How to Reduce Costs in your Greenhouse by installing a Tankless Water Heater
If you have a greenhouse of any type you probably have tried to think of ways to reduce costs. With the cost of fuel skyrocketing here in the US, many people, including me, have been actively seeking ways to cut cost without hurting our or stressing our tropical plants and orchids. While looking at my gas bill for the last few months, I noticed the cost of gas rising and without an end to the rise in site, I thought this is where I had better find something to cut.
My home and greenhouse both have 40 gallon water heaters. In my home, the water heater sits inside an in-closed room and for the most part seemed energy efficient. I was able to help the heater hold its heat a bit longer by investing in an insulating blanket designed for Gas water heaters. After wrapping it around the water heater, I felt pretty good about the improvement. So, I decided to try it on my greenhouse water heater but quickly realized that the humidity and moisture would soon cause the blanket to slip and again expose the huge tank of water to the greenhouse temps. Of course, I have always kept the thermostat turned to 'vacation' mode in the greenhouse when we are not using the heated water. But even setting the thermostat to 'vacation' mode requires the heater to keep heating the water and turning it off was not an option since it would take way to much time to relight the pilot light and heat the water to a level that would not harm the orchids. Faced with this issue, I started looking online for a solution. What I found was simply a miracle (at least for my greenhouse and wallet). I decided to take a chance and purchase a 'tankless' water heater.
There were many options and many varieties to choose from. The better models that use gas to heat the water cost up to and over one thousand US dollars. I opted for a smaller unit that would run on electricity since electric costs are much lower currently when compared to gas costs. The unit I settled on costs around two-hundred and fifty US dollars. I would need a few more supplies to install it. It would require running electric power to where I wanted to place the new unit and that would require heavy duty cable and conduit large enough for the large gauge wire. I would also need to purchase a double 50 amp breaker to power the unit. At first the thought of having to run electrical current and install a breaker scared me. I thought about hiring someone to do it, but after a little research and a few discussions with the folks at my local hardware store, I found that with my skills, I could install the breaker and wire the water heater. So, I purchased the supplies, ordered the water heater online through a big box store and everything arrived (except for some tools that I already had) within a week of placing the orders.
When the water heater arrived, it was even smaller than I imagined. I opened the box and the actual box the heater was in - was even smaller again. I thought that this was a mistake, so I went back to the website and rechecked the dimensions. It was correct. My new water heater measured about one foot across, about eight inches tall and about four inches deep. (Seriously) It has two threaded brass pipes sticking out from the bottom; one with a blue band on it and one with a red band, cold and hot respectively. I removed the cover by simply removing two cap screws on the front of the unit. What I found inside was really simple. It included a brass pipe and a few wires. There was a reset button and a LED to let you know when the unit is on. One tiny thermostat the size of a US dime and a place where the electric power would come into the unit. The entire unit weighed less than two or three pounds.
Water Heater with flex pipe and conduit bend
Ten-foot length of conduit with two bends
Water Heater with Cover Removed.
Once I was ready to install the new water heater, Louis and I went about removing the old 40 gallon one. Since it was a gas unit, it was vented through the greenhouse roof and had a gas line coming into it. When we built our greenhouse, we hooked the gas line directly to the water heater without installing a cut off between the line and the heater. This proved to be a challenge for about 30 seconds when we remembered we put a cut off in the line where it entered the greenhouse from outside. After turning it off, we shut off the water, drained the tank of the water heater using the drain on the front of the unit, and disconnected the gas as well as the cold water in and hot water out pipes.
Once the unit was empty and we could move it, we carried it out of the greenhouse and were left with a whole lot of extra space and more light where the tank water heater used to sit. After removal, we put a cap on the metal pipe gas line. It was simple. Because the line was threaded, we were able to screw on another fitting that a plug would then screw into. This was done using pipe wrenches and plumbers tape. After it was sealed, we turned the gas back on and used dish-washing soap to test for any leaks. If there was going to be a leak, we knew that it would cause bubbles in the soap. Finding none, we began moving plants to get access to the breaker box to install a new breaker.
Our electric service (breaker box) was about 10 feet away from where we planned to mount the new water heater. This required cleaning off the top bench all along that wall so that we could run the conduit for the electric service. While Louis worked on moving the plants to a new location, I mounted a 2x6 x 4.5' up on the studs of the wall where our new water heater would hang. We determined the placement by attaching the flex pipe connectors to the hot and cold water connectors of the unit and measuring how far away the hot and cold water pipes from the original water heater were. Using a tape measure, I marked where the unit would go on the 2x6 and then marked the studs to center the 2x6 at the right height on the wall. I used three inch screws to attach the 2x6 to the wall. It was very secure. After the 2x6 was attached, with the cover removed, we attached the new water heater to the wall. Louis connected the water connections and we were set except for the electric.
The breaker box would need a few adjustments before we would be able to install the new double breaker unit. Before purchasing the 50 amp double breaker, I took a photo of the current breakers and took my camera with me to the hardware store. I showed the sales person the type of breakers I had in my breaker box and she directed me to where I could find the same style breakers. At this time I also purchased the heavy duty electrical wire I would need. Since I did not know how much to buy, and because it was so expensive, the owner of the hardware store let me take about 25 feet of cable home with me with the understanding that I would return the unused cable and pay for what I did use. (It is nice living in a small town.)
Before beginning the installation of the new breaker, we turned off the power inside the greenhouse using the master breaker inside the box. This however, did not remove electrical power from inside the breaker box. We next had to go to the power supply that sent power to the breaker box in the greenhouse. When we built the greenhouse, we had a second electric service installed to power it. This electric service meter was placed on our barn and inside the barn was a master shut off for power going to the greenhouse. After turning that off, we used a tester to make sure there was no power inside the breaker box before continuing. Once we were sure, we opened a new hole by removing a 'plug' from the bottom of the box and installing a wire guide inside that hole to protect the wire coming into the box from being pulled out of its new home.
We also had to remove two square 'plugs' from the inside panel cover of the unit so that the new breaker would have a 'home'. Installing the breaker was very simple. It basically just slipped into place and was secured. However, running the wire to the breaker and to the grounding bar was not as easy since the wire was heavy duty (thick) and hard to bend. We realized that we would need to thread the wire through the electrical conduit since it was so hard to manipulate. This took some time since we were using one inch conduit. Once we had enough wire at both ends of the electrical conduit, we cut the huge cable. It turned out that we would be using thirteen feet of cable for the ten foot distance. The extra cable was for the turns going into the water heater and down and back up into the breaker box. We secured the electrical conduit to the studs of the greenhouse using conduit clips and 1 5/8 inch drywall screws. This held up the heavy wire easily and now all that was left was to attach the wire to the breaker and the water heater.
Once the copper wire was grounded, we could install the two hot wires. Now, when I first looked at the water heater and the breaker I was confused since the water heater required two 'hot' wires and a ‘ground’ wire and the breaker also had places for two 'hot' wires.
In normal electrical wiring that I was accustomed to, the black coated wire was always the 'hot' leg, the white coated wire was always the 'neutral' leg, and the green coated wire was the 'ground'. Current flowed from the black and returned through the white. In this set-up, even though we had a black wire and a white wire, both were going to carry current to the device being powered. There would be no neutral wire. In fact, the electrical wire we were using only had one white wire, one black wire and a bare copper wire for the ground. I read and re-read the instructions on how to wire the water heater. It was very brief and basically said, ‘Hire an electrician.’ LOL. I did some research on the internet and finally called my dad who has been doing electrical and plumbing for most of his life. He verified what we thought and we connected the wires to the breaker. On the end with the water heater, we had a little difficulty getting the huge wire into the tiny holes behind the screws. Finally we untwisted a couple of strands off of the actual wire and then slipped them into the connectors and tightened the two screws. After that was complete, we wrapped the copper grounding wire to the grounding screw inside the unit and tightened it down also.
We placed the cover on the water heater and replaced the cover on the breaker box. We then turned on the water to check for leaks at the unit. Finding none, we decide to turn on the power. This was probably the scariest part of the whole install. Louis went to the barn where the main power was turned off. He flipped the switch. When he returned to the greenhouse, we flipped the master breaker returning power to the breaker box. The fans in the greenhouse kicked on and everything seemed normal. So we decided to test the water heater. I turned on the sink and the little LED light came on. The heater made zero noise. Louis put his hand on the ‘hot’ water pipe where water was leaving the unit and it was getting warm. In a few moments I had hot water in the sink.
Since it was so cold here, we had to limit the amount of cold water going into the water heater to get the desired temperature we wanted for the orchids. By slowing down the water going into the heater, we were able to raise the temperature to the correct level. And long story short, this month our gas bill was greatly reduced and I did not really see any increase in the electric bill. We generally run the unit once a week for about two hours at a time. So far, we have had zero problems with it. Switching to a tankless water heater was the right choice for the greenhouse set-up.
I hope you enjoyed this process story. It was really easy to accomplish. I recommend that you hire an electrician and plumber to do your installation if you are unsure about any part of how to do it.
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