Leaking T&P valve/Expansion Tank question

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  #1  
Old 12-04-13, 10:30 AM
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Leaking T&P valve/Expansion Tank question

I've seen several posts with some good explanations to the problem I've been having with my boiler. Originally my T&P was leaking a fair amount of water due to the system pressure being around 30 psi. I went ahead and changed both the T&P and pressure reducing valve. After installing both and starting the boiler back up the boiler still gets up to 30 psi. I'm thinking its the expansion tank at this point but the tank I have does not have the typical valve to check the pressure. The tank is a Sparco-trol TK300. There is no shut off above the expansion so i guess I'm looking at draining the system to install the new tank. Any suggestions or comments are appreciated.
 
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Old 12-04-13, 11:37 AM
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The system will need to be depressurized, but not necessarily drained. Once depressurized, check the air pressure in the tank with a tire gauge. Restore it to 12-15 psi with a bike pump.

If you want to replace the tank, then Yes, you'll need to drain the system below the elevation of the tank.

T&P valves are used for water heaters, but hot-water boilers take a regular relief valve (no temp function).
 

Last edited by gilmorrie; 12-04-13 at 12:01 PM.
  #3  
Old 12-04-13, 12:24 PM
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does not have the typical valve to check the pressure
I don't understand what you mean.

On the end of the tank opposite the water connection there should be a 'Schrader' (tire valve).

There may be a plastic cap covering this valve that needs to be removed to access the valve.

Follow the step by step directions in the message below to properly check/charge the tank:

http://www.doityourself.com/forum/bo...sion-tank.html
 
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Old 12-04-13, 04:23 PM
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Thanks for the responses. There is a black cap on the opposite end of the water connection. I wasn't sure if it was removable and didn't really want to pry it out without knowing. I will try this tomorrow and get back with the results.
 
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Old 12-04-13, 05:20 PM
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Okay, I took a look and realized the black cap is actually threaded onto the Schrader valve. I depressed the pin inside of the valve and water comes out so I'm assuming the expansion tank is saturated.
 
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Old 12-04-13, 07:08 PM
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water comes out so I'm assuming the expansion tank is saturated
Yes, it's done. Means that the rubber that separates the air and the water is busted.
 
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Old 12-05-13, 05:32 AM
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So, before I get started I've got a couple of questions.
1) Shut down boiler and let it cool to below 100 degrees?
2) Shut off cold water feed.
3) Depressurize system. Basically drain water from lowest
point below the expansion tank height?
4) There are no valves to isolate the expansion tank in my
system. How will I be able to tell when the line above the
expansion tank has been drained?
I'm sure I'll have a few others but we'll start with those.
Any help is appreciated.
 
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Old 12-05-13, 05:47 AM
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Can you post a few pictures of the piping around the tank and the rest of the boiler?

It is possible, if you can work fast, to change the tank without having to actually DRAIN the system. You can take the PRESSURE in the system to zero. Of course, gravity will still be in play so you will get SOME water... you may want to cover the area beneath with a plastic sheet.

Is there room below the tank to add the optional valves which I recommended in the thread I posted a link to previously? If so:

First, remember that your tank will be HEAVY! You want to have a helper at the ready. One person remove tank, the other ready to screw the new assembly in place... QUICKLY.

Prepare the optional pipe nipple, shutoff valve, drain valve assembly and keep at arm's length so the tank can be removed and that assembly be grabbed and threaded in QUICKLY. CLOSE the shutoff valve so it doesn't leak as it is being threaded in place.

Once the optional 'stuff' is installed, you can leisurely install the new tank.

OR, you can drain the whole system... how will you know it's drained? If no water comes out when you remove the tank... it's drained... I don't know another way...

But let's see some pictures first.
 
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Old 12-05-13, 07:40 AM
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I'll take some pictures tonight once I'm home. I was definitely planning on adding the optional valves so I'll try to get all of the supplies for this weekend. I'd rather not drain the system so this may be the way to go.
 
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Old 12-05-13, 03:33 PM
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I'd rather not drain the system so this may be the way to go.
Don't blame ya for that... the less new water that has to be added to the system, the better.

Make no mistake, you will lose some water to be sure, but as long as the pressure is at zero, and you are prepared, it shouldn't be too much of a mess to clean up afterward.

Also, keep in mind that as soon as you pull the tank, your helper can be ready to stop the flow by putting hand over hole, then quickly swap in the new valve parts...

Choreograph your moves before you start! Like a dancer...

Waiting for pics.
 
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Old 12-05-13, 05:26 PM
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Trooper,
Yeah, I'm hoping it's a quick changeover. I'll be sure to put a tarp over
the boiler and try to keep the water loss to a minimum.
Here are a couple of pictures. Hopefully they're helpful.
 
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Old 12-05-13, 07:18 PM
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OK... please listen carefully! You will be standing on a ladder to remove this tank. Once the tank is loose on the threads, it will spin easily and feel like it has minimal weight to it. Don't let that fool you! It WILL be heavy!

Since you will be on a ladder, it's going to be extra difficult to work quickly when you've got water splashing out all over you.

See those three blue handled ball valves? CLOSE THOSE after you let the pressure off the boiler. Hopefully, with the pressure off, and those valves closed, there will be enough 'suction' in the system to hold most of the water back.

Can I ask a question? Do you smoke in the basement? I'll tell you why I ask after I hear the answer...
 
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Old 12-06-13, 04:18 AM
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Trooper,
I'm not sure if I'll need a ladder, but I'll be careful either way. Thanks for all of your help with this! I'm not a smoker, this is actually my Moms house, I'm guessing she smokes down there occasionally. Kind of curious to hear why you ask!
 
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Old 12-06-13, 05:30 AM
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Kind of curious to hear why you ask!
I noticed the 'staining' around the flue pipe... which looks as if it could be from tobacco smoke, but if it's not, it concerns me a bit. When draft is normal in a chimney, that 'hood' over top of the boiler should have a constant draw up the chimney. If there were a heavy concentration of smoke in the atmosphere, it would pull that air from around the area and up that hood.

On the other hand, it is also possible that the chimney draft is not adequate and what is showing there is exhaust byproducts coming out from under the hood.

Normally there is a 'blocked vent switch' on the lip of that hood which is a temperature sensor that will cut the boiler off in the event the vent is blocked or not drafting properly.

For safety sake, I think this would be something I would want to look into.

Please make sure that the CO detectors in the home are all functioning properly and placed so that Mom can hear them if they go off. You might want more than one.
 
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Old 12-06-13, 06:27 AM
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I actually work in a maintenance facility so I'm going to borrow the handheld CO2 detector from our maintenance department to be sure. There is actually a detector on the wall going down into the cellar and I know its got fresh batteries but I'll use the handheld to be sure. Thanks for mentioning the discoloration and what it could be. I don't think there is any vent switch on this unit. The name plate has a date of 1983 on it, not sure if those devices were in place then but I'll surely look into this. I'll be sure to post the results of the expansion tank change as well as the draft issue. Thanks again for all of your help!
 
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Old 12-06-13, 02:36 PM
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handheld CO2 detector
You mean " CO " yes? Carbon MONoxide, not CO2, Carbon DIoxide, correct?
 
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Old 12-07-13, 09:12 AM
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Oops! Yeah that was what I meant, sorry. Well I installed the new tank, but ran into a few problems.
When I depressurized the system I closed the 3 valves and the cold water feed. To relieve the pressure I opened the boiler drain and the pressure dropped quickly but when I closed the drain valve it wouldn't seat. So I lost maybe 5-7 gallons of water there. Otherwise not a lot of water lost. Do you think I need to bleed all baseboards?
 
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Old 12-07-13, 09:57 AM
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when I closed the drain valve it wouldn't seat. So I lost maybe 5-7 gallons of water there
Did you have to replace the valve? This is a problem with old infrequently used drain valves, and I should have mentioned that while you were getting supplies that you pick up some brass garden hose caps in the event of a non-closing valve. These can be used to stop a leaking valve until there is time to replace. And to use a 1/4 turn BALL valve drain as a replacement.

Is the new tank working well now? Pressure staying OK? You said you were going to add the optional tank service valves... can you show us? We like admiring other ppl's work!

Do you think I need to bleed all baseboards?
I don't see an 'air scoop' on the system, but I believe that there is an 'automatic air vent' on the top of the boiler. Is the cap loose on that air vent so air can escape? I would probably run it for a while and see if the AAV will take the air out, if you hear 'indigestion' noises in the piping, then yeah, you will probably have to bleed some.
 
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Old 12-08-13, 09:02 AM
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Trooper,
I did replace the drain valve, so that's taken care of. I bought a standard 3/4" boiler drain. There is an AAV on the top of the boiler but it seems to be leaking out of the shrader valve more than letting air out of the system, but not really sure. The system is pretty quiet so I went ahead and bled everything just in case. When the boiler is running the temp is 160 -165 degrees and the pressure stays at about 23 -23 psi. So far so good. Also, I installed a new CO detector in the basement just to be certain everything is ok. Thanks again for all of your help with this!!
 

Last edited by NJT; 12-08-13 at 09:32 AM.
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Old 12-08-13, 09:36 AM
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There is an AAV on the top of the boiler but it seems to be leaking out of the shrader valve more than letting air out of the system, but not really sure
Shouldn't be leaking... needs replacement eventually... can be operated 'manually' for the time being, just screw the cap down tight and open from time to time to let trapped air out, then close again.

Looks good! Good Luck!
 
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