georgesworkshop: water heater update

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This graph [click to enlarge] shows the big reduction in standby energy use between my old (blue) and new (red) water heaters at different basement temperatures. The new uses much less electricity, about 25% less. Same capacity, same size heat elements. 25 year age difference.

What's changed?

The new heater has better insulation, a DIY insulated mounting base and is time of use controlled so it does not use peak priced electricity.

I will show the key physical differences between the new and old. The old was produced in 1994.

My old water heater had been quietly making hot water in the basement here for 25 years. It was not leaking and did not require replacement. It had no maintenance during the last five years with me. It worked well but could have been more efficient.

I pay tribute to this fine Canadian product by Giant Factories Inc. It owed me nothing.

To become more efficient, I purchased a competitor's product from GSW (division of A.O.Smith). Although Fergus is on the nameplate, the GSW factory in Fergus hasn't made anything in years.

I might have made a better comparison by getting a replacement Giant. Local stock product was competitive in price.

In any case, I will compare old product to new product. Both are standard electric domestic hot water heaters, now called "Automatic Storage Water Heater". Both are the same size (give or take a cm or so, I lost my actual measurements). About C$350 cost now. The technology of even the most simple commodity hot water heater has improved dramatically. Much of the improvement is federally mandated to improve efficiency. My old and new have the same capacity and the same elements but are 25 years apart in manufacture.

In other words, GSW's Fergus product of 1994 is probably much like the Giant of 1994.

So if you haven't thought about improving your trusty old hot water heater, you might save significant electricity if you do. Here is what I found:

The top of the old with the cover removed. I can see the steel tank where there is no insulation.

I am holding the anode which does not help efficiency but adds life expectancy. This anode rod (aluminum or magnesium usually about the size of my little finger) is completely corroded. An anode rod is replaceable but who ever does that?

The anode protects the inside of the steel tank by being sacrificially dissolved itself as a dissimilar metal, like a zinc anode on the hull of a sailboat. When it is gone, the tank starts to corrode so this one is well past its best before date. 25 years old! Probably never been changed.

Note the iron pipe fittings out the top for inlet, outlet and pressure relief. Copper lines were attached to these fittings with no thermal break (insulated coupling).

These UN-INSULATED metal pipes had been heat radiators into my cold basement. The pipe from the hot water outlet (the one on the left with the pressure relief valve) was always HOT to the touch. Lost heat.

Note also that the insulation inside is a glass fiber wrap with lots of empty space/air! Particularly over the very top center. Perhaps I pulled some of it off with the top? It could not have been this bad could it?

I didn't determine how the steel tank was supported inside the steel can but there must be some metal support structure from the tank to the outside which would probably cause some heat loss.

The new heater has about 2.5in / 6-7cm of foamed in place insulation at the top near the center. I am measuring to the steel tank through the anode access.

In fact I had to dig out some insulation to get access. I wanted to look at the installed anode. The top of the anode rod bolt will be my measuring point for water tank temperature once I insert a sensor and cover/insulate the opening I have made in the insulation.

The anode access has a cute cover plug but once removed, you need to dig out the foam down to the hex head on the anode bolt.

Note the insulated fittings for hot and cold on the top of the tank. The pipes that lead to these fittings are no longer warm to the touch.

Likely the foamed in place insulation completely supports the tank mechanically (unlike glass fiber) so no need for a bridge structure hence lower heat loss.

The fitting to the drain valve at the bottom of the tank was an iron pipe to a metal valve. Both good conductors of heat to the basement.

The old tank used to sit right on the cold concrete basement floor.

"Verified for Energy Performance" in 1994!

The drain is now a recessed plastic valve, a much better insulator.

I've raised the tank off the floor on an insulated base, making it easier to do the annual residue draining and reducing the heat lost to the cold concrete floor.

The wooden base (about 8 inches high) is topped with a 1.5 inch foam disk.

The diameter of the base is larger than the water heater by about the thickness of a batt of rock wool insulation. It could have been a square platform to be simpler to make.

I will wrap the entire new water heater with an insulating blanket after installing seismic straps. Not required by the code here but a good idea anyway for a 100 year event. Earthquakes do occur in Canada.

Time of use inhibit I wrote about here.

I plan to install direct energy metering for the water heater as it is one of my top energy consumers. NRCan on water heaters. Note that there are no storage tank electric water heaters that are Energy Star rated. I think mine will qualify when finished!

Thank you for your interest,

George Plhak
Lions Head, Ontario, Canada.

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