crown boiler


Old 01-07-10, 04:04 PM
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crown boiler

iI have a crown gas hot water heater awi model.the tridicator reads 25 psi for the water pressure is this safe what should it read.....
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Old 01-08-10, 05:06 PM
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12 psi is enough pressure to even get water from a basement boiler to a 2nd floor radiator, with some pressure to spare. (This is based on the law of "water column" where water pressure is determined by the height of the water. About 1 psi for every 2 1/3 foot you go up in height) And precharged boiler bladder-type expansion tanks come precharged from the factory at 12 psi. (Those are the tanks that look like a barbeque grill propane tank.). The boiler's pressure relief valve is usually 30 psi. If you are running say 25 psi cold, and say the pressure builds some while heating, and then say you have problem with the expansion tank having water in it, then the combination of any of these things could put you over 30 psi, and have your relief valve open up, and start flooding the floor by the boiler. (It is nice to have a floor drain in that area, just for that reason.).

Only do this step if you have determined you do not have an expansion tank issue (and you have an issue if when the boiler runs, you see the temp of the boiler water climb by more than a few psi): You can drain out some of the water from the boiler drain valve located low on the boiler. Be careful not too drain too much. Watch your gauge. If say you have done that, and knocked the pressure back to 12, but then notice that the dial on your water meter(if you are on city water) keeps spinning, and or you hear water going through the water supply pipe, and also see the pressure gauge climbing - then you may have to reset your adjustable auto fill valve to a new position.

This diaphram valve(the auto fill valve) is usually located just downstream from your boiler's cold water supply shut off valve. Often these are located above the boiler somewhere. To reduce the pressure - you first loosen a hex locknut that goes around a protruding bolt that has a slot acoss the end of it, so you can use a flat screw driver to turn that bolt. Then you turn the protruding bolt in the normal opening CCW direction, to reduce the water pressure (These valves work backwards from logic. I.e., conversely, turning the bolt in, CW, seems like you would be shutting it off, but instead, it is opening the water flow/psi up more.)

But -you will not see the pressure gauge drop ONLY by reducing the auto fill valve pressure setting. You have to also let some of the water out of the boiler in the first place.

The best approach, so you know where you are at, and so you can monitor what is happening, is to first let more than the desired amount out the boiler drain valve. Drop the pressure to say 8 psi. Then when the auto fill valve tries to add water so it can climb back up to the 25 psi setting it is at, then as it approaches say 10 psi, slowly start adjusting the auto-fill valve per instructions above, so that you can hear the water starting to sound lesser entering the supply pipe, that the auto-fill valve is on. Then adjust the valve further as need be so it finally stops sending water in at 12. No need to worry about if you go over to say 15 psi. That is an acceptable number. 12-15 psi is fine.

If you need help in bleeding the radiators after this, we can help with that too.

If too much water enters the boiler, while you are fiddling, you can always let it out through the boiler drain valve.

Once you have it adjusted properly, you can then tighten back down that hex lock nut aound the adjustment bolt.

If your auto fill valve has something on it that resembles the throttle on a jet - if you ever want to quickly add water to the boiler, you can throttle that lever. Trouble is, you then bypass the feature of the auto fill valve to be the determiner in sending in the appropriate amount of makeup water at all times. (We can get into this more later if need be).
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