Random temporary loss of water pressure?

[kleetuss14]

Every once and a while I will lose water pressure to the point where showering or washing dishes is near impossible...after waiting for a few minutes the pressure returns to normal on its own.
My house has an old oil furnace, water tank/heater?, and an expansion tank.
Being a 1st time house owner I don't know if there is some type of maintenance that I must do to the water tank and/or expansion tank to keep them working properly. :confused:
Any insight would be appreciated.

regards,

JOE

[Ejbogusch]

Have you talked with neighbors to see if they are experiencing the same problem. This could be a city supply problem.

[kleetuss14]

I haven't talked to the neighbors...although that is a good idea..I'll have to ask them.

[PhilC]

With regards to the water tank, they often become waterlogged and must be drained. You must also verify that the P.S.I. is set correctly according to the tanks specs.

First though I want to clarify something. You state that you have "an old oil furnace, water tank/heater?, and an expansion tank". This would lead me to assume that you are either experiencing low HOT water preassure, or that you are on a well system and have an expansion tank with a preassure switch that regulates the overall pressure in the house.

Assuming your on a well, for example, you will have a switch with a cut in/cut off setting off say 20/50. The expansion tank has an air charge that as water flows in the tank compresses the air creating the preassure. Depending on the age of your system there are a few common problems:
1)Waterlogged tank
2)Incorrectly set preassure switch
3)Incorrect Pre-Charge of air in tank (DRY)

This applies to a hot-water heater systems expansion tank as well as your main supply depending on what exactly your describing.

Your switch will be labeled and you can verify by reading the gauge that it is cutting in and off and the specified range. If it is, Shut off supply (pump/main) and drain tank. Take a reliable tire gauge and check the schrader valve on the top of the tank. Depending on your Switch (read Label) it will tell you what the psi. should be in the dry tank. If this is off you can fill it with an air compressor :alarm: MUST BE SET AT 2 psi BELOW SPECIFIED SETTING.

For Example: the house I'm working on now has a 32gal Con-Air Tank with a 30/50 cut in/off switch. According to the label the pre-charge psi should be 28psi. Remember this is the DRY tank setting and if it is low and must be recharged must be set 2 psi below, as in this case at 26psi.

Again depending on a few more provided details from you, there are several causes of expansion tank failures. In regards to a well system the aforementioned waterlog is number 1 most common, with leaking air valve (tire valve) causing incorrect air preassure coming in second, and possibly a broken indicator gauge causing the settings on the cut in/out switch to be improperly set. Depending on your switch, in the case I mentioned above, you would hear an audible click when the preassure dropped to 30psi turning on the pump and then a click when the preassure reaches 50 psi-in turn cutting off the pump(water supply).

In this situation the tank had less than 10 psi pre-charge, a stuck indicator gauge, and incorrect settings (done with screws on the switch) due to someone basing their adjustments on a broken gauge and failing to reckognize a leaking schrader valve causing way to low of an air charge to create adequate preassure build up.

Might sound complicated but total repair time was less than 20 minutes.
Shut off power,
Drain Tank,
Insure correct Pre-charge tank preassure,
Replace broken indicator dial, (screw in/off)
Restore power
Insure switch is correctly set by reading new gauge and adjusting as needed,
Turn back on supply to home and flush air out of fixtures.

In the case of an older water heater expansion tank, shut off the valve that runs between the furnance and the tank. Attach a hose to the drain and then locate the air valve (older ones look like a preassure relief switch with a little handle. Open the drain valve and when water begins draining, open/unscrew the air valve to let air replace the void from the draining water.

Water stops flowing shut the drain and air valve, and then simply reopen the valve that connects the furnace to the tank, it will do the rest. Just make sure both Tank drain and air valve are SHUT prior to reopening the pipe line.

Depending on either situation your only real problem arises if you have a diaphragm tank that seals the air from the water. Although more reliable they often need to be recharged (psi), but a broken diaphragm equals new tank.

Your descrption though points to a waterlogged tank, so just describe the layout a little more and we'll give you the specific steps to take to correct the problem. I tend to type a lot but relax, as this is rarely a major problem, just part of regularly forgotten maintence that leads to your problems.

Since your reply to asking your nieghbors was not met with "I'm on a well", it's most likely a simple drain the water, fill the air, and problem solved. If there had been a city service problem the city would have been on it usually prior to most nieghbors even recognizing the problem exists.

Ignored regular maintence is most likely the culprit, so provide a little more details and the pros out here, and there are many helpful ones, will square you out in no time.

Check back later :coffee:

[kleetuss14]

My house is on city water supply, no well.
I'll have to take a closer look at exp tank and see if I can locate the valve you mentioned. I'm going to hold off on taking any course of action until I speak to a neighbor to see if they have experienced the loss of pressure as well.

thx.

[PhilC]

Sounds like a plan. You can also place a call to your local Public Works office to question any area problems.

Since I now know your asking about the expansion tank from the furnance:
Should you find that your situation is unique to the area, then the likely culprit is a waterlogged tank. You will have a a pipe (warm) running from the furnance to the tank which can be at floor leval or hung from cieling, but will be in close proximity.

Their is where you will find the valve connecting the two. The air valve will depend on the type and age of your tank, if you provide the model type and number, you could readily find a PDF manual online to aid in locating it.

Draining the expansion tank, as stated earlier should be a REGULAR ANNUAL maintence project, yet is rarely done or even known about. It's a simple task that will take very little time, and let you know immediately if the solution has been found.

Let Us Know How It Goes.

[Ed Imeduc]

You dont say if the pressure drop is in the hot water or the cold water Line or both here???? The exp tank on the boiler dont and cant have any thing to do with the water pressure in the home here. You can get a pressure gauge at lowes or Home depot That will go right on one of the outdoor hose sill c**k and see just what the pressure is. How old is the home ??? Do you have old gal iron pipes or copper for the water lines ???

ED ;)

[PhilC]

Ed,
I'm glad you put it in a much clearer concise reply. This is why I originally assumed he was on a well and was reffering to the tank from the pump. I anticipate a few more details as now I am extremely curious :confused:
Note to self: No more assumptions before replying. Last thing I want to do is confuse someone instead of helping.

Check back soon.