I have a problem with a low pressure (or no pressure) on throughout the house. It wasn't always like that. It has developed in a last year or so. My system has about 62psi at the entry point (measured via a $10 gauge from Home Depot at the outside spout next to the water pipe that's going into the house). I have a boiler with an indirect water heater. There are two expansion tanks. One at the entry points for the baseboard heat and another one just before the indirect water heater. There is also a water softener between the water entry point to the house and the rest of the system.

The problem is that when the washing machine is on (located in the basement), the first floor has almost non-existent water pressure and the second floor has no water whatsoever. When we flush the toilet anywhere on the first or second floor, the pressure in the faucets drops by half or more. It is pretty much that you have to wait for the toilet to fill out before you can take a shower. What's weird is that if you open shower while the toilet is filling up, the pressure in the shower is low and will stay low even if the toilet is filled up (shower pressure won't go up).

Any ideas? I have posted photos of the pressure readings from the outside by the entry point and a photo of a gauge that's on my furnace.


Outside spigot next to the water entry point.


Furnace gauge.

 

How old is the house or should I say the piping in the house?
Typically your condition is the result of clogged piping.
Do you have PRV? It might be bad.
I would call the local municipality to come out and check your pressure coming to the house.

 

The house is from late 80s. All copper piping (besides the main entry pipe) and yes, I do have a PRV valve next to the boiler.

The outside spigot from where I took the reading is within 2 feet from the water entry point so unless the $10 gauge is super bad, the reading of 62psi should be good. I read that correct pressure is between 40 and 60psi, correct?

 

I think closer to 60 to 80 might be better but I may be wrong. My first starting point us to check the PRV. Try changing the pressure and see what happens. A 20 to 30 year old PRV valve may very well need replacing.

 

The two pressure gauges shown in Post #1 are measuring two different systems and their differences cannot be used to troubleshoot your problem.

The upper gauge installed on spigot near water service is measuring the pressure in the domestic water system. (the one that you are troubleshooting.)

The lower picture is the gauge on your boiler (water = boiler, air = furnace) and is measuring the pressure in your closed loop heating system. There is a PRV at the inlet where domestic water connects to boiler to reduce the pressure to less than 30#. Also there is a pressure tank at the boiler that acts only on the closed loop boiler system. Neither of those has anything to do with your problem.

Your problem is reduced domestic water pressure due to volume restrictions. A washing machine inlet valve goes full open and will move a large volume of water. When that happens the pressure in the system is reduced apparently enough to cause low or no water flow above. The higher in the house you go the worse it is.

As an example: a single 1/2 inch main that branches to two 1/2 inch feeds (say toilet and shower) that has both open will have only half the original pressure at each outlet. A washing machine is the usual worst case since it is usually nearer to the source and opens fully.

There are many reasons this can happen. Problem with PRV at house source, buildup of scale in iron pipes, poor piping design (pipes too small--e.g. 1/2 inch mains, 3/4 inch feed to washer, 1/2 inch branch to bathroom.

Start troubleshooting at the source and work your way along the system to make sure any isolation valves are fully open. Pay attention to the pipe sizes to see if there is a smaller pipe causing a restricted flow. Check that the water softener is not causing the problem by using its bypass to eliminate it as the possible cause. Since this problem is recent I think that could be the cause.

A toilet flush causing a drop in water pressure in a shower on the same branch is classic and is one of the reasons that mixing/anti-scald valves are required in showers.

There may also be a pressure tank near the hot water heater to offset volume changes when the water in the tank heats up. This should have no bearing on your problem that is occurring on both hot and cold water.

 

Thank you 2john. I think I can cross off the water pipe diameter as the possibility as nothing was changed since we own the house and we didn't have the problem before. Clogging is a possibility but how do I deal with that? Plus would that happen on both hot and cold water pipes simultaneously? That's probably out too. What about the 62psi reading at the entry point? Should I call our water company to get that checked or it is within norm? Asides from that, I will replace the PRV. If it helps, then great. If not, then I will troubleshoot more.

 

Pressure at 62 is not abnormal. You should ask the water company what pressure they supply. Probably 60 to 80. Then measure pressure at a spigot after the PRV and compare. Measure at washing machine spigot if no other available. My guess is that PRV may not be the problem and softener could be. Check that first via bypass or measurement.

 

The water softener was added later when we moved in but if I recall correctly, the problem with the pressure didn't develop right after it was installed. Though, it is a piece that sits right between the main entry point and the rest of the system. I have a bypass built-in so I can disable the water softener and see if that helps.

 

How old is the softener? Has it been serviced. It may have clogged up or become inoperative over time. Use the bypass and see if the problem still occurs. You may have to open/close two or three valves to bypass.

 

It is 3 years old. Never been serviced. I just add salt. But I can bypass it to check if the problem is with the softener.

 

An update: It is not the softener. I have bypassed it for the whole day and still have the low water volume when something is used. It affects both hot and cold lines so I am suspecting that the issue may be with the pressure at which the water is delivered to the house. Will have to call the water company and have them check it.

 

Did you try monkeying with the PRV valve? It may be that it needs just a bit of change because the internals are hung up. Most likely it needs replacement. If your neighbors are not having troubles then I doubt the pressure from the municipality to your house is a problem.

 

No I didn't touch the PRV because I think it is only a part of the heating system (not water delivery). Here is a photo of how it looks and where it is located. Right above it are the four or five heating zones we have.



That's how my entry point with the meter looks like. Would that have a built in pressure regulator?

 

You should also check the flow volume so you have that information when you speak to them. Time how long it take to fill a five gallon bucket and convert to gallons per minute (GPM). Do this at an outdoor spigot, the washing machine connection or a tub faucet that will not have flow restrictors.

You can also see the rate of flow at the water meter but it will be in cubic feet not gallons.

You are correct, there is no PRV at the meter.