How much water loss can be attributed to bad main vents?

nybigapple

The honeywell pressuretrol for the steam boiler used to be set at 2 psi with a differential of 1 for years. Assuming the pressure gauge is accurate, It would reach 5 psi before cutting out. The front building has 3 hoffman 4a specialty quick valves installed. Assume another 2 in the rear building. All vents will leak steam during a cycle.

I look at the specs for the 4a and their max operating pressure is 2psi. Not hard to imagine why they all release steam. Now that I lowered the pressuretrol on the honeywell the gauge shows 3psi before cutting out.

I'm going from a half filled sight glass to empty in 24 hours, and maybe 20 heat cycles. Could I attribute a large portion of this to the main vents or is likely another issue?

Also If I was to replace all the main vents, is there a vent better suited than the 4a? If the current system is cutting out at 3 and the 4a maximum is 2, it seems like there would be no point to replace with the same.

Fred

It sounds like that Presuretrol needs to be re-calibrated. I have included the procedure below. That's a lot of water loss but it's hard to tell if it is just from the bad vents. A lot of it may be, if they are all steaming during a heating cycle. Those vents aren't likely enough but if you can tell us how long each main is and what diameter the main pipes are, we can tell you how much venting you need. The Barnes and Jones Bigmouth vents are excellent and one of those is equal to about two of the Gorton #2's . One on each main may be enough.
Re-calibration Procedure:
Inside the Pressuretrol, right below the micro switch, there is a pivot arm. At the end of that arm you will see a screw pin that is activated by the diaphragm at the bottom of the Pressuretrol. If you look very carefully at that screw pin, you will see it actually has a tiny (I mean tiny) hex head on it. It takes a .050 hex wrench and you can turn it clockwise (Towards the bottom of the Pressuretrol to decrease the Cut-out pressure or counter clockwise to increase the cut-out pressure (which none of us want to do but who knows, your Pressuretrol may be really screwed up!). Turn the power to the unit off first. You may find the first attempt to turn that screw a little bit stubborn (relatively speaking) because it has some Locktite on it but it does turn. Don't turn too much, a fraction of a turn goes a long way towards getting it adjusted where you want it (maybe 1/32 inch turn to start with). You may need to play with it to get it exactly where you want cut out to be.

Jamie Hall

3 psi is too high for most vents to stand for any length of time. If recalibrating the pressuretrol is difficult, you may want to replace it. You may also want to add a 0 to 3 psi gauge (don't lose the old one -- just add this one to the setup) as the 30 psi gauges which are required in many areas are none too accurate at the low pressures.

It is possible that the water is going out the vents -- actually, quite possible. But I would also check for possible leaks in any wet returns. The fact that you do get up to a fair amount of pressure suggests that the boiler isn't leaking -- so there is a good side to that!

nybigapple

Wow Fred you're on top of every post. Thanks for the great help.

With lowered pressure (3 psi vs 5 psi cutout) the farthest radiators aren't getting as hot as they used to before the cycle ends. I fear cutting the pressure even more would leave people on the fifth floor with inadequate heat in their radiators. At 5 psi the radiators will reach 220f, at 3 psi they only reach about 180f.

I mentioned that I believe there is some missloped piping in other threads you've replied to. You can hear gurgling, dripping, and lots of steam hammer in the beginning cycle in the last vertical riser. In this situation lowering the pressure wouldn't really help right?

The simple answer would be to try lowering the cutoff but I tried lower the pressure of the honeywell using your calibration instructions. The little pin refuses to turn, and I've put a lot of pressure on it with a .050 hex. Typing this out I realize I could just physically cut the pressure in and out myself and see the effects, though I would need another person to help see the effects while I was in the cellar doing this.

New England SteamWorks

nybigapple said:

Wow Fred you're on top of every post.

You bet he is!

Fred

What can I say? 3PSI is still too high. You may need to try to melt the lock-tight that is applied to that little screw to get it to move. If you have a long stem lighter, like you use to light a grill, you can hit it for a few seconds to melt that stuff. Just be careful.
How is your main venting on that system? Your boiler may be running longer than it needs to trying to push air out of the mains. That extra time will build system pressure. In reality, the pressuretrol should rarely be the device that shuts the burners down. It is really a safety device.

Chris_L

nybigapple said:

The little pin refuses to turn, and I've put a lot of pressure on it with a .050 hex.

I had the same problem with a couple pressuretrols I was trying to calibrate.

If you have a soldering iron, place the tip of the hot iron near the screw. As soon as you see or smell the thread sealant start to smoke, remove it. You'll then be able to turn the screw, though it may still take some force.

Jamie Hall

Venting venting venting. If your venting is inadequate, you will never manage to get decent heat to the fifth floor apartment. Further, you mention gurgling and water noises and water hammer. You maybe have missloped piping? Ah... yes. And, until you find it and correct it, there isn't much point in anything else.

So.

Step 0. Either calibrate that pressuretrol or get a new one. Set it to no more than 0.8 psi cutin with a 1.0 psi differential.

Step 1. Find the piping which is pitched incorrectly, and fix it. It is unlikely that you will have to repipe anything, but you may have to add some shims here and there and some new pipe hangers. But whatever, fix that.

Step 2. Make sure the mains in the basement and any dry returns are adequately vented. You may also find that adding vents to the tops of the risers, before they run out to the radiators, will help get heat to the fifth floor faster.

It would be nice to think that playing with pressure would fix the problems -- it's easy to do. It won't fix the problems.