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N4KIT

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Posts: 45
Reply with quote  #11 
I just noticed the graph is a bit hard to read, so here is an un-shrunk one (sorry if this exceeds the standards Scott!).

C.

2014-04-21 Graph.PNG

Something to note is the Groundwater and HEX output temps.  The ground water sensor is located on the incoming CW line right after the main shutoff valve.  At the moment that pipe is uninsulated and located in a semi-conditioned space (the garage).  The HEX output sensor is located on the output of the HEX, close to the tank, so it tends to see a higher temp due to proximity.  You may note that when there is a hot water draw, the HEX output temp goes up (as expected) and there is a corresponding drop in the groundwater temp as fresh water is brought into the system from the underground pipe from the well head.


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ChrisJ

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Reply with quote  #12 
Great job Chris!

How is the Alpha doing? What does it show for GPM & Watts?

ChrisJ

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Rhode Island
N4KIT

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Posts: 45
Reply with quote  #13 
Hi Chris,

Thanks!  The Alpha is doing fine.  I was hoping that the static/friction head on startup would fall within the range of the Auto-Adapt feature, but alas it is not so.  I have to run the pump on the high fixed speed setting.  Given that, I probably could have used a lower price fixed speed or 3 speed pump, but that's OK - nothing ventured, nothing gained.

On startup until the water level makes it to the high point, the pump runs at about 1 GPM and 43 watts.  Once the water level is "over the top" and the partial siphon begins to form, the flow steadily builds to max at 8 GPM with the throttling valve on the return wide open.  I have the valve cranked down to deliver around 4 GPM according to the pump display, but I have to confirm that by direct measurement this weekend.  The power reading is a pretty steady 43 watts.

The system made it up to full 150 degree setpoint on Wednesday about mid-day and is now in "maintenance mode".  I figure the pump daily power consumption is between 0.06 and 0.12 kWH depending on demand - or about 1 to 2 cents per day at current electric rates.

Here is yesterday's data plot.  I need to noodle out some solution to the short-cycling, or I may have to live with it until I put more load on it by adding the radiant floor heating.

Note the HEX, HWH and DHW sensors are reading pipe temperatures, so they fluctuate depending on if there is flow in the pipe.

Here's yesterdays plot:

2014-04-24 Graph.PNG 


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It's really kind of cool to have solar panels on your roof.
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ChrisJ

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Posts: 96
Reply with quote  #14 
Chris,

Can you give us an update on your system?

ChrisJ

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Rhode Island
N4KIT

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Posts: 45
Reply with quote  #15 
Absolutely Chris!

We've been running the system now for 7 months.  Except for a problem last week (more on that in a sec) we have been getting 100% of our hot water from the solar.  How do I know that you ask?  Well, actually, the electric backup heater has been off for the whole period!  I discovered that when I had to address the problem last week.

So the wife calls me at work and says the pump on the solar tank is making weird noise and the flexible vinyl sight tube is disconnected at the top and hanging bent over.  Oh Crap - says I... unplug the controller and I'll look at it when I get home.

So what happened was I think I made the sight tube (a piece of 1" thick wall vinyl tubing) too long (@18") and that allowed the hose-clamped upper connection to slip off the copper to the collectors.  I have now shortened that tube to 4" so there is not enough flex in it to allow it to come loose.

Bottom line is we pumped down 200 gallons of water and had to re-fill and re-heat.  Thank goodness there was no damage to the pump.

I suspect in just a few weeks, I'll get the "hot water isn't hot" call and have to turn on the backup heater, but I'm hoping to still get a substantial solar fraction over the winter.

Best to all!
Chris

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It's really kind of cool to have solar panels on your roof.
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N4KIT

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Posts: 45
Reply with quote  #16 
And 'cause everyone likes pictures - here's the last plot I did.  They were all looking pretty much the same, so I quit doing them (other projects to work on [frown]).

2014 May 31.JPG 


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It's really kind of cool to have solar panels on your roof.
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N4KIT

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Posts: 45
Reply with quote  #17 
One more thing since I last posted settings.  The final operations settings I have are:

DOn = 18 degrees F
DOff = 2 degrees F
Tank Hi Limit = 150 deg F
Pump is still set high fixed speed
Flow rate is throttled to between 1.5 and 2.0 gpm

Most days that we have good sun, the tank recovers to 150 deg easily.  It typically drops to about 140 or so with 2 showers and a load of dishes at night.  It will hold about 3 days of no sun conditions before the tank drops below 120.

C.

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It's really kind of cool to have solar panels on your roof.
Bill Gates
ChrisJ

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Posts: 96
Reply with quote  #18 
Hopefully no water damage!!

Thanks for the update, maybe solder a barbed fitting on for the sight tube.

ChrisJ

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Rhode Island
stmbtwle

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Reply with quote  #19 
Speaking of sight tubes, I discovered some time ago that 5/8 OD polycarbonate tube is exactly the same diameter as 1/2" CPVC pipe, and the fittings for CPVC are a perfect fit.  Even the CPVC glue seems to work.

I made sight glasses for the water tanks on my boat this way, and they work just great.

I've also discovered that 5/8 OD reinforced vinyl tubing from the home store glues into CPVC fittings.

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ChrisJ

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Posts: 96
Reply with quote  #20 
2 Winters later.... How's it going!?!?

ChrisJ

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Rhode Island
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