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Weil Mclain CGI pressure Relief valve


johnjohn

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My boiler has a leaky relief valve again so im going to replace it. I have done it once before but dont think i purged the system correctly previously. I have 3 zones and it has an airscoop. Do i have to worry about purging it since it has an air scoop? If more info is needed let me know...thanks

Its a CGI-7-pin

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Here are a couple of things that could be causing the pressure relief to leak.

  • Too much pressure in the system. Maybe the pressure reducing valve is set just a little too high or stuck. Install a pressure gauge somewhere. pressure is usually 12 lbs with a pressure relief valve set at 30 lbs
    DON'T TRUST THE GAUGE ON THE BOILER

  • The expansion tank does not have correct or any air charge. check the tank bladder pressure with a tire gauge , it should be at least 15 psi (maybe more, not really sure)When system is hot water expands, if expansion tank is not working the water has to go somewhere, so it leaks out the pressure relief.
  • Is the system loop water dirty? crud in the system can get under the valve seat and cause it to leak. If it is dirty ,To clean the loop, crank the pressure reducing valve down all the way to get new clean water in while draining the old dirty water out of the system. The pumps should also be running. keep an eye on the pressure , don't let it get to low.

About your airscoop(air separator).......from the looks of it the air bleeder on to of the scoop probably no longer works. I find they really do not last all that long. To flush air out of the system you Really should have a ball valve installed on top of the scoop so you can manually bleed air from the loop after a repair. Those air bleeders really cant handle a lot of air. they are intended purging a very small amount of air.

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ok im finally ready....when i replaced the relief valve b4 it was loaded with green scale....i assume its the same thing since i never ran water through it. Im going to start by replacing that.....

the expansion tanks schrader valve has 0psi....awesome...pressing the valve in results in nothing....no air..no nothing

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So my attempts to fill the expansion tank have failed.....it will accept no air whatsoever....i first tried my bike pump and then my portable air tank with 60psi of air in it...im suspecting a faulty schrader valve...could this be the source of the water being expelled fromt he relieve valve? im locating a scrader valve tool now to replace it

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ok have replaced the schrader valve and still no air can enter the tank....when i removed the schrader valve, no air or water came out

i again removed the valve and looked into the valve stem and see a blockage that looks like the rubber diaphram....

I drained the boiler completely to see if there was excessive pressure on it and i still was no able to fill the tank...

Im going to remove the tank now and

Hope it does not get cold soon

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My guess is the expansion tank was never charged with air or the bladder failed early on . The pressure from the system probably stuck/jammed the bladder into the charging port. Just a guess, anyway the tank is definitly bad if no air will a go into da tank.:flush:

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Ok new expansion tank and pressure relief valve as of just now....the boiler is empty i need instructions on filling it propery..i was thinking i would flush the internal tank aswell as it has never been done....im sure the zones need to be flushed too as i believe there is air in the system

Thank you

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ok well i needed heat so i went at it the best i though of...i have heat and nothing has exploded yet...no banging and the zones seem to be heating evenly so i assume its fine

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check out my first post above at the part about flushing out a dirty system, the same instructions apply to purging air from the system . it may take hours of flushing to get all the air out. to determine if you have all the air out, Every once in a while ,fill a clear container with the water that is being flushed out . if it is cloudy... there is still air in it. if it is clear..... no air in system. all pumps should be running while flushing so no air is trapped in high zones.

Good luck

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What should the pressure be after the boiler is running....I have it set to about 15 but it seems to be rising after the unit has been running?

Is the pressure reducing valve faulty?

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The pressure will rise when the water is heated..... you can expect about a 10lb pressure rise . The heated running pressure should not exceed the pressure rating of the popoff valve(usually 30lbs). If it does, then maybe you should reduce the pressure setting to 12lbs, that is standard setting unless the water is being pumped up very high. Then you need a higher pressure to help the water get to the high spots. The expansion tank air charge May not be high enough. Check that it is 12 psi.

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Ok i just shut the boiler the pressure is at about 30 which i know is too high. Im going to let it cool, check the pressure...if its at 12 then i dont know what to do...

I suspect my pressure reducing valve may be letting water in ...maybe its stuck open...

With the boiler off i will reduce pressure to 12 psi and let it sit for a while then go back and check...if it raised then it could only be the reducing valve i assume...Correct?

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Correct. If you let out pressure to 12psi and the loop temp is below 100.... the pressure should stay at 12 if set correctly and no pumps running. If, without the boiler firing the pressure continues to rise , the pressure reducer valve is leaking.

If this is the problem it is worth a shot to try to dismantle the valve and soak rubber parts in an acid (muratic acid works well) to dissolve scale buildup that is allowing the leakage.

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Well it is still rising and i even adjusted it to a lower temp but it slowly rose...im taking it apart right now

Thanks

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