Low Pressure Steam Gauges

Michael Flesher

Does anyone know where to obtain low pressure steam gauges? I am trying to find one with a range of 0 - 2 psi (or 0 - 3 psi), or one that is in ounces, to use on a commercial steam heating boiler.

nicholas bonham-carter

low pressure gauge

i found the best selection at www.gaugestore.com. mine is 0-15 ounces, ideal foe steam heating systems. i mounted it on the same pigtail as my vaporstat. if you have no vaporstat, and think your pressure may be higher, ask them how much over-pressure the gauge can stand without permanent dammage. my system cuts in at 3 ounces, and cuts out at 10 ounces.

be sure to mention that you heard about them on heatinghelp.com--maybe they will advertise here!--nbc

Michael Flesher

Low pressure gauge

Nicholas, what exactly is your brand and model/part no.? I spoke to someone at guagestore.com (Industrial Automation) who told me they do not have anything that low that will work on steam.
Mike

nicholas bonham-carter

steam gauge

i got a wika 0-15 oz. gauge, and when it is mounted on the pigtail, or "syphon tube" it is protected from the temperature of the steam. conventional pressure gauges have an "internal syphon", which is convenient for the gauge mfg. as it seems to plug up requiring replacement. the code requires the orig 0-30 psi gauge to remain on the boiler, but it is useless for our purposes.

if they would advertise here they could sell a lot of gauges!--nbc

Michael P. Bourque

The gaugestore does sell a low pressure 0-3psi. However you will need to install both a 0-30 and a 0-3 as the 0-30 is required by code.

Also these gauges cannot take a lot of heat and most are rated at 145 degrees. To remedy this you need to install a pigtail in the gauge port and make sure it is filled with water before putting on the gauges.

lovesteamheat

Aha moment with pressure but still???

I have a 100 year old single pipe system in a large Victorian home (9 radiators) that I have been tweaking with many of the recommendations in 3 of Dan's books. Re-insulated lines, new relief valves, etc and have saved some money and I am now looking at pressure, differential pressuretrol etc.  The pressuretrol sits on a 1/4" x 8" riser and is set to cut in at .5lb and out with a 1lb differential. Great right, wrong I guess, cuz when I put my shiny new pressure gauge on the same riser and boiled er up, guess what no pressure. I ordered a 15LB gauge because that is what was on there and not moving. I can blow about 2lbs pressure into the gauge manually so pretty sure it's fine and there is visible steam pressure coming out of the riser but I get no reading.



And so the pressure in ounces ???  Is my system operating on ozs of pressure? Is it possible that the differential pressuretrol calibrated in lbs (not ounces) and the 15lb pressure gauge were installed by a numbskull who should have had a pressuretrol calibrated in ounces?



And??? Do I need a pressuretrol calibrated in ounces?

BobC

If the boiler is matched

to the connected load it's possible for it to work at almost no pressure. If your sure the pigtail is clear so the pressuretrol and gauge can "see" the boiler pressure and the system is working good, you may have no use for a pressure device on that boiler.



If the above is true then the pressuretrol is just acting as a safety device, there is no need to calibrate anything. You could use a really low pressure gauge to see whats going on inside that boiler. As long as there is a pigtail between the boiler and the gauge, the gauge does not have to be rated for steam. On my boiler the input of the pigtail is blazing hot but the base of the gauge is just warm.



Bob

ChrisJ

Pressure

Under normal conditions I see around 1oz PSI on my system.  Even with two radiators shut down via TRVs which combined equal 99sqft I've only seen 7oz when it was -3.5F outside.



I did see the system cycle on pressure @ 1.5 PSI one time and it was after an hour and 20 minutes during a 9 degree recovery.

flyers03

I just installed a new pigtail with a tee for my pressuretrol on one side and a new 0-3 psi gauge on the other. My pressuretrol is set at .5 cut in and 1 differential. My question is regarding the new gauge. The needle twitches but never moves from the below zero position. Did I mess up the installation? I attached a picture. This picture was taken 30 minutes in with boiler running. Thanks!

jch1

How much water do you need to put into the pigtail?

Captain Who

@flyers03 - Unless all your main vents and radiator vents are hot and closed you won't begin to show any visible pressure on that 0-3psi gauge. Do an overnight setback and get up early before the system starts and observe.

flyers03

@Captain Who I'm sorry I'm kinda new to this. Did I purchase the wrong type of gauge? What do you mean by overnight setback?

Captain Who

@flyers03 - ha ha no problem. No your gauge and install looks perfect. If you have a digital thermostat you can program it to do an overnight setback. Mine is set for a setpoint of 61 F from 7:45am to 10pm and 53 F (8 deg setback) from 10pm to 7:45am. If you don't have a digital thermostat you can just do it manually before you retire and when you get up you can put it back up so you can give the system a workout and observe the pressuretrol cutting out out and cutting in on pressure.

If your pressuretrol has a mercury switch in it, you need to rotate that pigtail 90 deg relative to the rest of the assembly so that it doesn't tip when the heat hits the coil of the pigtail. They haven't made them with mercury switches for some number of years. Open up the case by removing the screw and check. You'll see a glass bulb with mercury in it if you've got one of the old ones.

flyers03

@CaptainWho Thank you. I'll try it tonight. I did run the boiler for about an hour and a half and the gauge remained below zero and the system never cut out. The digital thermostat read 69 degrees when I started and it raised the temp to 73 degrees (which I set it to go). The thermostat shut down the boiler when it hit the temp i set. Could it be that the pressure in my system is really low that the pressuretrol never really comes into play?

flyers03

@Hatterasguy‌ Thank you very much for the input. I am a bit anal so I might just have to go out and get the other gauge. I'm loving steam heat and learning more about maintaining the system.

Captain Who

"Could it be that the pressure in my system is really low that the pressuretrol never really comes into play?"

Yes it could but that'd be a bit unusual for an hour and a half of burn time. Were the radiators hot all the way across so that all the vents should be closed? Unless your boiler is very small relative to the total radiator load you should have seen "something" on that gauge.

You need to verify that when you do the test tomorrow morning. Check for vents that are leaking steam even though hot and look for any possible steam leaks at pipe joints (much less likely). Do you have to add lots of makeup water to the boiler? That'd probably be the case if you have leaks.

flyers03

@CaptainWho after running the system for an hour and a half all 11 radiators were hot all the way across. The vents on the radiators are adjustable so they are not all necessarily closed completely. I also recently updated them all to be sure they are all working. The main vents are both new this season.

I don't find myself adding water to the boiler often. Should I try completely closing the vents on all the radiators?

Now that I think of it, I did notice one vent in my back room that was making a whistling noise last night.

Captain Who

"The vents on the radiators are adjustable so they are not all necessarily closed completely."

That wouldn't cause them to not close if the radiator was heated all the way across. All steam radiator vents close on temperature. Check them tomorrow morning with a mirror. If the vent is hot and the mirror is showing a fog on it from steam, then the vent is not closing as it should.

flyers03

@CaptainWho Will do. Thank you for the direction.

flyers03

Hatterasguy said:

flyers03 said:

If you're anal, like some of us, you now go out and buy another gauge that reads in ounces, with a proper needle valve and snubber............but, there really is no need for it.

If I wanted to pick up a gauge that reads in ounces, which should I get: 0-10 oz, 0-15 oz?

flyers03

One last question on the gauge. Shouldn't the gauge register 0# prior to start up when the system has been at rest overnight? Or is it acceptable for the needle to be below 0. For example, the boiler was off for 6 hours. Prior to start up, the needle on the new 0-3 psi gauge was far below 0#. Just want to be sure that the gauge isn't faulty and that is normal.

Captain Who

@flyers03 - most gauges have a "zero adjust" screw on the back or the front (yours is on the front). It wouldn't be a crazy idea to adjust that so that it registers zero. The zero on yours is ill defined so just raise the needle up until it is just at the bottom of the black bar region. Having said that though, ideally it is more important to calibrate it at the operating pressure if you have a way of doing that. Since you don't have a U-tube manometer or a reference pressure gauge you don't have any way of doing that, so I'd zero it out with the adjustment screw.

nicholas bonham-carter

unscrew the gauge to make sure the water in the pigtail is not slightly out of balance, causing a slight negative pressure. I would be wary of doing any adjustments on the gauge.--NBC

flyers03

nicholas bonham-carter said:

unscrew the gauge to make sure the water in the pigtail is not slightly out of balance, causing a slight negative pressure. I would be wary of doing any adjustments on the gauge.--NBC

Thank you. Should there be a specific amount of water in the pigtail? Do I make sure it's filled to the top of the threading?

Captain Who

You couldn't fill it all the way up to the threads if you tried but you only need a few ounces of water in there. I'm not so sure that it is possible for a vacuum to really be there, provided that the pigtail is not clogged. The only other way there could be a slight imbalance would be if there was a lot of water in the pigtail and there was a different temperature in one of the water columns relative to the other. If the pigtail is at an even temperature you can rule that out. I'm assuming that since you just did this installation that you poked a rod through into the boiler to make sure that everything is clear and also that the pigtail is clear?

flyers03

Captain Who said:

You couldn't fill it all the way up to the threads if you tried but you only need a couple ounces of water in there. I'm assuming that since you just did this installation that you poked a rod through into the boiler to make sure that everything is clear and also that the pigtail is clear?

Yes I poked a rod through into the boiler to make sure it was clear. There was some blockage in there as I suspect it was never cleaned. The pigtail is new so no issues there. I didn't put any water in the pigtail when i installed it b/c i was under the impression that it would fill with water on it's own. (i guess that was a beginners mistake). Also, the old pigtail didn't seem to have any water in it when i unscrewed it. I mean there was trace amounts of water but nothing to write home about.

Captain Who

Adding water is just a precaution. In my opinion the length of the pigtail and piping below and above it provides heat protection in and of itself.

flyers03

Captain Who said:

Adding water is just a precaution. In my opinion the length of the pigtail and piping below and above it provides heat protection in and of itself.

the pigtail itself was extremely hot but the gauge and the pressuretrol did not get hot at all. I figured all was okay. I'll do as you said and check the vents to see if there is a steam leak at one of the radiators. Thank you for all.

Captain Who

Just one more suggestion. If you already know or are pretty sure that one of the vents is leaking (the one you said was whistling when it was hot) AND you have a new one to put in there of the same vent size, it would be a good idea to replace it before the recovery test tomorrow morning.

flyers03

thank you all for your help. As suggested I checked all of the radiator vents for possible leaks and found 1 that had an issue and replaced it. I also inspected all visible pipes and the connects and there doesn't seem to be any visible leaks. That being said, the pressure is still very low but since everything seems to be working great, i'm going to leave well enough alone. The boiler is quiet and the water is the cleanest i've ever seen it (thanks to scout). maybe one day down the road i'll pick up a new gauge that measures oz's instead to get a more accurate reading. Have a great weekend all!

nicholas bonham-carter

The vents whistle on the end of the cycle, when the vacuum begins to draw the air into the system, and usually hiss when the air is being pushed out.
With good main venting, the radiator vents should become almost completely silent.--NBC