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I've had repeated boilover problems with a solar water heater setup. The system worked pretty good for a year (just past the warrantee on the %#$&%*$ pump Grrr.) but now has lots of problems.
Here is the setup:
100 gallon storage tank, heat exchanger is 60 ft 3/4" soft copper coiled inside the tank.
El Sid 10W pump run on a solar panel
10W solar panel, bought to match the pump
(2) AET 7X4 ft collectors.
Wellsaver bladder expansion tank. I think it is 2 gallons (label is conveniently turned around to the wall, hard to read)
All piping is 3/4" copper, maybe 100 ft total length and about 14 elbows.
there is maybe 25 ft vertical from tank to collectors. Closed loop, so vertical rise does not mean pump head.
filled with Dy Na Flow propylene glycol 50-50%
P&T safety valve off a standard hot water heater, 210F or 150PSI. Outlet of safety valve goes into a bucket to conserve glycol. Safety valve is at the highest spot on the piping near the collectors.
There is an emergency heat dump that kicks in at 180F tank temperature. It has never gone off as far as I know. It dumps domestic hot water to drain if it goes off.
I can fill this system, see it all apparently run in the morning, come back in the evening and the P&T valve has popped, losing 3 gallons of glycol into a bucket, which I then carry back down a ladder, turn on the separate fill pump, refill the system, and bleed out all the air. Rinse. Repeat. I've done this maybe 5-6 times now.
If the pump stopped, for any reason, for a hour the system would boil over in full sun, just like it is doing.
Here are the tests I have run:
Pump electronics has never been wet
Pulled the El Sid pump. Ran it on 12V DC. Verified that it pumps water when the business end is put into a bucket.
Checked the solar panel open circuit voltage and short circuit current. All within spec.
Moved the solar panel. It was getting a little shadow in the morning, allowing the water to get up to 160F before it wasn't shaded. Now there is not even a trace of shadow on the solar panel.
Checked system temperatures on a sunny day with a thermocouple probe. 100F tank temperature, 100F coming into the panel inlet, 120F on the panel outlet, 120F coming back into the tank. Temp varies through the day but never over 140F.
Ran the pump in the system on 12VDC from a power supply. ran all day, didn't boil over.
Thoroughly checked the glycol for PH, freezing temperature, and reserve alkalinity. All within spec, despite having boiled over a few times.
Can watch the temperature gauges in the morning, and see about 20F delta T between the two collector pipes. No doubt about it, pump is pumping and collector is working of a morning.
Checked expansion tank air pressure. 30 PSI.
Twice, when I applied 12VDC to the El Sid pump, it failed to start for a little while. It has four LEDs, two indicate power and the other two indicates that El Sid thinks it is pumping. Only the first two LEDs came on, for a few seconds. This is fishy.
I can also sometimes hear the El Sid hum varying, like the pump is lugging up and down. This doesn't make much sense, there should be no variation in flow once all the air is out of the system. This is also fishy.
No flow meters in the system (mistake) so I can't tell for sure if the pump is pumping when its 4 LEDs light up. I can hear it hum though. I can also tell by temperature gauges - if the supply water is 100F and the return water is 120F coming off the collectors, then it has to be pumping.
So how come this system is boiling over all the time? Can anyone suggest a test I have not run? I can replace the El Sid pump driver, but that's a $250 shot in the dark.
Here is the setup:
100 gallon storage tank, heat exchanger is 60 ft 3/4" soft copper coiled inside the tank.
El Sid 10W pump run on a solar panel
10W solar panel, bought to match the pump
(2) AET 7X4 ft collectors.
Wellsaver bladder expansion tank. I think it is 2 gallons (label is conveniently turned around to the wall, hard to read)
All piping is 3/4" copper, maybe 100 ft total length and about 14 elbows.
there is maybe 25 ft vertical from tank to collectors. Closed loop, so vertical rise does not mean pump head.
filled with Dy Na Flow propylene glycol 50-50%
P&T safety valve off a standard hot water heater, 210F or 150PSI. Outlet of safety valve goes into a bucket to conserve glycol. Safety valve is at the highest spot on the piping near the collectors.
There is an emergency heat dump that kicks in at 180F tank temperature. It has never gone off as far as I know. It dumps domestic hot water to drain if it goes off.
I can fill this system, see it all apparently run in the morning, come back in the evening and the P&T valve has popped, losing 3 gallons of glycol into a bucket, which I then carry back down a ladder, turn on the separate fill pump, refill the system, and bleed out all the air. Rinse. Repeat. I've done this maybe 5-6 times now.
If the pump stopped, for any reason, for a hour the system would boil over in full sun, just like it is doing.
Here are the tests I have run:
Pump electronics has never been wet
Pulled the El Sid pump. Ran it on 12V DC. Verified that it pumps water when the business end is put into a bucket.
Checked the solar panel open circuit voltage and short circuit current. All within spec.
Moved the solar panel. It was getting a little shadow in the morning, allowing the water to get up to 160F before it wasn't shaded. Now there is not even a trace of shadow on the solar panel.
Checked system temperatures on a sunny day with a thermocouple probe. 100F tank temperature, 100F coming into the panel inlet, 120F on the panel outlet, 120F coming back into the tank. Temp varies through the day but never over 140F.
Ran the pump in the system on 12VDC from a power supply. ran all day, didn't boil over.
Thoroughly checked the glycol for PH, freezing temperature, and reserve alkalinity. All within spec, despite having boiled over a few times.
Can watch the temperature gauges in the morning, and see about 20F delta T between the two collector pipes. No doubt about it, pump is pumping and collector is working of a morning.
Checked expansion tank air pressure. 30 PSI.
Twice, when I applied 12VDC to the El Sid pump, it failed to start for a little while. It has four LEDs, two indicate power and the other two indicates that El Sid thinks it is pumping. Only the first two LEDs came on, for a few seconds. This is fishy.
I can also sometimes hear the El Sid hum varying, like the pump is lugging up and down. This doesn't make much sense, there should be no variation in flow once all the air is out of the system. This is also fishy.
No flow meters in the system (mistake) so I can't tell for sure if the pump is pumping when its 4 LEDs light up. I can hear it hum though. I can also tell by temperature gauges - if the supply water is 100F and the return water is 120F coming off the collectors, then it has to be pumping.
So how come this system is boiling over all the time? Can anyone suggest a test I have not run? I can replace the El Sid pump driver, but that's a $250 shot in the dark.
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