Go with booster tank or new electric hot water heater?

Joseph_4

I have a customer with oilheat with a domestic hot water coil. He currently has an electic water heater which has started leaking. The way it was set up (12 years ago) is that the hot out of the  domestic coil is the feed in to the cold side on the 50 gallon electric water heater.  A pump circulates water back to boiler if  water in electric hot water heater drops below 100 degrees. I'm used to seeing this set up with a regular booster tank. never saw with electric hot water heater.  It didn't look like the wiring was right. so I tested it with a meter. There was only one hot leg 120v. The water heater is a 240v water heater. Its never been messed with.  That means it was never wired right. He tells me he has never had a lack of hot water even with multiple showers one after the next. Now, strange as it sounds.(at my local plumbing supply)  A 50 gallon electric hot water heater is $350. A 50 Gallon booster tank is $445. I'm wondering if the old company put in an electric hot water tank simply because it was cheaper and didn't care to wire properly or was there a reason they put electric water heater?

 

Big Ed_4

Booster Tank

You can use an electric as a aquabooster , just disconnect the heating elements and use the lower aquastat to control the bronze circulator .. It has been done long before before someone labeled and packaged a "Booster" . It is the same.... a storage tank with an aquastat ... Piping there are a few ways with pros and cons

icesailor

Electric HW heater as storage tank:

I've been doing this for over 35 years. The reason for 120 volts is that it is probably running the circulator and switched through the bottom thermostat. I usually use a cord whip and just wire through the bottom thermostat. You can go in the top though and use one of the wires as a neutral and the other as the hot leg. You can also wire it through the high temperature energy cut off in the upper thermostat opening.

You noticed the difference in price between electric hot water heaters and designated booster tanks. (Shhh, don't tell anyone, booster tanks are water heaters without the elements and wiring.)

Put the circulator into the bottom of the tank by switching out the 3/4" drain and swap for a brass tee with an offset nipple and ell so you have room to get into the lower thermostat and element cover. Pipe it as you described. Some show the circulator in some in between place pumping somewhere but I find the circulator in the bottom works easiest. I always use Taco 006 BT threaded brass circulators. Though any brass circulator will work.

The indirect lovers may go ballistic over the thought of this application so if you would like to keep the noise to a dull roar, run the circulator off a SW 501 relay and have that start the burner. I consider it a waste of money though. I just leave the operating, low limit control set at 140 degrees and set the high to 160. No condensation on the boiler, it is clean when I go to clean it, and no one ever runs out of hot water.

My wife and I and four teenagers couldn't run it out.  

A plumber friend had to change a water heater recently that I had done years ago for a previous owner. He was going to install an indirect. When he saw what a project it was turning into, he called and asked me how I did it. He couldn't figure it out. Doing the indirect meant a two day project getting into old screw pipe. I went over and showed him. When he finally got it, he was stunned at how simple and easy it was. And it had been working like that for over 20 years.

Anytime I see a stand alone tankless, I try to sell a storage tank. Most customers will go for a storage tank because of the cost being reasonable but not an indirect. The labor and material is just so high.

Put a check valve coming out of the circulator going to the cold of the tankless.

Glad you posted this. Gives me a chance to comment on one of the most effective ways of making hot water. What's the difference if the indirect coil is in a water tank or a boiler? As far as I am concerned, the closer the coil is to the heat generating source, the more efficient it is.