My pressure gauge is between 20 to 25 right at the marker. Is that too high!
Hi all, I need help determining whether my pressure gauge is too high. The PSI reading is right at the marker. I attached some pictures for reference. My oil line was on empty and I had to reset the furnace. It took two attempts earlier in the day. The reading was close to 30 PSI as it was heating up the house so I was worried about air in the fuel line increasing the pressure. I attempted to bleed the fuel line, but a steady stream of oil came out, no air. I noticed after that the marker did go down to where it currently is (between 20 and 25 psi) but again no air came out when I let the fuel line. I’m wondering if this is too high and perhaps I have a clog somewhere and if so, should I just turn off the furnace until I get it service? It’s around 20°F right now where I am but if this is dangerous, I’d rather turn it off before I have a bigger problem. Also, the furnace I have is a Weil McLain Model QB-180, which was discontinued so I can’t find much online. Thanks for your help in advance!
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Firstly, the oil line has absolutely NOTHING to do with the pressure in the boiler.
28 psi is a bit high and it would be beneficial to determine why it is that high.
The best thing to do at the moment is to drain a bit of water from the boiler and lower the pressure to about 18 psi when it is hot. Then, keep an eye on it. You might have an expansion tank that is waterlogged and needs to be replaced. This would cause an large change in pressure each time the boiler heated up.
The vertical pipe on the left side has a faucet with a blue handle. Just connect a hose to it and run some water into a bucket or a drain until the pressure comes down between 18-20 psi………when fully hot (while it is running).
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I will try this. Thank you!
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You're welcome.
Just understand that this is not a permanent fix. When the boiler cools off, the feeder is going to bring it back to 15 psi………..then, when it fires up again and heats the water back to 180………….you might find yourself in the exact same situation with the pressure very close to 30 psi. There is no issue at 28 psi……….you can run it that way forever………….but if it gets to 30, you'll have water spraying all over the boiler and the room when the pressure release valve opens………..and sadly, they never close fully after this occurs…………must be replaced.
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BTW, the gauge shows the boiler at 23 psi.
This is a non-issue if it stays near that level.
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Thank you I appreciate your help. Yes, I understand. I need to get it serviced. Perhaps there was a clog earlier or still is since my fuel level went to empty. I read online that when that happens the furnace may pull up sludge that can clogged the line. I’m pretty new to all of this as a first time homebuyer. I don’t understand why it was at 30 psi earlier and now it’s at 23 psi, maybe the expansion tank is the issue as you stated. The 30 psi reading happened around 8:30am this morning and it’s been at 23 psi since around 2 PM this afternoon. I’ve been monitoring it regularly every few hours and it’s stayed at 23 psi. There are two vertical pipes on the left side each of them have a nozzle where I can connect a hose. One says basement return and one says 1st floor return. Do you know which one I should drain the water from? Also, do you still recommend draining the water at 23 psi?
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Yes, you are referring to the fuel line. Everything you stated MIGHT occur.
Do not confuse the fuel line with the pressure in the boiler. Two completely different issues. Not at all related.
The pressure varies in the boiler depending on the temperature of the boiler. When it heats up to 180°F, the pressure is going to climb. When it cools down to 75°F, the pressure is going to fall. The expansion tank keeps this rise and fall to a reasonable level………..maybe 8 psi up and down unless it has failed and is full of water.
If it stays below 25 psi you have NO ISSUE and do not need ANY SERVICE at the present time.
You can connect the hose to the return of your choice. They both end up in the same place.
If the boiler is at 23 psi………….bring it down to 18 psi just for safety when you are sleeping………………you DO NOT want to suffer the result of it climbing to 30 psi. You only need to remove about one pint of water for this drop in pressure.
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okay, I will do remove the water and then monitor it for changes. Thanks again for your help. I greatly appreciate it!
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I’m going to turn it off for now to be safe and use my heaters and then bring it down to 18psi first thing in the morning. Thanks again!!
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Good morning, can you please tell me whether I should turn off the power supply to the boiler and shut off both return valves before bleeding the waterline?
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You have no need to turn off the power supply or close any valves. Just connect a hose, open the valve slowly and watch the pressure gauge. Take you three minutes (or less) to bring it down to 18 psi.
However, it's already off from last night. Just leave it off and bring the pressure down with the hose and the valve.
BTW, what is the pressure this morning with the boiler dead cold? It might be down below 18 psi already. If so, lower it to 15 psi.
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I just did it! Thank you! I did not turn off the power switch. I only turned off my thermostat. It was at 20 psi with the heat turned off. It’s now closer to 15 after draining the water according to your instructions. Can you please explain to me the science of how draining the water helps? I know it’s a temp fix but I’m curious if I remove some of the water pressure from the expansion tank and it’s all connected to my water supply it could just quickly fill up with water again? I’m wondering if I should take steps to check the air level in the expansion tank? From what I understand, it can be done by draining the expansion tank and using a tire gauge and I would also have to measure the pressure of my water line. The tank pressure should be close to the pressure of my water line if not I can introduce air with a tire pump to fix it. I’m curious if that could solve my issue? I also did the sound test and it sounds like the bladder in the expansion tank is fine. There is definitely water at the top and air at the bottom.
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The water in the boiler wants to expand when heated. Expansion creates pressure. The Extrol tank when properly sized is designed to absorb the expansion therefor managing the pressure. If the bladder loses air pressure, the extrol tanks expansion capability becomes diminished. This causes an undesired pressure increase when system is hot. That is the science. As LRCCBJ has explained, this has nothing to do with the fuel system. It is almost like your car. Gas in the tank has nothing to do with the air in the tires.
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Well done.
You have a fixed volume in the system that contains the boiler, the piping, the radiators. If you fill up that volume with water and stuff too much water into it, the pressure will climb because there is no more space. Likewise, if you drain a bit of water, the pressure must fall as the volume remains the same and you have less water in the same volume.
The expansion tank creates another variable. It has a bladder in the middle so that when the boiler heats the water in the system, it must expand slightly. The tank absorbs most of this expansion by moving the bladder slightly within the tank and increases the volume of the system.
When the tank fails, the bladder in the middle deteriorated and the air cushion on the bottom of the tank is now gone. So, the tank becomes part of the fixed volume of the system and doesn't allow any "cushion" to prevent the pressure from climbing too high.
The first and fastest way to check the expansion tank is to simply push on the pin in the shreader valve on the bottom of the tank. It's just like the valve stem on a car tire. Just push it very briefly. You will either get all air or you will get air with a bunch of water. If the latter, the tank needs replacement. If the former, the problem lies elswhere.
Keep an eye on the pressure and see if it slowly climbs toward 30 over the next week.
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With my apologies for butting in, if no water comes out of the Schraeder valve, it is not a conclusive test. One must determine what the actual air pressure is in the tank. Customarily it should be about 12 psig. If the pressure is low, that is likely an issue. The tank could be good, just low on air pressure. Air pressure must be tested at near zero psig system pressure.
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