Needing controls for solar water project

[netttech]

As Mountian mentioned in a post, now is a good time to tinker with solar thermal. I'm currently re-designing my failed solar water radiant heat project to try again (I don't give up easily).

One thing I hadn't figured out/or found previously is a good control method to activate the pump (to circulate hot water). I have an old heat/fan limit switch I used for my solar space heating panel. I was going to try using that, but really need the correct equipment to measure the water temp in the panel to activate the pump.

SInce I really didn't know what I needed, I wasn't able to truly locate the parts/controller I felt was necessary.

So can someone give me an idea what I need & where to find these parts?

Remember, I don't want the pump to activate on/off based on room temp (house thermostat), but when the water temp in the panel is hot or not.

Thanks
Jeff

[kbhale]

I'm in the process of building a couple solar water panels. Plan to store the hot water in barrels. To circulate heat in the house I will use a regular line 115 volt Thermostat to trigger pump and fans. For the panels Snap disk or Bi-metal Thermostats. I'm looking at * SKU: 3F05-1 * Brand: White Rodgers .. $11.89

http://www.pexsupply.com/pex/control/category/~category_id=644/~refine=200644+1000009+10090

[Mike90250]

http://solarroofs.com/solarroofs.com...pricelist.html has a lot of good DIY gear.

Mike

[netttech]

Thanks Mike, KBhale. KB I came up with the idea installing radiant heat after I browsed the Pexsupply website. I had never found those thermostats though. I was trying to figure out how to build-in/use my old limit switch into my solar hot water (if/when I get it working).

Mike I went to your suggested website. Ironically, my new design, is about about the same as their collector. Nearly same materials, size, etc. I came up with the idea after browsing a few other links from this forum & realized my flawed original design.

I am about finished with my test panel. I actually have 2 designs in mind, finishing the 1st.

It's supposed to be sunny this weekend & I will be able to give the 1st design a good test.

Thanks again
Jeff

[mountain]

A differential thermostat is key to squeezing every possible Watt-hour of energy out of any solar-thermal harvester.

I build my own digital version that works like this:
If temperature sensor TS_A is 4 DegC warmer than TS_B, then turn fan relay ON
If (TS_A + 2 DegC) is < TS_B, then turn fan relay off

For my solar air harvesters, TS_A is located at the warm-vent entry point.
TS_B is located immediately adjacent to, but not directly in, the cold-vent.

The relay can control a fan or pump.

If you Google "differential thermostat", you will get lots of links.

The commercial ones are not cheap. Homebuilt for $40.00 no problem.

[mountain]

source for disk thermostats

http://www.alliedelec.com/
search "selco"

there will be hundreds of fixedT disk thermostats listed.

for simple solar-thermal stuff, you want "close-on-rise" type

[netttech]

I checked out the website...thanks. I agree, these are exactly what I am looking for. I just didn't know what they would be called. I will look around locally to see if I can buy it here. There's should be a local supplier to provide the product to Heat/Ac/Furnace businesses.

Buying local (if possible) is a quirk of mine. I try to buy eveything I can locally to support business. Yea, I know at times, I could likely save a few bucks, but the extra few bucks stays in the area.

Well our weather forecast changed, so my solar thermal test panel will have to wait until Monday. However, my free-standing wood/coal burner/converted to boiler, I should still be able to perform a test tomorrow.

My orignal idea was to have both, solar thermal & the wood-burner boiler work in conjunction with each other for radiant heat. On sunny days, the solar thermal runs, at night the boiler. I have plotted my pex loops & how to get one or the other to work...when needed. All I needed was the correct controls to activate them automatically.

I will post my test results (maybe some pix too).

Thanks for the info guys.

[russ]

You end up with a mismatch between solar thermal temps and temps the boiler requires İ believe - probably means another mixing arrangement and possibly tank.

[netttech]

Yes, I agree Russ on the mismatch. However, neither would be running/ producing heat at the same time. The boiler needs wood to produce heat, which I would start in the early evening. I have it plotted where auto-valves would shut-off (or turn on) depending on which heat source is activated.

I didn't explain my functioning plan correctly. Both systems would compliment each other, but not work in conjunction. If it's a sunny day the solar heats the water, pumps thru the loops. After I return from work, I stoke up the wood-burner, to pump the boiler heated water thru the loops. Never at the same time though.

I do appreciate all the feed-back though.

Thanks
Jeff

[markocale]

My http://www.differential-thermostat.com/

[russ]

Hi markocale - Welcome to Solar Panel Talk!

Russ

[LucMan]

As Mountian mentioned in a post, now is a good time to tinker with solar thermal. I'm currently re-designing my failed solar water radiant heat project to try again (I don't give up easily).

One thing I hadn't figured out/or found previously is a good control method to activate the pump (to circulate hot water). I have an old heat/fan limit switch I used for my solar space heating panel. I was going to try using that, but really need the correct equipment to measure the water temp in the panel to activate the pump.

SInce I really didn't know what I needed, I wasn't able to truly locate the parts/controller I felt was necessary.

So can someone give me an idea what I need & where to find these parts?

Remember, I don't want the pump to activate on/off based on room temp (house thermostat), but when the water temp in the panel is hot or not.

Thanks
Jeff

This will work for you, has many different system type options.

http://www.shuangri.com/en/List.asp?Shop_ID=362