norwegian market by (Norwegian only). (It should also be available in Austria, Slovakia and Germany. More information on the product can be found at the SUP technology site in the Czech Republic ). There it was. Just what I had been looking for. I talked to the salesperson who explained a bit more how it worked. Cold water from the house pipe connects to 1. Drainwater from the shower flows into 4 and heats the copperpipes of coldwater inside the box, before it exits out and down the drain at 3. Preheated cold water will exit from 2 and on to cold water pipe of the shower. The salesperson said the coldwater would increase 12-15 C (53-59F). He claimed it to be actual measured numbers.

I ordered it and prepered to put it to the test.

Continue reading here: 3.Looking inside the heat exchanger

Monday, November 3, 2008

1.Looking for a heat recovery unit for our shower

I have found several good systems for heat recovery of drain water from a shower, that I can not use.

They all work on the same basic idea of a big water pipe with one or many smaller pipes wrapped around it. The drain water from the shower heats the big copper pipe, which in turn heats the smaller pipes where the incoming cold water to the shower flows. There is a heat transfer from the drain water to the incoming cold water. When the cold water heats up, we can use less hot water and still achieve a nice warm shower as before.

Here are some links to different units of the vertical type:

The problem is that all of them have this vertical design and can not be fitted underneath our shower cabinet that is placed on the floor. They are great if you are doing work on your house, or for installation when you build your house. We have a shower cabinet that is fully enclosed and abut 4 inches above the floor. I need to fit a heat recovery in this tight space. I was thinking that I could just get a long 32mm hose and the fit an equally long 12mm copper pipes inside of it, forming a simple heat recovery system. I even went to the library to borrow some books on thermodynamics to learn more. Then a month ago I was so happy to find someone selling a heat recovery unit that will fit underneath a shower cabinet. I decided to buy one.

Continue reading here: 2.The small bathroom heat exchanger - miljødusj