Water Heater Help - Fuel Economy, Hypermiling, EcoModding News and Forum

trikkonceptz · 02-12-2009, 08:43 PM

I recently changed the water heater in my house. My heater was 13 years old and began to leak, costing me money ...

A couple funny things though ... The old heater had the energy rating sticker on it still and compared to the new one I bought, it uses less energy than the new one. How was this possible?

ANyhow, to late now. I have the new heater on a timer to avoid running at all times of the day. Their are 2 adults and one baby in the house, which equates to 3 showers a day and 1 bath a day, duration no more than 10 minutes each.

How should I set me timer? How long does it take a heater to heat up new water? I will be shutting it down during peak power times, but how long should I let it run to warm the water that was used in the showers?

Thanks ..

gascort · 02-12-2009, 09:18 PM

Good question. I assume you are on electric, from your comment about having it on a timer. Maybe the energystar assumptions include different electrical rates, or over the years they changed the assumption of how much hot water people used? Like the EPA's new fuel economy ratings?
Why not a tankless water heater?

trikkonceptz · 02-12-2009, 09:36 PM

Tankless was an option except this is a 2 story townhome and each heater requires 60amp breakers. The current home was not wired for it and running the cables would have been cost prohibitive. It will be the answer to any future home I buy new or move into as a permanent residence.

Frank Lee · 02-12-2009, 09:37 PM

I think you will just have to experiment to find your optimal times.

I experimented with my gas water heater- too bad I can't put that on a timer. So I put a water heater blanket on it varied the temp setting. Dropped it lower and lower until I felt the showers just didn't feel good anymore, then bumped it up a teensy bit.

order99 · 02-13-2009, 12:58 AM

Do you still have the old tank? You didn't mention whether the elements failed or the tank itself blew out...if the Tank is is in good shape you can make a nice Solar Heater to boost your new one.

If the Tank rusted out, keep it anyway and make a Kick-ass Woodstove out of it! You'll need to cut it a little anyway, so a small hole or two won't matter.

Here's some Water Heater info:

Solar Water Heating Projects and Plans

And a Water Heater Woodstove:

The Amazing $500 Wood-burning Stove ... That You Can Build for $35 (or Less!)

Ryland · 02-13-2009, 02:22 AM

I think it takes around 30-40 minutes for most hot water heaters, the main thing I try to avoid is running our hot water heater between 11pm and 5:30am as we don't need hot water after 2am alot of the time and according to my room mate who took a 4am shower the other day "it was still nice, not scalding hot but nice" after 5 hour of being off, and it's set low enough that I can stand a shower with just the hot water on. so I know it's not to hot either.
If I had more tabs to turn ours on and off I would have it run from 5am til 7am and from 3pm till 6pm and maybe again at 10pm to 11pm as we still live in a state that allows smoking in bars, and the best live music is in bars.

trikkonceptz · 02-13-2009, 11:37 AM

The old unit was toast, the tank was leaking and apparently the elements were failing or I was running just with one, because the difference in the water temps now is incredible.

For example before I would set my shower dial to the 10 o'clock position for a comfortable shower. Now with the new heater I have it set at 2 o'clock to get the same amount of hot water, which is considerably less.

BTW I learned yesterday that my water heater uses more energy than my a/c. I learned this through FPL.com, my local power company.

TestDrive · 02-13-2009, 11:53 AM

Not surprising, when you consider the mass of a cubic meter of water is about 850 time the mass of a cubic meter of air.

NiHaoMike · 02-13-2009, 01:01 PM

Has anyone thought about building a two stage control for an electric water heater? My idea is to use contactors (with internal interlocks) to select between 240v and 120v (hot to hot or hot to neutral). An electronic temperature probe will be used to measure the actual temperature of the water and a flow sensor (could just be another temperature sensor on the outlet pipe) to determine when hot water is actually used.

A microcontroller can then be used to select between full power, 1/4 power, or no power. One way to control it would be:
* During night or when away, completely off.
* Otherwise, 1/4 power as necessary to maintain temperature.
* When in use, switch to full power.

The contactors will be mechanically interlocked as closing both would result in a short circuit. The existing thermostat, set to something like 140F (well above the intended setting), would be the safety control.

Ryland · 02-13-2009, 01:46 PM

it sounds like you might have the thermostat set higher then you need it if you are able to turn your hot water down on your shower, turning that temp down will save money as it's not getting as hot, it will also protect your kid from getting burned by to hot of water.
there are alot of water heater timers out there, mine runs on a 24 hour program so it treats every day of the week exactly the same, there are 7 day timers that let you change the heating times each day of the week, the most expensive timer I've seen has a temp sensor on the water heater and so it over rides the stock thermostat and lets it simply be a back up, that timer I think can both be programed and appeared to be self learning to throttle back by learning your use patterns.