Idea For Storage, (harebrained)

Would it be possible to use multiple reels of pex to build something that would substitute for a storage tank? The whole assembly would be insulated. I have no idea how/if it'd work.

Wad'ya think?

I think it would be cheaper to use an old LP tank. You'd need alot of length to get any volume. Plus that would be a lot of oxygen barrior to let oxygen into your system, as the barrior is really a retarder which works well in systems that do not have thousands upon thousands of feet of it. Just MHO, don't shave that hair off your brain yet!

TS

I'll second TS
i ran double 1" pex lines from my boiler building to my house,i used 600 ft total,i have a manifold and a unit heater in my house at the moment,plus a large radiator in the construction area.In the boiler building is another manifold,plus the backup oil boiler and a large plate heat exchanger.I filled that side of my system with glycol,i used 3/4 of a drum to fill it,aprox 35 gal.Surprised me,i bought 4 drums of glycol for that side of the system,i have a big stack of cast iron rads to install,but i will end up with extra glycol.
Piping has surpising low volume,at least to me
Thomas

Well, if you used 1" pex let's see how the numbers work out:

1" inside diameter is about 9.4 cubic inches of water per foot of pipe.
At 231 cubic inches per gallon, that means it would take about 25' of pipe to hold a gallon.
That works out to 25,000' to hold 1000 gallons of storage.

I'm thinking that would be one whacking big pile of pex! On the other hand, that would be almost enough to heat my house from your boiler, so maybe it's a good idea after all

Did you just say "one whacking big pile"? I think that made my day.

At a dollar a foot, maybe, for 1" that would be $25,000 for 1000 gallons.
Maybe not a good deal even if it would work.

You could maybe improve on the coils of pex by wrapping them around something that could absorb/hold heat.

What that something would be though is another issue - and PEX doesn't transfer heat all that good. Which is sometimes good & sometimes not.

Ya never know what hairbrained ideas will lead to sometimes.

I'm thinking around a big tank of water - maybe 1000 gallons or so?

If I were just a smidgen less self-conscious I'd own up to all of the hare-brained ideas I considered myself before I did my own storage. One was a 50,000 gallon inground pool under the basement floor with a movable thermal barrier - enough to store a whole season's worth of heat, and enough to cool the house all summer.

I was originally thinking about larger pipes of pvc, then I read they melted with hot water.

I think a whole buch of pex stuffed into a big water tank could make for decent non-pressurized storage. Doesn't transfer heat anything like copper, but is way cheaper & easier to handle. Not sure how much more of it than copper you'd need to make up for the heat transfer issue though. I think I've got everything in place here to maybe get a handle on that aspect, I just haven't hooked up my temp probes to it yet.

One of mine was....
I was going to build a house out of a 50' tall tank,4 storys,with a lawn on the top. It probley wouldn't have been to much more work than my log house.
Thomas

Just out of curiosity,

What would the pressure loss be on 25,000 feet of pex?

gg

According to the Viega pressure drop table, it's about 0.016 psi pressure drop per foot for 1/2 inch pex at 1 gpm. So figure 400 psi for 1 gpm, about 800 psi for 1.5 gpm. Of course I'm sure there'd be two or more parallel circuits, so it wouldn't be anywhere near that bad!

Well for a round trip of 2.36 miles! I love calculators, much better than the slide rule, besides my cell phone would have to be much bigger to acomidate a slide rule

TS

Just remember that whatever you use in a tank, run the coils vertically, that is to say the inlet is at the bottom, outlet I'd at the top and the loops going left and right. Doing it the other way causes a huge mess of air lock and it won't transfer heat very well.
Also, the greater the difference in temperature between the coil and the water in the tank the more heat exchange takes place, so to get the greatest heat transfer the hot side of the coil should be the top of the tank. In my system, the coils used to dump heat from boiler to tank are also used to take heat from the tank to heat the house, so this allows the water to be as hot as it can be before leaving the tank.