thermal storage tank progress

[sunspot]

Originally Posted by randen

Sunspot
check this out...
DIY Geothermal Heat Pump + PV System - No Heat Bills!
Randen

I'd seen that before but worth reading a second, third, etc. time. Nothing short of amazing really. A very dedicated and talented individual.

[solarhotairpanels]

Sunspot.. I took one look at that storage tank and had to jump in here to compliment you.

that is an extremely well built tank which will serve you well for many years to come. Way to GO!

I also have a solar hot water system here at my house I put together over time.. and after reading some of your thread I thought I'd just shoot out a few things on how I setup my system.

Return Collector Water.
I used 3/4 copper TO and FROM.. all the way back to my drainback storage tank for 2 reasons. Ease of water flow when collector pump shuts down and to combat high stagnation returning water temps. So far so good. Water returns very quickly and never a problem with higher then normal water temps.

Collector Head Pressure and Pump Speed:
I use a Resol DeltaSol BS Plus solar controller on my system to operate my collector pump/s which happens to be a Grundfos Pump.

The controller allows me to set/adjust the water flow/pressure/pump speed after initial startup of the pump, so I have mine set to run at full speed (100% pump speed) for about 10 seconds then drop down to 40% pump speed. It does it automatically for you once you are done setting up the controller to your specific specs, which is sweet. You can mess around with different pump run percentages to fine tune things on the fly.

Pre-Heating Your Storage Tank with Wood Stove:
Personally? I think that's a great idea. Of course we would all like it better if we had full sun on our collectors from 6:30am to 5:30am every day of the week but that's just never going to happen... so yes! Having a wood stove involved with the process is a kick butt way to heat your storage water up in a very short amount of time.

Once heated...The GIANT SIZE of your storage tank allows you to circulate this stored hot water thru your radiators/radient floor etc., for a much longer periord of time. Great idea for sure.

My System:
I only have 2/ 20 tube evacuated tube collectors in place so my storage tank size is only 45 gallons. It's a used Superstor stainless steel tank I picked up for cheapo bucks.

I run the hot water from that tank out to a very long Runtal Radiator mounted on one wall of my big family room to supplement heat in that area of the house. The Runtal radiators work great with lower water temps because of their design, so I got lucky to find one used when I did.

At the same time my returning collector water is heating my 45 gallon storage tank (for radiator use) my return pipe splits off in order to preheat a tank tied in before my domestic electric hot water heater.

but back to your system..
Plan on as many collectors as you can get for that big tank and by all means, and as long as you can do it health wise.. keep using that stove to preheat that big tank. I honestly believe you'll do real well doing it that way because the amount of volume you have in that big tank will hold the hot water temps for many many hours.

Good for you Sir!
Have a great Holiday Season and keep up the great work!

[SDMCF]

solarhotairpanels, It seems your system is very similar to mine. Copper pipe all the way, Resol controller etc. My system has a diverter valve to either heat the hot water or feed heat (via a heat exchanger) into the central heating return pipe. I have 5 x 20-tube collectors and my water storage totals 900 litres made up of one 600 litre tempering tank feeding into a 300 litre tank that is also electrically heated.

My system can stagnate if power fails so the pumps can't run. I found out the hard way that when this happens soldered joints are not good to have. Connecting to the panels I used compression fittings but I had a soldered joint about 1 metre after the final panel and that leaked after the system overheated.

[solarhotairpanels]

woW?

I can't imagine what caused that fitting to leak if it was up by the collector?

Once the water drains back down into your drainback tank there's no liquid in the collector or pipes to cause a problem that I know of?

Can you tell me again.. what you feel caused it to leak or what you discovered?
I must have missed something?

Heck, I connected my 2 evac tube collectors side by side together in the middle with regular automotive radiator hose and no problems at all. Year 2 with system running now..

Stagnated Water in Collectors:
If you are holding water in your collectors when the pump shuts down (power outage or unplugged?) something seems to be wrong.
It may be that you have a check valve in your collector pump that is not allowing water to drain back to the tank. The check valve can be removed in most cases to avoid this problem.

let me know when ya get a chance... I'm very interested in knowing the solution and GREAT SYSTEM you have there. Are the 5 collectors doing the trick in December? What kind of water temps are you getting in December??

[sunspot]

Thanks for the compliments and encouragement Pat.

"I use a Resol DeltaSol BS Plus solar controller..."

I've got a lot to learn about controllers. Each manufacturer has so many models and options it takes some time to get familiar with them. I like the idea of varying pump speed to match conditions though. I'll spend some time researching the Resol lineup. Thanks for bringing them to my attention.

"I run the hot water from that tank out to a very long Runtal Radiator..."

More interesting stuff! It seems information is a little thinner on radiators than in floor systems so I'm all ears when I hear of a system using hot water, not steam, in radiators. Have you measured your water temperature at the radiator? You say you're successfully getting supplemental heat in a large room, that's encouraging.

"Have a great Holiday Season"

To you as well. Thanks again.

[SDMCF]

Ah, I wasn't clear. Mine is not a drain-back system so there is fluid in it all the time.

The system basically does nothing at this time of year. The skies here are cloudy at year end. Early in the year we get lots of clear skies though, and that is when the system really works well. Plenty of heat collected even if it is below -30C outside.

The temperatures never get too high in my system unless we get a power outage and lots of direct sun at the same time. I extract the heat very effectively and mostly put it into the central heating. So most of the time the temperatures never exceed 60C. It really is better to run the system cooler if possible. That seemed counter-intuitive to me when I started and took me a while to understand.

When the pipe joint leaked the system got well over normal boiling point and the pipework was making a very ominous noise - bad enough that I kept away from it in case it exploded. I don't know the temperature it got to as I had nothing available to measure that high, but it melted the solder on the joint.

[solarhotairpanels]

If you would like I can help you setup your controller to automatically adjust your pump speed shortly after start up.

What's cool about doing this is.. it's very easy to see if you slowed it down too too much because no water will return to your storage tank.

I'm sure you can hear the water returning when it's pumping now.

What I did was set mine to return at 60% pump speed after startup... then 50 then... 40 and as far down as 30% pump speed while each time listening for the water returning from the collectors. I finally settled in at around 40% pump speed.

The people I purchased my evac tube collectors from told me the collectors will collect more heat by moving the water thru the collecters slower, so that's why I went that route.

If you would like me to tell you how to adjust the collector pump speed using your controller I can make a post right here with step by step instructions.

Once you get the hang of it.. you'll be entering the SETUP mode of your controller in seconds making all kinds of adjustements to 'differential settings' Delta T etc... 12/6 or 12/4 or 10/4 or whatever you want the turn ON/OFF settings to be.

Shortly after getting my controller hooked up I called the MFG and they walked me thru the controller SETUP process step by step.

I never forgot it.

Radiators:
Yes.. Runtal radiators are very thin steel... so they are SUPER to radiate heat rathern then using a regular baseboard or older style radiator.

VERY EXPENSIVE but I found my 15 foot long Runtal on Craigslist for $75 bucks. WHAT a score!

[solarhotairpanels]

Sorry about the mix up.. I thought I was responding to Sunspot when I asked about a leak at the collector with a drainback system.

I can not afford to fly to Finland but if I could I would come out there and try my best to get you to switch your system over to a drainback system.

Much less complicating.. no pressure.. no glycol... no nothing and they work flawlessly.

[solarhotairpanels]

Sunspot..

getting back to my water temps to radiator..

believe it or not... in December my 2 evac 20 tube collectors heat the storage water up to around 115 to 140 degrees.

I have a separate circulator pump that pumps the stored hot water out to my Runtal radiator.

Once the water circulates a couple times the radiator is at around 115 degrees.

This style thin steel radiator does a great job throwing a nice even heat into the room for a steady 3 to 4 hours... and even when the radiator temp drops down to 80 degrees this thing is STILL radiating heat..

Hard to believe I know, but I am not kidding at all about this.

STORAGE TANK SIZE
I want to mention that the storage tank I use in conjuncion with the big long radiator is only 45 Gallon capacity. It is a stainless steel USED Superstor water tank. The reason it is only 45 gallons is because 'that' is all I could afford to buy after purchasing my 2 evacuated tube collectors. I wish I had money to buy more collectors but this will take some time. I am retired now so on a fixed income. I have to do things in LITTLE steps to accomplish my missions. Ha!

[solarhotairpanels]

SDMCF

are you using evacuated tube collectors on your system?