Hot Water Tank and Timer

[Xringer]

Originally Posted by herlichka

Just a footnote to my choice of timer; the battery backup feature of the INTERMATIC timer I chose is critical to the success of the project. Here in Penetanguishene we are subject to frequent power interruptions, mostly because of geography, we are on the SE shore of Georgian Bay, east side of Lake Huron, and summer thunderstorms and winter snowsqualls roll off the bay on a very regular basis, and I did not want to be constantly resetting the timer. I realize that there are less expensive mechanical timers out there, but they lose time when the power is off.

At first, I was worried about not having battery backup on my timer..
http://ecorenovator.org/forum/conser...ent-timer.html


I was interested in the INTERMATIC too. But wondered if my wife
would be able handle the programing etc, if I wasn't around..

But, our grid seems be getting more reliable, or our weather luck is amazing. (We just dodged a hurricane).

After a grid failure this spring, (while we were not at home) I noticed
the burn started up at the wrong time, but it only took about 10 seconds to reset the clock..
For us (lucky folks), the less expensive mechanical timer ($38) fills the bill perfectly..

[Ryland]

The electritions that I know who don't like wiring up electric on demand hot water heaters are that way because they have complaints from customers, my boss installed one such water heater in his spare bath room, it called for a 80amp breaker and 4 gauge wire at a cost of over $2 a foot just for the wire, the heavier the wire the longer it takes to install so the higher the install labor cost as you can't just fish 4 gauge wire in a wall like you can with 10 gauge.

Originally Posted by herlichka

she told me that she got competing quotes from two local plumbing/mechanical companies, and they both insisted on quoting on 40 gallon tanks, despite her request for a small heater and timer, they ignored the timer entirely. I think that if the project had fallen into someone elses lap we would have wound up with the larger tank and utility bill. It makes me wonder how many missed opportunities happen out there, I think that we have plenty of technologically smart choices, we just have to open our eyes and minds to see them.

That is the sad thing, I have a plumbing book that says not to install timers because of increased call backs, because people forget about them or don't understand them then they find they don't have hot water at 3am or if the power goes out having to reset the timer.
To me that is an issue of needing things to be idiot proof.

Just a footnote to my choice of timer; the battery backup feature of the INTERMATIC timer I chose is critical to the success of the project. .

I think a lot of people would do fine with a timer that had battery back up in their house, my timer was set to come on for only 2 hours per day, before I woke up and before I got home.
I'm still day dreaming about getting that self setting water heater timer put together, but all of my computer programmer friends have to much going on.

One of my favorite on demand gas water heaters is more or less a 5 gallon tank water heater with a large burner and the tank is super insulated, draw back of course is that it's rather expensive, but unlike a lot of on demand water heaters, the water temp is very consistent.

[The master plan]

Xringer...you seem real handy with electronics. Could you build a board to run say three water heater elements. You could use a flow sensing switch to turn on the power. Wouldn't just simple elements with the thermostat on them work, they would limit the water temp and as back-up you could use a tempering valve.

They look exceeding simple to make as far as tanks, plumbing. Would be a fun project I would think. Sometimes I wonder why the heck some things are so dang expensive.

There are other pics higher end units and they are all of similar design.

[Xringer]

It looks like three high temperature cut-offs are in series with each of the three elements.
Those are easy to find and should be retained in a DIY heater..
That processor is the complicated part..

It seems like you could find an SSR Crydom Solid State Relay SSR H10D4850 50amp | eBay
that could control heating elements. (Maybe one SSR for each element).
This type of SSR can be switched with just about any digital controller.
By turning the SSR on and off rapidly, you can control the power used by the heater.

I'm not sure how those flow sensing switches work, but it seems like they
are pressure activated.
Might be hard to DIY one of those gizmos.. But, if you could buy a cheap
flow sensing gizmo, G6 (3/4in) DC3-24V Water Flow Counter/Sensor | eBay (253 PSI)..



I'm pretty sure you could use it to drive an SSR...
Just about anyone with a little e-tech skill should be able to built the controls, for the plumbing shown in your picture..

When the cold water stops flowing to the heater, you would have to make dang sure the heater power stops too.

Cheers,
Rich