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This Woodford had a solid brass stem. I soldered 3/8 hard drawn copper tube over it to make the extension.
The bib was already there, under the deck, I just extended it

That looks like a Navian combi boiler, not a tankless. The pump in the unit is the primary pump.

Assuming the return beside each zone pump is for that zone then it is proper primary secondary piping.

What is the issue with the system, is there no heat and DHW or neither works?

I think I see a circ inside the boiler? If so that is the primary pump and it needs to run when any zone calls.

Tankless don't generally have a circ inside, are you sure it is not a boiler? Or a combi boiler.

The boiler is within the primary loop.

If the boiler circ is not running, the boiler will probably hit high limit quickly and shut down.

Now if those secondary circuits are not connected properly, supply and it's related return right next to it, (closely spaced tees) then it is more of a parallel loop, not P/S, and those circs would move some flow thru the boiler.

Always had trouble with flame rods and consider them unreliable. I have cleaned hundreds of them, cleaned the ground path, the flame rod, ran separate ground wires everything. Sometimes they work and then they don't.

Some controls like the Siemens LFL do not have test jacks and you have to wire your meter in series with the FR. Riello gave up on the flame rods and went to ultraviolet.

That being said a Flame rod is the safest flame detector because it uses the flame for circuit conductivity that is if you can get them to work. Rooftop MU air units frequently came with FR detection and didn't work well. I converted many to UV

Flame rods are only for gas, not oil.

Ultraviolet can be used on oil and gas but works better on oil which has more UV light.

I always found flame rod signals weak and erratic

Infrared (otherwise known as lead sulphide) works on oil or gas.

I have always found that the MFG recommended flame signals are on the low end. What they tell you is the minimum reliable signal is usually lower than what you need for reliable operation.

The signal also needs to be relatively steady. A higher signal that is erratic is worse than a lower steady signal.

It is also better to use an analog meter for flame signals. You can see the meter needle move. Some digital meters can't move fast enough to catch the low and high meter readings

Yes Prier aquired Mansfield almost 20 years ago.

Prier and Sioux Chief are close together near KC. I thought that they might combine at some point.

troubleshooting

Electrical high and low voltage

Circulators

X tanks

how bout combustion analysis; diagnosis, troubleshooting and adjustments.

best