Excessive Water Pressure in Taps 3

[CoachH]

We had a call from a homeowner re: excessive internal water pressure (150psi). We tested a local hydrant outside the house and found that while the water pressure at the hydrant remained constant for two days(95psi), the taps in the house experienced spikes ranging from 95psi to 150psi, every few hours. The house used to be connected to a well, but it doesn't appear to be still in service. Is it possible that the old well pump is providing the spikes, or is there another reason that the spikes are occuring?

 

[dicksewerrat]

Turn off the power to the well pump.

 

[CoachH]

We have confirmed that the well pump has been removed. We are guessing that the hot water tank may be contributing to these spikes (maybe steam?) Has anyone come across this?

 

[LHA]

I can't imagine a commercially available water heater which can be set to 212F, since 180F will meet even food service level dishwashing. And to create steam which can vaporize in water already at 95 psi, it would have to be hotter than that. I've also never seen one without a pressure relief valve. Also, assuming the valve sticks AND the thermostat fails, the breaker (typically only around 30amps) would surely trip before generation of superheated steam by an electric coil (unless it's gas, then I guess it could heat indefinitely).

Sorry, I don't buy the water-heater-from-hell scenario. But this is interesting, please follow up this post when you discover the problem. I'm curious now. Thanks.

 

[btrueblood]

I do buy the water heater theory: check to see if the relief valve is even still there. I know a few people who bought a pipe cap from the local hardware store to replace the "leaky pipe" on their water heater. Then, if this is an older house without water-hammer arrestors (air traps), the thermal expansion of the water in the tank can cause pretty severe pressure rise in the now closed-volume, low-ullage system.

Ben T.

 

[cvg]

I would also suggest a pressure regulator / reducer at the point of service to reduce the 95 psi down to a more reasonable 40 or 50 psi.

 

[PUMPDESIGNER]

Just to be sure, how are you monitoring the pressure and discovering the spikes?
Data Logger seems the only way to have reliable objective data.

PUMPDESIGNER

 

[krb]

I would second btrueblood, and ask if the hot water from the tap is excesively hot, which is an indication of a faulty water heater. You did not mention is the heater is gas or electric, each of which has different failure modes. Check out the following link, it is an interesting look at water heaters

http://www.esmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2503,132221,00.html

 

[CoachH]

We have determined that the problem was a faulty water heater. FYI, Data Loggers were used to monitor the pressure. Thanks to all who responded

 

[tgreif]

This house must have a check valve in the supply line. Water expansion due to thermal effects would normally just push the water back out into the supply line in normal household services. Something has to trap the water to get a buildup. Why are you using check valves on service supplies?

 

[semo]

Her first post explains it.

We always use setters with dual check valves on the discharge side. Especially with rural districts where a home is being taken off of a personal well.

This reduces the possibility of a cross connection with a contaminated water supply should the homeowner reconnect the well without the PWS knowledge.

The home should/could have installed some water expansion devices (tank/chamber) however to help with this and water hammer.