I saw it with my own eyes, the pump was moving the water backwards.
When I was working for a plumbing and heating company in Alaska, many times I would be called to assist other plumbers in the company when there was a problem they could not figure out.
On one of those days a very smart and talented plumbing and heating technician called me to come and help him with an unusual problem, he could not get one zone to heat. This was the way this building was set up, it had 4 apartments all on the same level, and there was no second floor.
The boiler was in the middle of the building; there were 2 apartments to the left and 2 apartments to the right. The boiler had 2 zones controlled by 2 circulators, 1 zone heated the 2 apartments to the right and the other the 2 apartments to the left. Each zone was a single 1Ē copper loop (not mono flow tees) each zone had a flow check valve installed. The 2 apartments at the end of the buildings had the thermostats that controlled the heat the 2 inner apartment had thermostats that had wires that just went into the crawl space and did not connect to anything (this led to many future calls for service)
This was the problem the technician was having, the zone to the left was working fine and the return pipe to the boiler was hot, but the return line from the zone to the right was not getting hot, being this was Alaska, frozen pipes are the first thing you check in this situation, but the zone purged easy, the boiler feed was on the supply side and the purge setup was on the return side and the valves were new ball valves, the water flowed freely and all the air was out of the loop, but the water would not circulate.
I turned the working zone off to be sure the vibration I was feeling was not coming from the other circulator, I could feel and hear the circulator running, but the water was not moving, I checked the power going to the circulator, there was power going to the circulator but the water would not move, I thought the circulator must be defective some how so I replaced it with a Grundfos circulator (Oh, NO! I did not have the pump in backwards) with the new Grundfos pump installed I had the same problem, the pump was running, there was no air in the zone, the zone was not frozen but the water would not flow.
I thought there had to be something stuck in the flow check valve but the other technician just replaced it, I was truly stumped, this should have been very simple to figure out but it just did not work. At this point the office called the other technician off this job to go do something else. I decided it had to be in the flow check valve or the nipple attached to it,
So I took the head of the flow check removed the flapper pushed a small piece of pipe down through to be sure there was no obstruction in the nipple then put the head back on with out the flapper installed, refilled the system and turned to power back on. To my amazement the water was now circulating, but not from the supply to the return, it was moving from the return to the supply (as I said I did not install the pump backwards) not as fast as it would if it were working properly, but not as slow as it would if it were moving by gravity.
How can this be? This does not make any sense, I have been doing this for years and never seen anything like this before, and I cannot explain it.
Finally the water made itís way back to the supply hot, the zone was working but backwards and not very fast, but this is not acceptable and I will not leave this like this. Iím missing something; I over looked something, but what? Where do I start looking? Taco and Grundfos pump cannot run backwards even if you cross the wires they will still run in the same direction, but both of the pumps did the same thing.
Sometimes when we arrive on a job we focus on the abject of the job, in this case the boiler, and we donít notice other things in the room that are out of place, like electrical boxes with the covers removed and live wires sticking out of the sheetrock with out even a wire nut on them, but if you have been doing this as long as me, you see this as normal as many boiler rooms are in this bad and dangerous shape.
Now Iím sure it has to be electrical, even though I can feel and hear the pump running and I know it canít be running backwards, I have to solve this problem.
I start looking at the electric boxes with the covers removed, testing to see what wires are hot I notice in one box both the black and white wire are hot, itís possible it is a 240 volt power supply to something in the building, this is not unusual, but then I noticed they (the black and white wire) are on the same leg not 240 volts, was I getting power feedback on the white wire?
So I traced it back till I found the problem. Some handyman (want to be electrician) crossed the wires in an out let box he installed, at this point he tied the white common wire to the black hot wire it did not pop the breaker because the power only went down the white wire from the box and not to the white wire going back to the common connection on the breaker panel.
I traced this white wire all the way to the circulator, so both wires connected to the circulator were hot but the same leg, and I guess the body being grounded to the ground wire and the boiler itís self being grounded caused this pump to either run backwards or to just vibrate.
I fixed the cross connection and the circulator worked normal. To this day no one believes me about the pump that ran backwards. And if I had not seen it myself I would not believe it either.
How insane is it to allow anyone who does not have a license to work on electricity?
About as much as it is to let someone do plumbing or heating with out a license.
The real kicker here is, once I got this working correctly I made a note on the invoice for the landlord to get a license electrician in there to fix all of the other wires that were sticking out of the wall and to make sure there were no other wires crossed.
Well the landlord had the same idiot come back and caused another problem that caused the same zone to fail (2 weeks later), my manager went out there and found a loose wire in the control box for the circulator that caused this whole problem and convinced himself that this was the problem all along and I and the other technician just missed it.
To this day I have not been able to convince him that the loose wire was the result of the idiot coming back and messing with the wires again.
So I'm the only one that saw this pump run or appear to run backwards and everyone including the tech I came to help, have poked fun at me for saying the pump was running backwards, but I know what I saw.