I replaced my hot water tank

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I replaced my hot water tank

Post by Colibri » Fri Aug 17, 2018 1:52 pm


I just want to share my experience with replacing my 20 years old electric hot water tank with a much smaller unit. The replacement is not done yet, I will book a plumber in early September. The big change comes from switching from a 185L (49 USga) tank with two 3000w upper and lower(busted) elements (240 volt) to a 43 L (11 USga) tank with one 1500w element (120 volt). I bought the new tank yesterday.

My main motive to replace the tank is of course to reduce the electric bill and stop heating so much water when I don't need it. Also, my home insurance company is not very pleased with my 20 years old tank.

I can't wait to see the change. The only time my roommate and I use hot water is for washing dishes and showering. I believe with a low flow shower head, we will be just fine to enjoy a reasonnably long hot shower. I was not sure about going to that extreme in terms of downsizing the tank but I think outside of North America, small tank are the norms. And having lived without running water and off the grid most of last summer, I experienced a solar shower which was about 20L (5 USga) and was just fine (except if I let grow my hair to my lower back :o )

Anyone with similar experiences ?

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Re: I replaced my hot water tank

Post by jacob » Fri Aug 17, 2018 2:23 pm

The tank in our RV was 10gal. This was not a problem as long as we didn't take two showers in a row in which case the second person would quickly run out.

We only heated water (with natgas) when we actually needed warm water. Otherwise, the burner was kept off. This was easy to do since we had an electronic ignition model operated with a switch from the inside of the RV.

My experiment with cold/navy showers detailed on the blog is due to those circumstances---that way DW could take a shower right after me w/o ... you know. We spent almost nothing on gas for cooking and heating water: <$100/year.

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Re: I replaced my hot water tank

Post by prognastat » Fri Aug 17, 2018 5:17 pm

and an upside is cold showers are supposed to be good for you. Congrats on replacing the tank btw.

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Re: I replaced my hot water tank

Post by IlliniDave » Sat Aug 18, 2018 5:52 am

Yeah, kudos on the d-i-y and proactive initiative, not sure if I'd be comfortable tackling one of those myself. Since I'm selling my house w/in two years I'd be reticent to downsize more than required. Recently there were new regulations put into effect in the US that restricted tank heaters in single-family dwellings to I think 55-gal. I believe my current one is 70 or thereabouts, so to be compliant I'd have to downsize a little assuming the regulation has not been rescinded. My cabin has one that is way too large for my needs (it started life as a vacation rental unit designed to sleep 6-8 despite it's small size) and to me it is a dilemma when it comes to discarding a perfectly good existing item in favor of a more energy-efficient alternative, although they can be partly recycled.

Once I get relocated to basement country where plumbing is not run in concrete slabs I'll likely switch to a distributed in-line system since my use rate is low (I've read that around 40gal/day is the efficiency break point for those). I know a few people who have switched to those for the convenience (essentially infinite supply and no delay) and they seem to like them and encounter minimal problems.

The power coop that services the remote areas around my cabin has programs where they offer discounts/rebates for using timer systems that will only energize water heaters during non-peak times (they try to source a lot of their power from green sources and that means they have trouble/additional expense servicing surges). Basically the water heater will be "on" once a day (nighttime in the summer, daytime in the winter) for a couple hours to heat the tank then you rely on insulation and conservation to make it last for the day. They will come out and free of charge and install a second service line on a switch they control. They did lobby against the lowering of heater tank sizes because of that program, and last I knew were lobbying for an exception to preserve the viability of the program. On a more robust grid you could do the same thing with a timer (or manually like jacob described) and/or lower the thermostat setting. I may do that in the interim at the cabin while I wait around for the existing water heater to wear out. I like the coop up there, I got nearly half the cost of a new refrigerator back via electric bill rebate for replacing the broken one with one that was smaller and EnergyStar compliant. They have many such programs I might take a look at (using underground heat pumps, augmenting with solar, dwelling efficiency upgrades, etc.) On the downside the availability charge is high, but that's understandable given the low customer density (few customers per mile of distribution line).

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Re: I replaced my hot water tank

Post by OTCW » Sat Aug 18, 2018 6:49 am

I've done two recently. The second one went much faster. I foresee a third in my immediate future, and it should be a piece of cake. They do make a difference on the power bill, but I wonder if they will last as long as the ones I replaced.

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Re: I replaced my hot water tank

Post by Colibri » Sun Aug 19, 2018 11:03 pm

I do rinse shampoo off my hair with cold water from time to time. I used to do it almost everytime. Not sure why I stopped.
The small tank is the next step, and maybe I could graduate to cold shower later.

I looked into other options, including switching to on-demand tankless hot water. My current service and panel would not handle the electric on-demand hot water. I only have a 60amp panel (old house), and not looking to change that if I don't have too.
That is a very good idea what your power coop is offering and make sense for low demand usage. Maybe I could look into putting a timer as well. But I am still counting on heat loss from the tank to keep the area around the tank warm so the plumbing lines don't freeze during the coldest nights. The tank is at the very end of a closet, quite away from the nearest source of heat and there is all kind of water/sewer pipes running around. I made the mistake one winter to shut off the hot water tank while I went away for 2 weeks, it was during a cold spell. When I came back, the hot water line had froze... :roll:

Yeah I wonder how long this tank will last, like I said, the current one is 20 years old. I am doutful if that new tank last more than 10 years. Too bad. Althought, there is a 6 years warranty...

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Re: I replaced my hot water tank

Post by Riggerjack » Mon Aug 20, 2018 9:53 am

A few things to consider.

All electric heat is 100% efficient. So there is no energy savings in ever changing one form of electrical heat for another. Newer hot water tanks will not ever be more efficient than an older electric tank.

Bigger tanks are just as efficient as smaller tanks at HEATING the water. Efficiency gains are made by reducing the surface area that radiates the heat. So smaller tanks have less surface area, and mild gains could be made there. Go feel your tank and lines, that will give you a very good feel for how much heat is lost.

All your hot water lines are also losing this heat, how well you insulated these will have a great impact on the heat loss.

This heat loss is within your house. So heat not released in hot water lines, needs to be added by HVAC, in heating environments, and is a double savings in cooling environments.

In my Marysville house, with an electric furnace, and electric water heater, this means I insulated my tank, including installing a styrofoam pad underneath, and my lines in my garage. I don't care about heating my garage. But being in a northern climate, heat will be added to my house most of the time, so whether it comes from the furnace of the water heater makes little difference.

On Whidbey, I had access to all my water lines, so I insulated them, and added a circulation pump, so all the faucets run hot nearly instantly. Waste waiting for hot water is eliminated. The energy the pump wastes, is again, 100 percent efficient electrical heat, inside my home.

All of that math changes with gas, or in a cooling environment.

As to heater recycling, water heaters are (in the states) steel sheet metal, coated in glass, wrapped in insulation. Not much there to recycle.

But tanks fail in a few, predictable ways.

Component failure. Heating elements and thermostats are available cheap from home Depot. As are anodes. Changing these out is as simple as turning off water and power, draining the tank, and using a socket. YouTube will show you how.

Tank failure. The tank is glass coated steel. The hot/cold cycling described above causes different rates of expanding and contraction and can lead to hairline cracks in the glass. After this failure by corrosion is inevitable. But can be slowed by the anode. Changing anodes every 5 years is the recommendation. This is the part that is disposable in your tank. Change the anode, or change the tank, it's up to you. BTW, anodes are made from magnesium or aluminum, and are the most recyclable part of the system.

If you find a bit of leakage, that isn't from a fitting, it means your tank has corroded through. It is toast. No fixing it. And that tiny pinhole leak, is about to become a gushing nightmare. Remember, this is a pressurized system, and that pinhole is going to get bigger as more corrosion eventually opens that pinhole, and the erosion does more, and soon, homeowners insurance is a consideration. A little wetness at the bottom of the tank is a serious issue, even if you don't care about the surface that is getting wet.

TL:DR, change out your anode. Insulate your tank and lines, if you don't want the heat in that area. Save upgrades for places where they will save your money and energy. Hot water heaters are not usually one of these areas, if you have electric heaters, and live up north.

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Re: I replaced my hot water tank

Post by EdithKeeler » Sat Sep 01, 2018 10:11 pm

I just bought a tankless hot water heater today, to be installed Tuesday. My old tank was 13 years old, and due to changes in tank circumference and height, a new tank would not have fit in the attic and met code (too close to rafters and walls) and there’s no place else to put it. Tankless are very expensive—installation is expensive—but at least it will last a long time.

Because it’s only me and I don’t use a lot of hot water, it’s supposed to be more energy efficient—saving up to $100 a year. Woot. At that rate it will pay for itself in... 50 years.😢

The one good thing about this whole crappy situation is that because it’s in the attic, I had the risk of tank failure and doing water damage to the ceiling, etc. Less risk of that with tankless, unless they make a bad connection or something—heaven forbid. And they’re supposed to last 25 years or so.

I’ve been taking cold showers for the last week. Not so bad... but it’s August in Memphis, so “cold” is relative. Not sure I want to do it in December.

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