How to temporarily disable batch solar heater

[jeff2013]

Hi, I need to drain and disconnect my solar hot water heater on the roof in order to get to the roof shingles
beneath it. This heater was installed without a pressure tank and eventually I found the pressure to be 150 psi
and release valve on the heater is 125 psi, so drained constantly for prior owner and trashed part of the roof shingles.
I want to move those cruddy looking shingles beneath the water heater and swap out the good ones underneath the heater.
The shingles are discontinued.
Question is how to turn the unit off if I drain it and whether using the valves in the photo hw_heater 002.JPG will allow me
to use my standard hot water heater without the solar. It sort of looks like I have only on/off for the cold water
for both heaters. That red handle valve is probably on/off for both right?

[foo1bar]

That red handle valve is probably on/off for both right?

I can't tell from the picture what valves are for what.

I would diagram out the entire setup - each pipe and valve.
Hopefully there's a easy way to bypass the roof system. If not, you probably go without hot water while doing the roof work. (or you add a bypass)

[SunEagle]

There should be a procedure to drain the panel for either freeze protection or removal. At least I know I can do that to my system.

My guess would be to close both the red and yellow handle valves and then open the blue handle valves after you have connected a hose to drain the water.

Make sure there is some way of allowing water to get to the tank and allow it's backup element to heat it.

[jeff2013]

There should be a procedure to drain the panel for either freeze protection or removal. At least I know I can do that to my system.

My guess would be to close both the red and yellow handle valves and then open the blue handle valves after you have connected a hose to drain the water.

Make sure there is some way of allowing water to get to the tank and allow it's backup element to heat it.

The more I look at it, I think the whole system goes down if I shut off the solar heater. I think you're right about how to drain. Only question I have is what happens if I'm doing this on a sunny day and the solar heater is empty of water. Does that harm the components since it is still "solaring" away. Should I tape some cardboard or something over it. I'm guessing I would need to do something like that, but I'd love to hear from someone who knows the answer to that question. Thanks for responding.

[jeff2013]

I can't tell from the picture what valves are for what.

I would diagram out the entire setup - each pipe and valve.
Hopefully there's a easy way to bypass the roof system. If not, you probably go without hot water while doing the roof work. (or you add a bypass)

I think I'll be going without hot water til the job is done. I was hoping not to have to do that, but the way it's designed I don't see a way to split the systems. Thanks.

[SunEagle]

The more I look at it, I think the whole system goes down if I shut off the solar heater. I think you're right about how to drain. Only question I have is what happens if I'm doing this on a sunny day and the solar heater is empty of water. Does that harm the components since it is still "solaring" away. Should I tape some cardboard or something over it. I'm guessing I would need to do something like that, but I'd love to hear from someone who knows the answer to that question. Thanks for responding.

Well I have flushed and drained my panel during the day but it wasn't empty for that long.

I do not know if an empty panel under the sun will hurt it or not. Maybe check with the manufacturer to see if it can handle to be empty and hot although I would imagine it should be fine.

[Mike90250]

I would cover the panel with cardboard ($5 for a roll of super duct tape) and sleep better, not worried if the sun cooked it. They ARE designed to collect a lot of heat and rely on fluid being present to absorb it,

[jeff2013]

I would cover the panel with cardboard ($5 for a roll of super duct tape) and sleep better, not worried if the sun cooked it. They ARE designed to collect a lot of heat and rely on fluid being present to absorb it,

I agree. It woudn't take long nor be expensive so I'll play it safe. thx.

[jeff2013]

I also meant to ask since I'm disconnecting the unit, should I have it serviced? I'm guessing the last owner never had
anything done to it, so it's about fifteen years old. Do batch solar heaters require any maintenance? If so, does it require a pro or something I can do?

[Wy_White_Wolf]

I also meant to ask since I'm disconnecting the unit, should I have it serviced? I'm guessing the last owner never had
anything done to it, so it's about fifteen years old. Do batch solar heaters require any maintenance? If so, does it require a pro or something I can do?

Do you have a way to charge the system back up? I see an expansion tank in the picture so it is a charged system.

WWW

[jeff2013]

Do you have a way to charge the system back up? I see an expansion tank in the picture so it is a charged system.

WWW

The expansion tank is for relieving pressure from the standard hot water heater. It is not a solar water heater expansion tank. I'm glad you mentioned it though because my plumber installed it and therefore I never boned up much on them. Come to find out, I have to check whether it's working now and again and check the pressure. I'm a little confused though since I've read up on it some. I thought this expansion tank was for reducing pressure as I had high water pressure in the house...up to 150 psi. I measured it at the washing machine supply. After the tank was installed, my pressure went down to about 50 psi. I don't recall the plumber measuring the pressure in the tank as he was supposed to. He also didn't check house water pressure. So, I guess he just went with the default pressure the tank is delivered with. And through some miracle, my water pressure was down to 50. That's not how the unit was supposed to be set up as I've youtubed this subject. One instructional said to first check the house pressure and if it's not between about 40 to 80 psi (normal pressure), then get that pressure problem fixed, then install the expansion tank. I originally read that expansion tanks can relieve pressure which is why I bought it. Then these instructionals all say to get the pressure reading, then pump up the expansion tank to match that pressure. Shoot, if I had installed the tank, I might have tried to pump it up to 150 psi. As it turns out, installing the tank with default pressure seemed to have done wonders with my overall house water pressure. I am really curious now what the pressure in the tank is and I'm going to buy another gauge with schrader valve.
Thoughts?

[foo1bar]

The expansion tank is for relieving pressure from the standard hot water heater. It is not a solar water heater expansion tank. I'm glad you mentioned it though because my plumber installed it and therefore I never boned up much on them. ...
Thoughts?

An expansion tank isn't directly changing the pressure. It provides a place for hot water to expand without going back out to the city water supply.
If there's a valve on your water supply line from the city that prevents backflow then expanding hot water can't flow back to the city water tower (or your neighbors)
And expanding water in a confined space results in high pressure.
Probably your actual water pressure from the city is around 50. And probably you have a valve that prevents backflow. And probably that valve with no expansion tank results in you having 150psi when the water is heated. With the expansion tank, it can stay very close to 50.

The other possibility is the city pressure is 150 to start with. The plumber installed a regulator that keeps it to only 50psi on the house side. And that regulator would also include a backflow preventer. And because of that new backflow prevention he did the right thing and installed a expansion tank.

[jeff2013]

An expansion tank isn't directly changing the pressure. It provides a place for hot water to expand without going back out to the city water supply.
If there's a valve on your water supply line from the city that prevents backflow then expanding hot water can't flow back to the city water tower (or your neighbors)
And expanding water in a confined space results in high pressure.
Probably your actual water pressure from the city is around 50. And probably you have a valve that prevents backflow. And probably that valve with no expansion tank results in you having 150psi when the water is heated. With the expansion tank, it can stay very close to 50.

The other possibility is the city pressure is 150 to start with. The plumber installed a regulator that keeps it to only 50psi on the house side. And that regulator would also include a backflow preventer. And because of that new backflow prevention he did the right thing and installed a expansion tank.

It's actually a deep well, but I think I have a backflow valve. I just measured my house water pressure and it was almost 50 which is good. I felt the expansion tank and it was warm on the bottom and cool on the top, so seems like it's functioning properly. I ordered a gauge to test it though.
thanks. So, if I were to remove that tank, would air leak out and I'd have to recharge it with a bicycle pump or something? Or does it retain the air even if I unscrew it from the system. Similarly, if I turn off water and drain the lines, does that allow air to leak out of the expansion tank?

[foo1bar]

Or does it retain the air even if I unscrew it from the system. Similarly, if I turn off water and drain the lines, does that allow air to leak out of the expansion tank?

Think of it as a big rubber balloon filled with air inside of the metal casing which has water everywhere the balloon isn't. And the opening to the balloon is the valve for pumping air into it.1
If you open the air pressure valve, the air will come out (pushed out by the water pressure on the other side of that balloon).
If you unscrew it from the water pipe fitting, the water will come out, but the balloon keeps the air inside of it (although the balloon gets a little bigger)

Any air bubbles on the water side will dissolve into the water before too long. (ex. drain the system, then add water back in - there will be air bubbles, but they'll dissappear into the water by themselves - and they'll act as buffers against water hammer and over-pressure for the short time they exist.

[jeff2013]

Think of it as a big rubber balloon filled with air inside of the metal casing which has water everywhere the balloon isn't. And the opening to the balloon is the valve for pumping air into it.1
If you open the air pressure valve, the air will come out (pushed out by the water pressure on the other side of that balloon).
If you unscrew it from the water pipe fitting, the water will come out, but the balloon keeps the air inside of it (although the balloon gets a little bigger)

Any air bubbles on the water side will dissolve into the water before too long. (ex. drain the system, then add water back in - there will be air bubbles, but they'll dissappear into the water by themselves - and they'll act as buffers against water hammer and over-pressure for the short time they exist.

Thanks for the explanation. That it was pre-charged makes more sense now and it seems also that I don't have to worry about pumping it back up if I drain the system. That was the big question for me.