215 gal. of SS / PEX DHW on line tonight

Just finished our 215 gal. 201 SS tank that holds a PEX tube HX which consists of 300" of 1" well water supply and parallel 235' (total of 470') runs of 5/8" PEX boiler system water lines. Heats much faster than I thought it would.......

Turned the LP on the water heater to "vacation".........

Stay tuned.............

LP still taking a vacation...........and there's plenty of hot water. Wood boiler heat now. HDPE solar collector coming on line by May.

Works great. The tank is roughly 32"x32"x50" high. I thought it would stratify more, but there's only 3 to 7 degrees difference from top to bottom. I still need to finish the insulation, but before I close it up I'll take some pictures this weekend and post along with a couple CAD drawings.

Maine said:

Let me see if I get this right, you are charging your tank with a pex, hx, and also removing heat with a pex hx. Something I was considering with my 750 gal tank.

Steve

Click to expand...

Yes. I installed a separate storage tank (from the furnace storage tank) and made it from type 201 SS. 201 is similar to 304, but much cheaper. The tank walls are 12 ga. and welded at the vertical corners. The bottom horizontal corners of the tank are 3"x3" SS angle and the top lip is supported by 1"x1" SS angle. It holds ~215 gal. We run boiler water through it in parallel 5/8" pex. Parallel to slow the flow and increase heat transfer. 5/8" because that's what I had left over from our floor install. Then I ran well water supplying the LP gas water heater through 300' of 1" pex in the tank.

The 5/8" and 1" are coiled around a SS slotted unistrut support frame I welded up. Both 1" and 5/8" pex are coiled together on the outside of the frame and just the 1" on the inside loop. The pex is attached to the slotted strut frame with tye-wraps rated for 185* and tied 4 to 8 times for each loop. The frame is supported by 3"x3" SS angle at the bottom and 1"x1" SS angle at the top. Hopefully this will last for a few decades.

I'm using the same pump that runs water to my fin and tube coil in my furnace and back to the boiler plate hx. The water flow is controlled by a stat set at 100*. That stat closes a valve when the supply water drops below 100*. That way the preheat tank won't cool off while I'm heating the house from my storage tank and the temps get down low. It's also separately valved with ball valves allowing me to heat the tank directly from my boiler plate hx without heating the rest of the house.

The preheated water then runs into my LP water heater, which has been turned off for 3 days now. We've had more than enough hot water for all our needs (including 2 teenagers). Just checked the tank and it's at 139* at the top, 129* at the bottom.

This will save us $500-$600 per year. The tank materials cost ~$925 including the SS sheet, SS angle, 308L welding wire, 1" and 5/8" pex, pex fittings, black pipe, vales, tye-wraps, plywood and insulation. Less than two year pay back.

If I were to install the loops in the large storage tank the cost would be less, but we might be still use some LP because the large storage tank drops down to 80 degrees at times. Not enough heat to supply all of our hot water. And the length of time we'd have stored water to heat the house with would be less.

I'll send photos and CAD drawings later this evening......

CAD drawings.......

Pictures to follow after the tank cools down (it's 120* right now) and I can remove the insulation.

Garnification,

Thanks. It took a little time to weld, but the 1" tubing was easier than I originally thought. I took an old wood cable spool, cut one side off just outside of the center and modified it with some 2x2s so that it was 48" tall. Then I put it on a 4 wheeled cart and just wound the pex coils onto it and dropped the SS frame over it. Next I started tying off the tube, flipped it back over and wrapped the rest around the outside of the frame. The 5/8" was much easier and all wrapped around the outside. If anyone is interested I can take pictures of the coils to help with your project.

You could go with a round tank. The guys at USEMCO could roll one for you, but there's more volume in the square. For our use a square tank fit into the space we have and gives us the 200-250 gal. I was designing around. If you do go with a round tank, a 34" dia. X 60" tall and get you 236 gallons and still fit through most doorways. Or you might want to find a HDPE tank. They are rated for 140*. I have one that runs up to 155* on a regular basis with no problems. I went with the SS because it was only another $100 and I could make it the custom size required. That and there may be times when I run it up higher than 150*, to make beer for instance.

Because I'm using PEX loops for both heat and well water I can use the tank water for the solar collector directly. Then drain the solar panels at the end of Sept. when we start burning again.

The pre-heat tank is at 125* right now. So far it has varied between 110* and 139*.

It's been over a year since we topped off the LP tank. It's down to 40 gal. but I'm not going to fill it. The solar panels are next on my list, and if they work well we won't be using the LP again. Now that's a feeling of satisfaction! Toss in a log, grab a beer and listen to the packers. Life is good.

Tank temps this am are 120* on top, and 119* at the bottom. Stayed above 110* yesterday even with the warm temps and little wood burned.