System fill, automatic refill.

ralman

My PRV is set for 12 PSI. The Expansion tank is set for 12 PSI. I filled the system until the boiler gage reads 12 PSI. With the system calling for heat I try to bleed the CIBB's. If I bleed out a gallon of water, will the PRV let a gallon of water in to the system if the boiler PSI is now 18 PSI due to the raised water temperature?

Steamhead (in transit)

Not right then

but when the water cools down and the pressure drops, then it will refill.

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ralman

Thank you, Steamhead.

I have 16 emitters on a monoflo T system. I have a difficult time bleeding the air out and usually get a large amount of water drained out when I go around and bleed them. It had just occurred to me this morning. How will the water automatically feed in if the pressure is 18 PSI during the call for heat? Thanks for the response. I will have to make sure the boiler cools enough for it to refill. I don't think the pressure will drop because of the triple aquastat settings.

Empire_2

Hello Ross.

First, you are confusing water in gallons with pressure, psi. You can have"X" amount of water @ 12 psi and the same @ 1 psi. Your expansion tank may be the problem and I know that Monoflo are tough to bleed, but Your PRV should take care of any draining/Bleeding you do with pressure, Not volume of water. Bottom line,...If there is pressure on the system, your concern of gal. or anything else is irrelevant. 1 psi lifts water 2.34 approx feet above the PRV. Any additional expansion can be a result of bad gauge, bad tank, or your PRV not shutting down. That's in a "Nut Shell" ;-)

Mike T.

Unknown

Ross................

your a "blast", are you still playing with that, I have got mono-flo here, and it takes right-off. Did you put an air-scoop into your scheme?

ralman

Hello Dave

Hey what can I say, is killing me. I put a spirovent on it. I posted an unfinished picture the other day. I moved the circulator and I don't think it works any better. This morning after bleeding I was wondering how the system would automatically refill if the aquastat was keeping the pressure above the prv setting. Steamhead confirms my suspicion, It won't, unless the boiler cools below the prv setting of 12 PSI. I have already lost a gallon trying to get good flow in some baseboards. I will probably lose another before I get all the air out. Either I am doing something wrong or ?
Thanks Dave.

ralman

Hello Mike T.

I appreciate your help. I have difficulty conveying my thoughts. Here is what I am trying to get at. I start with 12 PSI PRV setting and 12 PSI expansion tank setting. I then fill the boiler and zone using the fast fill feature of the PRV. I power purge with a setup decribed in Dan Holohans book, Pumping Away. I then move the fast fill lever to automatic and open the power purge ball valve, and close the boiler drain valve. I wait until the PRV stops letting water into the pipe and I check the boiler pressure gage. It is stopped at 12 PSI, I think the system is full of water. I start the boiler and only fire to 160*. Then I start the circulator, some emitters are air bound. So, I go around and bleed air from the emitters. During this process I lose about a gallon of water. I was wondering if the PRV would replace this gallon of water. I did not think it would because by now my boiler gage is at 18 PSI due to the heating of the water. So, I felt the water would have to cool down for the pressure on the boiler gage to drop low enough for the PRV to open. My boiler is on a triple aquastat and I don't believe it will cool down to the 12 PSI unless I interrupt that control. Steamhead, I think is saying the same thing in his post. I will probably be minus at least 2 gallons of water by the time I get all the air out. Then the system would be 2 gallons of water under full and will not refill as long as the boiler is firing off the triple aquastat settings. My expansion tank appears to be okay. It is not waterlogged and has held the 12 PSI charge. Am I concerned over nothing?

Timco

Are you pumping away from the point of no pressure change?

ralman

Yes.

Steamhead (in transit)

What circulator

are you using?

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ralman

I changed over from the Taco 007.

I put a Grundfos 15-58 3 speed circulator. I have tried all speeds and currently I am using speed 2.