Bell & Gossett series 100 pump

[mjz]

Question about the B&G series 100 pump:

Is it possible for the pump to lose its ability to pump even though the motor is running fine?

I am asking because my hot water circulation is no longer working and I have ruled out air lock and other obstructions. The pump just seems to no longer pump. It sounds fine - motor is rotating, the pump impeller and shaft are tight and strong (not sheared). There is some circulation, just very very slow. 4 hours to warm the pipes that normally took 5 minutes.

The only thing different is that the pump body (where the impeller fits into) was badly rusted and pitted (since cleaned) and I think perhaps the impeller no longer is fitting snugly in order to create a "draw" and move the water into the impeller and sling it out the edges.

Has anyone experienced this? I'm prepared to buy a whole new pump because I think part "p00351" is bad. I would replace it with the NRF-22

Very strange ... the pump is only 5 years old (cast iron) and worked normally only a few hours a day (morning showers).

 

[johnjh2o]

Which pump are you using, a bronze body or a iron body? If you at using a iron body on a domestic system it is more then likely plugged with rust. That pump is designed to be used on a heating system.

 

[mjz]

Which pump are you using, a bronze body or a iron body? If you at using a iron body on a domestic system it is more then likely plugged with rust. That pump is designed to be used on a heating system.

It's an iron body. When I took it apart the pump body where the impeller sits was loaded with rust - not completely, but enough. I thought I had found my problem. I cleaned it out and re-assembled. But no change in operation.

Today, I will dismantled the pipe below leading into the water heater. It's possible that rust settled down and is plugging the pipe itself. It doesn't seem like it since water does flow when I open the valve.

 

[Mr_David]

Yeah most likely the line going into the heaters plugged

 

[mjz]

Yeah most likely the line going into the heaters plugged

I found the problem .... ()(#(*)$_@)(#@_$%

Taking a look at the picture:

https://www.dropbox.com/s/v5f0m68gobvnr5t/20161130_132403.jpg?dl=0

The bottom drain pipe inside the water heater is clogged. I found out by shutting down the gate valve below the circulating pump and opening up the hose bib drain. No water flow - or actually very slow water flow.

I didn't discover this earlier because I was stupid. When I opened the hose bib earlier, it flowed great, but the loop valves were open. I wasn't thinking. The water simply flow around the other way. At least I know there is no air in the loop now !! It's certainly been purged. Once I closed down the valves the water from the hose bib slowed to a trickle and should not have. The inlet water valve was full open - plenty of pressure.

So ... the problem is a clogged bottom port from lime buildup (Houston water is moderately hard). The water heater is 5 years old with plenty of life left. I don't want to have to replace it. I tried reversing the flow into the bottom of the water heater with house pressure hoping it would break free the clog (probably calcium buildup). The only other thing I can think of is to drain the tank, take off the valve and break up the clog by sticking something in the port. The problem is the tank won't drain very fast (days probably since the flow is so slow.

Any suggestions?

(p.s. I didn't think there was anything wrong with the Bell & Gossett pump - it's been a fabulous work horse).