Refilling the boiler (noob trying to wrap up)

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Old 07-23-19, 05:00 PM
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Refilling the boiler (noob trying to wrap up)

Hi all,

Some of you helped me figure out how to drain my boiler a few weeks ago. Now I have completed my work on the radiators and I am trying to figure out how to refill the boiler. So far, I have heat in the first floor circuit, but I can't seem to get it up to the second floor. Here are the pictures again:


So I turned on the water (valve in front of the expansion tank in the bottom picture). I started the heat and, as I mentioned, I only got heat on the first floor.

I have a feeling I am supposed to turn of the valve on the return line (yellow in top right of bottom picture) and then open the red faucet and let a bunch of water and air come out. Is that correct? if so, should the heat be on while doing it?

Another option would be to just keep waiting and let it take its time. But would it get all air out effectively and would it ever get heat up to the second floor?

Thanks beforehand for any input...
 
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Old 07-24-19, 12:03 PM
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D,
You must bleed the air from the system to restore heat.

First, you do this with the boiler off. Then you close the yellow handle valve on the return and open the one on the cold water supply.

Then by lifting the lever on the feed valve you raise the boiler pressure to 25-28 psi and open the drain on the return line bleeding the air from the system keeping the boiler pressure high until you get a good steady steam of just water.

Then you shut the drain valve and return the lever to auto on the feed valve. At that point you should still have at least 25 psi in the boiler which you will drain until you reach 20 psi. This will be your operating pressure. Open your return valve and turn on the boiler to test.

This should restore your heat when you're done.

Hope this helps a little.
 
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Old 07-25-19, 11:21 AM
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That helps a lot!

So i went down, shut the return valve, connected a hose to the outlet, opened the incoming water line and opened the outlet. I also started to lift the feed valve and i built up to 20 PSI. Lots of air and water coming out.

I also tried shutting the outlet and building up extra pressure by opening the feed valve. I think I got up to 25 and then I released the outlet. I heard air and water coming down in the top floor return pipe.

I have two loops: first and second floors. However, there are no shut-of valves on either, so I guess the bottom one fills up really easy. Anyway, I had pushed up water to the top floor now with the extra pressure.

However. I noticed that one of my soldered fittings was leaking on the top floor. So I had to drain and cut and re-solder.

After repairing, I went and bled the system again. I was a bit more careful this time and i don't think I went above 20 PSI. I noticed that the feed valve says: "SET 15 PSI", so is that the operating pressure? I was more cautious because of this and also because of being a bit weary of repairs.

Anyway, I must have been too cautious because the heat did not reach the top floor as i tried running the heat afterwards.

So now I have to wait for the boiler to cool down (you're not supposed to flush cold water into a hot boiler I heard). Then I think I will go back and try to purge the air out with some more pressure. I feel like it actually worked the first time, but I was too hesitant the second time after the leak.

Thanks again for the help!
 
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Old 07-25-19, 01:54 PM
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Your feed valve, if set at 15psi, will automatically start adding water to the system if it drops below the 15 psi setpoint. Your safety relief is set for 30 psi. The boiler nameplate should list the maximum working pressure, probably 30 psi. When jacking up the system pressure to help with bleeding air, it is nice to try to avoid getting too close the 30 psi relief valve setpoint - so you don't get water discharging onto the basement floor. But, if the relief valve lifts, it shouldn't otherwise be a problem. The maximum design pressure of the boiler will exceed the maximum working pressure.
 
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Old 07-25-19, 03:36 PM
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I tried again and it worked!

I let the feed valve be open for longer. I think i got up to 27 PSI and then i would put it back. I got hot water coming back from the upstairs return line.

Also, no leaks anymore!

Will the new water get depleted from oxygen automatically or must I run the heat continuously for that? The system will just sit now for a few months with fresh water. Is that ok?

Thanks again for the help!
 
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Old 07-25-19, 03:57 PM
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If you only get heat on the first floor, there is still air blocking the system.
 
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Old 07-26-19, 07:21 AM
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I have heat on both floors now... Maybe my last post was a bit unclear... Thanks!
 
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Old 07-26-19, 11:47 AM
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D,
It is fine to leave your freshly filled system for the summer. I would recommend 20 psi as your operating pressure. That 15 psi on your feed valve is what they come factory set at but are adjustable for individual needs. You will get much better results with your system at 20. You can either unscrew the lever and adjust the feed valve or lift the lever until you reach 20. I would just lift the lever in your case.

Just my thoughts, thanks for the update.
 
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Old 07-26-19, 03:36 PM
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Spott, what do you see as the pros and cons of running a hot-water boiler at 20 psi, vs 15 psi? I assume that at 20 psi, any air would be compressed into a smaller volume and perhaps be more likely to be moved around and expelled by air elimination devices? My 70-year-old boiler has always been run at 15 psi, but when bleeding air after maintenance, I always temporarily jack up the pressure to, say, 25 psi. (With my monoflo system, bleeding air needs all the help available - but I have installed valving to allow a power purge of the more troubling parts of my system.)
 
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Old 07-27-19, 07:42 AM
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gil,
For me, it just always seemed to solve a lot of air problems but not being an engineer couldn't explain why but I have been using that pressure for years. I started doing it when the wet rotor pumps started coming out to solve some noises caused by air in the pumps and for me it worked and everything quieted down and it seemed to get rid of the air trapped in the pump.

Sometime later in future TACO actually came out and recommended using 20 psi with their wet rotor pumps to prevent cavitation which is air trapped in the pump which kind of validated what I had found.

With the older style pumps with the separate motor, bearing assembly and volute somehow it took care of itself with the air but apparently the design of the new style pump worked better with the added pressure which a lot of times is not needed so much for the heat but to prevent cavitation and help keep the system air free.

I guess in short gil, all I really know is I've had no problems at this pressure and it works for me.
 
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Old 07-28-19, 03:07 PM
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Thanks guys!

I have it sitting at 20 PSI right now actually. So basically it will be like that for the rest of the warm months and I assume it will operate at that pressure.

There is probably some air left, but the water is fully circulating and I figured any left over air will be expelled eventually once I start running the system. I definitely have full heat coming from all parts of the system.

I can also bleed some more in the fall, if it turns out it's too noisy or something. Now that I know how to do it!
 
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Old 07-29-19, 03:07 PM
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The system will operate well at 12, 15 or even 20 psi. If the pumps are on the supply side pumping away from the expansion tank the pump will add pressure to the system. One thing to remember if you have a bladder type expansion tank your air pressure must be equal to the static water fill pressure. 20 psi water pressure means 20 psi air pressure in the tank with no water pressure on the tank. When water pressure is on the tank you cannot properly adjust the air charge.
 
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