water heater conversion

[hoola]

I changed my gas water heater over to electric in a simple and cheap method when my local gas supplier hiked the base rate and minimum usage from $12 monthly up to $30. Since I don't use gas for any other function in the house, and use very little hot water, I tried a modification to the existing setup that has worked great for the last 2 years. I disconnected the gas, took off the flue, and placed a 100 watt light bulb down into the flue, extending about 2/3 of the way down, on a ceramic socket and high temp wire. I plug in the light bulb in series with a variac that regulates the voltage. I keep the variac set at about 50 volts in the summer and around 60 volts in the winter. I placed a glass cap over the flue with a small port to allow the wire to come out. The glass allows me to see if the light is on, as once the bulb fused and had to be replaced so I check on it on occasion. I use a conventional cheap incandescent, although heavy duty bubs are available and more reliable. I have plenty of hot water for bi-weekly showers, doing dishes and other small uses. I have a bimetal themostat mounted on the tank that shows a very steady 125 deg f. reading. Other than twice a year adjusting the variac, I never touch it, except when leaving town for a week or so, I turn down the variac to 40v. I have another house that has a feedback circuit that leaves a 40 watt bulb on constantly and turns on a 100 watt bulb when the temp goes below 115 deg. and off at 120 deg. I will eventually secure parts for the more complex arrangement here, but for now things work quite well. I never tried to figure out what my electrical cost for the single bulb running at half power all the time, but now I have one less bill to pay and figure my added electricity cost is considerably less than $30 monthly the gas company wanted to charge me. My next move is to connect my solar array to the hot water heater as the bulb can work fine with DC and I can dispense with any need for an inverter. It will have six 12 volt, 45 watt panels in series for approx 240 watts available at 72VDC at peak sunshine to heat the tank and will connect a set of six 12V, 7.2ah batteries hooked in series, across the DC input for storage. I will change to the more complex 2 bulb circuit with feedback regulation when converting over to solar later this month. As I plan on getting both houses "off the grid" as much as possible with photovoltaics, I figure the water heater is the place to get started.

[Acme]

Couldn't you convert the heater to use propane?

Edited October 17, 2015 by Acme

[Sensei]

100 W = 0.1 kWh/h * 24h * 30d = 72 kWh/month

Here we pay $0.165/kWh. Which would be $11.87 for all the time running light bulb.

 

Why don't you simply put metal with high resistance to water, it'll be like heating element, or heating element by itself, like for making tea ($2 cost or so).

You could control amount of energy simply by adjusting where is wire plugged to 2nd end.

Edited October 17, 2015 by Sensei

[John Cuthber]

Why don't you simply put metal with high resistance to water,

One possibility is that he doesn't want to get electrocuted.

 

However, if I were seeking to use solar power to heat water, I wouldn't turn it into electricity and back, because there would be losses at both stages.

 

Searching the web for DIY solar heater gets a stack of ideas.

[hoola]

a light bulb down the flue is a "cheap resistance to water", and how does one store heat energy in direct conversion, when backup batteries do the job with the photovotaics? What about all the plumbing that direct heating would require with attendant pumps, and worry about freezing in winter when piping hot water directly from collector to tap? The point is to get off fossil fuels, not to switch to another one. And what about the expenses of adding a propane tank seems problematic, certainly more complex and expensive than the light bulb (cost $1) being dropped down a flue. The variac to control the ac voltage is the most expensive thing, and could be substituted with a standard light dimmer, or by juggling the wattage of the bulbs slightly lower and dispense with the controller altogether.

[John Cuthber]

a light bulb down the flue is a "cheap resistance to water",

What do you mean by the bit in quote marks?

Nobody said it, so it's not a quote.

[Externet]

Interesting ultrasimple modification, hoola.

 

But I would inspect the gas heater for the presence of unused fittings/ports as the same tank (wall) may be used by factory in electrical applications. If there is a way to insert a heating element that will have intimate contact with the water inside, should provide better efficiency instead of wasting some bulbs heating in the flue cavity.

And the inserted heater element can be of your wattage choice, or underdriven with half wave rectification, or variac to suit your demand.

A drain port can also be a route of insertion of a heating element if no ports are found.

 

Keep informing your progress.

 

https://duckduckgo.com/?q=water+heater+element&t=canonical&iax=1&ia=images

[hoola]

Externet....as per wasting of bulb heating in the flue cavity, the top is capped except for a small hole in the glass at the top for the AC line to go in, so nowhere for the heat to go except into the water...I am losing some small efficiency as I leave the bottom partly open, to prevent moisture condensation inside the flue. I am saving up money for another 500 watts of solar and have all the batteries, wiring and conduit I need. When I switch to DC the thermostat will work as usual instead of the variac. I had tried the half-wave rectification briefly, but then went to a "2 bulb" idea, as I am using standard bulbs, and if one goes out, the second bulb with at least keep the tank from going cold, as it takes a full day to warm up a cold tank with this process. These are just standard incandescent bulbs, but with the lowered voltage to them they last for years. A standard electric water could be used of course, but the amperage would be more than my proposed small solar outfit could handle, so I am using the "slow and gentle" method along with keeping my hot water use to a minimum....thanks for your interest...

J. Cuthber, sorry, I meant "high resistance to water"....hoola

[hoola]

I am anticipating getting the next solar 500 watts shortly, and will combine that with upping the efficiency of my shower with a heat exchanger. I plan on adding a helical coil of 1/2" copper, tightly wrapped around a couple feet of the 2" tub drainline. This coil will be added between the main supply line and the inlet of the water heater for that bathroom. This should recycle some btu's going down the drain, back into the tank.

further efficiency upgrades with happen when I install a small (3 gals) electric heater in the kitchen under the sink. The main heater will no longer supply the heat to the kitchen this way, with saving the loss of heat due cold water not being dumped into the main tank, as it takes a full minute for the water to warm up in the kitchen, and I usually only need it for a few seconds. A further savings could be by adding a heat exchanger there too, with the 2" drainline/coil idea...but since I use little hot water there, I probably won't bother with it.

I am wondering which end of the shower heat exchanger should have the cold water going in....at the hottest (nearest the drain), or at the other end of the coil... it seems that by coupling the hottest part of the drainpipe with the coldest water would allow a maximum heat transfer.....and hooking it up the other way would be a more linear heat extraction over the length...possibly delivering the same btu transfer amount...I imagine this question is a settled issue with the mechanical engineers out there..

Edited December 27, 2015 by hoola

[HaroldCoe]

You must have taken some plumbing help. Plumbing problem like sewer line repair haddonfield NJ, sewer line repair burlington county nj, etc. requires professionals help to be tackled properly.