Solar hot water heater on a larger scale system

[Lucas]

So here's the deal, I live in a show home and have a separate unit above the garage. Around 1000 sq ft. The main house is 8500 sq ft.

No one really lives in the main house. Sometimes the owner of the company comers, but rare.

My house runs off the same hot water heater. I've mentioned that I should have a separate smaller system, no one wants to spend the money. I may eventually buy a small heater to stop hearing them complain.

I'm trying to dial in the current system. It is located in my bathroom behind an access panal.

The solar system is off currently. Never set right. The hot water heater has two thermostats.

I can't find a brand name on the solar system to find the directions. But I know there must be some sort of balance between the water heater setting. I think initially they were working against each other.

First, the water heater has two thermostats and two heaters. It's like 80 gallons. It sucks water off the bottom and returns it for the solar. There is also a drain back tank.

How should those two be set? Hotter on top? Hotter on bottom?

The solar display will tell me the temp the water heater is hitting. Then I can set it I guess?

Anyone know how to work this mystery box? Or general settings for solar? Hotter? Colder?

Here's some pics.

[KarTek]

That must be an older system to have a drain back. I'm building a solar hybrid system for my house now and it's glycol based, like a car radiator with a heat exchanger.

I'm no help with your problem but I'm always curious how these systems work.

As far as the water heater is concerned, I would set the thermostats the same temp. The way they're supposed to work if they're wired properly is the upper unit comes on (quick heat) and then when it turns off, the lower unit is allowed to turn off for full reheat.

[spdrun]

Originally Posted by KarTek

That must be an older system to have a drain back. I'm building a solar hybrid system for my house now and it's glycol based, like a car radiator with a heat exchanger.

I'm no help with your problem but I'm always curious how these systems work.

As far as the water heater is concerned, I would set the thermostats the same temp. The way they're supposed to work if they're wired properly is the upper unit comes on (quick heat) and then when it turns off, the lower unit is allowed to turn off for full reheat.

Hopefully propylene glycol not ethylene. (!) Ethylene glycol getting into a home water supply would be bad mojo.

[KarTek]

Originally Posted by spdrun

Hopefully propylene glycol not ethylene. (!) Ethylene glycol getting into a home water supply would be bad mojo.

Oh yeah, propylene for sure! Seamless heat exchanger.

[Lucas]

Yes it's about 10 years old. I'm guessing cheap as the controller doesn't have a brand name. Doesn't look cheap. Stainless hardware.

Idk. It would be nice to dial it in. Glad to know to set the temps the same on the heater. They said to turn the bottom one 20 degrees colder and just use the top....

[KarTek]

Originally Posted by Lucas

They said to turn the bottom one 20 degrees colder and just use the top....

Yep, you can do that. You just get about 1/3 the capacity of the water heater, saves money because you're not keeping a large quantity of water hot.

If you find yourself running out of hot water, turn the bottom one up a notch and try again for a few days until you have what you need on a normal basis.

[barry12345]

Usually when a solar system is turned off is because there is a problem with it. Of course there are exceptions.

Years ago I became a believer In the simplest system that will do the job. The panels can be damaged by overheating with no circulation on certain panel designs as well.

[Lucas]

I've been adjusting for days.

I think it was never set up right.

I'm gonna play with these settings and see what the options are. It must have to be colder or hotter.

[rocky raccoon]

I used to have a roof-mounted solar hot water heater when I lived in Connecticut. The tank was "stone lined" (actually concrete). Amazingly, even at that latitude, the solar coil provided all my hot water (120 deg F) for about 7 months out of the year without ever turning on the lower electric backup coil. That backup was set to come on at 100 deg F. Even in the dead of winter, the we still got considerable solar gain and the electric element only had to raise water temperature about 30 to 40 degrees.

Efficient operation presupposes the collectors are set to the proper orientation and elevation for the location and that potentially shadowing trees are topped or removed. The system was of course a secondary heat exchange system using propylene glycol as the medium. In places like Florida, the best efficiency can be realized by a direct heat exchanger with a drain-down capability to handle the ice apocalypse should it ever occur.