When the tank pressure is HIGHER than the boiler pressure, it does tell you something.

Two possibilities:

Presuming that both your tire gauge and your boiler gauge are accurate and properly functioning, it tells you that there is too much air in the tank.

With a few exceptions which I'm , measuring the air valve at the tank will give you the HIGHER of the two pressures.

It might be telling you that one or both of your gauges are inaccurate.

 

I would not doubt for a moment that the gauge is crap.

I would be EXTREMELY surprised to find that the tank was bad.

What DOES sometimes happen with a brand new tank is that the rubber membrane 'sticks' to the inside of the tank and doesn't let water come in. The usual solution for that would be to drop the tank air to about 4-5 PSI and apply boiler pressure on the other side. This will get the bladder unstuck and after that the tank would be recharged and no problem from then out.... this tidbit from tech support at Amtrol several years back.

 

- I'll try your suggestion Trooper and lower the tank psi.

- Never got out to get a another new boiler guage today so will just have to do for today...

- I called the boiler guage crap yesterday..may have been premature since I only let out
maybe 2 quarts of water trying to "zero" the boiler last night. Didn't know the system
may hold about 13 gallons!

- I'm inclined to trust the digital tire guage more, because...
Boiler guage, NEW, reads 12psi
Guage attached to boiler drain reads 0psi
Exp-Tank reads "27.5"psi with the digital guage i bought

Hard to believe the boiler has 0psi and the tank 27.5. If tank psi is really the boiler psi,
the boiler guage can't be right...Right? Unless I'm still not understanding

Just ordered the Webstone 40612W 3/way valve... "Lead Free" for between the Exp-Tank and Air Scoop. Not too bad, about $19 shipped from PexUniverse. That drain would sure come in handy.

 

I think you are not understanding.

The tank PSI is NOT the boiler PSI...

UNLESS the boiler PSI is higher than the PSI of the air charge inside the tank when the water side of the tank is at ATMOSPHERIC PRESSURE... i.e. when the boiler pressure is ZERO on the gauge, or the tank is disconnected from the system...

OR, when you get that new valve installed, you have the tank isolated from the system by closing the ball valve and opening the drain valve. (Because this is the same as removing the tank from the system. You are exposing the water side to atmospheric pressure)

Perhaps this diagram will help explain:


image courtesy arttec.net

The left side shows the boiler pressure LOWER than the tank pressure. You can see that the rubber diaphragm has nowhere to go. Even completely disconnected from the system you can have higher pressure inside the tank than outside.

The middle and right side images show the tank in two states of higher pressure on the boiler side than on the air side.

As the pressure in the boiler increases, water enters the tank and pushes the bladder down, compressing the air inside.

So, since the higher pressure in the boiler is compressing the air, you can see how when this is the case, if you measure the air pressure when the tank is connected to the system with the pressure higher in the system, you will read the HIGHER of the two pressures.

If you have 12 PSI of air in the tank when there is NO WATER in the tank, and you have it connected to a system with say 15 PSI of water pressure, you will read 15 PSI at the air valve.

12 PSI in the tank, and 20 PSI in the boiler, you will read 20 PSI at the air valve.

Always (almost always, but not going into the exception because it would only serve to confuse at this point) will read the HIGHER of the two pressures at the air valve.

Verstehen?

 

Yes, finally!
While the tank is connected, it IS NOT at atmospheric pressure.
If "isolated" & "drained" using the #40612 valve, then it IS...

Thank You Trooper!

PS.. Did you know that I was told it's LAW/Code, whatever , only a licensed plumber can
replace a feed valve in Massachusetts! ? I know you're not in MA Lol

PS. I do have another question.
You may remember me saying..with the water feed shut off to the HWC, I still had minor water
at the hot taps. First warm obviously, then cools off . Is there any way, OTHER than the shutoff leaking through that this is possible? I have put 2 new ball valves on now, and can even get water through the HWC OUT, there is a drain after the mixing valve. I am asking this because, as long as I can't stop water flow to the HWC, how can I rule out, it leaking into the boiler?

 

In the words of Johnny Carson, " I did not know that! "

But what I do know is that MA has some fairly strict, and some weird, rules, codes, and laws.

Not in MA now, but Melrose, Framingham, Tewksbury, (and others) are probably glad I'm gone!

 

How can this be! Lol

Q.. My boiler guage is resting at 8psi cold, "old one i took out seemed to be stuck around there too" can't get any lower by draining. Is it possible to use the tank psi as an indicator of how many psi i am repressurizing the boiler to?

 

Got the 40612 valve today for between expansion tank and air scoop...
Took the tank off, full of water and won't hold pressure. The air comes right through!! Did I cause this? Home Depot tank WATTS, made in Tiawan... Grrr

Well...can't get anything else today and need heat so back to get another!!

I had meant to ask, I noticed the HWC cold feed, on the elbow connected 1" away from the Coil connections has been leaking...slowly. Evident by the stain on the front of the boiler door.
Looks like at the solder joint. Never actually seen it drip! I really didn't think it's contributing to the boiler pressure but, thought I would mention it..

 

When testing the boiler water pressure reducing valve, "Watts B1156F" by running the boiler with the water supply off, what indications will determine it's bad? What I am to monitor?

Thanks

 

Not sure about the quality of the Watts expansion tanks as I'm new at all this (mine that I replaced says it was made in Italy), but the price difference at my Home Depot was only about $5 ($37 vs. $32 IIRC) to get the Amtrol which is made in the good ol' USA.

Worth it to me to support companies that produce goods in the USA, but again I know nothing of the quality of either.

 

Hey Forrester,
So, you're new here as well; welcome and don't worry, you will learn!

I would have preferred a different brand expansion tank but nothing else was available local. I
I couldn't wait. At least Home Depot gave me a new one, THIS TIME it had 13psi in it, not
5psi like the first Lol
And, they told me i would void the warranty if I checked it first! Crazy...

 

Good grief, that's just total BS...

more later...

 

I gots more too! Later
Think "tidbit"

Oh, about water coming to the hot taps when the HWC feed is off...
Mixing valves, or whatever they are called for, say a jacuzzi/hot tub/ bathtub with massage jets in it. Do they call that a rough In? Any bearing on this happening?

Just on my way out so... Later!

 

No further information will be divulged!

Well... yes... sorta... but not really advisable.

Remember what I said about the air gauge will read the HIGHER of the two pressures?

In theory at least, you COULD tell the pressure in the boiler if you KNEW for absolute certain what the pressure on the air side was.

Let's say you KNOW that there is 12 PSI in the tank.

You start to pressurize the boiler from zero...

When the boiler reaches 12 PSI (same as the tank pressure), the tank pressure will begin to increase.

The problem with this is that every time you measure the tank pressure, you probably lose about a half PSI... pssssssst... pssssst.... ok, now there's only 11.5 PSI in the tank. etc... etc...

Interesting...

Are you sure that it was a tank for HEATING SYSTEMS? and NOT for potable water use?

What was the full model of the tank?

Was the box FACTORY SEALED when you got it?

I know ppl do unscrupulous things... what if someone bought a new tank, removed the one from their system, cleaned it up and put it back in the box and returned it to HD?

Where do you think the tank YOU brought back is gonna go? Yup... probably back in the box and back on the shelf.

I like to write 'DEFECTIVE' with a permanent marker on stuff I have to bring back for this reason. I have been burned buying stuff that was obviously, after opening the box, returned.

No, it's not. Of course it should be repaired eventually, but remember that the DOMESTIC water is totally separate from the BOILER water.

 

Monitor the boiler pressure.

If the reducing valve is leaking through internally, the boiler pressure will slowly creep up... depending on how bad the internal leak, hours, days, weeks, months...

A bad expansion tank (if it's ONLY a bad tank, and not a multiple problem issue) will typically only blow the relief valve when the boiler gets HOT.

If your reducing valve or your hot water coil are leaking, the pressure rise will be gradual, and occur even if the boiler is not firing.

 

The expansion tank is :WATTS ETX-30, For Non-Potable Water / Hydronic heating systems.
Has a bladder in it, I looked, typically stuck to the topside/Inside!

HWC has been on since 10am this morn, no increase in psi so far. It's been averaging 19-22lbs psi, can hear air vents occasionally still so hoping it will settle down. No leaking at the relief valve since yesterday morning. Mmmm, nice to have steady heat back! hehe

I'll probably be swapping out the boiler guage again, unless it was only go back to 8psi because I never let enough water out to allow it to zero!. Never let more than about 2 quarts out at any time, other than when I did a R/R on the first new tank, discovering it was ruptured!

Anyway, the clock is being watched now Lol

Thanks bud; I'll give it another 24hrs and post the results so far!

Hating snow....another 12" tomorrow

 

Rather than another combination pressure-temperature gauge I would recommend using a pressure only gauge somewhere on the boiler or nearby piping. Add a valve to allow removing the gauge without shutting down the boiler.

 

Trooper,

Yup, while lurking i happened upon mention of this!

Ummm, I've noticed the occasional drop from the backflow preventor vent pipe, wouldn't fill a cup in 6 months so, any concern here? Is it just doing it's job or will "I" be doing another job? Lol

 

Furd,

A separate PSI guage could be handy; if known accurate! I could certainly mount one but immediately I'll exchange the new one only a few days old anyway!

 

You did say that the flow went to a trickle though, right? That would indicate the pressure was off to me... maybe that new gauge is bad too? Dunno...

I'm with Furd, pressure gauge only somewhere...

Didn't you pick up one of those 'testers'? If so, all you would need to do if find a 0-30 or 0-50 gauge and swap it for the 0-100 that's on the tester now. Leave it on one of the hose spigots and open the spigot when you want to check the pressure.

So, if your gauge is 8 PSI high at zero, you might be able to say that this is really 11-14 PSI or thereabouts... presuming the gauge error is linear (which it may not be, but still reading high).

We aren't getting hammered with the snow like y'all are, but DAMN! IT'S COLD! We could get as much as 4" over the weekend, but temps won't be above 20 for the next couple days, and lows near zero. It was 9.4 last night. Colder tonight I think...

 

No real concern as far as the boiler goes.

Only other concern is if it picks up (which it probably won't) drip speed. They sometimes drip after they've been 'exercised', which yours has... It may stop dripping by itself. Have you seen the 'cutaway' drawing? Did I post that in your thread? It helps understand what that valve does... how it works.

Keep a container under it.

Fortunately, they are very easy to change.

 

Yes, I had mentioned the new guage; lowest the boiler psi would go was 8psi. When I pressurized the system I only let it go to 11psi on the screwy new boiler guage. The new tank, NOT ISOLATED" read 12.5psi. After I install the new tridicator, I'll readjust... Yes? Lol

SNOW? COLD? I'll take that over losing power and running my backup generator for days! $$$$

Lmao I know I do! < "Is Mod erasable"

 

I meant the 'screw on the drain test gauge'. You can remove that 0-100 and replace it with a more suitable gauge. You have the fitting already.

Waitminnit Willis... whatchoo tawkin bout?

If the new tank was precharged to 13 PSI, how could you read LESS at the air valve when you pressurized the boiler?

You DID check the tank before you installed it, correct?

You should never have been able to read LESS than that precharge...

No. You guessing wrong...

Unless someone has already 'messed with' the reducing valve ( you? ), then LEAVE IT ALONE. No good will come of trying to adjust that valve. Trust me on this.

Leave the tank charge right where it is... if it was 13 when you checked it BEFORE you installed it, just leave it alone.

 

My Bad! BIG EDIT!

1) I HAD adjusted the regulator.. mentioned that, and that I had let the system sit all day to make sure it was stable.

2) Too much on my brain..what I should have said was... When I pressurized
the system it went to 11psi on the boiler guage, and the tank read 12.5 "not isolated" obviously because I had let some out in checking it... When I said LET it go to 11psi, I mean I didn't adjust the regulator higher. Sowwy!

3) Yes I know you meant the guage I mounted on the boiler drain..

4) Yes, I checked the tank before install 13psi

 

Snow? I haven't seen any snow for about two years. Our mountain snow pack is at about 40% of what it should be. It hit 61 degrees here today and it has been bumping 60 for several days. Even the lows have been in the 40s although Weather Underground is predicting 36 degrees next Tuesday.

 

Crap... I opened the HWC feed about 10am this morning. Been pretty stable around 20 all day, Just checked and seen it had hit 26psi...

Still a toss up between the Fill Valve and the HWC. I haven't been home long enough to trust leaving the boiler water feed off to test the fill valve.

I'll shut the HWC feed and check the boiler psi when i get up... should that be long enough to point to one or the other?

Just rechecked... Temp is down to 155F from 170F, after a basement heat call and the boiler PSI is already back to 11psi. ? Have not shut the HWC feed yet.

Upon refiring, the boiler psi went up almost immediately up to 22psi... hit just 24psi before it stopped firing at 170F ?

This rapid drop in psi.. is that normal? No leaks that I can see/hear ,nor from the relief valve, and
it doesn't always drop so quickly. The guage sticky?

 

36? Looks good on ya for boasting!
I caught the weather channel a bit ago, thought I seen 60F on Sunday...Until I realized that was the WIND gust speed! Grrrr!