Hopefully this is an easy one. Long-ish standing leak it recently occurred to me I might be able to do something about.

See picture. Leak is out of the open down facing pipe that surely serves just that purpose for some reason. I know very, very little about my boiler so please feel free to use Boilers for Dummies language as that would be completely appropriate.

Thanks!

 

your leaking at the PRV "Pressure relief valve".
Most people first inclination is to call it faulty and replace it, but most of the time the valve is not faulty. It's a pretty simple device, it opens and discharges water if the pressure gets above a preset amount (usually 30 PSI on residential system).
Pressure normally builds above the relief valve set point due to the lack of a place for the heating water to expand. Since these are closed systems and water does not compress, we need a place for the water to expand as the system water heats up as the boiler fires.
This is called an expansion tank. There are a few types, some are mounted in the ceiling area (these are called air cushion tanks), some are smaller and mounted near the boiler (these are pre-charged tanks).
An air cushion tank can water log over time, and simply needs to be drained. A pre-charged diaphram tank can lose its charge thru a air leak at the schrader valve, it's diaphram can rupture also.

Seldomly do we see fill pressure regulators (these maintain a system pressure in the boiler) and cause an over pressure.

So, find the pressure guage on your system, and tell us what it reads.
Then, make a heating call, and record the pressure as the boiler water temp raises. If it just keeps climbing as the boiler heats, then your expansion tank is not doing its job.

 

Thanks so much TOHeating. That kind of basic detailed explanation is really of benefit to somebody at my knowledge and experience level, so I very much appreciate you taking the time. On your description I located the expansion tank mounted near the ground at the back of my boiler installation. I will look closer at things over this evening and weekend. I did note this morning that the PRV is still slowly and steadily leaking at the presumably stable pressure (I'm assuming stable as the heat is currently turned off) indicated in my gauge picture in the other thread. As Mike indicated in the other thread it's only sitting at about 12 or 14 psi, so does that still suggest focus on the expansion tank?

 

There are a couple threads you should read, hopefully not too 'techie'...

This one deals with those evil entities commonly called pressure gauges:

http://www.doityourself.com/forum/bo...ure-gauge.html

It is possible that the gauge is lying to you.

If the gauge is NOT lying to you then you do in fact have a defective pressure relief valve.

This second one has some information on expansion (compression) tanks:

http://www.doityourself.com/forum/bo...sion-tank.html

 

Thanks...based on previous feedback had already located and read both of those...and not too techie. Found this ready to go solution at Home Hardware:

Home Hardware - 2" Top Mount 3/4" Garden Hose Thread Pressure Gauge

...but not optimal I guess due to resolution, so will look at other options. Found gauges that went to 60 at Lowes but guess I can still do better than that. Will try to find proper plumbing supply place on Monday and check out the home brew angle tomorrow.

Will explore checking pressure on overflow tank this weekend as that sounds like a good maintenance practice regardless of the source of PRV leak. Will probably need assistance locating the water supply valve in order to turn it off.

Appreciate the reply.

 

Since you aren't really looking for ABSOLUTE accuracy, only a general indication that your boiler gauge is 'reasonably' accurate, it appears that the gauge you linked to at HH would be adequate. You should be able to tell if your boiler gauge is reading 12-14 and the pressure in the system is actually 30 and causing the relief valve to leak.

If you can buy that gauge locally for like $10-$15 it will do what you need it to do.

Going back to your video from the other thread, the water shutoff for the boiler can be seen at 0:18 - 0:20 ... it's the yellow handle valve on the COPPER pipe ahead of the previously mentioned (in the other thread) 'backflow preventer'. It is NOT the other yellow valve seen at the same time on the STEEL pipe. That other valve is your GAS SUPPLY valve to the boiler (which is also good to know!) You might want to hang tags on those for future reference if your memory is like mine!

BOTH of those valves are 'quarter turn' valves. When the handle is parallel with the pipe the valve is fully OPEN. When the handle is perpendicular to the pipe, the valve is fully closed.

Let me ask a bit more about the leaking relief valve:

WHEN does it leak?

All the time? drip drip drip ?

Or, only after the boiler has been running for some time during a heating call?

If you find that the boiler gauge is reading correctly, and the valve is dripping all the time, then it would be a safe bet that the relief valve is at fault.

If the relief valve only leaks when the boiler gets HOT during a heat call, then the safe bet is that your expansion tank is at fault.