# Hot water expansion tank



## camping479 (Aug 27, 2003)

I'm thinking of putting an expansion tank somewhere in the coach to absorb the hot water expansion when the water heater is running. There is quite a bit of pressure buildup when the heater runs for a few minutes and no faucets are opened, I'm sure it gets well over 100psi after a few minutes since it is such a small system. My vanity faucet has a persistent leak at the cold water fitting and I think it is because of the pressure build up. It also can't be good for the fittings, etc. to have so much pressure build up.

I had this problem in my house. After everyone showered, the pressure would build up to over 110psi after a few minutes and the water would blast out of the faucet when one was opened. I installed an expansion tank and that solved the problem.

I know Kirk you put a bladder tank in, does that absorb some of the pressure? Anybody else have any concern or solution?

Mike


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## Y-Guy (Jan 30, 2004)

Mike I haven't noticed any leaks or water blasts due to the water expansion. I wonder if you faucet might need to be checked out and/or replaced. This seems like a normal condition that would occur in most campers, and I can't say I've read about a lot of problems or mods to solve that problem.


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## camping479 (Aug 27, 2003)

Will reset the air gap in the heater and give that a try, I forgot about that.

Mike


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## camping479 (Aug 27, 2003)

I couldn't resist and bought an expansion tank and plumbed it in with, believe it or not, a piece of white water supply hose and barbed fittings. Worked great, I cut the supply hose just befor the water pump, put in a "T" and strapped the tank to the floor with plastic plumbing strapping. Now the water heater can run and run and there is no pressure build up at all.

Paul, I got out the manual and it said to reset the air gap, but for a permanent solution, suggested an expansion tank.

My wife was very impressed with her new expansion tank and lighted switch for the electric element in the water heater.









Mike


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## aplvlykat (Jan 25, 2004)

Mike sounds good but I am confused







. You put the tank in before(in-coming fresh water) the pump or after(presurized water to heater and faucets) the pump??


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## camping479 (Aug 27, 2003)

Kirk,

I cut it into the flexible hose right where it come into the trailer. It's just before the water pump. As far as I could tell, there is no check valve or anything on the pump where the incoming city water line connects to the pump. In any event it works.









I tried to keep it as easy as possible, I didn't want to get into tying into the pex tubing when I could tap into that short piece of hose with barbed fittings.

Mike


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## 2001rotax800 (May 30, 2011)

camping479 said:


> Kirk,
> 
> I cut it into the flexible hose right where it come into the trailer. It's just before the water pump. As far as I could tell, there is no check valve or anything on the pump where the incoming city water line connects to the pump. In any event it works.
> 
> ...


Hello everyone, great forum!! I am don't see how putting the expansion tank up stream of the pump would help. There is a check valve in the T at the outlet of the pump, if there was not, then when your pump was running and trying to build pressure it out blow out you city water connection.


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## 2001rotax800 (May 30, 2011)

HAHAHAHA woops just realized this thread is from 2004!!!


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## Lmbevard (Mar 18, 2006)

Still, this isn't a bad thing to revisit. Normally there is a small amount of air left in the tank to act as an expansion tank on it's own and each tank has a Pressure-Temperture Relief valve (that must be checked for proper operation several times during the season) that protects the water heater. An expansion tank can be installed to do a couple of things. First of all, it will protect the system from over pressure and it will also allow the pressure in the system to build up so far and give some extra water storage at pressure so that the pump will not run as much. The proper place to put this is after the pump and before the cold intake in the hot water heater. If it's easier, yes it can be put any where on the city intake line since that hooks up after the pump. If you can look at the water system, there is a check valve built into the pump, another at the city water intake and another on top of the hot water heater. There is none on the tank cold water intake side. So if there is pressure build up, the whole system, not just the hot water side suffers. You can find a small expansion tank at Manard's or Lowes for about $30-40 and it only takes one T fitting and a small piece of plastic line to hook it up. Good luck.


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## CamperAndy (Aug 26, 2004)

2001rotax800 said:


> Kirk,
> 
> I cut it into the flexible hose right where it come into the trailer. It's just before the water pump. As far as I could tell, there is no check valve or anything on the pump where the incoming city water line connects to the pump. In any event it works.
> 
> ...


Hello everyone, great forum!! I am don't see how putting the expansion tank up stream of the pump would help. There is a check valve in the T at the outlet of the pump, if there was not, then when your pump was running and trying to build pressure it out blow out you city water connection.
[/quote]

The city water line is pressurized from the pump all the way up to the actual city water connection as the check valve for the system is in the hose connection fitting.

There is also a check valve on the inlet and outlet of the water pump but those are just for pump operation.


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