Indirect HW is cold

Steve Garson_2

I had to replace a bad expansion tank on my hydronic system. I bled the systems but the indirect hot water heater does not get hot. In reviewing the piping, I wonder if it was piped incorrectly all along. Photos are attached, with this description:

1. The zone valve servicing the indirect HW heater is open and the pipe rising out of the valve is hot, all the way to the water heater.

2. The return pipe on the water heater is connected to a pipe that goes to the rest of the heating zones, with a one-way valve and air separator located between the boiler and the indirect HW return connection, directing water away from the boiler to the rest of the house.

3. The To-System pipe on the boiler (WM GV7) is the return pipe.

4. It appears that the "From System" pipe gets hot all the way to the indirect HW heater.

All the zones heat correctly. I feel like I have bled the indirect HW zone well, but perhaps not.

Is there a piping problem? Or is the solution just running more water to try to eliminate an air bubble that is blocking the water circulation?

On the WM manual does "To System" mean to the heating loops and "From System" mean from the eating loops? Or vice-versa?

Thanks for your assistance! See new photos in response to this thread.

Tom_133

Can you take your pics from further back? We can usually decipher most of it if we can see all of it

HVACNUT

Yeah pics from farther back and different angles. 
Need to know where the PRV (auto feed valve) is piped into the system. 
I see a drain on the supply manifold but no shut off valve down stream of it or the water feed downstream of that, so I don't know what that's for.
Looks like a common return for the indirect and at least one other zone. 
All other zone valves are closed except the indirect when you purge, right?

Steve Garson_2

Here is the long view.

All was working fine before I drained the system to replace the expansion tank.

I'm a bit confused on the water flow. Until I just finished another bleeding of water, the pipe coming out of the zone valve was the hot pipe. Now the pipe other pipe is the hot pipe. Weird.

The pipe connected to "To System" connects to the one-way valve which points away.

Note: One-way valve and air separator flows from right of screen to left.

Steve Garson_2

Might the coil be clogged?  Or is that unlikely?

mattmia2

Unlikely the coil would just clog because you changed something else. Or ever unless something was really wrong with your system water.

Is the cap open on that automatic air vent on the air scoop? Looks like it was leaking, did someone close the cap so it would stop leaking and also would not vent?

Where is the circulator? I don't see a circulator near the boiler.

HVACNUT

Open the zone valve to the indirect. 
Make sure other zone valves are closed.
Close the ball valve with the Blue handle behind the boiler aquastat. 
Connect a hose to the drain valve near the zone valves and purge.
Make sure the feed valve works.

Your labeling is wrong.
The scoop is on the return. It's ok because the boiler uses an internal circulator it's still pumping away. 

Steve Garson_2

Thanks everyone for your suggestions. It turned out that the circulator had failed.

mattmia2

Well that would do it.

HVACNUT

Steve Garson_2 said:

Thanks everyone for your suggestions. It turned out that the circulator had failed.

But you said the heat was working fine and there's only one circulator. 🤔

mattmia2

There is another circulator. it isn't clear what it does from the pictures, maybe a lower temp loop.

HVACNUT

mattmia2 said:

There is another circulator. it isn't clear what it does from the pictures, maybe a lower temp loop.

I see a bronze circulator connected to pex that looks like a recirculating line.
The boiler has an internal Taco 007 that controls the heat and DHW.
I'm confused. Wouldn't be the first time. 

mattmia2

It seems to be connected to some sort of a thermostatic valve. Could be for dhw.

EDIT:
Er that looks like a PRV and the feed to the boiler near it so it is probably DHW recirculation.

EdTheHeaterMan

The Expansion tank is not piped as the diagram illustrates. However the way it is piped is fine. There is no pumping away from expansion tank unless you use this diagram.

Here is what I see The zone valve closests to the boiler (Left) should be from the return of the DHW Tank

HVACNUT

I thought the supply would be the higher of the two taps in the boiler.