Slantfin Galaxy Boiler Pressure Mystery

chiefswabjockey

Hi guys, first time posting but also first time trying to figure out owning a boiler.

I recently started looking at the pressure gauge on my boiler since it has started kicking in to heat the house. Everything is fine, comfort wise, now that I bled quite a bit of air out of the system but I'm perplexed at the pressure gauge on the boiler.

Here's what I've seen. I saw today that when the boiler has been firing for a few minutes and the temperature reading gets around 170F the pressure gauge is reading around 35 psi. My understanding is that this is TOO HIGH. The confusion started when I noticed that the relief valve which is marked at 30 psi wasn't tripping automatically at that pressure.

So I tripped it myself and got things down to what seemed more "normal". I waited for the water temperature to drop to around 100F which the manual for the boiler states it should be around 12-15 psi. At this point, it was still 20 psi so I tripped the relief valve some more to get it down to 15 psi and then I noticed the sound of water going through the pressure reducing valve and the boiler pressure increased back to around 20 psi before it stopped letting water through again (still around 100F).

So, I'm figuring that the chances of both the reducing valve and relief valve being bad at the same time are less than the pressure gauge on the boiler being inaccurate to around 5 psi on the high side. The question now is, what needs to be done about it? Nothing? I have yet to have my first annual maintenance done on the boiler and will certainly bring these findings up when I get around to choosing a contractor to come out and inspect it but I want to go into this with a few more kernels of knowledge to protect myself from getting gouged.

My only thought about why the pressure was high to begin with was that perhaps the previous home owner had gone ahead and forced more water into the system in a dumb attempt to get the radiators on the second floor to heat properly rather than bleeding the air out of them. I will continue monitoring it to see if it eventually reaches the same high pressure before I started releasing it manually in which case I may have a faulty pressure reducing valve that is letting more water in than it should slowly over time but that doesn't really match what I was seeing with the relief valve unless I misunderstand how they work and they don't instantly trip as soon as the pressure goes above the rated threshold?

Any advice appreciated!

beenthere

Most likely an inaccurate pressure gauge. What kind of expansion tank do you have. is it a bladder tank, or a big steel tank.

chiefswabjockey

It's a modern steel bladder tank (Watts). The top of the tank doesn't seem to get warm (or any part of it) even after the boiler has been operating for some time and it sounds empty though I'm not experienced in what it SHOULD sound like when tapped at the bottom.

I don't have a bicycle pump (really thinking about braving the rain out there and getting one because this is bothering the snot out of me) and I don't want to use my car tire gauge because it tends to suck and let a lot of air out before I can get a seal on it without having anything to fill it back up again so I haven't done any kind of pressure test on the tank.

There is no valve in line with the inlet to the tank, the only valve is upstream of it past the reducing valve and backflow valves. All I know is that when the boiler temperature is reading below 100F and I trip the relief valve water refills the system and eventually it stops out at reading approx. 25 psi which seems insane. I have released the pressure a number of times between heating cycles and it always goes back. Other than the gauge giving me the creeps the heating system seems to be working normally with no abnormal pipe noises or leaks at any of the rads (which are all less than 8 years old, same goes for the boiler itself). The actual pressure reducing valve's top nut isn't loose or anything so I don't see how it could have gone out of adjustment by itself.

I'm feeling it's probably not safe for me to fiddle with this much more, though the tinkerer in me really wants to force open the reducing valve to see when exactly will the relief valve automatically purge.

Thanks!

beenthere

I've seen gauges show 25 PSIG in the system, when there was no water pressure in the system. Install a new valve before doing anything else.

biggles

the pressure when the boiler shuts down from the stat setpoint should be under 30PSI my off cycle 20PSI i've seen on my Weil Mclain 160F-170-F setpoint made.....the relief is 30PSI trip could be a spring characteristic of that one..it will trip but very generic might be slightly off.the red water regulator should maintain 12PSI with the boiler COLD leaving you 18PSI for heated water within the system and the expansion into the tank before even getting to 20PSI.next warm day drain off the boiler to 5psi and see when the water pressure regulator stops feeding if it goes over 12PSI and close to 15-20 note it to the maint guy..slight CCW on the adj screw will bring it back to 12 as it feeds when you see that on the PSI guage..

chiefswabjockey

My problem right now is that I don't want to go adjusting the screw on the regulator without knowing whether or not the pressure gauge on the boiler is off. Of course, it looks like the home depot does have a water pressure gauge (looking online) but it says it's rated only for cold water and goes all the way to 200 psi... It seems like you can adjust the regular too far in either direction from the installation instructions I found for a similar Watts unit online and cause something bad to happen to it otherwise I was ready to just go ahead and set the thing to the lowest setting (counter clockwise turn) and see what's what but now I'm afraid to fiddle with it. The fact that the boiler is reading close to 25 psi after releasing the pressure manually to around 15 and allowing the auto fill is a BIT suspicious since the range on the regular is 10-25 psi and part of me just wants to believe that for some reason somebody stupid who installed it decided that it should be opened all the way and it's been like that for the last 7 years. Why they would do that though doesn't make sense because that would be extra work as they are supposed to be factory set to 12-13 psi as labeled.

Starting to think the expansion tank can't be the problem because the tank doesn't matter at all when the boiler hasn't fired in a while, right? The real issue is getting to the bottom of why it reads high psi sitting below 100F - bad gauge or maladjusted regulator.

biggles

let the maint.guy coming in look at the pressure reg.doubt it is the PSI guage that 12 PSI tag on the regulator is a industry standard...but even below that is OK to have a boiler start to heat the water during a heating call and cycle it off way before that 30PSI blow off

chiefswabjockey

The heating guy isn't due to come until next week so I've continued to try to diagnose myself. I think the pressure is fine and the filler is doing what it should do but the pressure gauge is messed up and here's why and let me know if you agree.

As an experiment, I waited for the boiler to cool to 100F, I closed the fresh water intake valve and then I released some water to get it down to read 15 psi and waited a while. Then I went to the 2nd floor to open one of the radiator bleed valves. A little air came out then... nothing. There was no water in it on the second floor with the boiler telling me there's 15 psi in the system. I opened the water valve and water came back into the system and the radiator got warm and water bled out again, but now the pressure gauge on the boiler is reading something like 28 psi and it's not even hot.

How big of a procedure is it to replace the gauge on these things? I don't want to rely solely on the relief valve, I'd like to have an accurate idea about what is going on in my heating system.

biggles

to flip a new a PSI guage in just shut the feed and drain the boiler pressure off if you have a plug or nipple with cap just flip it into the opening the guage was removed from and see if the guage zero'd out in hand..that no water on a bleed on 2 is weird? 2nd story of a house riser shouldn't need more then 15PSI to push water out a vent with the feed closed....

chiefswabjockey

Yeah, everything I've read says 15 psi is over and above what you need to raise the water up to a 2nd floor... my only conclusion is that when it was reading 15 psi on the gauge the pressure was zero otherwise there would have been water in the upstairs rads.

It just went through a heating cycle where the starting pressure was showing something like 28-29 psi at something like 80F and at the end it heated to 135F or so and it is showing around 35 psi now. I watched the drain where the overflow is directed to and didn't see a drop of water come down.

biggles

that relief is then the proof the PSI guage is out of wack if it's not even dripping at 35PSI... best thing out of all this is what the pressure is from a cold start 12PSI city reg feed..to a heated up system system and what should be the PSI be when the stat shuts the sytem off at setpoint well below that relief....to blow off.think there might be crap in the rads lower bottom on the 2nd floor restricting the water flow down thru it?as much as it might be the supply if you get a hot rad during a bleed off the water going out might be restricted when you shut the bleed maybe check where the out water goes from that 2nd fl rad and is that pipe hot to the touch during a heating cycle..

chiefswabjockey

Problem is that the installer (8 years ago when I wasn't the owner) had actually directed the blow off from the boiler directly down into the basement floor drainage system so the bottom of the discharge pipe is not visible to me only the outlet to the nearest floor drain a number of feet away under the floor. Still, I would have expected to see at least some dribbling (though at 35 you would expect that the valve would be wide open) when the system is heating over 35 psi for any length of time make it's way down the pipe - it certainly comes out freely when I manually open the relief valve.

I'm pretty sure that the ins and outs of the rads upstairs all get hot when heating, the rads themselves get good and toasty and they are all new low profile rads up there less than 8 years old so I doubt they would be clogged already.

I guess for now I will just have to take solace that the blowoff valve isn't going and take for granted that things are OK until the heating guy can come out next week but I'm thinking I may as well call them and tell them to bring a new gauge and replace it either to save myself from another service call later as I can't even locate the part myself right now.

biggles

If you have a www.Grainger.com near by they welcome home owners and have 2 listed for hot water boilers #1X808 and #1X810 that give psi and temperature.. the shank is the difference prices out of their catalog its cheap change out....if your interested...double check the piping size on the old one 1/4" NPT on the threads on the new ones as stated..i would cut that piped into the floor relief line right at the floor level unthread the lenght out of the relief and recut that piece so you can scoot a bucket under that re installed piece to eyeball any water action..during the heating season

beenthere

15 PSIG will raise a column of water to a height of 34.5 foot.

REP

It seems pretty obvious that your gauge is broken.Replace it.Fill the cold boiler to 12 lbs(make sure you bleed thye seciond floor rads) and THEN SHUT THE FEED VALVE OFF like it says to do in the instructions.
I believe if you check local codes you will find that you should be able to see if the relief valve opens.You may pipe it to a floor drain but the piping must terminate above the drain so that you can see a water discharge if there is one.
It would be highly unusual for a relief valve to fail by staying shut on a pressure rise but it should be checked by your mechanic just the same.