expansion tank too small


  #1  
Old 12-16-19, 10:30 AM
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expansion tank too small

Hello there, I have an issue with a noisy boiler. I have bleed the system and it seems to be better, never completely noise free, but it is better. Thinking now it may be the expansion tank. Not sure how old the expansion tank is, at least 10 years old since I bought the house so maybe it has gone bad. Also, I see that my expansion tank may be undersized. My system has an Amtrol EX-15 installed and when I look on their website they say a EX-15 is good up to a 50,000 BTU boiler but my boiler is rated at 120,000 BTU. Was going to upgrade to the bigger size but the EX-30 looks to be too big to fit into the space. Been looking unsuccessfully for a bigger expansion tank that is larger than the EX-15 but not as large as the 30. Are there other options or am I stuck with the EX-15? Thanks for any help!
 

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12-25-19, 11:24 AM
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Rockledge,
Merry Christmas. Don't let doughess spoil your Christmas with his usual needless banter. He has a bad habit of either reading half a post or not understanding what he reads. My guess is he doesn't understand those are pics from 2 different people. I have learned from past experience that most of his posts do not pertain to the problem being asked about, so once he chimes in and usually knocks the advice of anybody that actually works in the field, I hold my tongue and just bow out.
 
  #2  
Old 12-17-19, 06:47 AM
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What is the system pressure when it's cooled off and what is it when it's hot? If the system is able to maintain the correct pressures, ~15 - mid 20's then the expansion tank is sized correctly. When was the last time you checked the charge on the tank?
 
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Old 12-17-19, 09:44 AM
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Ok, that makes sense, I will check pressure when cool and when hot. I did check the expansion tank pressure just a few days ago. It was a bit high so I brought it down to 12 psi.
 
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Old 12-17-19, 02:45 PM
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You must check the charge with the exp tank off the boiler or with no pressure on it. Meaning draining the boiler a bit either way!!!!

Pics will help..

Yes a 30 is better.

The tanks air charge should be set to about 12 psi typically.
 
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Old 12-19-19, 07:37 AM
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I've attached a couple of photos. I think a 30 may just fit with maybe an eighth to quarter inch clearance from the pipe and the flue. When I took the pressure reading of the expansion tank I got a little water when taking the reading so the current expansion tank is probably bad.
 
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  #6  
Old 12-19-19, 08:01 AM
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You can offset the location of the tank with a few short black pipe nipples and 45 degree elbows. So instead of the tank being directly below the air scoop, you would move it back away from the pipes. You can also add a ball valve for if/when you ever need to replace the tank in the future.

While you're at it, you should also consider adding a ball valve between the air scoop and the air vent to make swapping out the vent an easy chore if it ever leaks.
 
  #7  
Old 12-19-19, 08:57 AM
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Would there be alot of weight hanging off the redirected nipples and elbows? Would I need to support the tank someway? Also, what size nipples and elbows? Pipe threads are a mystery to me, haha. Thanks for your help!
 
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Old 12-19-19, 09:50 AM
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When I replaced the boiler in my home a few years ago I had a similar issue (needed to offset the xtank). What I did was, I used a 90 degree "street elbow" off the bottom of the air separator. making sure to tighten it to a point where the female end of the street elbow faced the direction I wanted to move the tank. Then I threaded a 2.5 inch long nipple into the street elbow. Then I added a ball valve onto the end of nipple, then added another street elbow onto the other end of the ball valve. That left me with a perfect length (for my purposes) away from the boiler to thread the extank into (moved it over about 6 inches from being directly below the air separator). The setup is strong and solid, no weight issues at all.

https://www.doityourself.com/forum/a...1&d=1576777882

(The zip tie on the ball valve handle is so that won't get accidently closed).
 
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Old 12-19-19, 11:30 AM
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Very cool, I will try that! Thank you very much for the help!
 
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Old 12-19-19, 02:10 PM
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Use a good pipe sealant (I like RectorSeal T Plus 2) and have a couple of pipe wrenches handy to tighten things up real good. Many people use a little Teflon tape on the male threads and then add some pipe sealant on top of the tape in order to get a nice tight seal.

I can't tell from your pics if there is any way to isolate your expansion tank from the rest of the system piping; if not, then you will have to think about how to best drain the water from the system, and then purging the system of air once you fill it back up with water after the repair.

I suggest doing some internet research, there are some instructive videos out there on how to work with black iron pipe, as well as how to drain, fill and purge a hydronic heat system.
 
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Old 12-19-19, 04:47 PM
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Good advice, thank you! Is that all 1/2 inch NPT threaded pipe and elbows I would use?
 
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Old 12-19-19, 06:43 PM
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Is that all 1/2 inch NPT threaded pipe and elbows I would use?
The threads at the bottom of my air separator are 1/2", same size as the expansion tank inlet, so for me it was a no brainer to use 1/2" pipe and fittings. From your pics, it looks like you have the same situation.

In any case, you can always use reducing bushings (or reducing couplings) to make things work with 1/2" piping.
 
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Old 12-22-19, 05:33 PM
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Had a question on pipe material, are the elbows and ball valve brass and the nipple black iron? Will the different types cause corrosion or is corrosion between iron and brass negligible?
 
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Old 12-22-19, 06:48 PM
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The only reason I used brass street elbows is because I had several of them lying around (my late father was a plumber by trade and left me a smorgasbord of fittings). If I had to buy the elbows, I would have gone with black pipe. Much less expensive.

IIRC, the ball valve came from the supplyhouse website along with several of the other parts I needed to complete the installation of the new boiler. I'm not positive but I believe the ball valve is brass (most hydronic ball valves are). It is common practice to join threaded brass fittings and black pipe.
 
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Old 12-23-19, 08:53 AM
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Yeah, pipe fittings I've noticed are not cheap. Much more expensive than I was expecting. Have ordered the expansion tank and will pick up the pipe fittings. Thanks again Rockledge for the response!
 
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Old 12-23-19, 11:40 AM
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As a DIYer am very cost conscious.

The local plumbing supply places here in suburan New York charge double HomeDepot prices.


Even with 24 or 48 hour shipping SupplyHouse.com is often 50% less than HomeDepot. They also are big supplier to plumbers.

https://www.supplyhouse.com/Plumbing-Supplies-1000
 
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Old 12-23-19, 12:02 PM
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Excellent tip! Supplyhouse is definitely better priced! I noticed Rockledge mentioning adding a ball valve between air separator and hy-vent. Thought I would do that as well. I noticed that there is a 1/8 MIP by 1/4 FIP ball valve at supplyhouse but not sure I have clearance between the lever and the body of the hy-vent. Or if there is enough room between the flat piece that hangs below the threads of the hy-vent and the ball in the valve. Anyone have picture or suggestions of what they did for that? Thanks, you all have been a great help!
 
  #18  
Old 12-23-19, 01:53 PM
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There are two pictures of expansion tanks. One shows valve with cable tie around handle that can be opened. Other shows no valve.

If clearance is needed for 1/2” tank valve remove handle. Take the yellow sleeve off it. Use small touch to heat handle and bend slightly.

For auto vent shut off use tiny 1/4” valves. They are also good for oil lines.

https://www.zoro.com/zoro-select-min...SABEgLDIvD_BwE
 

Last edited by doughess; 12-23-19 at 02:26 PM.
  #19  
Old 12-24-19, 10:28 PM
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There are two pictures of expansion tanks. One shows valve with cable tie around handle that can be opened. Other shows no valve
I just posted a response to your questionable post that somehow, mysteriously, disappeared into thin air. Not the first time this has happened to me on this site.

So I will ask you again: show me (and the forum) the picture whereby you claim there is no zip tie on the ball valve leading to the expansion tank ON MY OWN BOILER. Post the picture.

And, are you claiming that you know more than I do about the boiler that I myself installed? I know the zip tie (and ball valve) are there, and have always been there, because I PUT THEM THERE MYSELF during the installation of the boiler.

Post the picture.
 
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Old 12-25-19, 06:55 AM
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See ketting-1 post #5, first 2 pictures there is no zip tie or valve
 
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Old 12-25-19, 11:24 AM
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Rockledge,
Merry Christmas. Don't let doughess spoil your Christmas with his usual needless banter. He has a bad habit of either reading half a post or not understanding what he reads. My guess is he doesn't understand those are pics from 2 different people. I have learned from past experience that most of his posts do not pertain to the problem being asked about, so once he chimes in and usually knocks the advice of anybody that actually works in the field, I hold my tongue and just bow out.
 
gilmorrie, Rockledge voted this post useful.
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Old 12-26-19, 02:59 PM
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Rockledge,
Merry Christmas. Don't let doughess spoil your Christmas with his usual needless banter. He has a bad habit of either reading half a post or not understanding what he reads. My guess is he doesn't understand those are pics from 2 different people. I have learned from past experience that most of his posts do not pertain to the problem being asked about, so once he chimes in and usually knocks the advice of anybody that actually works in the field, I hold my tongue and just bow out.
Thanks spott. Merry Christmas to you too!

You are one of the great assets to this forum with your level head and sound advice.

Hope the New Year brings you good health and much happiness.
 
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Old 12-27-19, 06:36 AM
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My apologies for not “understanding” two photos on this thread were from different systems.

From subsequent posts it looks like my #18 post has become cannon fodder for the egos of some.

I made not comment pro or con about the cable tie on Rockledge valve. Obviously he is very sensitive about a boiler he installed and that cable tie.

On DIY.com, I try to post helpful data with related links when possible. Kettling-1, starter of this thread, found my post helpful. Other posters seem fixated on negatives, splitting hairs on trivial points, derogatory comments, etc.. Those with thousands of posts seem to generate the most misleading info. Maybe someone can come up with an algorithm for it.
 
  #24  
Old 01-05-20, 04:53 PM
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Thanks everyone for all your help! Just got the new expansion tank installed and already notice a big difference. Really enjoy it when a DIY project goes well Posting pics of the new install

Did notice my fill valve may be defective too. I drain to around 10 psi and then watch it gradually increase. After about 10 to 15 minutes it is 12 psi but if I come back in an hour it is reading 13.5 psi. Guess it isn't shutting off all the way and there is some leak by. Oh well, I'll tackle that issue at another time.

Thanks for your help!
 
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Old 01-06-20, 04:41 AM
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Don't sweat the 13.5#. If it continues to rise, then it's worth tending to but 13.5, I certainly wouldn't worry about it. The gauge likely isn't that accurate.
 
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Old 01-06-20, 09:31 AM
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trying to post picture again, looks like I had reached my quota.
 
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Old 01-06-20, 09:38 AM
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Good job. Certainly no picnic to replace if you have to but with the space available, you did what you had to do.
 
 

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