A Quick Plumbing Question

billw · Post by **billw** » Thu. May. 22, 2008 5:18 pm

I have an expansion tank on my current system. I'm adding an EFM boiler to run in series with what I've got. Do I need to get a larger expansion tank or is the one I've got good enough?

I hate to keep bothering you guys with basic questions but I don't want to screw this up. Thanks.

rberq · Post by **rberq** » Thu. May. 22, 2008 7:39 pm

I'm not a plumber, but ignorance seldom stops me from offering an opinion. I think expansion tank size depends on total water volume in the system. When my oil-fired boiler was replaced, the installers said they put in an oversize expansion tank because I have hot water radiators, therefore much more total water than a baseboard system. Then when it leaked they went back and got an even bigger one. Search the internet -- you will probably find a table somewhere specifying how big a tank is needed for how much water.

Freddy · Post by **Freddy** » Thu. May. 22, 2008 9:18 pm

Ya, Bob is right.....go figure

.... what I'm going to do when I hook my coal boiler up is try my existing tank. If it's too small you will most assuedly leak water out the pressure relief. If that happens, it's time for a bigger tank. Or, you could follow his good advice & try to find a chart that shows size tank vrs gallons of water in the system.

gregsmit · Post by **gregsmit** » Thu. May. 22, 2008 9:20 pm

Check out the following - see page 4 and also page 8.

http://www.amtrol.com/pdf/extrolbrochure.pdf

Regards,

-Greg

Freddy · Post by **Freddy** » Thu. May. 22, 2008 9:44 pm

Greg! You're da man!

Sting · Post by **Sting** » Thu. May. 22, 2008 10:03 pm

billw wrote:I have an expansion tank on my current system. I'm adding an EFM boiler to run in series with what I've got. Do I need to get a larger expansion tank or is the one I've got good enough?

I hate to keep bothering you guys with basic questions but I don't want to screw this up. Thanks.

This isn't a basic question and no its not a bother!

the short answer - if you haven't any other hidden drama --- is no!

billw · Post by **billw** » Fri. May. 23, 2008 11:31 am

Thanks, I guess I'll run what I brung for now. If the pressure relief valve trips I know I have to increase the tank size.

LsFarm · Post by **LsFarm** » Fri. May. 23, 2008 12:32 pm

Hi billw, it will really depend on the size of the current expansion tank, if it is oversize the increased volume of water may not be an issue.. but if it is marginal,, then you will have too much expansion for it to absorb.

If you are doing the plumbing right now,, I'd add a tee in the system where you could add an addtional expansion tank,,, install a ball valve.. and if you find you need an extra tank,, you just install it, and open the ball valve, and you are done.. it would take about ten minutes.. and no water spilt.. just an idea..

Greg L
.

billw · Post by **billw** » Fri. May. 23, 2008 1:46 pm

Hey Greg, thanks, I like that idea. My father in law's friend designed the system and bought the equipment for me 15 years ago. I just did all of the grunt work. Neither are around anymore for me to check with. Nothing worse than an amateur.

Bill

rberq · Post by **rberq** » Fri. May. 23, 2008 7:09 pm

"If the pressure relief valve trips I know I have to increase the tank size."

I rubber-banded a clear plastic food-storage bag over the bottom of the pipe from the relief valve. That way the water stayed in the bag and it was obvious the valve was opening. Before that, floor was damp, but it was damp lots of other places too....

Post by **coaledsweat** » Fri. May. 23, 2008 7:44 pm

I personally prefer two as they should be right off the top of the boiler. If there are isolation valves between the two boilers and/or, them and the system, it is a must I would think.

Yanche · Post by **Yanche** » Fri. May. 23, 2008 9:42 pm

LsFarm wrote:Hi billw, it will really depend on the size of the current expansion tank, if it is oversize the increased volume of water may not be an issue.. but if it is marginal,, then you will have too much expansion for it to absorb.

If you are doing the plumbing right now,, I'd add a tee in the system where you could add an addtional expansion tank,,, install a ball valve.. and if you find you need an extra tank,, you just install it, and open the ball valve, and you are done.. it would take about ten minutes.. and no water spilt.. just an idea..

Greg L
.

Plumb the expansion tank with a bleeder port ball valve. Make sure the bleeder port is towards the expansion tank. Why? Because if you ever need to adjust the initial expansion tank air pressure it needs to be removed. Having a bleed port allows you to leave in place, close the valve and then remove the bleed port. Any excess water pushed out by adjusting the air pressure will just squirt out the bleeder port. Tag or remove the valve handle so some idiot doesn't close it.

If you have more that one tank they must each be set to the same initial air pressure. When adjusting pressure the water side must be open to the atmosphere.

BIG BEAM · Post by **BIG BEAM** » Mon. May. 26, 2008 9:45 am

Code says no valves between the tank and the system because if the homeowner has a leak very often they shut off every valve they can see.That being said I often put a valve there and take the handle off.

DON

Yanche · Post by **Yanche** » Mon. May. 26, 2008 10:20 am

BIG BEAM wrote:Code says no valves between the tank and the system because if the homeowner has a leak very often they shut off every valve they can see.That being said I often put a valve there and take the handle off.
DON

I've ofter been told of code requirements for no valves here or there, but have never been able to verify it in any code. It you have a code reference that specifically references no valves on expansion tanks please post the reference. What I see when reading, a minor subset, of all the ASME, Mechanical Code, Plumbing Code, etc. is that service valves are permitted. They must be tagged or made nonoperational except for qualified service technicians. I'm starting to believe it's urban legend.

BIG BEAM · Post by **BIG BEAM** » Sun. Aug. 17, 2008 9:32 am

Sorry about the late reply I just been reading some of my old posts today.I think you answered your own question.I guess you can put a valve in(we always did in the old style tanks,without bladders they had to be drained from time to time)but it must be nonoperational.Thats why gramps used to make us take the handle off and tie it with a string to the feed valve.
DON