Water Feed and Pressure Question - ??

Kentucky_Steam

Cold weather has finally come to Kentucky this season.  My Weil-Mclain EG-75 has been operating only a few times so far, but we're "into it" now.

I have a Hydro-Level VXT-24 digital water feeder on the boiler (this is 2-pipe steam) and this morning I was quick enough getting down to the basement when I heard the water feeder kick in, and see this thing in operation.

I wasn't surprised to see the burner was off, since the low-water condition that (after a 2-minute delay) had activated the VXT-24 feeder had also turned off the burner.  What did surprise me was that the pressure guage was showing a little over 4 lbs.  I have the Pressure-Trol set to about 2.5 lbs with 1 lb differential.

I'm wondering... did the additional pressure within the boiler come from the make-up water (at Louisville city water pressure) being added by the water-feeder device?  Since I've not seen this feeder in action (quick as a bunny as it is), I have no way of knowing if this is a normal, momentary occurance. 

Jamie Hall

Actually...

if you have your pressuretrol set to 2.5 (that's the cutin on a pressuretrol) with a 1 differential, you'll get a cutout of 3.5 psi -- which is too high, incidentally.  Try setting the pressuretrol to 0.5 instead.  But anyway, with the cutout at 3.5, and a 30 pound gauge showing a bit over 4, that's not too surprising (since the gauge is none too accurate at that low a pressure, and, for that matter, the pressuretrol isn't exact either...).



And no, the feedwater coming in didn't do that (unless all your vents were clamped tight shut -- all of them -- which is unlikely at best).

will smith_4

PressureTrols

I'd pull the p-trol and gauge and clean the pigtails. Also make sure the pigtails are primed when you re-install each. As far as the pressure goes, what type of p-trol do you have-is it additive or subtractive? As anyone around here would (likely) say, try for a 1/2# cut-in with a 1 1/2# cut-out. If your pressure gauge is accurate and you're getting too high of an operating pressure, I'd suspect either the pigtail for your operator is plugged up, or the operator itself is out of whack. If it's a mercury switch, make sure it's spot on level, and that the pigtail is properly oriented.

All the Best!

brian_44

Mine was just as inaccurate

I have the same exact boiler as you (installed last year) and the same crud pressuretrol. I seriously have NO idea why they even waste the time of putting these things on residential boilers. With mine, I had the unit cranked all the way down to .5 with a 1.0 differential. It STILL wouldn't cutout at almost 5 PSI.



I took the entire until off (pigtail, gauge and pressuretrol) and fiddled with it until it shut off as low as I can get it (which is probably around 14oz as it's right under 1PSI...but hard to tell with that useless gauge). I tested it by physically blowing into the thing. One other way to do it is to stand over the unit when you start to build pressure and keep turning the screw until you cutout.



Either way, the gauge and pressuretrol are worthy of trash (although I understand you need the gauge due to code).



I have a low pressure gauge and a vaporstat on order so I don't waste any more $$ on uselessly burning fuel.

ryanr256

pressuretrol setting adjustment

I have a 0-3 PSI gauge and used it to set the p-trol. My problem was that I ran out of thread screws before the p-trol would cut out. Oh, it did cut out, but that's because I backed the screw all the way out. Even with the screw engaged by a half a thread, the cut out was over 3 PSI.



With that little of engagement the whole adjustment system was wobbly, for lack of a better term. It's only held on by the pigtail of the spring hooked onto the rocker.



I was able to get mine to consistently cut out at 1.5 pounds and cut in at about .4 pounds as registered on the 0-3 gauge. The scale on the front of the p-trol is no longer accurate, but I've taped over it and marked where the cut in is .5. I will put a notice on the unit that it is to be used in conjunction with the gauge to set the cut in, not the manfacturer provided scale.



-Bob

Kentucky_Steam

Thanks for your help

I've been out of town a day or two, so just now getting back to this.  Last year, for my birthday, the kids asked what I wanted.  When I sent them a link to Wika low-pressure guage, they thought I'd flipped out.  The one that came with the boiler was a 30-lb guage.  You couldn't tell "anything" (my polite word) from that one.  The one I got is a 10-lb range, where you can read things much better.  I might ask for a Vapor-Stat, but those dudes are expensive aren't they ($200+)?

Also, I tried adjusting the P-trol as low as possible, but (as you've said) you can cause that thing to slip right off the threads of the screw-control trying to it go lower, beyond a point.  Seems like a very crude instrument for the precise control that "expert steamers" say we should be using here.

nicholas bonham-carter

Presuretrol=crud?

Not completely useless as it can be used as a bookmark to keep the installation manual open to the right page for a skilled steam installer!!!--nbc

ryanr256

pressuretrol = crud?

Well, I did get mine to consistently cut out at 1.5 and back in at around .5 (maybe .4 or .35), but I don't recommend everyone open theirs up and start bending things.



My theory for why mine was out of whack is that from the years of over pressure, the metal tabs were bent from their original position. Of course I have no way to recalibrate it to the scale on the front, so I used the gauge to set the cut out with the diff wheel at 1. I'm not talented enough to overcome the 1 pound differential so I'm stuck with that.



If I go by the printed scale, my cut in is 3 pounds. Of course that's not right so I've taped over the scale so it won't confuse anyone. I'm going to experiment and see how low I can get the cut out. I'd be happier with 1 pound, but I don't know what will happen on the cut in.



Oh, my p-trol is the micro-switch type, not the mercury type.



-Bob