Adding a low pressure gauge to my steam boiler

da13ear

Hey guys,

Looking to add a low pressure gauge to my pigtail.  Picked up a black T and elbow and a few .5" nipples along with a 5PSI gauge.  

Before I install, do you see any problems attaching this to where the pigtail goes?

Thanks so much,

Chris 

pecmsg

As long as the pig tail is connected to the boiler no problem.

Dan_NJ

In that location - before the pigtail loop - in case where the pigtail is clogged in the loop you would not be seeing the same pressure that the pressuretol is seeing. Mine is mounted off a T attached at the top of pigtail, between the pigtail and the pressuretrol. I also used brass fittings.

You would also want to protect the gauge from live steam hitting it, another reason mine is on the cold side (non-boiler side) of the pigtail loop.

JUGHNE

The way you are holding that in your hand, I am not sure of how you will be installing.
But, the pigtail would be first and then the gauge and control mounted after it.
The pigtail provides protection for both from the steam.
Prime with water before attaching components.

EBEBRATT-Ed

@da13ear

I would use all brass fittings. I know they are more $$ Black is ok if you check it to make sure it's not plugged up from time to time.

I would put a 1/4" ball valve or petcock under the new gauge to save ware and tare on it. Keep it off and just open it when you check the pressure

jmho

Chris_L

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead.

As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures.

My low pressure gauge was formerly set up just like @Dan_NJ's-after the pigtail. It never read anything until the pressure began to rise just before a Pressuretrol shut-off (when recovering from setbacks). I recently moved it to a tee on the pressure relief valve with a long vertical riser, and now it reads 1" to 2" of water, when the boiler is steaming but not building pressure.

As for materials, I agree you should stay away from black. I've been using stainless steel as it is generally less expensive than brass.

Dan_NJ

My gauge is 0-3 PSI range and I can see it dance around the first few tickmarks for the majority of cycles. I see no practical purpose in trying to read the first 1/2 or 1 oz of pressure (1-2" wc) on my plain vanilla one pipe system. If it were some kind of vapor/vacuum, 2 pipe arrangement that might be useful. In my case I really only care that it stays very low most of the time, and that it doesn't exceed my cutout when it does cycle on pressure.

da13ear

Hey guys,

Thank you all for the feedback.  I picked up all the parts in brass as recommended.   I couldn't get my hands on an 1/4 ball valve so I've put this on hold for the time being.  Will revisit it next week and share some pictures.

One question I need to solve between now and then - the entire setup ends up being too big to spin onto the boiler without removing the low water cutoff.  Any suggestions on how to get around that without removing the low water cutoff?

Pic attached for reference

delcrossv

Chris_L said:

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead.

As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures...

Dunno. Works for me. But it does "bounce" a little. The black scale is oz/in2.

ChrisJ

delcrossv said:

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead. As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures...

Dunno. Works for me. But it does "bounce" a little. The black scale is oz/in2.

That's much higher than I measure.  12 times higher.

Also what does that gauge say when the boiler is off?

Chris_L

delcrossv said:

Chris_L said:

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead.

As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures...

Dunno. Works for me. But it does "bounce" a little. The black scale is oz/in2.

Have you ever checked that gauge against a manometer? I'd be curious how closely they match at very low pressures--say 0-3 inches of water. (I am guessing not very if the gauge is on a pigtail.)

Also, I'd be curious what folks think about the chance of water from the pigtail getting pushed into the gauge. I don't think capsule gauges like the OP's are designed for liquids. Note that the distributor describes his as a diaphragm "gas" gauge. (I think it is really a capsule gauge.)

delcrossv

Goes to zero with the boiler off. My system operates at 4 to 8 oz, so I have no need to measure at  3" WC.

EBEBRATT-Ed

@da13ear

yes buy a 1/4" brass union. then you won't have to spin it

Jells

Chris_L said:

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead.

As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures.

My low pressure gauge was formerly set up just like @Dan_NJ's-after the pigtail. It never read anything until the pressure began to rise just before a Pressuretrol shut-off (when recovering from setbacks). I recently moved it to a tee on the pressure relief valve with a long vertical riser, and now it reads 1" to 2" of water, when the boiler is steaming but not building pressure.

As for materials, I agree you should stay away from black. I've been using stainless steel as it is generally less expensive than brass.

Thanks for the shoutout to my thread! So the 'long vertical riser' takes the place of the pigtail in keeping water out of the gauge? How long is 'tall'? I'd love to see anything on my 1-3 psi gauge. Do I need a oz/sq in gauge?

Hap_Hazzard

da13ear said:

I couldn't get my hands on an 1/4 ball valve so I've put this on hold for the time being.

Is there a Harbor Freight near you? https://www.harborfreight.com/14-in-full-port-ball-valve-63553.html

ChrisJ

Jells said:

If you want to see very low pressure on that gauge, I would not put it on a pigtail, and I would not put it an that position. Mount it well above the top of the boiler instead. As @ChrisJ noted on this thread: https://forum.heatinghelp.com/discussion/186629/can-you-balance-a-system-with-no-measurable-pressure-ever#latest if you put the gauge on the pigtail, it won't read very low pressures. My low pressure gauge was formerly set up just like @Dan_NJ's-after the pigtail. It never read anything until the pressure began to rise just before a Pressuretrol shut-off (when recovering from setbacks). I recently moved it to a tee on the pressure relief valve with a long vertical riser, and now it reads 1" to 2" of water, when the boiler is steaming but not building pressure. As for materials, I agree you should stay away from black. I've been using stainless steel as it is generally less expensive than brass.

Thanks for the shoutout to my thread! So the 'long vertical riser' takes the place of the pigtail in keeping water out of the gauge? How long is 'tall'? I'd love to see anything on my 1-3 psi gauge. Do I need a oz/sq in gauge?

I used an 18" tall 1/2" steel pipe but I'm sure shorter could work. I just used what I had on hand and could fit.

It creates an air trap to block the steam.  Air can't get out so steam can't get in.

You'll need to choose a gauge with the range you need.  I'd recommend a Dwyer Magnehelic.  Something with a 4" range +-

delcrossv

Jells said:

Thanks for the shoutout to my thread! So the 'long vertical riser' takes the place of the pigtail in keeping water out of the gauge? How long is 'tall'? I'd love to see anything on my 1-3 psi gauge. Do I need a oz/sq in gauge?

I'd recommend that. 0=3 psi gauges are IMO too large a range . Most well tuned steam systems run at 8 ounces or less.
Supply house has Winters ounce gauges for a lot less than a Magnehelic, ( unless you're measuring low inches of WC pressures- and you don't know that yet.)

ChrisJ

delcrossv said:

Thanks for the shoutout to my thread! So the 'long vertical riser' takes the place of the pigtail in keeping water out of the gauge? How long is 'tall'? I'd love to see anything on my 1-3 psi gauge. Do I need a oz/sq in gauge?

I'd recommend that. 0=3 psi gauges are IMO too large a range . Most well tuned steam systems run at 8 ounces or less. Supply house has Winters ounce gauges for a lot less than a Magnehelic, ( unless you're measuring low inches of WC pressures- and you don't know that yet.)

There's multiple reasons I recommended a Magnehelic.

First they tolerate water.

Second even a 2" Magnehelic will not be damaged by as much a 15 psi.

They are a better gauge and will last longer and take more abuse.  They can almost always be found on eBay for $30-50.

cross_skier

@ChrisJ
Any issues mounting the Magnehelic gauge?  I doesn't look like other gauges with npt threads

ChrisJ

cross_skier said:

@ChrisJ
Any issues mounting the Magnehelic gauge?  I doesn't look like other gauges with npt threads

They have two sets of holes, I think 1/8 npt female.

I say sets because they have negative pressure connections and well as positive depending on what you want to measure.  

Since there's 2 of each you plug the one you're not using.   The new gauges come with plugs.

They are aluminum with would do better with steel connections but I used brass and I'm sure one day I'll pay for it.

JohnNY

delcrossv said:

Goes to zero with the boiler off. My system operates at 4 to 8 oz, so I have no need to measure at  3" WC.

Isn't 1 ounce of pressure = 1.7 inches w.c.?

Chris_L

@Jells wrote:

Jells said:

Thanks for the shoutout to my thread! So the 'long vertical riser' takes the place of the pigtail in keeping water out of the gauge? How long is 'tall'? I'd love to see anything on my 1-3 psi gauge. Do I need a oz/sq in gauge?

With the riser and fittings, my gauge is about a foot above the top of the boiler and 2 feet above the water line. Since the pipe to it never gets hot, I presume steam never reaches it.

See below. (I need to put the case back on it.):


The scale on this is 0-10" of water. (It is a gas manifold gauge I found on eBay.) If you want to see what pressure you operate at, I'd suggest a simple manometer like the one below. Just put a hose barb on the valve at the bottom of your sight glass and attach some tubing to measure the pressure. Though you can't see it very well in the picture, the pressure in inches of water is just the distance between the water level in the sight glass and tubing in inches.

But do this carefully! The open end of the tubing should be near the ceiling, and be sure to turn the valve off well before the water rises that high (roughly 2 psi depending on your ceiling height and boiler) so you don't get a hot shower. Keep the valve the hose barb is attached to closed when not reading the water column.

Jells

Chris_L said:

  If you want to see what pressure you operate at, I'd suggest a simple manometer like the one below. Just put a hose barb on the valve at the bottom of your sight glass and attach some tubing to measure the pressure. Though you can't see it very well in the picture, the pressure in inches of water is just the distance between the water level in the sight glass and tubing in inches. But do this carefully! The open end of the tubing should be near the ceiling, and be sure to turn the valve off well before the water rises that high (roughly 2 psi depending on your ceiling height and boiler) so you don't get a hot shower. Keep the valve the hose barb is attached to closed when not reading the water column.

I LOVE the stupidly simple solution here! Thanks!

da13ear

@EBEBRATT-Ed is it ok to put a union between the pigtail and the presuretrol?  Just trying to stick to the best practices.

@Hap_Hazzard I do! Thanks so much for the feedback.

ChrisJ

Hint hint

https://www.ebay.com/itm/175028297960?epid=7046120044&hash=item28c07fe0e8:g:QlwAAOSw0aNhltiv

cross_skier

Thanks, I happened to pick up one this morning

Jells

Hap_Hazzard said:

da13ear said:

I couldn't get my hands on an 1/4 ball valve so I've put this on hold for the time being.

Is there a Harbor Freight near you? https://www.harborfreight.com/14-in-full-port-ball-valve-63553.html

It also seems Home Depot has them in the air tools dept, not in plumbing.

https://www.homedepot.com/p/Husky-1-4-in-Full-Port-Ball-Valve-HDA70100AV/100039901

cross_skier

@ChrisJ. Would a stainless reducing nipple 1/4-1/8 work well between the gauge's aluminum case and the brass plumbing?

https://www.ebay.com/itm/292369195531

EBEBRATT-Ed

@da13ear

Well if you can't spin it put a union there. You don't have another choice unless you pipe it above the boiler jacket

ChrisJ

cross_skier said:

@ChrisJ. Would a stainless reducing nipple 1/4-1/8 work well between the gauge's aluminum case and the brass plumbing?

https://www.ebay.com/itm/292369195531

90% sure that would be far worse into aluminum than brass.
Steel is much better than both, SS might be the worst.

Hap_Hazzard

da13ear said:

@EBEBRATT-Ed is it ok to put a union between the pigtail and the presuretrol?  Just trying to stick to the best practices.

I have one on mine. I got tired of having to disconnect the wires.

Hap_Hazzard

ChrisJ said:

90% sure that would be far worse into aluminum than brass.
Steel is much better than both, SS might be the worst.

Is all sched 40 SS pipe and fittings 300-series stainless?

cross_skier

I went with a carbon steel reducing nipple between my brass plumbing and the aluminum gauge.  I would post the link but it hasn't arrived.  Gauge is great, got a killer deal on a new gauge like @ethicalpaul's.  Two left if interested. --
https://www.ebay.com/itm/143917746131

Jells

@Chris_L I did the tube from the bottom of the sight glass. No pressure. But my heat guy says it's not a valid way to measure steam pressure! He's well thought of here, but my gut says he's wrong. Pressure is pressure, whether you tap it below the waterline or above. How do I convince him?

Hap_Hazzard

Jells said:

How do I convince him?

Introduce him to Archimedes.

Jells

Hap_Hazzard said:

Jells said:

How do I convince him?

Introduce him to Archimedes.

Sadly, old Archie is long dead, damn Romans.

Marc_18

Dan_NJ said:

In that location - before the pigtail loop - in case where the pigtail is clogged in the loop you would not be seeing the same pressure that the pressuretol is seeing. Mine is mounted off a T attached at the top of pigtail, between the pigtail and the pressuretrol. I also used brass fittings.

You would also want to protect the gauge from live steam hitting it, another reason mine is on the cold side (non-boiler side) of the pigtail loop.

Why didn’t you include the original 30psi gauge to meet code?

Dan_NJ

The original 30 psi gauge is there per code, out of frame. Still connected directly to the boiler end section via its tapping, and probably to this day still reading 5 psi 24/7/365 (I would confirm for you except I've been out of that place for some time).