Mystified by a Solar Heating System I Need to Remove

[mike s.]

Hi, I'm new to this forum. I have a solar water heating problem that I really need some help to solve. My house was built in 1981. It has a solar water heating system above the attached garage, with a large storage tank in the garage. I bought the house in 2004 and the system was already disconnected then: a controller and water pump on the water tank was unplugged, and a copper line with a Grundfos pump on the end of it comes out of the wall in my (propane) water heater room and is capped off. At least, I thought the system was disconnected. The roof is now leaking where the panel pipes come through, and the solar system has to come out. I thought it would be easy to disconnect the system, but not so.
Four pipes go into (or out of) the water storage tank. Two go through the roof to the panels, and two (one insulated, one not) come from the house. I thought I could just cut and cap the pipes coming from the house, but when I shut a valve on the non-insulated pipe just above the water tank, it shut off all hot water in the house! So I traced back the 2 pipes going into the house, hoping for a manifold or something. No manifold. The pipes come in from the garage into the house attic, and then go down into the same wall where the propane water heater lines come out to the heater.
This is very confusing. It seems like the 2 pipes from the solar tank are going directly to the propane water heater. But then, how is hot water being distributed through the house? If the propane heater is sending water to the solar tank, why is one of the lines uninsulated?
I'm guessing there must be some sort of mixer in the wall by the propane water heater, but why would anyone build it that way, with it all hidden in the wall? There is a sort of manifold system with a control valve above the water storage tank, but why would it be put there, 50 or 60 feet from the house, proper?
Since the water storage tank is still plumbed into the system and closing a valve above the tank shuts off hot water to the house, what was that capped line in the water heater room for?
Am I going to have to open up the wall in the water heater room to figure this all out? Is this something completely obvious to solar water heater professionals?
If I get pics loaded, you'll see that I twisted a copper pipe when trying to disconnect it from the storage tank. Thank goodness I stopped what I was doing before I turned the house into a "cold water only" house.
Very sorry for all the questions. I don't expect anyone to try answering all of them. I just need a few words telling me how to get this mystifying system disconnected.

[Mike90250]

Check with your city and see if there is a system diagram in the permit file for your house ?

[mike s.]

I can try doing that tomorrow, though when I bought the house I got county schematics (e.g., for the septic system) but nothing for solar. Hour+ drive each way, too.
So if no one else has suggestions, it looks like I have to take out a wall to see what pipes go where.

[PNPmacnab]

Usually the solar heating pipes are a closed system. The solar part goes into a loop coil in the tank and exits. Pump operates when hot enough. That may not be the case if your roof is leaking. From only a cursory look, the pipe you twisted up is the hot water exit to the house, the other is the cold entrance. That T looking connector is a tempering valve. It mixes cold water with the hot should the hot water be over 120F. If replacing the tank, this is where you would connect like any water heater. If you cap off the bottom and side pipe, the roof should stop leaking. Looks like you are due for a new tank.

[AzRoute66]

In the past I have used a $5 stethoscope to trace pipes (and wires actually) by having someone tap the pipe at the far end.

[LucMan]

The line going into the bottom of the tank should be the hot coming back from the panels, don't see a valve on that line. If you put a plug in that line that should solve your problem.
The other solar line should be the line coming off the side of the tank and that valve is closed so should be ok unless the valve is leaking by.
No need to open the wall there is nothing in there except maybe some elbows.

[mike s.]

Usually the solar heating pipes are a closed system. The solar part goes into a loop coil in the tank and exits. Pump operates when hot enough. That may not be the case if your roof is leaking. From only a cursory look, the pipe you twisted up is the hot water exit to the house, the other is the cold entrance. That T looking connector is a tempering valve. It mixes cold water with the hot should the hot water be over 120F. If replacing the tank, this is where you would connect like any water heater. If you cap off the bottom and side pipe, the roof should stop leaking. Looks like you are due for a new tank.

The closed system makes sense. The leak is from rain through panel mounts. The panels have to come off and the roof has to be redone. I plan to remove the panels and solar water tank for good. If I completely remove the solar system (tank & panels) then I guess I still have to get into the wall because the water line from the street must be in there somewhere, and I will need to connect it directly to the propane water heater.

"In the past I have used a $5 stethoscope..." I have one and good idea; I might just have to do that.

"No need to open the wall there is nothing in there except maybe some elbows." But water must be coming in from the street somewhere in that wall, and I'll need to connect it directly to the propane water heater.

Two things that still don't make sense are that: 1) both lines coming out of my propane water heater are insulated, while one of the lines going to the solar tank is uninsulated (so maybe behind the wall the street line is going directly to the solar tank...?); and 2) why is there a disconnected water line and pump in my propane water heater room?

Anybody live in Socal and have a use for the system if I ever get it out?

[NEOH]

This picture shows the solar heat panel ( pump (cold) line & return (hot) line ) connections into the side of the tank and
the domestic hot / cold lines on the top of the tank.
The pump draws cold water from the bottom of the heat exchanger coil inside the tank.
The connection into the side of the tank is the hot return from the solar heat panels, going into the heat exchanger coil inside the tank.

4 PIPES in the wall, from Left to Right, in your 3rd and 7th photos ...
Left Most ... Domestic Hot Water out of tank to the house
Then ... Solar Hot Water Return down from the Solar Heat Panel into the tank's coil
Then ... Solar Cold Water Supply from the tank's coil up to the Solar Heat Panel
Right Most ... Domestic Cold Water into the tank


http://www.hotwaternowco.com/images/...olarlayout.jpg

[mike s.]

Got it. Water supply goes directly into the solar tank. So I guess I have to open the wall behind the propane water heater and re-direct the water supply directly into the heater. Still want to know what the disconnected line and pump in the water heater room is all about, since all other hardware seems to be accounted for.

[mike s.]

Great schematic, by the way.

[LucMan]

Got it. Water supply goes directly into the solar tank. So I guess I have to open the wall behind the propane water heater and re-direct the water supply directly into the heater. Still want to know what the disconnected line and pump in the water heater room is all about, since all other hardware seems to be accounted for.

HW recirc line to keep hot water at the taps.

[SunEagle]

HW recirc line to keep hot water at the taps.

Sometimes using a circulating pump for the HW will use more energy then just letting the main water heater keep the tank hot and losing some cold water at the taps waiting on the hot water.

[J.P.M.]

Sometimes using a circulating pump for the HW will use more energy then just letting the main water heater keep the tank hot and losing some cold water at the taps waiting on the hot water.

Like always. Hot water recirculators in a residence for the purpose of instant, or semi-instant hot water are a complete and utter energy hog. Such systems are needed in large building. In a home, and for a lot of reasons, they are no more than an extravagant waste.

[bcroe]

Like always. Hot water recirculators in a residence for the purpose of instant, or semi-instant hot water are a complete and utter energy hog. Such systems are needed in large building. In a home, and for a lot of reasons, they are no more than an extravagant waste.

Do you have a pool? Bruce Roe

[J.P.M.]

Do you have a pool? Bruce Roe

What does having a pool got to do with a DHW recirculating system ?