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Old 01-02-2008, 08:22 PM   #1
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How to install an expansion tank in my hot water furnace?


Hello, I just purchased a home with a very old hot water furnace. There is no expansion tank connected to the system, and I was told I should have one installed. Is this hard to do my self? Can someone give me steps for how to do this?

Where should it be installed with respect to the pressure reducing valve, and pressure relief valves? Currently my pressure relief valve connects to a pipe which drains water into my utility sink. I see it dripping from time to time.

Should it go like this

>>====fresh cold water in===>>[Pressure Reducing Valve]>>==>>[Pressure Relief Valve]]>>====T(Expansion Tank)==Furnace

And keep the bottom of hte pressure relief valve draining into my utility sink?

Here is a pic of my PRV's


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Old 01-02-2008, 08:29 PM   #2
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How to install an expansion tank in my hot water furnace?


Ayuh,.......

The pressure tank should be "T"ed in just to the Right in your photo......

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Old 01-02-2008, 10:38 PM   #3
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How to install an expansion tank in my hot water furnace?


Are you sure that you don't have an open tank in the attic? I have seen a lot of screwed up boiler jobs but never one without an expansion tank. Look around the attic and make sure,that was a common practice not all that long ago.
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Old 01-03-2008, 07:16 AM   #4
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How to install an expansion tank in my hot water furnace?


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Are you sure that you don't have an open tank in the attic? I have seen a lot of screwed up boiler jobs but never one without an expansion tank. Look around the attic and make sure,that was a common practice not all that long ago.


I just looked in my attic and didn't see any expansion tanks. There was one part of the attic that was obstructed, so i guess it could be installed there. Where would the expansion tank connect to? Whatever heating line was closest?
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Old 01-03-2008, 06:02 PM   #5
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How to install an expansion tank in my hot water furnace?


Pretty much. If you had no tank whatsoever, let's say the boiler water temp was 140F and the pressure was 15# psig, then the burner came on, as the temp rises the pressure would jump to well over 30#psig and the relief would pop, there is no way around that.
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Old 01-04-2008, 09:54 AM   #6
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How to install an expansion tank in my hot water furnace?


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Pretty much. If you had no tank whatsoever, let's say the boiler water temp was 140F and the pressure was 15# psig, then the burner came on, as the temp rises the pressure would jump to well over 30#psig and the relief would pop, there is no way around that.
I think something like this must be going on... Currently the pressure relief valve drains into a sink, and I noticed it would drip, but didn't think it was any significant amount of water. Well I put a bucket down there about 24 hours ago, and when I checked it this morning the bucket was full(5 gallons). I would assume this is more water than I should be discharging, and also indicates that I DO NOT have an expansion tank.

My furnace is under contract with BG&E, I wonder if I can convince them to come out and fix this.
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Old 01-04-2008, 04:55 PM   #7
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How to install an expansion tank in my hot water furnace?


You need to have that fixed asap, if you are bringing in new water all the time to make up for what came out you will rust/rot out the boiler in no time flat.
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Old 01-05-2008, 09:36 AM   #8
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How to install an expansion tank in my hot water furnace?


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You need to have that fixed asap, if you are bringing in new water all the time to make up for what came out you will rust/rot out the boiler in no time flat.

Is this something that is an easy DIY, or would it be better to hire this out? I dont really have any plumbing experience, and am slightly concerned that I might start a project that I am unable to finish. How much do you think this would cost to hire out?
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Old 01-05-2008, 09:19 PM   #9
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How to install an expansion tank in my hot water furnace?


The tank needs to be sized for the amount of water held in the system, it has to be piped in correctly, hire a pro.
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Old 01-05-2008, 11:49 PM   #10
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How to install an expansion tank in my hot water furnace?


Just to add my 2 cents...those components in the picture look rather new. Certainly not old.

I would continue to search for a hidden tank.
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Old 01-06-2008, 07:27 AM   #11
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How to install an expansion tank in my hot water furnace?


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Just to add my 2 cents...those components in the picture look rather new. Certainly not old.

I would continue to search for a hidden tank.
According to the service sticker the PRV's were replaced around 1993, but the furnace/ is old as hell. I am definitely discharging 5+ gallons of water a day from the pressure relief valve, wouldn't that indicate the system is closed and there is no expansion tank?
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Old 01-06-2008, 08:41 AM   #12
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How to install an expansion tank in my hot water furnace?


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Originally Posted by BarryKaraoke View Post
Just to add my 2 cents...those components in the picture look rather new. Certainly not old.

I would continue to search for a hidden tank.

B&G the brand of those components hasn't made the parts in that pic in the last ten years. Everything looks different,labeling, color,material,etc. Don't let the paint job fool you.
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Old 01-16-2008, 06:10 PM   #13
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How to install an expansion tank in my hot water furnace?


I can not picture a boiler that old not having a Expansion tank in it at some point. Usually it is on the supply side of the boiler. (The pipe going from the top of the boiler to the radiators.) The old tanks are usually up between the floor joists. Really old ones can occasionally be found in the attic.

If you do find an old style tank you may just need to drain it. That may stop the relief valve from leaking. But the valve will likely need to be replaced.

A picture of the whole boiler and its piping would be very useful in solving the problem.

I wouldn't put it right beside the boiler feed as one person suggested, usually there isn't enough room, and it often will reduce the lifespan on the tank.
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Old 01-16-2008, 10:07 PM   #14
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How to install an expansion tank in my hot water furnace?


The best place to put an expansion tank is off the top of an air scoop, with the PRV connected just below it. The air scoop should be a balance point, supply water from pump into scoop, expansion tank or extrol tank and feeder all at that point. Check with IBR or any Dan Holohan info and that is what they recommend.
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Old 01-17-2008, 06:51 PM   #15
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How to install an expansion tank in my hot water furnace?


I still can't seem to find my expansion tank. I would expect it to be in the attic, but what poking I have done in the attic hasn't yielded anything.

I noticed that TWO of my closets in the upstairs bedrooms have lower ceilings than the bedroom ceiling. Each could probably fit the expansion tank in the space created by the lower ceiling. Both of these closet ceilings are permanent, w/out any sort of access door. Would you expect an access door to the expansion tank? One of the closets is in the back of the house where the roof slants and the attic is non existent. Therefore IF the expansion tank was there, I would have to knock out the ceiling of the closet to access it.

Also last time I was on my roof, I only remember seeing two exhaust pipes, and I believe both of these are for my sewer exhaust(one for the bathroom, and one for the kitchen, i have two sewer pipes leaving my house). Could the expansion tank tie into one of these?


Does anyone have any ideas?

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