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changed from tankless instant hot water to Solar hot water

Posted by toad08 (My Page) on
Sat, Dec 18, 10 at 19:14

I recently changed from all electric tankless instant hot water to Solar hot water system. (No gas).
The problem:
Water from two faucets is 120 degree F but the other faucets such as the kitchen faucet where I need hot water for the auto dishwasher is 100 degree F. This is not clean enough to clean the dishes.
Both elements have been turn up to the max in the solar hot water tank.
The reading from the digital meter: collector: 91.4; tank 134.6 hP 111;
This problem has all of us stumped from the solar installer to the plumber and electrician.

Can anyone explain. ???
The 100 degree F is ok for showers but I like it a tad hotter. It is really strange that only two faucets have 120 degrees F + and the others don't. All the plumbing pipes is in good order. The plumbing worked perfectly when the tankless instant hot water was working.

As you can see in the photo there is a mixing valve on the hot water "red pipe" on top of the solar hot water tank. There is a silver pipe from that going to the cold blue pipe. And from there it is hot to the touch on the cold blue pipe up to the first elbow before the wall. Then the blue pipe is cool to the touch.





Follow-Up Postings:

RE: changed from tankless instant hot water to Solar hot water

I have solar water myself, and have not experienced this! Usually, they want a back-up heat source, such as your instant water thing. I have a back-up water heater that I have turned off at the fuse box 11 months of the year.

Is the distance far from your elements? I am far from technical, but am interested in what your solution turns up being.

Good luck,

RE: changed from tankless instant hot water to Solar hot water

I am not clear on your set up. What are you not telling us? I do not understand what “tank 134.6 hP 111” means. Where is the blue pipe connected to & what temperature is the blue pipe water?

It seems to me that for this to operate properly, especially with a mixing valve, that you may need a buffer tank between the solar collector and the active tank. Can you possibly supply us with a detailed schematic including temperatures & flow chart?


RE: changed from tankless instant hot water to Solar hot water

As stated in my first post the blue is the cold water.

RE: changed from tankless instant hot water to Solar hot water

Have you tried removing the mixing valve?

According to the schematic, the solar water heater tank should be passive. Your tank is active, based on the electrical connection seen in the photo.


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