High pressure hot water

[bluestang65]

I have a 7 year old hot water tank in a house of the same age. Last Winter, I noticed that after the hot water pipes have had time to cool, the system seems to be pressurized more than usual. When a faucet is turned on, it gives a momentary burst of pressure followed by normal pressure. Any ideas on what's causing this? The tank's valve on top leaks year round even though the over pressurizing seems to happen only in winter. Any thoughts on what I should expect to fix this problem?

[Mr_David]

Water expands when it is heated.
In the winter the incoming water is colder therefore expands more when heated.
Expansion tanks are installed near the outlet side of the heater.

[bluestang65]

Is the increased pressure cause for alarm? Should I install an expansion chamber to protect the appliances and faucets?
What's the deal with the dripping valve on top of the unit? What's it do and should it be replaced, or is it doing its job?

[phishfood]

I am guessing that the dripping valve is an expansion valve that is dripping because of the increase in pressure. Is it attached to the water piping or is it in a fitting into the water heater tank itself?

If it is in fact an expansion valve, the BEST way to fix this is to install an expansion tank. That will take care of the excess pressure, and the water wasted by the dripping valve.

[Jasper15]

Its a t&p releif valve (temperature/pressure) It is a saftey device to releive pressure from the tank if it reaches either 210 degree's or 150 psi. Yes you should install an expansion tank.

[CHRISM]

"Hello Everyone"

THIS Subject and the replies has REMINDED Me of some of My Posts earlier in
the Year - When I was stating that I was `VERY SURPRISED`that Hot Water Tanks/Cylinders in the United States did NOT have Expansion Vessels fitted to `Take Up` the VOLUME INCREASE of the Expanded Water - During & After
Heating.

I was `INFORMED` that U.S. Specification Hot Water `Tanks`[Cylinders] did NOT need Expansion Vessels - I wrote `At Length` about this being `Strange` to Me - As the BEST way to `Accommodate`the extra VOLUME of the Heated Water is DEFINITELY with an Expansion Vessel.

Without checking back - I have a feeling that my Colleagues who have AGREED that in this situation You SHOULD install an Expansion Vessel - were the SAME Colleagues that INFORMED Me that THESE were NOT necessary on Hot Water Tanks [Cylinders] in the United States !! [?]

While I realise that in THIS instance they are trying to advise You HOW to solve a problem - By suggesting that You Install an Expansion Vessel - I seem to remember that when I was `Debating` the issue of how necessary these Vessels are to a `Well Designed` Hot Water System - THEY would NOT AGREE with Me.

If I remember correctly - again I have NOT checked back - I wrote PAGES of text while `Debating` the Use of these Expansion Vessels !!

It seemed to me at that time that I had `come upon` `Dangerous Practices`
regarding the Design and Installation of Hot Water Tanks [Cylinders] in the U.S. - And I wondered WHY Expansion Vessels were NOT used on Hot Water in the U.S. ??

I DID receive some answers - basically stating that as the Hot Water Tanks are so `Strongly Made`/ `Robust` that they CAN `Take Up` the Additional Volume and Pressure of the Expanded Water.
I would `View` this as an `Archaic` Design.

I MAY Post a section of some of my previous Text regarding THIS subject - to try to `illicit` some replies to the ABOVE points.

TO `SUM UP` :

When I was suggesting that the answer to a particular Post was that the Expansion Vessel had either lost its charge OR needed renewing - I was told that Expansion Vessels are NOT used on Hot Water Tanks [Cylinders] in the U.S.

I then `Questioned this - regarding WHERE was the extra VOLUME of the Expanded Water being `Accommodated` ??

I was eventually informed about the `Strongly Built` Steel Tanks [Cylinders] -
being `Strong Enough` to `Take` the Extra Volume & Pressure of the Expanded Water.

During ALL of my `Posts` and the Replies that I received - It was NEVER agreed by any of the `Responders` that these Vessels SHOULD be part of the Design and Installation of Hot Water Tanks - and would be `Much Safer`.

When I wrote that I could not imagine that Expanded Water was allowed to continuously `Drip out`of the Pressure Relief Valve - to `Waste` - I was informed that THIS was `Quite Normal` in some States - Obviously with an Expansion Vessel Installed - THAT would NOT be necessary !

NOW - I have seen my Colleagues write here that Fitting an Expansion Vessel
would be the `BEST` way to solve Your problem with Expanded Water !

IF my Colleagues would like to be reminded of what I am writing about - I will try to `Post` some previous Text on here - Please let me know.


Sorry if this does not help with your Enquiry - but I had to respond to what I saw.

No `Sour Grapes` regarding my comments about what our Colleagues wrote on this subject previously - If you look back into my Posts about Hot Water Expansion - you may see what I am `commenting` about.


"Regards" to Everyone, CHRISM.

[Mr_David]

Originally Posted by CHRISM

Without checking back.

I believe this is the decussion CHRISM is referring to

what is this called?

[Psycho99]

CHRISM:

I did read part of the original post, the only thing that I see that might be giving you a fit is some of the posters said you DON'T need an expansion tank; this only applies to certain circumstances.

[Mr_David]

Originally Posted by CHRISM

"Without checking back - I have a feeling that my Colleagues who have AGREED that in this situation You SHOULD install an Expansion Vessal - were the SAME Colleagues that INFORMED Me that THESE were NOT necessary on Hot Water Tanks [Cylinders] in the United States !! [?]


That's not what they said

TO `SUM UP` :

When I was suggesting that the answer to a particular Post was that the Expansion Vessal had either lost its charge OR needed renewing - I was told that Expansion Vessals are NOT used on Hot Water Tanks [Cylinders] in the U.S.

I have gone back and reread the previous discussion several times.I don't recall seeing anyone say that.

In my area the typical water supply pressure could be between 80 to 150 PSI
In the past the expansion of water was accommodated by being relieved back into the supply system as long as the supply did not exceed the limits of the system.
Pressure reducing valves were equipped with a built in bypass to allow excess pressure to back flow back into the supply system.
But with the newer requirements of reduced pressure back flow valves installed on supply systems that this is no longer possible.
In a typical single family home the amount of expansion in a typical system does not require a tank. IF they experience T&P valve opening then a tank maybe the solution.

[CHRISM]

Quoted from a reply from Phishfood to one of my Posts in MAY 2010:


05-30-2010, 09:57 PM #7
phishfood
Senior Member


Join Date: Jan 2010
Posts: 746

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In my experience, it is not the norm for water heaters to have a built in expansion tank. Expansion is relieved either through a relief valve, or through means of an externally mounted expansion tank.

In all new construction cases that I see, check valve arrangments HAVE to be installed between the dwelling and the water main, so obviously, the water main cannot be counted upon to absorb the expansion.

The thermal expansion valve that is at issue in this thread is meant to be the primary expansion relief system. If it were to fail, the backup would be the Temperature and Pressure Relief valve that is also required. It is designed to discharge at a much higher pressure than the thermal expansion valve, and is also designed to release in cases of excessive temperature.

As I noted above, expansion tanks are the best option, but in some areas expansion valves are allowable by code.


Phishfood stated that it is NOT the `Norm` for Hot Water Heaters/Tanks/Cylinders [What I was writing about] to have Expansion Vessels.