Boiler circulation problem

Alex Giacomuzzi

Jimbo
Given the recent run of cold weather, could any of the pipes be located near the outside or foundation wall such that a frozen pipe might be a possibility??

This also would cause the symptions that you are experiencing ---- no flow..

Good Luck.. Alex

Jimbo_5

Boiler circulation problem

I am experiencing a problem with my tenant's boiler. He complained of no heat, suggesting the t-stat was not working. I tried it, the boiler would not fire. (It is an old Weil CG-3, gas fired, from 1978.) Without looking further, I replaced the old t-stat. Well, the boiler fired, came up to temp, and shut down. I could hear and feel the circulator pump constantly running. But the return pipe remained cold to the touch. The supply pipe was hot, and the gauge was at 180*. Upon closer examination, I could see the coupler spinning freely. However, the pump is noticably "louder" than its twin on the boiler sitting alongside it, for my apartment.
I am wondering if the pump itself, its impeller, is not working. I cannot figure any other scenario. The boiler fires, gets hot, the circ pump runs . . . but no flow through the system's fintube. What do you think? Short of pulling the pump, might there be another means of checking to see if it works? Any suggestions?

steve carvelli

it can be a couple of things. the system may be air bound and needs to be bled out. if you have baseboard heat, there should be a shutoff valve on the return pipe before the circulator and a draw off valve above the shutoff valve. shut off the ball valve and hook a house up to the draw off valve and open it up. there should be alot of air or bubbles coming out of the hose. let it bleed for about 20min. after that,shut off draw off valve and open up the shutoff valve again. it should start to heat up again. maek sure there is at least 15lbs of pressure on the gauge. also check the circulator pump. if it is a b-g pump, make sure the coupler is spinning the bearing assembly as well

Brad White

Could be

a sheared or worn impeller. If the impeller seized, the motor torque could well have sheared it.

Take an amp reading and compare it to the nameplate. If the impeller sheared the amperage will drop.

Eliminate all of the normal variables (venting, cavitation, pressure) first of course.

It does seam that for whatever reason the circulator is not moving water. I always keep a replacement handy.

Jimbo_5

Thanks

The circ pump is a series 100. Unfortunately the installer did not cut-in isolation valves on the supply or return piping. However, up until 2 days ago, the system functioned fine. The return pipe is COLD when the circulator is running. I can clearly see the cuplink spinning. Nonetheless I cannot see the impeller shaft because of the way the boiler was installed, in a corner facing away from me. If it were the coupling, it would be easier to change the entire pump rather than the coupling itself. I don't suppose anyone changes the impeller itself, do they? I have to tell you, it is absolutely frustrating trying to figure this thing out!

Brad White

Doncha Just Hate That?

That is why I am a huge fan of lots of valves...

I mean, I am a scuba diver and all, but there is a place to be warm and wet and near a boiler is not one of them....

Maybe at least you can open the flow-check valve and get some gravity flow?

In the end, I would say that replacing the circulator is how I would go if it were me in your position. That's just me. Do what Bruce says below, first.

Not to say that it's not a simple coupling in the end but if you are wrong... the time spent putting in a new circulator (with valves this time) is a better investment IMHO.

Isolation and drain valves are God's work on earth.

brucewo1b

Jimbo, you need to

Yes you can change just the bearing assembly, pull the motor then the four bolts in the casting and pull the assembly, you want to have the new one handy and ready to put back in. You will need to shut off electricity and take the water pressure off the boiler and then change as fast as you can but should not loose much water. If there is a problem getting the old gasket off stuff a rag in the hole to keep as much water in as possible. Install a new coupling at the same time.

brucewo1b

Jimbo, if you need to

Yes you can change just the bearing assembly, pull the motor then the four bolts in the casting and pull the assembly, you want to have the new one handy and ready to put back in. You will need to shut off electricity and take the water pressure off the boiler and then change as fast as you can but should not loose much water. If there is a problem getting the old gasket off stuff a rag in the hole to keep as much water in as possible. Install a new coupling at the same time.

steve carvelli

in that case, it sounds like you have radiators in the house or castiron convectors. try bleeding the radiators or the convectors. if the pump is working and the supply is hot, there could be air in the system

Jimbo_5

Thank you all

There are no rads, just 3/4" copper element fintube. And it is all on one floor, runs from the basement to the second floor, loops around and comes back down. I never thought of changing just the bearing piece, nor who might even stock that alone. Considering the differcnce in "noise" between the circulator that IS working and this one that does not, I tend to believe the pump may very well be shot. After work tomorrow I will try to amp it out. I may just remove the whole pump and put it on the bench for a look-see. Aside from the zero-space factor, removing the circulator doesn't seem too hard . . . looks like 4 rusted bolts and a piece of bx or greenfield. Yet I hate to drain the entire system. But if I do, I will certainly install valves on the supply and return. Right now the only valve I can see are 2 balancing-tupe "things," that look like a 3/4" copper tee with a bushing and slotted screw head in it. I presume they were some primative balancing valve. I've got to say, this problem has fried my brain trying to figure out what might be causing what not to work.

Jimbo_5

Didn't think of that

I never really thought of that possibility. Actually it is fairly warm in the apartment. But I will check. Did not notiice any water anywhere, either. At this point, I am thinking of installing a Taco 007 rather than replacing the B&G 100. For my application, I do not think I really need the B&G. It has 40 or 50 feet of copper fintube, nothing more. I am wondering just how difficult it will be to swap the 007 for the B&G, pipe-wise. It would be nice if the flanges were the same.