High Pressure NEED HELP


  #1  
Old 10-08-08, 09:32 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
High Pressure NEED HELP

Hi! I am new to this posting thing and know little to nothing about boilers, so hopefully one of you guys can give me a hand. I have a gas-fired cast iron Slant/Fin boiler. I also have an expansion tank with a TACO fill valve. When we bought our house 2 years ago the previous owner installed this unit so it is approx. 2 years old. My wife's cousin is a plumber (who can also be a scammer) came over when we fired it up for the first time this season. He informed me that the psi on the boiler was going way to high. He said it should be around 12-20 when it is firing. I had the heat up all the way for approx 1 hour and the psi was up around 30. I shut it off when it approached 30 as he said that is way too high. He then had me turn the water off that goes into the fill valve and then the tank and had me run the bioler for about an hour. When we did this the max psi got up to about 22. He claims that the problem, for sure, is my fill valve. I have read alot of these posts and I am starting to think it could also be my expansion tank. He had me buy the new fill valve and wants 225 bucks to put the new one on. I want to know if this is definately the problem or not and how do i know if replacing the fill valve will stop the problem. He also told me I could run the bioler without the water being on to the tank. The house heats up fine buit I am worried that I may be doing more harm to it. Could someone help me out please!!!!1
 
  #2  
Old 10-08-08, 12:36 PM
plumbingods's Avatar
Member
Join Date: Apr 2008
Location: Manch-vegas, New Hampshire
Posts: 1,985
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hello, and welcome to DIY forums.

If you shut off the water feed to the boiler and the boiler pressure stays between 12 and 17psi, everything is fine with the boiler and the problem is you fill valve. If it still reaches 30psi with the fill valve shut off, the problem is with the expansion tank, or the water heater coil if so equipped. If there is no water heater coil, that leaves the expansion tank to be the culprit.

You may run the boiler without the water turned on as long as the boiler is not empty or dry. Any pressure reading will assure this, but slightly higher pressure readings are required the more floors you need to get that water up to. Pressure equals altitude.

Hope this helps.
 
  #3  
Old 10-08-08, 01:43 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
high pressure

Hey thanks for getting back so quickly..... When I ran the boiler with the water valve off the psi is less than it was when I ran the boiler with the water valve on. I think it maxed out around 22 psi with it off, It got up to around 30-31 psi with the water on and I shut it off when it did so as it continued to climb. I have a 2 story house and the boiler is in the basement. Is there any other way (for an idiot like me) to make sure it is either the tank or the fill valve that is bad. You said if it runs around 30 with the fill valve shut off...... how do you know when the fill valve is shut off? by turning off the water supply to the boiler? Also when does the release valve open and water come out (when the pressure reaches a certain point) hopefully these questions are not dumb and make sense.
 
  #4  
Old 10-08-08, 03:57 PM
plumbingods's Avatar
Member
Join Date: Apr 2008
Location: Manch-vegas, New Hampshire
Posts: 1,985
Upvotes: 0
Received 0 Upvotes on 0 Posts
A relief valve on a residential boiler should start to drip at around 29-31psi. Sometimes it will drip, and others it will completely blow, scaring the **** out of you, and making a small mess.

Close the shut off valve feeding the boiler. Find a boiler drain or purge drain and drain the boiler water pressure down to 15psi and leave it alone. Turn the heat up to the highest setting at one or all thermostats. If the boiler stays under 20psi when running. Watch the pressure gauge while waiting for the temperature to climb to its highest operating temperature it is set at. In other words, wit until the boil shuts off. Around 200*. What is the pressure reading now?If it is still around 15-20psi, the expansion tank is working fine. If you open the feed valve and the pressure climbs to 30psi, replace the automatic fill valve. (Make sure the automatic fill valve is not in by-pass mode first)
 
  #5  
Old 10-08-08, 04:02 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 39 Upvotes on 31 Posts
Do you have a digital camera? If yes, then take several pictures of the boiler and the piping around it and post them. Also tell us more about your home and the heating system. Is it an old house with large pipes and cast iron radiators or does it have relatively small pipes and baseboard convectors? Is your hot water heated by the boiler, either by a coil inside the boiler or by a separate (but connected) water heater? Or do you have a totally separate gas or electric water heater?

To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected.
 
  #6  
Old 10-08-08, 04:54 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
High Pressure

Thanks furd!!

I dont have a digital camera at this time but I think I can describe it for you:

I have an old house... maybe 1920??? 2250 sq feet. Old big pipes, cast iron radiators (big and heavy). The water is heated by the boiler and we have a seperate hot water tank. The boiler is a Slant/Finn (sentry) boiler.... next to the boiler is some piping and an expansion tank and a fill valve (taco)both I believe are set at 12 psi. Above the tank is another taco valve that I beileve has something to do with the air in the pipes. On top of that valve is a small silver tab that I believe allows the air to escape. Now, when I run the boiler with the temperature all the way up (water line open to tank and fill valve) the psi continues to increase and has gotten as high as 32 psi. I think my release valve is set at 35 psi as it has not released any water that I can see. I also tried running the boiler with the water line shut off to the fill valve/tank and the psi also conitnued to clim to around 32 and I shut it down. The boiler fires nicely when it is turned on and it warms the home just fine. All of the registers get nice and toasty as they should. I just dont kinow if I should keep running this thing.
 
  #7  
Old 10-08-08, 05:50 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Having lots of trouble with the website tonight, so let me keep this short ...

Do NOT run the boiler with the valve to the expansion tank closed !
 
  #8  
Old 10-08-08, 06:12 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
why

I was told that I would be ok to run it with it closed. Why shouldnt I? I did run it earlier with it off..... I will turn the water line back on but if the boiler fires up the psi will rise it got to 32 earlier. What happens if you do run it with the water line closed? I was told that no new water would be able to get back into the boiler but that would be ok for a while. If the water line is open and the release valve opens due to high psi, wont the water keep running out if the line is open?
 
  #9  
Old 10-08-08, 07:05 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Website seems better now, maybe I can get a reply in without getting knocked off...

I think there's a misunderstanding about which valves your are talking about.

There is a valve that feeds water into the boiler. That valve MAY be operated closed for a time... if there is a leak in the system, you run the risk of firing the boiler dry, possibly destroying the boiler and burning down the house.

As long as there is NO LEAK, and you keep a watchful eye on the pressure, you will be OK to run with the valve closed until you have a chance to replace the feed valve.

I thought you may have been talking about another valve, in the line going from the boiler to the expansion tank. THAT is the one that I meant to leave open.

Without pictures, there's gonna be all kinds of corn fusion...
 
  #10  
Old 10-08-08, 07:48 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
im not very good at this stuff so I have a few questions....

The line I am talking about shutting off is a cold water line that goes first through a fill valve and then to the tank ...my buddy who is a plumber said that by shutting off the water line, no water can go through the fill valve and "fill up" the boiler when it runs low.....he said that the water level should not drop until we can fix the issue with the psi increasing also when you say feed valve do you mean fill valve? I may be confused on what exactly the fill valve does. But regardless, I still need to know why the pressure continues to rise when it is running. It has been off now for about an hour and the psi has dropped to around 25-26 psi, not running and the tempo at or around 80-100. when i turn it on the boiler runs fine , fires up good and heats the house, but the psi continues to rise it has not reached 35 yet but i shut it off before it does. If it did, will the release valve open and flood my basement or will it just let out enough water to bring the pressure down? Sorry if this is too much and hopefully it makes sense. Thanks, Blishy
 
  #11  
Old 10-08-08, 09:21 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 39 Upvotes on 31 Posts
Often there are several words that can relate to the same thing. Feed valve, make-up water valve, fill valve, pressure reducing valve, PRV, auto fill valve can all refer to the same valve. Also, there are no two systems that are installed the same. Various manufacturers of the "peripherals" of the system and while they act the same (or do the same job) they can be installed differently and also look different. This is why pictures are so helpful.

The first thing I want you to do is find the manufacturer's specification plate on the boiler. This is where the maximum pressure will be stated. It will state max. press. or MAWP or something similar and then have a figure after the letters. Most common is 30 psi although some boilers will be rated as high as 60 psi. You could have a dual rated boiler in which case it will state steam 15 psi (or 15 psi steam) and then a rating for water.

Then I want you to read the tag on the safety valve. It will state the pressure set point and it should also have the letters ASME with a BTU rating. Post the boiler pressure rating and also the safety valve rating.

Next measure the expansion tank and post the diameter and length. Also look to see if the expansion tank is connected to the boiler piping on one end and the other end has what appears to be a tire inflation valve.

Is your water heater in any way connected to the boiler? Or, to ask the question in a different way, does your water heater have four pipe connections plus a temperature & pressure (T&P) valve and a drain valve?

Do you see why pictures become so valuable?

Here's what MAY be your problem. You have a (relatively) modern boiler and what appears to be a diaphragm type expansion tank if it as I previously described. With the large pipes and cast iron radiators your entire system holds far more water than a modern system. Since water is incompressible when the water is heated it must expand somewhere, that somewhere is the expansion tank. If the expansion tank is too small it cannot control the pressure when the water expands. You may need a larger, or additional, expansion tank.
 
  #12  
Old 10-09-08, 07:47 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
im gonna try to get pictures up by tonight. I have to borrow my dads camera as mine is broke.
 
  #13  
Old 10-09-08, 12:14 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
high pressure

I finally got a hold of an old friend who is a plumber today and he told me to do the following.....

He had mr drain water out of the boiler (with the water shut off to the fill valve/tank) until the pressure got down to about 8-10 psi. He then had me turn the water on to the fill valve/tank after it sat cool at 8-10 psi for a while. He then had me shut the water back off when the psi went to about 12 to 15 psi. He then had me run the boiler on high to see what happened with the pressure and it went back up to the mid 20's psi. He then had me drain it again down to 8-10 psi with the water to the fill valve off. This time he had me turn the water on to the fill valve/tank and had me keep the water line open until it stopped filling the boiler. This time the pressure went up to 20-22 without even firing the boiler up. He seems to think it is my fill valve for sure that is bad. Now he wants me to drain it once again down to about 8-10 psi and adjust the screw on top of the fill valve (after loosing the nut) a few turns to the right to essentially close off the fill valve. He then said to turn the water back on and after I did slowly open the fill valve (by turnign the screw on top of the fill valve to the left) until i get it to stay at around 12-13 psi. he then wants me to run it again to see what happens with the psi. Like I said after explaining my issues to him and tyring the things he told me to do earlier he still thinks that it is definatley the fill valve that is malfunctioning. What does everyone think?
 
  #14  
Old 10-09-08, 02:41 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I tend to agree that the "Feed valve, make-up water valve, fill valve, pressure reducing valve, PRV, auto fill valve" is probably leaking through.

I also believe that your expansion tank has a low air charge in it if it is indeed a bladder tank. If it's a conventional tank, it is more than likely waterlogged, and needs to be properly drained. It may also be undersized as furd suggests.

Let's see the pictures... then we'll talk more.
 
  #15  
Old 10-09-08, 05:50 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks

Thanks Trooper! I took some nice pictures but of course my dads camera will not allow me to get them on my computer. I will be going to my dad's house in the a.m. and the pictures should be up before noon, est. Just an update on what my buddy had me do today..... I drained the boiler until the pressure went down to around 8-10 psi. I then turned the water off to the fill valve and loosened the nut on the top of the fill valve so i could turn the screw like top (flathead). I turned it several small turns to the right to close it essentially. I then turned the water on to the fill valve and it did not sound like any water was passing. I then loosened the screw until i heard the water start coming in slowly. I watched the gauge and when it got up to 12-14 psi i tightened the nut and left it. I now have the water on to the system and the oiler is off, the water is colled down to around 80 degrees. It has stayed the same for a few hours. Should I try something else now or wait to post the pictures..... anyways they will be on by tommorrow at noon. Thanks
 
  #16  
Old 10-09-08, 06:10 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
If the valve is leaking internally because of a bad seal or something, adjusting it as you did may delay the overpressure, but it won't 'fix' anything permanently, though stranger things have happened. If for example there was a piece of 'crud' under the valve seat... maybe it has been dislodged by the adjustment.

Tell us about your expansion tank. Does it have a plastic cap with a tire gauge on the end opposite where it connects to the system ?

furd asked this:
Next measure the expansion tank and post the diameter and length. Also look to see if the expansion tank is connected to the boiler piping on one end and the other end has what appears to be a tire inflation valve.
You need to answer furd's questions... if you don't, then we can't really answer yours!
 
  #17  
Old 10-09-08, 06:37 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
i forgot about furds questions sorry. i will post those answers later tonight or tomorrow and have those pictures up before noon tomorrow. Thanks alot for your help. Blishy
 
  #18  
Old 10-10-08, 09:00 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
high pressure

Here are the answers to furds questions ( i think)

It is a slant/Fin gas boiler (sentry)

mawp, water 50 psi
max water temp 240 degrees
minimum relief valve capacity 76 lbs/hr

csa input btu/hr 90,000
d.o.e capacity btu/hr 76,000
net i-b-r water btu/hr 66,000


saftey valve info:

30 psi / 535,000
3/4''

btu/hr
nb\crn# og8547.5c


tank info:

elbi tank 5 gallon capacity
12 psi precharge pressure
max working pressure 115 psi
max temp 210 degrees

the tank is approx 11 inches wide and 16 inches long. There is a black cap on the base but the tank hangs too low to the ground for me to see it or get to it. the pictures should ne up soon did i leave anything out?
 
  #19  
Old 10-10-08, 09:56 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
pictures

hopefully i did this right

here the pictures


http://s414.photobucket.com/albums/pp224/ToddBlish/
 
  #20  
Old 10-10-08, 01:17 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Todd, is there at least enough room under the tank to get a tire pressure gauge on the fitting ? And then if it needs air, the pump or compressor hose ? If not, you've gotta find the installer and give him a good 'up side the head'.

Do you have an accurate tire pressure gauge ?

And a bicycle pump ... or a small air compressor with a tire chuck?

Drop the pressure in the boiler to ZERO, and put the tire gauge on the fitting on the bottom of the tank. Tell us what it reads. You won't get an accurate reading on the tank with ANY pressure in the boiler, that's why you have to drop it to zero. If you get ANY water out of the tank, the bladder has ruptured and you need a new tank.

Judging by the size of the old piping, that tank is probably marginally small. It may be OK though, as long as you maintain the pressure. If you ever have to replace it, you ought to probably go to the next size larger tank... IF it fits ...

By the way, in the pictures, it appears that the pressure in the boiler is now below 10 PSI ... what's the current reading ?
 
  #21  
Old 10-10-08, 03:02 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks again Trooper!

Unfortunately, the bottom of that tank is millimeters away from the ground. I cant even slide my finger under it. I can tell that it has a black ruber cap on the bottom but that is it. It is just too low to do anything underneath it. Can I take it off like I was going to replace it and then check it? Or does it have to be hooked up to the system to work? Also, if I replace it (and it is the problem) there is no way a bigger tank can go in there unless the bigger tanks are the same height as the small one, which I doubt. Is there any chance the tank is just too small for the system and whoever put it in was an idiot? Hopefull not cause I would imagine I would have to have someone re-do all the piping to fit a bigger one The system has been off since around 5:00 pm yesterday. When my buddy left the house yesterday, he adjusted the screw on the fill valve until the pressure got to about 10-12 psi. It has stayed at that reading since then, but like I said it has not been on and it is obviously cold. The water line i open to the fill valve/tank however.
 
  #22  
Old 10-10-08, 03:30 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
If there is not enough room to even get a gauge on it, then I'd have to say that whoever installed it was either an id10t, or he just simply didn't give a rat's donkey.

If you take it off, yer gonna lose lotsa water. You might not even have enough room to unscrew the tank ! Figure that the threads are engaged by at least a half inch...

Yes, you can adjust the air with the tank removed.

If the water valve is open, and the pressure is staying put, then the feed valve just might be OK.

If the expansion tank is properly charged, and the correct size, you shouldn't see much more than maybe 5-8 PSI increase from cold to hot.

In order to properly size the tank, you would need a fairly good idea of how much water was in the system. Then, size the tank so that it will accept appx 4% of that water volume, since that's appx how much the water will be expanding.

If you did need a larger tank, it doesn't have to be mounted where it is. They make tanks that have a base on them for floor standing. It would be a pretty simple matter to pipe one of those tanks with black iron threaded fittings to the fitting where the existing tank is now.

If that '5 gallon' capacity is how much water that tank will accept for expansion, then your system could hold up to 125 gallons... I bet that originally there was a smaller tank, and not so close to the floor, and they found they needed a larger one and wiggled that in there... it's _probably_ big enough, and just needs air. The pics look like there's enough room under it ... but I'll take yer word cuz pics can be deceiving that way.
 
  #23  
Old 10-10-08, 03:42 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
what next

So Trooper, what should I do next? Should I just replace the expansion tank and see what happens? If they got the tank on where its at, shouldnt I be able to get it off? What if I replace the tank and the pressure continues to rise? Thanks for pointing me in the right direction though...
 
  #24  
Old 10-10-08, 04:13 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
More than you wanna know...

but if you are curious, good info here:

http://www.amtrol.com/pdf/extrolbrochure.pdf
 
  #25  
Old 10-10-08, 04:23 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
If you've got the water valve open, and the pressure is holding steady at 12 PSI, then _maybe_ you don't need to replace the regulator. It _might_ have been 'crud' in the valve, but it might mess up again.

Chances are VERY good that there's not enough air charge in that tank.

The first thing I would do is what I mentioned earlier... drop the pressure in the boiler to zero, and check the expansion tank air charge. No matter what the feed valve is doing, you still need to check that air charge anyway. If you can't get a gauge on it with it installed, then you have to remove it to do so. If you pick up a 1/2" NPT pipe plug, and you work fast, you may not lose all the water in the system when you remove the tank. Unscrew the tank, zing that plug in there while you check the pressure. Then, un-zing the plug (that's a technical term by the way) and slap the tank back in quickly. There's gonna be water ... you may be able to minimize the loss by closing the valves above and below ... the ones on the pipes going to and coming from the radiators... just DON'T FORGET to open them again !!!!
 

Last edited by NJT; 10-11-08 at 03:50 PM.
  #26  
Old 10-10-08, 09:53 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 39 Upvotes on 31 Posts
Thanks for the pictures.
I noticed the wiring on the walls and I do not see the type NM cable fastened within the specified distance of the boxes, you might want to correct that error. Nor do I see any valves in the gas piping to the water heater or boiler. This means that if you ever have to replace something like the water heater or the gas valve on the boiler you will have to turn off all the gas in the house.

In the first picture I see a Taco low water cut off switch but I don't see any wiring to it. It won't work without wiring. I would also prefer to see this unit closer to the boiler.

I agree with Trooper that the existing expansion tank is likely not the original and that the installer found out after all the piping he had a problem of high pressure. As it is it is certainly a poor installation. You would not necessarily need to replace it with a larger tank, providing that tank does not have problem other than being too small but you could add another tank in parallel with the existing tank. You have enough valves on the system that you can isolate the boiler and probably remove the tank with minimal water loss. Ideally you would want to install the tank (or if necessary an addition one) on the suction side of the circulating pump. Unfortunately soldering that large copper piping will take a large torch and some skill.

There IS one other thing that you could do since the MAWP of that boiler is 50 psi and that is to replace the 30 psi safety valve with one of a higher pressure rating, either a 40 psi or even a 50 psi. That wouldn't change the dynamics of your system but it could be an easy fix if the only thing wrong is an undersized expansion tank.
 
  #27  
Old 10-11-08, 07:29 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
In the first picture I see a Taco low water cut off switch
I didn't notice that it wasn't wired ! that's funny ... I thought at first that it might be an LWCO, but then while on the Taco website noticed that the paddle type flow switches look very similar to that.

Todd, is there hidden wiring going to that thing ? What's it say on the label ?
 
  #28  
Old 10-11-08, 12:05 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
There is no wiring to the low water cut off switch. It is a taco-low wtare cut off. Model # LNA0243s-1 Auto reset 24 VAC 3/4 inch NPT Short Probe. It has a green button that says power and it is not lit. There is a red button that says low water and it is not lit. So do I now change the expansion tank to see if that is the problem? Is this something I can do? If so , can u guys help me do it?
 
  #29  
Old 10-11-08, 03:48 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I have no idea why you have a low water cut off and it's not wired up... makes no sense at all.

Todd, you first need to CHECK THE PRESSURE IN THE TANK. Don't change it out yet because we don't know if it's too small yet. You need to CHECK THE PRESSURE first. Then, after you CHECK THE PRESSURE IN THE TANK, and run the boiler, tell us what the pressure starts at cold, and then when it's fully hot, like 180F. But, you need to CHECK THE AIR PRESSURE IN THE TANK FIRST. That's the first thing to do, CHECK THE AIR PRESSURE IN THE TANK.

By the way, did I mention that the first thing to do is CHECK THE AIR PRESSURE IN THE TANK ?

Sorry for repeating myself, I just wanna be sure you heard me.
 
  #30  
Old 10-11-08, 04:02 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
So you are saying I should check the air pressure on the tank?

Just kidding. I have never changed a tank on something like this before. I obviously have to do it when it is cool, but besides that I havnt the foggiest as I am not very mechanically inclined. Any assistance would help alot....
 
  #31  
Old 10-11-08, 04:32 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
I'll try to get a 'step by step' up here later... gotta go out for a while soon.

How are you fixed for wrenches ? You will need TWO to get that tank off. You don't want to just spin the tank, you need to hold the fitting above the tank to prevent it from moving.

Go to HD or Lowes and pick up a threaded plug ... 1/2" NPT ...

And, you are going to need some absorbent materials, because you will spill some water doing this.

It's a durn shame that you can't get a gauge on that thing without removing it... would be SOOOOOOO much easier !
 
  #32  
Old 10-11-08, 05:26 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks

You are the man Trooper! Ill get the threaded plug tomorrow a.m. so whenever you get to it cool..... I have gotten lucky as it has been beautiful here the last few days and isnt supposed to get too cold at night. Thanks again and Ill look forward to hearing from you.
 
  #33  
Old 10-11-08, 11:34 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
Received 39 Upvotes on 31 Posts
It appears that you have enough valves that you can trap most of the water in the system piping. When you get ready to remove the expansion tank turn off the power to the boiler and close all the valves to the system piping. Allow the boiler to cool to around 100-110 degrees and then open the drain to relieve the pressure to zero. Close the drain when the pressure is gone and the water is no longer freely draining.

At this point there should still be water in the boiler and no pressure. Remove the expansion tank and insert the plug as Trooper suggested. Turn the tank so that you can connect the tire pressure gauge and see what the pressure is. If it is zero then see how heavy the tank is by lifting it. Extremely heavy means it is full of water and the bladder likely is ruptured. If it seems full of water then remove the valve core form the tire valve fitting and see if you can get water from this fitting. If yes, then the tank needs to be replaced.

If there is no water in the tank (or just a little) try to pump the bladder to about 12 psi. If it holds this pressure you can re-install the tank but if you can't get it to the 12 psi figure then the bladder is ruptured and you need a new tank.

If the pressure IS about 12 psi then the tank is probably too small for the system. At this point you can either replace the safety valve with one that has a higher pressure rating (but no more than the 50 psi MAWP of the boiler) or you can install a second expansion tank.
 
  #34  
Old 10-12-08, 07:48 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Everything furd sed (shut off boiler and feed water, drop boiler pressure to zero), and:

The SUPPLY pipe is the one that comes out the top of the boiler, and the RETURN is the one going in on the bottom to the circulator pump.

There are two red handled ball valves on the supply pipe, close them both.

There is another red handle valve on the return pipe, close that.

Closing these valves will prevent the radiators/baseboards from draining. You are going to lose some water, but not nearly as much.

Using the two wrenches, remove the tank, expect some water, maybe have a helper ready with the threaded plug and a mop.

Then follow furds advice for checking / adjusting the air pressure in the tank.

Reinstall tank, open any valves you closed, and fire it up...
 
  #35  
Old 10-12-08, 09:23 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
thanks, I am looking forward to trying this and seeing what happens. Do I need to put any more thread tape or putty on it when I pout it back on?
 
  #36  
Old 10-12-08, 03:49 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Yes, you can use tape and/or pipe dope... rectorseal #5 is good, Hercules makes a blue dope that's good ... if you use tape, keep it away from the first three threads or so, you don't want pieces of tape floating around in the system.

I like to use BOTH tape and dope ... put the tape on first, then a light coating of the dope over top of it.

Don't monster tighten it when you reinstall... it needs to be tight, but don't strangle it ...
 
  #37  
Old 10-15-08, 10:36 AM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
I replaced the expansion tank last night. The tank, when I got it off, weighed about 40 pounds. I do believe that is not good. I put the new one on and ran the boiler for 2 hours last night and the pressure starts at 10-12 psi and gets up to about 20. it didnt go up anymore. I think it is fixed. Thank you so much for the info, it helped out a great deal. Anything else I need to do other than keep an eye on the pressure?
 
  #38  
Old 10-15-08, 04:38 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 19,710
Upvotes: 0
Received 8 Upvotes on 6 Posts
Any more room between the floor and the tank with the new one? same dimensions ?

Yeah, if it weighed 40 LB, it had a bad bladder and was full of water on the air side...

20 PSI is fine... but at what temperature ? That's sorta important because if you weren't at 180 (or whatever the high limit is) then it could go a bit higher. Yer probly still OK though... if you do ever find it creeping toward 25 or so, consider adding another tank to the system...

Just look at the pressure from time to time... and every other year or so, check the air charge in the tank.

By the way, you DID check the pressure in the tank before you installed the new one, right ? The manufacturer _says_ precharged to 12, but it's always a good idea to check...
 
  #39  
Old 10-15-08, 08:01 PM
B
Member
Thread Starter
Join Date: Oct 2008
Location: New York
Posts: 34
Upvotes: 0
Received 0 Upvotes on 0 Posts
yep 12 this tank is a tad smaller then the last one and fits better as well. Thanks again for all your help./
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: