85 Therms of Natural Gas

Rinnai RL75iN Tankless
Natural Gas Water Heater

New for 2016, we installed an instant hot natural gas water heater :) This made in Japan RL75iN is a cool unit for a small family

Comparing the Energy Guide stickers from the old water heater to the new water heater, we stand to save a claimed 85 therms of natural gas per year, but I think we will save more than that :) Meg and I are not the average hot water users. I tend to take shorter showers, and not every day of the week, depends on activity level, Meg operates in a similar way. We eat healthy, are relatively fit, and do not produce a lot of body odor, well relative to others that we know. We also do not have children, only a Kitty who seems to magically keep her self clean.

We had purchased the new instant hot before moving into this house, knowing that the old one was 17 years old and on its way out. This was back in Nov of 2015. I actually received the new unit when Meg and I were living at our old studio apartment :) and had to move it with the rest of our stuff, all 56lbs in its dual box shipping container.

The old 1998 40gal water heater gave up the ghost on Jan 18th, it was a 34,000 BTU unit with an estimate annual natural gas consumption rate of 268 therms per year. I went over to my good buddy Jaesons house after work on this day to borrow his truck and saw, and got home late.

On Jan 19th before work I started unboxing the new unit, and before work on the 20th I mounted it to a skid plate made of screwed together 2x4 boards, custom made by yours truly. I did this to make lifting it into place easier, since I have a  residual fragile back from an old back injury and the spot where we installed it is not easy an easy install location. Meg helped me with the entire process. Before work on the 20th I went to the Home Depot in Bellevue and got some parts for the install. After work I spent the entire evening into the wee hours of the next morning draining and removing the old water heater. It was a turd to drain, despite undoing everything, the output sickout was

The old 40 Gal GE 34000BTU Natural Gas Water Heater
Being delivered to the 1 Green Planet in Renton
In the Back of Nathan the Nissan Truck
Thank You Long Family 

On Jan 21st the installation began and we started by loading the old water heater into the truck, along with some styrene foam for recycling. We used nylon string doubled up and a steel hook screwed into a beam in the garage ceiling to lower the old tank into the truck, the bed door was down and backed up to allow the tank to fall into the truck bed. We used the same yellow nylon string to tie the busted old water heater in place for the journey to the recycler.

Using my rugged Kyocera Brigadier on Verizon LTE, I found 1 Green Planet in Renton that would accept the old water heater for recycling for free. I had previously recycled appliances here and was roughly familiar with the location, but use the phone with Google Maps for precise direction. The truck lacks power steering and is manual, so its more to think about when driving. I then navigated to IKEA where I thought the styrene recycling was still operating, only to find a construction site. I used my mobile internet phone to locate the number for Styro-Recycle and found out over the phone by calling that they had moved 7 miles south into a new industrial park in Kent. I happily brought all the styrene there and returned home.

The installation required 2 more trips to our local McClendons hardware, where Steve the retired plumber gave me priceless installation help selecting the parts and pieces to get everything hooked up. I consulted with a family friend named Trapper, who is a natural gas pipe line installation expert before hooking up the gas. Meg helped me with the bubbles to leak test the pipe, I used Sector 5 thread sealer to make sure there were no leaks, everything was snug and tight. Lots of telflon tape, I went through 1 roll of 200inches hooking up all the purge valves, and on my second trip to the hardware store I picked up another roll, along with more pipes to move the hot and cold water to make the hookup easier. I spent a total of $238 on plumbing pipes and parts, and I am not completely done with the blow-off valve system, although the shark-bite fitting is already there waiting for the 3/4 inch copper pipe. I have all but a few copper corner fittings to finish that job soon. I even managed to snag a copper tube cutter from my dads old tool collection when visiting my mother.

I learned from the units owner manual and Steve the retired plumber that my swiss knife retrofit of the instant hots exhaust system into the galvanized system of the previous water heater is only temporary, as the exhaust volume from the new heater is significantly greater and hotter. Seems to be working ok for now. I have been monitoring it for a few days and the only thing I am going to do for now is make a better aluminum foil gasket for the adapted fitting connection, by adding more aluminum to make it a tighter fit to keep any exhaust gases from leaking back into the intake. In this picture you can see the aluminum foil gasket at the end of the galvanized 3in exhaust where it meets up with the bespoke exhaust system for the unit. I am going to paint that ugly white exhaust tube to match the body of the unit as well.

Beta Installation of the RL75iN
Stable Temporary Install
Pending Blow Off
Pending New Exhaust System

I got the new instant hot online after purging the water lines and Meg hopped into the shower by about 8pm on the 21st, and what a relief. I followed with a shower, it had been a few days for Meg and more than 2 days for me, this during our work week, few, what a relief to get the hot water online again. I ordered another $260 worth of special exhaust tube fittings to hook up the exhaust system to vent directly out the side of the house. I will spend another weekend day in the future hooking that up. It requires cutting a large 5inch round hold in the side of the house, presumably with a pilot hole alignment drilled, with stencil markings for the sawmill on both sides to make clean circles. That will be an interesting project of its own. Af of Jan 28th the pipe extensions have arrived, but an abdominal lower chest injury of some kind will have me putting that installation off for at least another week. I think the 28th, since I have some time off of work, I will fabricate the blow off tube network by braising together some 3/4inch copper pipes after I pick up the elbow pieces from the hardware store. I have to go to the dentist in a few hours, so I will combine the trip. I will post the finished install pictures in a few weeks when everything is finished up.

Energy Savings $85 per year

The new unit has an estimate energy consumption of 183 therms of natural gas per year. This compares against 268 therms per year for the previous unit. Doing the math, that is 85 therms per year of natural gas savings. We pay about $1 per therm around here. I think Meg and I will use less natural gas then the unit claim because we use less hot water than a Typical household in the USA. Before the retrofit, our natural bill, including the natural gas for our furnace, was only about $30 per month. I am curious to see how our bills are affecting in the future, as they will be the real proof of the savings. Teasing the impact on my natural gas bill apart from the net consumption will be a little tricky without a few years worth of data, as our furnace also consumes natural gas, incidentally right next to the new instant hot. Our normal natural gas bill is really low, only around $30 per month. Our garage temp seems to hover in the 45 to 60 deg F range during the winter, not that we have had much of a winter at all the last few years. I am light on data as we have only been living in this house for about 3 months. Time will tell :)