Pressure Gauge Need Replacement??

mgambuzza

I have owned this home for the past year and a half. One item I was wondering about on the boiler was the pressure gauge, where in all this time, it never budges past zero. At one point I purchased a pigtail and gauge, but before I went through replacing, I thought I'd ask the members if there is something else that could be causing this(plugged pigtail, etc), defective gauge, or configuration as shown in the picture below. This has been in service since around 2007 when the previous owner changed out from an oil fired to natural gas.

Subsequent question - the replacement pigtail seems to be steel, metal, not copper. Looking for recommendations on whether I'm better off cleaning out the copper than using the metal (concerns of corrosion).

Jamie Hall

Not a bit surprised that that pressure gauge doesn't budge. You need it for insurance and the building codes -- but it won't tell you what the system is doing. Mount your new low pressure gauge on the same pigtail with it, using a T and a few elbows and nipples. While you are doing that, make sure that the pigtail is clear all the way into the boiler, but I see no reason to replace the pigtail unless it is hopelessly blocked -- and if I did, I'd use copper or brass, not steel.

SteamingatMohawk

And an isolation valve to protect the low pressure gauge, but NOT the 30psig gauge and the pressuretrol.

It should not be left on line unattended. I realize is an annoyance.

SteamingatMohawk

I crude sketch of two ways to do it. Instead of the elbow at the left you could use a tee with a pipe plug to serve as a cleanout.

EdTheHeaterMan

@SteamingatMohawk has a good idea. you dont want to spend good money on a more precise gauge to have it go bad in a year or two.

https://www.supplyhouse.com/Everflow-BMCR0014-1-4-Black-Cross
https://www.supplyhouse.com/Bluefin-GLP25-32WC-BM-2-5-Steel-Low-Pressure-Gauge-Bottom-Mount-w-Brass-Internals-0-32-WC
https://www.supplyhouse.com/Bluefin-BLN025-300-1-4-x-3-Black-Nipple
https://www.supplyhouse.com/Webstone-40530W-1-4-MIP-x-FIP-Full-Port-Forged-Brass-Ball-Valve
https://www.supplyhouse.com/Bluefin-BLE025-1-4-Black-90-Elbow
https://www.supplyhouse.com/Thread-Sealants-1861000

mgambuzza

You guys are the best!! Thank you - I wish I thought of posting this earlier so I could've use it on my Christmas wish list.

Greatly appreciated and will let you know the results.

SteamingatMohawk

@EdTheHeaterMan Thanks, also, if you remember multiple discussions a few years ago, I did some checking with manufacturers and some of the low pressure gauges would fail before the relief valve 15psig setpoint. Depending on the pressure and structural integrity of the gauge, it could just leak or something worse at something like 130% of the gauge range. 5 psig gauge fails at 6.5psig,

In those discussions one of the guys (maybe @ChrisJ) advocated for Magnehelic gauges which can withstand pressures above the relief valve setpoint. If my memory is correct, he even mentioned being able to get them on eBay or one of those used stuff websites with model numbers to save $$.

I couldn't resist. Here's the title if you want to get a headache:

Low Pressure Heating Boiler Regulations


Be Safe, Not Sorry

SteamingatMohawk

@EdTheHeaterMan's sketch might be better because one principle with the Pressuretrol is to have the device oriented such that as the pigtail sees pressure it will tend to uncoil. Having unbalanced weight on the sides may have an effect on how the pigtail might expand and affect the Pressuretrol setting.

I have no technical details on the extent of such movement, just look at the installation diagram to make sure you have the proper alignment compared to the pigtail.

See the sketch in this and don't go wild with pipe dope.

https://customer.resideo.com/resources/Techlit/TechLitDocuments/95-0000s/95-5361.pdf

EdTheHeaterMan

SteamingatMohawk said:

@EdTheHeaterMan's sketch might be better because one principle with the Pressuretrol is to have the device oriented such that as the pigtail sees pressure it will tend to uncoil. Having unbalanced weight on the sides may have an effect on how the pigtail might expand and affect the Pressuretrol setting.

I have no technical details on the extent of such movement, just look at the installation diagram to make sure you have the proper alignment compared to the pigtail.

See the sketch in this and don't go wild with pipe dope.

https://customer.resideo.com/resources/Techlit/TechLitDocuments/95-0000s/95-5361.pdf

That is really only an issue with older mercury balance controls. I don't believe that control has mercury in it. But it is a good point for those that read this who may have older controls

SteamingatMohawk

Great point, I should have thought about that.

mgambuzza

EdTheHeaterMan said:

@SteamingatMohawk has a good idea. you dont want to spend good money on a more precise gauge to have it go bad in a year or two.


The good - I disassembled the old setup, the pigtail came out, and was FILLED with sludge. Took me a while to clean out, rinse, clean out rinse, then completely clean. Reassembled with this configuration with new parts, but still no movement on gauge. The only thing I thought of after the fact and reading some more posts was the inlet feeding the pigtail should've been cleaned out (dope). Thankfully all disassembled without incident, so now I guess I'll get a little practiced in disassembly later tonight/tomorrow and make sure the inlet/outlet is cleaned out. I would rather as you'll see in the picture it will be better as well for the ball valve so it's not obscuring the gauge.