Weil Mclain Boiler Banging After Water Circulator Swap

Roamer · 12-10-2008, 10:02 AM

I am need of dire help, let me first introduce myself as a very novice handy man, that can do basic home improvement projects but by no means would I have the experience of the board members.

Now my problem, I recently replaced my Bell & Gossett water circulator with a Taco circulator, the Taco circulator is 1/4 of the size and weight of the Bell & Gossett circulator but the guy at home depot told me that the Taco circulator is an equal replacement part (I doubt this now).

So I swap out the water circulator no problem, then I go to start up my Weil Mclein boiler and proceed to bleed the system by going to each radiator and opening up the valve to get all the air out. About 10 minutes into the job I hear loud banging in the pipes, as if the pipes are going to explode, so I figure that this must be air in the system and continue to bleed. The banging noise subsides a bit, in that it would only happen evey few hours instead of every ten minutes, it is late at night now and cold so I let it be. In the morning I get up to leave for work and I hear the banging again, so I turn off the boiler by bringing my thermostat down to 60. As soon as I do this the pressure release valve in the boiler engages and water starts to pour out.

Now I feel that my heating system is not heating as well as it should be (i.e. it takes longer for the house to heat up), but really I could care less as long as it eventually does heat up. Here is my question, what have I done wrong? Why would the pressure release valve start going off now and not before the swapping of the circulators, also why all of a sudden all this banging noise in my pipes? I am perplexed, I feel that simply unscrewing 4 bolts and 2 electrical wires to swap in a new circulator should not be that hard but now I have created 2 new problems.

Any suggestions would really be appreciated.

Marvin Gardens · 12-10-2008, 11:31 AM

First off the Taco pumps are good pumps. It is all I use and have had a very good experience with them. Since I don't know the specs on either the pumps you mention I can't say if they are equal in performance.

When you introduce air into the system it won't come out at the first bleeding. There is diffused air in the water that will take a little time to come out. If you have an air scoop this will do most of that for you over time and the air will eventually bled out. The system should run for a while and then bleed it again since the air scoop will not get rid of large volumes of air except over a long period of time. You have to bleed out the majority of air manually.

Also check your pressure in the line. No pressure means that your pump is most likely cavitating and that is a big killer of pumps. Cavitation can cause the hammering that you hear. You should have at least 12psi at rest and no more than about 25psi running.

Then there is the pressure tank that will equalize the pressure. That is what keeps the pressure stabilized so that it stays above a set psi and doesn't go over a maximum psi.

Let the system run for a few days and then bled the system again. Start at the bottom of the system and work your way up. Keep in mind that removing water means you have to replace it with water. Some systems have an automatic filler if the system gets low.

**beenthere** · 12-10-2008, 01:10 PM

Do you have a bladder tank.
Or a big steel tank.
If a large steel tank, it may now be water logged.

Are you sure you have the circ in right. That you didn't reverse the flow through your boiler.

Is the Taco you got an IFC, or a regular 007.

SKIP4661 · 12-10-2008, 06:16 PM

Sounds like air in the boiler itself. This will create steam and cause the relief valve to pop. Did you double check the pump direction. Does the arrow on the new pump point in the same direction as the old pump. The
Taco pump is a good pump.

Roamer · 12-11-2008, 02:28 PM

"Do you have a bladder tank.
Or a big steel tank.
If a large steel tank, it may now be water logged.

Are you sure you have the circ in right. That you didn't reverse the flow through your boiler.

Is the Taco you got an IFC, or a regular 007"

I do have a steel tank, this is the expansion tank correct? If this is water logged how do I undo this? I think the Taco part I got was a regular 007, its whatever home depot sold me really,

"Sounds like air in the boiler itself. This will create steam and cause the relief valve to pop. Did you double check the pump direction. Does the arrow on the new pump point in the same direction as the old pump. The
Taco pump is a good pump. "

I am sure the arrow points in the same direction as the old pump. If there is air in the boiler itself how do I get this out? I do not see any other way to bleed the system except from the radiators themselves. I am soo perplexed!!!

**beenthere** · 12-11-2008, 02:55 PM

Post pics of your expansion tank piping.

SKIP4661 · 12-11-2008, 07:42 PM

When you bled your radiators, did you get any water out of the bleeders? Did the air hiss when you bled it? May have an issue with the pressure reducing valve. The boiler may not be refilling properly.