Hi,

My hot water boiler made this loud thump (according to my wife) and started spewing water and steam (dirty water) out onto the garage floor though the Pressure relief valve. I shut off the water to the heating system and shut off the electrical to the system. I see on the top of the boiler that the air vent is all clogged with debris. boiler pictures by vsantaiti - Photobucket Is this something that I could get at a local hardware store? I have a 2 zone home heating system gas fired boiler (Peerless Cast Iron - intermittent pilot control). The 2nd floor plumbing line has a 45 PSI max air vent. The one above the boiler is unreadable. The PRV is set to 30 PSI. I tried turning on the water and the water kept coming out of the pressure relief valve into the garage again. I guess I need to replace the PRV?

 

Hi Vinny, the air vent isn't what is causing your problem. It may in fact require replacing, but it's not what will cause the relief valve to open.

You more than likely have a problem with your expansion tank... I haven't looked at the pics yet.... will do later... have some chores my better half is bugging me about...

So, if the pics don't show everything around the boiler, take more pics and upload them... I'll be back in a bit.

 

OK, you don't have enough pics... I just took a quick look. Take pics of everything associated...

 

I uploaded a couple of pics of the main boiler. There is an expansion tank above the boiler system (Extrol model 30) in line to the 2nd floor. I tried turning on the water and the system will not maintain pressure, the water just runs out the PRV into the garage. Please help.

 

Vinny, go to the other side of the garage, and take a couple shots so we can see the whole thing...

Find the pressure gauge on your boiler. Tell us what the pressure and temperature are reading.

Here is a procedure for charging the air side of your expansion tank that should be followed at LEAST every two years. If your tank has lost it's air charge to time (they will lose air over time - normal) or a busted bladder (you will have to replace the tank) this procedure should get you to that point. You MUST follow this to the letter, else you will still have problems:

=========================================

1. Shut off boiler and allow to cool to under 100°F.

2. Shut off water supply line to boiler.

3. Drain only enough water from the boiler drain to drop the system pressure to ZERO. REPEAT: Do NOT drain the entire system. ONLY ENOUGH TO DROP THE PRESSURE IN THE BOILER TO ZERO!

4. With an ACCURATE tire pressure gauge, check the air charge in the tank on the air valve opposite the end of the tank that's connected to the system. If ANY water comes out of the air valve, the bladder inside the tank is shot and the tank needs replaced. If no water comes out the air valve, and the pressure is less than 12-15 PSI, continue to step 5. If the pressure is OK, turn the water supply to the boiler back on and repressurize the system, turn the power back on to the boiler, no service is necessary.

5. Using a bicycle pump, or a small air compressor, add air to the tank until you have 15 PSI air charge.

6. Check the boiler pressure gauge again, and if it has risen off ZERO, drain some more water from the boiler drain until it is again at ZERO.

7. Check the air charge on the tank again. If it is below 15 PSI, add air to the tank until it is at 15 PSI.

8. Repeat steps 6 and 7 until the boiler stays at ZERO and the tank stays at 15 PSI. At this point, the tank is properly recharged and the water supply can be turned on to re-pressurize the system, turn the power on to boiler and return to service.

 

The expansion tank is the cause of this sort of problem like 90% (or more) of the time. The other thing that may cause this is a defective PRESSURE REDUCING VALVE (which I don't see in your pics), but we'll get to that in due time. The first thing to check is the tank.

Yes, you probably should replace those air vents eventually, but if they are not leaking water, leave them alone until spring time. There is another vent on the device that the expansion tank is screwed into, that is the one that will do most of the work of getting the air out of the system. Is that one in good shape? It should not be dripping any water, and the little cap on top needs to be LOOSE so that the air that it catches can be vented.

If the one on the top of the boiler is leaking (it appears to be), you can CLOSE TIGHT that cap to stop the leak until you have a chance to replace it... in the spring.

 

It is also possible at this point that your pressure relief valve won't stop leaking. Very often an older valve that opens will not seat properly again once it has vented. You may have to replace it... AFTER you get the problem that caused it's opening in the first place taken care of.

I don't see a picture of that relief valve either, so include that when you upload.

 

Thanks for your help. The PRV outlet pipe ended in the garage about 1 inch from the floor. So I decided to first cut the outlet copper pipe so I could fit a 1 gallon pail underneath the PRV outlet. This made troubleshooting the issue a little easier since the water wasn't being expelled to the floor! When I turned on the water (w/o touching the expansion tank), I noticed that the prv valve kept expelling water. I looked at the system pressure and verified that it kept rising well above 15 psi. So my thinking (and a little of my Dad's plumbing knowledge) told me that the water regulator was not working properly. The working pressure should be 12 to 15 psi. We went to a local hardware store and picked up a water regulating valve then replaced the old one. The PRV did drip a little after turning on the water once again but it eventually stopped. It looks like all is well. Isn't the expansion tank for the 2nd floor since my house is a 2 zone system? Why do I need to recharge it?

 

The expansion tank has nothing to do with how many floors are in your house. When water heats up, it expands and that tank gives it someplace to go. With a bladder type expansion tank, part of it is filled with water and the other with air. The air side needs to be pressurized to the desired system pressure when it is cold. That would be 12 psi for most systems. These types of expansion tanks will loose their air charge over time. The bladder inside can also fail. If either of these occur, it will cause your system to over pressure when the water heats up and spill it out the PRV.

 

Vinny, what Droop said. EVERY hot water heating system has an expansion tank, even if it's a ranch house.

When heating water from room temp (say 70) to 180 high limit, the water in the system will expand a little under 4% by volume. That means that if you start with 10 gallons in your system, you end up with 10.4 gallons. Water can NOT be compressed, but AIR can. The expansion tank is where that air is located, and compressed when the water expands, and that 0.4 gallons of 'extra' water goes into the tank.

Sad fact is that nearly every boiler tech thinks that those expansion tanks are 'set it and forget it', and will NEVER check to be sure that the correct charge is in the tank. The MANUFACTURER of the tanks states that they will lose between 1-2 PSI PER YEAR. If you start with 12-15 PSI in the tank (the correct charge), how long before there is 4-5 PSI ? and that is generally when the relief valve will start opening... because the 'cushion' is gone.

One other thing to point out... once the air cushion is gone, the rubber bladder inside the tank is allowed to S T R E T C H way more than it was designed to... so, let the air charge checking go, and you will be replacing those tanks way more often than necessary. Maintain the proper charge in the tank and it will last many years.

I maintain that the expansion tank charge should be checked a MINIMUM of every two years, and EVERY year at the start of the heating season is way much better.

How often do you check the tire pressure on your car?

 

Thanks for the replies. I was able to reduce the system pressure to zero and reduce the temp to less than 100 deg F. I opened the red cap below the Extrol 30 expansion tank and used a tire gauge to check the pressure. When I checked it, some dirty drips of water came out but mostly air (The air did not stop coming out.. it sounded like a nail in a tire). The pressure was really low, it didnt register on my tire gauge that had a min reading of 10 psi. When I attached a bicycle pump to the opening a lot of air came out and I pumped some air into it. If even a little drips of water comes out, does that mean that I need to replace the expansion tank? Thanks for your help.

 

Unfortunately the answer is yes, your expansion tank is toast.

 

Yes, if there is water on the air side of the bladder, the bladder must be leaking. Replace the tank. But first, pressurize the air side of the new tank to 12 psi.

 

And if ya wanna make future life easier, mount a ball valve below the air separator, then a drain, and THEN the tank.

 

Hi,

I purchased the expansion tank from home depot for $32. It was difficult to remove the old tank. We used a plumbers pliers and a iron pipe (and me and my dad) to get enough torque to turn the nut (at the top of the tank). I checked the new tank and it had the right pre-charge air pressure of 12 psi. We installed it by hand with teflon tape around the threads. We turned the water on, then the electrical, then had the system call for heat. The current reading on the boiler gauge is around 25 psi and 210 deg F. Is this normal? Do I need to adjust anything? Of course there isn't any water coming out of the pressure relief valve pipe in the garage but I will wait 24 hours to be sure. I think all is well and in just enough time for below-freezing temperature outside tonight! Thanks for all your help.

 

Your system has too much water in it. Remove water until you have 12 psi when cold. You don't want to do this when your water is hot, you can burn yourself.

You should have used a wrench to get that off. A properly sized open ended wrench would have been better than pliers. I think even a pipe wrench would have been ok. I also find that with tight connections, short applications of high torque will work better than constant pressure of all your might. Much like an impact wrench.

 

Hang on a minnit...

25 PSI at TWO HUNDRED TEN degrees isn't all that terrible...

Shut the boiler off and let it cool down to 100 or less, and read the pressure gauge again, and let us know what it says when the boiler is cool.

BUT...

210° is way higher than you need or want.

I can't see it in the pics, but:

Somewhere on your boiler is an AQUASTAT. Might be a gray box, about 4X6 inches... there might be one screw on one side. TURN OFF POWER TO THE BOILER THERE IS LIVE 120VAC INSIDE THIS BOX. Loosen that one screw and slide the cover straight off. There should be a temperature dial inside. Tell us the setting of that dial.

 

Wow. I didn't even pay attention to his temp. 210 is real close to boiling.

 

Not at 25psi. More like 240F.

But still 'stat should be max around 180....

 

Hi, I opened up the Honeywell Aquastat L8148E and noticed that the setting was 210 on the high end and 180 on the low end. I can just turn the dial lower, right? This is the high limit switch, right?

I drained some water out of the heating system to reduce the pressure to 15 psi (before I just in the morning). But even though I did that, the boiler pressure is now higher at 20 psi (for 120 deg with the heating system off). Of course, there still is very little water dripping out of the PRV when the heat is on even though I replaced the 15 psi expansion tank, and the 15 psi water regulator. Please let me know how to get the boiler pressure to 15 psi again. Thanks for your help.

 

vinny, you mean that those are the numbers in the 'window' of the aquastat? there should be a pointer in the middle of that window... that's the setting. Yes, the dial turns, lower it so the pointer is on 170-180

The pressure is only going to be the same at the SAME TEMPERATURE. If you are comparing pressures, you must compare them at the same temperature.

 

Not being a professional, I want to add something that can be missed by someone new at DIY. When you turn your hi limit to 180 you need to turn your lo limit down as well. I think 160 is average, a 20 degree differential. If not weird things can (will?) happen.

Easy to overlook if your new at this. Even easier to forget to mention if you a pro...

 

Hi, my Aquastat has a high setting dial but no noticeable way of setting the low temp. I read the instructions and there is nothing to lift with a screwdriver. The min high setting is 180 and I set it to that. This should save me a lot in energy costs and make the entire hot water boiler system run more efficiently.

 

My mistake, that's why I prefaced what I typed that I wasn't a pro. I read into your post that you had your lo limit set at 180 and your hi limit at 210. I misunderstood that this was the range on your hi limit setting.

Apologies to all

 

Hey, Can anyone tell me why my boiler pressure is still 20 pounds or higher? This is the case when the heat is on and off (whether the boiler is cool or hot). I am confused since I replaced both the water regulator and the expansion tank. As far as I know, typically the operating pressure should be 12 to 15 psi. Please help. Thanks all for the replies.

 

The auto fill valve could be bad or it needs to be adjusted. Do you have a manual shut off on the water supply line to the boiler? I would shut that off and see if it solves your pressure problem.

 

Vinny, how do you know the pressure gauge on the boiler is accurate?

I'm gonna say what I've said a bazillion times... Do NOT trust the gauge on the boiler. If I had a nickel for every inaccurate pressure gauge I'd be retired right now...

Before you pull any hair out trying to figure this out, you need accurate data, and the only way to get that data is with an accurate gauge.

Go to HD or Lowes and pick up an adapter from a hose fitting to 1/4" female thread. They probably won't have the gauge you need there, so on the way home swing by a plumbing or pool supply and pick up a 0 - 30 PSI pressure gauge. Screw the gauge into the adapter, and onto a boiler drain. Open the drain and read the pressure and validate your existing gauge. THEN come back and ask again if you find the pressure still high.