Expansion vessel question

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I have a question about the installation of my expansion vessel. I pressed the valve on it yesterday and got some water from it. I'm guessing it needs replacing.
I was looking at the existing installation and was wondering if it is possible to install them "upside-down"? The water feed to mine is from the top which made me wonder, would it not be better for the water connection to be at the bottom to allow gravity help expel water when the system cools? My thinking is that installing it like it is, encourages water / sediment to gather inside. I also read that it's better with the water at the top as it means the hot press / airing cupboard won't flood if the vessel is ever disconnected. Confused.

Any advice would be appreciated as I'm looking at replacing it asap. BTW pressure doesn't fluctuate greatly - usually between 1 bar and 1.5 bar but I do need to top up the sealed system 2 or 3 times a year.
 

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Gravity doesn't expel the water from the EV, its the air pressure on the other side, if the system is drained down, then the EV must be emptied of water as well by using 0.5bar air pressure to push the diaphragm up against the water end and then pre charging to its normal, 0.75 to 1.0bar, the filling valve is then opened to give a filling pressure of 1.3/1.5bar. If your system is only rising by 0.5 to 1 bar on system heat up then no worries, the top up air always contains moisture so eventually this will settle to the bottom of the EV and and will be expelled when you open the schrader valve, you should only get maybe a thimbleful full every 4 to 6 months.
 
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Yours is upside down.
Shrader valve should be at the top.
intergas rapid schraeder is at the bottom, complete PITA to be honest, but really doesnt matter , as long as the bladder is properly charger schraeder can be anywhere
 
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Boiler manufacturers often have the valve at the bottom.
It's normal for a little water to collect in the vessel on the air side but more than 1/2 a cup and you'd assume the diaphragm is perforated.
 
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And if the diaphragm was perforated the air space would fill with water and the PRV would lift every time the system heated up.
 
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Tbh. I've always seen Air side up.
Even zilmet MI's show it that way.
And most CH vessels are zilmet.
 
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Thank you all for your replies. I only briefly pressed the valve and saw water come out so I released it immediately. From what has been said above, I have to assume that because my pressure reading is only varying by about 0.5 bar between hot and cold, my vessel could be OK? Should I be expecting a much larger variation if the diaphragm was gone? @Johntheo5 states that the PRV would activate when the system heats up.

BTW in my original post I stated (confusingly) that pressure varies between 1.0 and 1.5 bar. What I meant was 1.0 bar when cold and 1.5 bar when hot.
 
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Yes, you would experienced higher & higher final (hot) pressures as the air space is getting water logged until finally the PRV will lift at 3bar.
If the schrader valve is leaking air then the same thing will happen, not a problem for you, due to your upside down EV!!, you will/would get water dripping from the schrader valve first.

Also, the filling pressure should be 0.3 to 0.5 bar > than the pre charge pressure as it gives a modest water reserve with a cold system to make up for any microscopic leaks etc and extends the top up frequency. For example, assuming precharge/filling pressures of 1.0/1.3 bar then the water reserves and final hot pressures assuming a 100L system with the following EV sizes of 8L,10L,12L&18L are 1.04L/2.0bar, 1.3L/1.83bar, 1.57L/1.72bar & 2.35L/1.57bar. You can see from this that you cannot oversize a EV, the bigger the better, as the greater the water reserve and the lower the final pressure.

You don't know what your precharge pressure is and we don't know what pressure you are topping up to? but I would suggest increasing the top up pressure by say 0.3bar and you may run for 6 months or more without any top up required. I look after a few relations oil fired systems with 18L EVs and I keep the filling/topup pressure 0.5bar higher than the precharge pressure of 1.0bar, this gives a reserve of 3.6L and a final pressure of ~ 1.8bar with the cold pressure only dropping to ~ 1.2 bar after 9/12 months.

I can't post spreadsheets but here is a screenshot(s) for anyone interested in building their own.
1661153466378.png

1661153514550.png
 
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