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mkdsk · Dec 11, 2008, 06:33 PM

My boiler keeps going to 30 psi when ever it runs. How do I adjust the pressure reducing valve installed on the cold water inlet to bring the pressure down to 15 psi.

hvac1000 · Dec 11, 2008, 06:48 PM

Are you sure it is the pressure reducer valve? It could be the expansion tank causing the problem. If the expansion tank is not doing its job as the boiler heats up the water pressure will go up with it. I never adjust the valve unless I know for sure it is the problem because once you set a pressure reducing valve they almost never need adjusting. Check the expansion tank first.

mkdsk · Dec 11, 2008, 07:02 PM

I just replaced the expansion tank and it didn't help. What else could it be?

hvac1000 · Dec 11, 2008, 07:08 PM

When you replaced the expansion tank was it the type that has a shrader valve on the bottom? If so did you check the air pressure? These are called bladder expansion tanks. OR was it just a plain expansion tank?

mkdsk · Dec 11, 2008, 07:17 PM

It has a shrader valve on the bottom and there is 12 psi in it.

hvac1000 · Dec 11, 2008, 08:13 PM

12 pounds is the factory pressure setting. How many stories high is your home

greghvacguy · Dec 11, 2008, 08:16 PM

It can feeding water all the time. After you get boiler back to 12-15 check and see if the water keeps feeding if so need new valve

hvac1000 · Dec 11, 2008, 08:52 PM

Originally Posted by mkdsk

It has a shrader valve on the bottom and there is 12 psi in it.

(Remember, the fill valve’s setting is determined by the height of the heating system: 1 psig for every 2.3 feet of lift. Whatever it takes to fill the system, add 4 psig to ensure good positive pressure at the high points of the system.)

Most fill valves have a lock nut and a screw driver slot in the top. Loosen the nut back screw out for less and in for more pressure BUT do not mess with it unless you have checked all other items that can cause problems ESPECIALLY air in the system. If you changed the tank you allowed air to get into the system. Make sure all auto bleeders are working and hand bleed where necessary. I usually cold start the boiler allowing the pump to run with out firing the boiler over. In my system the water will circulate for less than 10 minutes before all air is gone but I have 4 high point auto bleeders so it is automatic. Once the air is eliminated I turn on the gas or activate the gas valve to allow the boiler to heat up. I bring it to a max of 190 degrees and do a final pressure check. My system actually runs at a slight negative pressure on the suction side of the pump but I designed it that way for scavenger effect.

A normal system will run between 12-15 psi on the gauge at rest when cold depending upon how many floors the building has.

You can also cold bleed by filling the system to aprox 12 psi then start the pump for a minute then bleed while making sure system pressure stays at aprox 12 psi. Repeat till air is gone.

mkdsk · Dec 11, 2008, 09:41 PM

hvac1000,
I have a 2 story house so how many pounds should I have in my expansion tank? A few more questions questions for you. What should the psi be on the boiler gauge when the boiler is running? Also, you said the fill valve has a lock nut and a screw driver slot in the top. You said to loosen the nut and back screw out for less and in for more pressure. I need to get less pressure to get the psi down so I need to back out the screw BUT my question to you is "if I back the screw out too far and it comes all the way out, will I just be able to screw it back in or will WATER squirt out all over the place?

hvac1000 · Dec 12, 2008, 05:58 AM

Originally Posted by mkdsk

hvac1000,
I have a 2 story house so how many pounds should I have in my expansion tank? A few more questions questions for you. What should the psi be on the boiler gauge when the boiler is running? Also, you said the fill valve has a lock nut and a screw driver slot in the top. You said to loosen the nut and back screw out for less and in for more pressure. I need to get less pressure to get the psi down so I need to back out the screw BUT my question to you is "if I back the screw out too far and it comes all the way out, will I just be able to screw it back in or will WATER squirt out all over the place?

The screw should not be a problem since it does not actually plug the water from getting out to start with. It just puts more or less tension on the diaghram/spring combination. To lower the water pressure to start with you will have to drain off some of the water in the boiler.

mkdsk · Dec 12, 2008, 05:59 PM

Originally Posted by hvac1000

(Remember, the fill valve’s setting is determined by the height of the heating system: 1 psig for every 2.3 feet of lift. Whatever it takes to fill the system, add an additional 4 psig to ensure good positive pressure at the high points of the system.)

Most fill valves have a lock nut and a screw driver slot in the top. loosen the nut back screw out for less and in for more pressure BUT do not mess with it unless you have checked all other items that can cause problems ESPECIALLY air in the system.

I turn the fill valve out to reduce some pressure and so far for one cycle the psi only went to 25 with the boiler running which is GREAT. When the boiler is cold the psi WAS at 10. I will see what happends when the boiler gets cold again but I think it will go to 10 again.

mkdsk · Dec 12, 2008, 06:02 PM

I turned the fill valve out to reduce the pressure and cold it went to 10 psi which is great and when the boiler is running the psi went only to 25 which is great. Now I will see what it goes back down to when the boiler get cold. I think it will go back to 10 psi which would be perfect.

mkdsk · Dec 12, 2008, 06:04 PM

I turn the fill valve out to reduce some pressure and so far for one cycle the psi only went to 25 with the boiler running which is GREAT. When the boiler is cold the psi WAS at 10. I will see what happends when the boiler gets cold again but I think it will go to 10 again.

hvac1000 · Dec 12, 2008, 06:05 PM

I hope it does the trick

mkdsk · Dec 13, 2008, 10:15 AM

Okay another problem. My relief valve from my water heater is now leaking. Why would that leak?

hvac1000 · Dec 13, 2008, 10:26 AM

Originally Posted by mkdsk

Okay another problem. My relief valve from my water heater is now leaking. Why would that leak?

If your water heater is a stand alone unit and not connected to the boiler then the relief valve is defective OR the water pressure in the home is to high. Usually it is just the relief valve that is bad.

NOTE:DO NOT CAP OR PLUG THE VALVE TO STOP THE LEAK.IT IS A SAFETY DEVICE. I wanted to make sure I got your attention.

mkdsk · Dec 13, 2008, 10:43 AM

It is a stand alone unit. Do the relief valves go bad? Would that be the only reason why the valve would start leaking? I just changed my upstairs shower to a different shower but I doubt that would make the relief valve leak on my water heater.

hvac1000 · Dec 13, 2008, 10:53 AM

Yes they can go bad. If you played with the lever on the valve they can get dirt on the seat and will never seal again. Changing a shower head should not make it leak.

If your water heater is a stand alone unit and not connected to the boiler then the relief valve is defective OR the water pressure in the home is to high. Usually it is just the relief valve that is bad.

mkdsk · Dec 13, 2008, 10:56 AM

Okay, it is a Kenmore Power Miser 12 water heater and the serial number is G02310380. Do you know how I get the relief valve off the water heater and where I can go to get a new relief valve to replace the old one?

hvac1000 · Dec 13, 2008, 11:16 AM

Usually a large pipe wrench works since they screw on. The new one should be of the same pressure and BTU rate as the old one. Home Depot/Lowes has them. Make sure to use pipe dope on the threads of the new one before screwing in.

There is probably a copper line going to the base of the heater. This is there to prevent burns from steam/boiling water if the safety pops off. This line must be replaced to the new valve and if one is not there put on one it. It is called the overflow pipe on this web page. NOTE unless you have drained your water heater on a regular basis do not drain it now. The valve on the bottom has a 75% chance of failure to stop leaking if the heater has not been drained regular basis to clear sediment.

If you decide to use the drain pick up a brass hose thread cap and washer when you get the new pop off safety valve since if the drain does not completely shut off you can put the cap and washer on it to prevent dripping.

Turn off cold water supply to heater and lift safety to take pressure off tank. If you do not drain a bit of water will come out when the pop off safety valve is removed.

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