Clean and adjust a boiler pressure relief valve?
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AdrianN
- Posts: 51
- Joined: 9 years ago
There's a faint hissing coming from the boiler relief valve. Using a mirror I identified the source as marked on the photo.
For one reason or the other it looks like the top fittings on my boiler are impossible to remove without taking out the boiler (I tried everything on the water level probe lower nut, as described here Water level probe removal - help needed ) Maybe the guys at the La San Marco factory used thread locking compound when installing them, or maybe the crush copper washers are keeping everything real tight, fact is I had to stop pulling harder on the wrench in fear that I may damage the boiler against it's mount).
Now, the hissing is very faint and you cannot actually see steam, it's only enough to condensate on a mirror. Is it worth to try and unscrew the top of the relief valve in order to clean it a bit? Or just live with it until it's overhaul time (as in taking out the boiler, placing it between wooden blocks and use whatever force/tools needed to unscrew the top fittings).
If anyone is familiar with this kind of relief valve (looks to me like it's adjustable and it has some sort of safety screw placed on it) please share your knowledge. Thanks in advance
For one reason or the other it looks like the top fittings on my boiler are impossible to remove without taking out the boiler (I tried everything on the water level probe lower nut, as described here Water level probe removal - help needed ) Maybe the guys at the La San Marco factory used thread locking compound when installing them, or maybe the crush copper washers are keeping everything real tight, fact is I had to stop pulling harder on the wrench in fear that I may damage the boiler against it's mount).
Now, the hissing is very faint and you cannot actually see steam, it's only enough to condensate on a mirror. Is it worth to try and unscrew the top of the relief valve in order to clean it a bit? Or just live with it until it's overhaul time (as in taking out the boiler, placing it between wooden blocks and use whatever force/tools needed to unscrew the top fittings).
If anyone is familiar with this kind of relief valve (looks to me like it's adjustable and it has some sort of safety screw placed on it) please share your knowledge. Thanks in advance
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cannonfodder
- Team HB
- Posts: 10511
- Joined: 19 years ago
That is the emergency pressure release valve. Not an adjustable part. They are normally calibrated to open at around 1.8 bar. If your pressurestat sticks in the closed position (heat) that will open to vent the pressure so the boiler does not explode. How high is your boiler pressure, and are you sure?
It could be scaled in place. It could also just be stuck or have a bit of galvanic corrosion on the threads which will lock it up tight. A deep socket and impact wrench may be what you need to get it off. The valve itself does not look bad. If they are leaking or have popped a few times they tend to get some scale or oxide on the brass (turns white or green) from the water.
It could be scaled in place. It could also just be stuck or have a bit of galvanic corrosion on the threads which will lock it up tight. A deep socket and impact wrench may be what you need to get it off. The valve itself does not look bad. If they are leaking or have popped a few times they tend to get some scale or oxide on the brass (turns white or green) from the water.
Dave Stephens
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AdrianN (original poster)
- Posts: 51
- Joined: 9 years ago
Thank you for your reply. We're talking about the same thing, as the purpose of this part is to limit the pressure inside the boiler to a preset value. And this is done by relieving any extra pressure by pushing up the spring located inside the body of this valve.
The part on my machine is obviously adjustable, as screwing or unscrewing the upper cap adjusts the tension of the spring, therefore adjusting the operating pressure of the valve. However, this is not supposed to be done outside the factory, as proven by the anti-tamper screw.
If you look at the picture, just above the red mark that I've made, you will notice some sort of notch which protrudes forward. That little thing prevents using any kind of deep socket (not that I had one that deep anyway) .
As things are now I see three possible options:
1. Allow the boiler to get up to operating pressure (1.1-1.3), install some sort of temporary water retention container around the valve to avoid making a mess and then pull up the center pin using a chain and a ring. This will went some steam quite violently through the vents located near the base and may clean up the piston inside the valve.
2. If 1. fails to deliver results, mark the current position of the upper cap and unscrew it, paying attention to the number of turns required. Clean the little piston inside (apparently it should have some teflon cap, which is probably worn out -in which case finding a replacement is mandatory and may prove to be difficult).
The problem is that the seat inside the base piece is most likely gunked up with limescale and cleaning it while mounted on top of the boiler will be difficult.
3. Live with the faint hissing until it's time to do a complete overhaul.
P.S. I don't have any means to double check the current working pressure, but the boiler also has a thermal probe designed to cut off power to the element if the boiler overheats. Since it's not a common occurrence to see the pressurestat triggering but being overridden by the thermal probe , I guess the pressure reading of the machine's gauge is quite accurate.
The part on my machine is obviously adjustable, as screwing or unscrewing the upper cap adjusts the tension of the spring, therefore adjusting the operating pressure of the valve. However, this is not supposed to be done outside the factory, as proven by the anti-tamper screw.
If you look at the picture, just above the red mark that I've made, you will notice some sort of notch which protrudes forward. That little thing prevents using any kind of deep socket (not that I had one that deep anyway) .
As things are now I see three possible options:
1. Allow the boiler to get up to operating pressure (1.1-1.3), install some sort of temporary water retention container around the valve to avoid making a mess and then pull up the center pin using a chain and a ring. This will went some steam quite violently through the vents located near the base and may clean up the piston inside the valve.
2. If 1. fails to deliver results, mark the current position of the upper cap and unscrew it, paying attention to the number of turns required. Clean the little piston inside (apparently it should have some teflon cap, which is probably worn out -in which case finding a replacement is mandatory and may prove to be difficult).
The problem is that the seat inside the base piece is most likely gunked up with limescale and cleaning it while mounted on top of the boiler will be difficult.
3. Live with the faint hissing until it's time to do a complete overhaul.
P.S. I don't have any means to double check the current working pressure, but the boiler also has a thermal probe designed to cut off power to the element if the boiler overheats. Since it's not a common occurrence to see the pressurestat triggering but being overridden by the thermal probe , I guess the pressure reading of the machine's gauge is quite accurate.
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AdrianN (original poster)
- Posts: 51
- Joined: 9 years ago
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ira
- Team HB
- Posts: 5535
- Joined: 16 years ago
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AdrianN (original poster)
- Posts: 51
- Joined: 9 years ago
Thanks for the suggestion. Given the fact that my boiler has just one mount (located in the middle) and that the mount is just some 2-3 cm wide, I'm not that eager to start using power tools in order to apply serious forces to the boiler.
What I did today was to cut a hole in the bottom of a small plastic bottle, place a piece of towel inside it around the walls, then lower the whole thing onto the valve, until the bottom of the bottle touched the boiler . Sorry, no pics but it's easy to figure out.
Then I pulled up (using a small chain, NOT by hand) a few times the ring that I installed on the valve's pin. This way most of the steam was absorbed by the towel instead of making a mess inside the machine.
After a few strong steam releases, the hissing became almost inaudible, so I guess most of the debris was flushed away. So I will order the part and replace it when it's the moment to do major overhaul, as in removing the boiler from the machine.
Honestly, I don't understand why this high quality machine doesn't have hex grips soldered at the top of the boiler. Maybe the folks at La San Marco want to give the companies doing service for their products ample opportunities to "milk" the customers.
What I did today was to cut a hole in the bottom of a small plastic bottle, place a piece of towel inside it around the walls, then lower the whole thing onto the valve, until the bottom of the bottle touched the boiler . Sorry, no pics but it's easy to figure out.
Then I pulled up (using a small chain, NOT by hand) a few times the ring that I installed on the valve's pin. This way most of the steam was absorbed by the towel instead of making a mess inside the machine.
After a few strong steam releases, the hissing became almost inaudible, so I guess most of the debris was flushed away. So I will order the part and replace it when it's the moment to do major overhaul, as in removing the boiler from the machine.
Honestly, I don't understand why this high quality machine doesn't have hex grips soldered at the top of the boiler. Maybe the folks at La San Marco want to give the companies doing service for their products ample opportunities to "milk" the customers.
