Tankless water heater annual maintenance - flushing with vinegar!

Back in 2010, our propane fired water heater tank sprang a leak and I took this as an opportunity to install a tankless on-demand water heater (detailed blog).  These heaters are much more efficient because there is no heat loss from a large tank.  When the hot water faucet is opened, the heater kicks on and fires up a propane flame to heat water passing through the heat exchanger.  The moment the hot water faucet is shut off the heater shuts down. 

Like all equipment, this device does require minimal preventive maintenance.  Most people never think to do maintenance on their water heaters but doing so can dramatically extend their life and replacing a water heater is always an expensive proposition.  Recently I blogged about replacing the anode rod in my solar storage tank which is actually an electric water heater that is disconnected electrically.  This has the potential to more than double the working life of that tank by preventing the walls of the tank from rusting through.

Maintenance for a tankless heater is a little different.  You need to take a gallon or so of virgin food grade white vinegar, and pump it through the heat exchanger to dissolve scale build up inside of it.  (Rinnai recommends using 4 gallons of vinegar but I think this is more than is necessary).  While the warranty from my heater is 12 years for the heat exchanger and five years for parts, I believe firmly in doing routine maintenance like this on an annual basis.  My Rinnai heater has valves and hose connections to simplify the process of flushing heat exchanger.

Here are the valves with the fill/drain caps removed:

The flushing procedure involves putting vinegar in a 5 gallon bucket and using a small electric pump to pump water from the bucket through the heat exchanger and back down into the bucket.   I already had a pump and several short lengths of clear garden hose that I use to drain and fill my solar heating systems annually.  I made up the hoses by purchasing clear plastic hose and adding standard hose male and female connectors to the ends so that I can see the fluid moving through them.

Here I have connected the hoses and reversed all of the valves to isolate the heater from the building water supply and switch everything over so that the vinegar passes directly through the heat exchanger and does not enter the building's plumbing:

The image below shows the complete set up:

I wired a foot switch to the pump so that I can start and stop it quickly as needed.  After running the pump for several minutes the water turned slightly turquoise which is the color of the copper plumbing oxide.  This confirms that I am removing scale build up inside the heat exchanger.

Here's a picture showing two bottles of vinegar, the one on the right contains the vinegar I used for the flushing process so you can clearly see the change in color:

By the way, the other use I have for white vinegar is as a natural weed killer.  I use a small spray bottle of 100% vinegar and spray it onto broad leaved weeds in the middle of a sunny dry day.   When the plants are thirsty they try to ingest the vinegar and it kills them quite effectively. I plan to reuse the flushed vinegar as weedkiller which is why I saved it back in the original bottle.

I am aware that I make this procedure seemed rather simple, but it does involve some experience and special equipment.  So if you are not DIY inclined, and you have a tankless water heater, you may wish to hire a plumber every year to perform the flushing procedure to ensure your investment is protected.   Tankless water heaters are significantly more expensive than a tank style heater so there is real value in this relatively affordable maintenance.

From a sustainability standpoint, maintaining equipment like this extends its life - keeping it from the landfill.  When my heater eventually fails, I intend to responsibly recycle as much of it as possible.  The heat exchanger itself contains a significant amount of valuable copper which can be recycled for instance.

If you are looking to buy a tankless water heater, here's a good review of current models: https://www.reviews.com/tankless-water-heater/

My solar lawn mower - still going strong

UPDATE 2022 - I "retired" this mower and purchased a new Greenworks mower  performs really well!  Back when I built this mower, cordless electric ones were not available and now there are dozens of models.  I was able to sell the huge motor for $200 and recycled the lead-acid battery.

Over eight years ago years ago I was inspired by a small article in Home Power magazine in which a guy named Al Latham described how he had converted his standard 22 inch gas powered lawnmower to use an electric motor and battery that he charges from solar.   I decided to make my own conversion and have been using it consistently to cut tall grass and weeds in our so-called lawn ever since.

At this time of year I transition from charging the mower from a standard automobile battery charger to using a couple of small solar panels on the south facing roof of my storage shed.  These panels combine to a total of 40 W which is enough to charge the mower in one day of clear sunlight.  The 10 amp automotive charger can charge it up in a few hours.

Gauges on the handlebar show battery Voltage and Amps drawn when the motor is running.  As you can see it draws up to 30 A and can sustain this for 20 minutes or so which gives me enough time to mow a large section of our quarter acre lawn.  

In the middle of the summer 20 minutes is about as much as I can handle because this mower is quite heavy with the very large motor and lead acid battery and it becomes sweaty work.   Nonetheless, it is a delightful mower to use because it is very quiet and powerful enough to cut through tall weeds.

Maintenance involves sharpening the blade every year and replacing the battery every 2 to 3 years at a cost of $60-$80.   So this is definitely more expensive to operate than a gasoline lawnmower, but it has zero emissions and may last significantly longer than one of its gas cousins.

If you want to learn more about the construction of my solar mower, I have a detailed blog on my website with clear instructions on how to build your own.

Firewood: it warms you twice

wood pile and my workshop building

It is early May and spring is finally here in Maine and we are getting some warm days with temperatures peaking as high as 80°F already.  I spend much of the day in my home office sitting in front of a computer or my electronics workbench where I design and develop electronic products so my days are relatively sedentary and I look forward to outdoor activities at this time of year where I can use my big muscles. 

Each year I set a goal of cutting 1 cord of firewood from our 2 acre woodlot behind our house.  This is just enough to augment the solar/propane heating system for my super insulated workshop,and it is great exercise.  As they say; "Firewood warms you twice, first when you cut and split it, and then when you burn it".

woods behind our house in Maine

The woods behind our house are relatively young - the land had been clear-cut 50 to 60 years ago so we have a lot of small young trees competing for the canopy.  Many of them do not make it and I find them dead or dying.  My strategy for responsible forestry management is to start by harvesting these dead trees or blow downs from the winter storms first.  Very often I will find trees that have been dead for a while and are already debarked and quite dry.  I place this on my pile closest to my workshop door because it will be the driest wood.  Ideally, wood cut from living trees needs to season for a minimum of 6 to 9 months, so my next step is to seek out trees that are crowding each other out and cull them to allow nearby trees to grow to maturity.  

As a sustainable guy, I cannot countenance using smelly fossil fuel powered chainsaws so I have two electric chainsaws.  One is a 14" lithium battery powered cordless saw made by Oregon:

Oregon CS250 cordless chainsaw

I use this to fell and de-branch trees back in the woods and then cut them into lengths that I can carry to my cutting station.  I am extremely pleased with this chainsaw, it cuts really briskly and the battery lasts for 20 minutes or so which is plenty of time to fell several small to medium-sized trees and cut them up.  By the time the battery needs recharging, I am usually ready for a break and charging takes about an hour or so.  It also has an unique feature in that it has a built in sharpener.  Best of all, it is relatively quiet and there is no stench of gasoline fumes.  It is also completely carbon neutral since the power for the both chainsaws comes entirely from our solar array.

I also have a Poulan 3.5 hp electric chainsaw that I run on a long extension cord:

Poulan PLN3516F 3.5 hp chainsaw

This is the saw that I use at my cutting station to buck the logs to 16 inch lengths:

bucking logs in to 16 inch lengths
photo: Rebekah Younger

Finally, I split the larger logs:

splitting a log 
photo: Rebekah Younger

I have spent about three afternoons so far and have prepared about a half cord of wood:

about 1/2 cord cut and stacked

For the uninitiated, a cord measures 4 ft. X 4 ft. X 8 ft. and has a volume of 128 cubic feet. The amount of solid wood in a cord varies depending on the size of the pieces, but for firewood it averages about 85 cubic feet.  Firewood needs to be stacked and left to dry, so I cover the top with a tarp to keep the rain off but leave the sides open until the winter.   Before the first snow I typically cover the entire wood pile with a large tarp.   Last winter we had over 3 feet of snow on the ground and it is important to keep the snow off and the wood dry.

Fortunately, the weather on the days I have been working has been pleasant and in the 60s.  As the weather gets warmer it becomes less enjoyable to work, so I try to get as much cut as I can before the warm weather.  When the heating season starts in late September, I enjoy reminiscing about the specific trees that I cut and split as I put them in the wood stove.  There is also a layer of satisfaction of knowing that I harvested all of the wood myself.  For the house where we use 2 to 3 cords of wood a year, I capitulate and purchase pre-cut firewood that we have delivered.  There is still some sweat equity involved in stacking this wood though! 

From a sustainability standpoint modest use of responsibly harvested firewood is essentially carbon neutral since I am simply shortening the carbon cycle of trees that would naturally fall and decay thus releasing their carbon.  By giving precedence to dead or dying trees, I'm reducing my impact on the natural cycle.