Gifford loop and slow returns

EBEBRATT-Ed

@ubipa

Just sit back and think for a second about what's happening.

You forcing the water in the returns to back up 6 or 8" higher than it need to be because of the height of the tee. If the water is allowed to back up into the steam main whtat will you get Banging Your complaint in your first post is that you have banging and slow returns. I mentioned in my first post about measuring the height of the gage glass and the height of the return tee

. At least part of the problem is staring you in the face. The water is returning into the boiler and entering the steam space not the water space

ubipa

@EBEBRATT-Ed

Thanks for this.. yeah, I think I agree that the loop being so close to a possible steam space could be causing the noise. Please do take notice the setup is newer but it’s been in service for the last 2.5 seasons with this only recently occurring. So no way am I saying a Gifford loop is a problem. A Hartford loop, a check valve, returning directly to the bottom of the boiler...all seem to have their own shortcomings.

I’m now more interested in understanding the situation and feedback from experience with Gifford loop setups. It would particularly be interesting to hear ppl’s experience using Gifford loops on systems that run 1-5psi pressure and low volume wet returns.

EBEBRATT-Ed

@ubipa

If it was my boiler I would lower the tee at least to the normal water line and probably skim the boiler. I think then you would be ok. The rest of the piping is a really nice job..

Steam systems need attention from time to time and the fact that we here all the time that"it worked ok for a period of time" is something we constantly encounter in heating systems.

Trying to find out what has changed is the challenge.

I have been reading about Giffords, not sure I agree with everything in that article but I have long felt that raising a Hartford loop could help on some jobs

Chris_L

ethicalpaul said:

Well I have a sight glass on my return so I know how much water is returning. The boiler manufacturers usually tell how many gallons per minute.



It’s more than very little!

You can calculate the amount of condensate formed from the EDR of your boiler. In gallons per minute, it is 0.0005 * EDR (See: https://heatinghelp.com/systems-help-center/conversion-factors/)

So for my little 266 square foot boiler, that works out to about 0.133 gallons (or 17 ounces) per minute, which doesn't seem like very much.

I imagine how much is flowing through the Hartford loop at any moment depends on how steady the water line is.

nicholas bonham-carter

What does that metric pressure equal in psi?
Remember that the water level in the returns will rise 1.75 inches per ounce of pressure, and that pressure is too high, it could flood the main vent.—NBC

Chris_L

I am not sure what you mean by "metric pressure" (or if this question is even for me).

As Gifford explains, using his loop does reduce the "A" dimension, but it is only a matter of inches. Even with the higher loop I have, the water would have to rise 36" to reach the dry return (main).

So it really isn't a concern for me, particularly since I never run the boilers at more than a half pound of pressure. (And remember it is the pressure differential, not the boiler pressure itself that matters.) For those lacking in "A" dimension, it might be different.

nicholas bonham-carter

This is the apparent metric pressure: " fluctuate 1-2kpa", I was referring to.--NBC

ubipa

> @nicholas bonham-carter said:
> What does that metric pressure equal in psi?
> Remember that the water level in the returns will rise 1.75 inches per ounce of pressure, and that pressure is too high, it could flood the main vent.—NBC

0.125-.25 psi.. 3-7in of rise. Interesting, that is what I was seeing in the leg of loop. Based on the volume of water in the return, resistance of the piping and pressure equalization of the main, I wouldn’t think this would happen so quickly.