Hot Water Solar Collector Temperature Gauge Sought

[LowGear]

I've built a remarkable solar collector out of 4" ABS but have a high spot that will keep air so I've decided to bleed it out as needed.  I'll have a half inch NPT hole (I could go smaller or larger depending on the chosen gauge) at the tippy top and have decided to fill it with a temperature gauge.  This is a non-pressure system for an outside shower and should it prove significantly productive I'll plumb it into the hot tub via a small pump and differential thermostat.  I'd really like the gauge to be a vertical one that I can read from a sideways view.

I've looked at the water boiler units and I'd like a bigger dial and I have no need of a pressure indicator. 

Suggestions?

Casey

KISS-KISS  Keep It Simple Stupid - Keep It Simple Smarty - Please Just Keep It Simple!

[Tom Reed]

How about something like this


http://www.mcmaster.com/#pipeline-dial-thermometers/=qr4k9o

[Mad_Labs]

Just curious, any more details or a pic of your collector? I am interested as I have a solar powered hot tub myself.

Jonathan

[LowGear]

Thanks to you both.

Tom:  I almost crashed my mouse on the way to McMaster.  And then I slammed into the $80 parking sign.  But yes, that's what I want.

Jonathan:  Aaww; Jezz; I think my dog ate my camera; Now where did I put that collector.  Ok!  I may have overstated it's design elegance.  I'll do a couple of whiskey neats and see I can get it done.  If I show you mine will you show me yours?

Casey

[Tom Reed]

Where I used to work, the place was riddled with this type of thermometer. I was lucky to inherit a few in scrapped equipment. I never realized they were so pricy. For a cheap economical version you could use a meat thermometer through an 1/8" compression fitting.

[Carlb]

you could use one of these just make a small hole and epoxy the sensor in since you are running the system unpressurized.  All you need to do is convert from C to F.  you could use a thermowell but i don't see a need.

I use one of these in my basement freezer so i know at a glance what the inside temp is without opening the door.

http://www.ebay.com/itm/LCD-Refrigerator-Freezer-Fridge-Digital-Thermometer-Temperature-50-110-c-R1-/370973296977?pt=LH_DefaultDomain_0&hash=item565fbb4951

[Mad_Labs]

Heck, I'll even show you mine first. I call it the hillbilly hot tub, if a tub could have a beer gut and wear a wife-beater this one would! Mind you, the beer gut would be from fine micro-brews and grass fed burgers...

As you can see I have three thermal panels and three PV panels. I built a controller that senses tub and panel temp and decides when to run the pump. Also runs it at night if it is close to frosting to prevent popping a thermal panel from freezing.

I also have a Chofu, a Japanese made, wood fired hot tub heater for those days when there isn't enough sun.

[LowGear]

Holy Moly Jonathan,

Have you considered Hot Tubs Anominys?  (That's my best Hill Folk spelling.)  

I think you've got a great program going there.  Of course now I'm a bit curious how you heat the secondary priorities of your life like the home?

I got the photos taken but I'm really embarrassed to show them now that I've seen yours.  They always told me to go first in speech class as an easy way out.  Later today.

Casey

OK, I'm back.

[Mad_Labs]

Yeah, I have a hot tub addiction. Still cheaper than a crack addiction. I scrounged the panels, they were all popped from frost so I brazed 'em up. The PV panels I got for cheap and the wood for the shed and mounts I got in a trade for bypassing the safety controls in a skid steer that wouldn't start. So it is kinda fancy but it didn't cost me much other than a TON of time.

Embarrassingly enough, the hot tub is my only cool heating scene. When the economy went in the dumper I had to give up my rental place and move out on to my property in a trailer. Not worth trying to rig that for alternative heating, so I use a propane furnace. I am going to start building my house this year or next and I will be doing solar hydronic heating with wood back up. When I move the tub to the permanent location I plan on co-genning a 8kW Chinese diesel genny for some bonus winter heat.

Jonathan

[Ronmar]

Thats interesting Casey, how do you insulate the collector?

[LowGear]

Thanks to carlb my head is spinning again.  

I didn't go very far with Carl's lead before I was at the temperature guns.  I could even shoot the hot tub water for a reading and the pool as well all from the same position.  I really wanted some old frumpy gauge sticking up in the air but a brass plug with a probe sticking down into the water would work.  Heck, the ABS would probably give a pretty true reading on the shady side.

Stick a waterproof box on the backside of something for easy and quick draw of my < $15 gun and Bob's my Uncle.

This units starts spending much time above 120 degrees F. and I'll be shopping for a cheap differential thermostat to control a secondary flow to the hot tub.  That 1400 watt heater element costs about 50 cents an hour to happen.

Step one:  Get it installed on the collection platform.  OK, set it on the wall facing West and see how it performs.  Yes, South would be smarter but sometimes you just have to work with what the rotation of the earth delivers.  Have I been in the tropics too long.  Happily accepting what the universe delivers to my doorstep. 

I guess I could cut a piece of dead hot tub cover into a triangle, wrap it with aluminum tape.  I could even put a couple of mirrors behind it for even greater solar exposure.  Hmmmmm, what kind of clear giant bubble could I put over it?  Step 1.  Step 1.  Step 1!

Casey

And thanks to you all for your continued support and inspiration.

[Carlb]

Casey,

I saw something that looked like that at Blue Man show in Las Veags

[Ronmar]

I did some experiments with a black poly collector on my small above ground pool.  The collector was in the barn when I bought my house, about 4' X 10' consisting of a series of small molded tubes about 1/4" all fused side by side into a flat sheet, connected to a 1 1/2" header tube on each end.  It isn't particualrly effective.  Yes it did get a little warm, but the output wasn't outstanding.  SInce it was un-insulated, I think it shed as much heat(if not more) to the atmosphere than it transfered into the water.  The best it did was when I put it into the pool and pulled a clear plastic cover over the top. I think a portion of that increase in temp was due to reducing evaporation off of the pool top:) 

I was contemplating making a round one by coiling thin black poly pipe into a 12' coil to cover the entire pool surface. This would cut down on evaporation and allow me to better seal a clear pool cover on top to trap more air for better insulation.   But fusing that much black poly together into a flat coil that can be easilly handled is a little problematic... 

[BruceM]

I'm presently building a 128 SF hot water collector and 800 gallon storage tank for my offgrid homestead.  I'm using the well tested aluminum fin over copper design by retired aero engineer Gary Reysa at BuilditSolar.com   I think Gary has done more for advancing affordable DIY solar (and all the good that means for both planet and regular folk's pocketbooks) than just about anyone on the planet.  Lots of good designs, comparative performance data, etc.  And totally not for profit, no advertizing.  I'd nominate him for a Nobel if I could.

There's plenty of interesting stuff on plastic based collectors there, too.

Solar domestic shower hot water heating for Hawaii would be interesting and cheap- no freeze worries, high ambient temps.  Enough volume to do a shower within black plastic even sans glazing might work out fine if you limit water use to afternoons.
Let us know how it works out, Casey.  A classic solar batch heater tank (plenty of info on these at builditsolar) would certainly work fabulously.

Best Wishes,
Bruce

[LowGear]

Small steps here in Hawaii.  We're about 20 miles out of Kailua-Kona so I'm dependent on a small Ace hardware for minute to minute items.  Something like a threaded PVC 3/4 to 1/2 adapter means a trip to "The Big City".  Drilling and tapping the ABS on a joint went surprisingly nice.  What have I done right?

Updates to follow.

And Yup.  I'm going to ABS glue that PVC fitting right into the threaded bleed hole.

Casey