At Ask Me Help Desk you can ask questions in any topic and have them
answered for free by our experts. To ask questions or participate in
answering them you must register for a free account. By registering you
will be able to:
Get free answers from experts in any of our 300+
topics.
I have a new home with a pressure regulator. When set at 50 psi the flow at all locations is very weak. When set higher the flow is acceptable. The plumber says it must be set at 50psi. The flow at this setting is much weaker than normal (normal being virtually any other location, our last home, public restrooms, other homes, etc., etc.) At what pressure can I safely set the system?
I have a new home with a pressure regulator. When set at 50 psi the flow at all locations is very weak. When set higher the flow is acceptable. The plumber says it must be set at 50psi. The flow at this setting is much weaker than normal (normal being virtually any other location, our last home, public restrooms, other homes, etc., etc.) At what pressure can I safely set the system?
How are you testing it to show it is set at 50PSI?
Is there a gauge on the Pressure Reducing Valve -- Or are you pressure testing with a gauge elsewhere?
How are you testing it to show it is set at 50PSI?
Is there a gauge on the Pressure Reducing Valve -- Or are you pressure testing with a gauge elsewhere?
There is a tempory guage on the hot water heater drain faucet. It has a tell-tale that shows the maximum pressure as the plumbing company wanted to check for pressure spikes. In the last 3 days it has been as high as 65 psi, typcially 50 psi and as low as 40 psi. The reason the plumbing comapny is checking this is that the water heater pressure relief valve is leaking. It is the third pressure relief valve installed. I think it is leaking is due to too high water pressure as one of my "friends" adjusted the pressure reducing valve without a guage and I subsequently found the water pressure was well in excess of 100psi. Good news, nothing blew up or leaked, except the pressure relief valve on the water heater. Water flow was good, better than good I guess. Until now the plumbing company has changed the pressure relief valve without checking the pressure, even though I asked them to.
There is a tempory guage on the hot water heater drain faucet. It has a tell-tale that shows the maximum pressure as the plumbing company wanted to check for pressure spikes. In the last 3 days it has been as high as 65 psi, typcially 50 psi and as low as 40 psi. The reason the plumbing comapny is checking this is that the water heater pressure relief valve is leaking. It is the third pressure relief valve installed. I think it is leaking is due to too high water pressure as one of my "friends" adjusted the pressure reducing valve without a guage and I subsequently found the water pressure was well in excess of 100psi. Good news, nothing blew up or leaked, except the pressure relief valve on the water heater. Water flow was good, better than good I guess. Until now the plumbing company has changed the pressure relief valve without checking the pressure, even though I asked them to.
Testing pressure at the HW Tank is not going to give you an accurate reading -- Thermal expansion is going to give you a reading of +/- 10 PSI.
BTW, 50 to 65 PSI, if deliverable, is the recommended pressure for a residential potable water supply system.
Does your system have a back flow preventer, and if so, do you have an expansion tank on the hot water heater? When you add cold water to the hot water tank on each hot water draw, it then expands. If the additional volume isn't free to go out the inlet, PRV, water meter, and anything else between the hot water heater and the city line, the pressure will go up through out the system until something gives. Usually it is relief valve. They are cleverly set below the pressure rating for all the other components. I fail to understand how you could have a 10 psi. differential between the water tank and PRV with an open 3/4'' pipe connecting them and no flow. In a connected system, the fluid will flow to equalize the pressure everywhere in the system.
I fail to understand how you could have a 10 psi. differential between the water tank and PRV with an open 3/4'' pipe connecting them and no flow. In a connected system, the fluid will flow to equalize the pressure everywhere in the system.
I'm pretty sure we've had this discussion before, Labman -- If the tank is fitted with one way inlet and outlet nipples, as most newer tanks are, the pressure built up by thermal expansion will not flow back through the cold side of the system.
1 The relief valve leaking due to a back flow preventer and no expansion tank.
2 Low water flow due to construction debris somewhere in the system. %0 psi. should be plenty.
3 A plumbing company not seeing and correcting the above. I do admit that a few years ago it took Tom and I a while to catch on to needing expansion tanks with the back flow preventers. As more and more public systems add them, it seems to me that practicing plumbers should have caught on to them by now.
It is ludicrous to think those little plastic flaps are going to hold much pressure. I still have the nipples that came with the water heater I installed last year. I just tried blowing through them. I can easily blow through them in both directions. Since Tom says you don't need dielectric unions, I had thrown them in my junk box without looking at them. With some of the posts I am seeing here, that may be the best place for them.
They may slow down little convection cells saving a certain amount of energy, but I wonder how much? I do have the pipes insulated on my tank.
If you have water flowing when you measure pressure, it is going to be lower the further from the source and closer to the outlet. Otherwise, when no water is flowing, the pressure will be the same everywhere in the system, little plastic flaps or not.
Having looked at the professionally installed tank at my church, I certainly hope Tom is right about not needing dielectric unions. Oh yes, it has 1'' ones coming directly out of the 60 gallon tank. Then there are 1'' X 3/4'' galvanized reducing couplings that the 3/4'' copper pipe adapters screw into.
I am assuming by pressure regulator you mean a pressure reducing valve.
If it is, it means the pressure from the street is higher than is allowed by the plumbing code.
Find out what the plumbing code allows in your area. Mine is between 40 and 80 PSI but many houses go up to 100PSI.
PRV's have a built in backflow valve, this allows water to flow in one direction. If you have a gauge on your water system past the PRV take the pressure as soon as you shut off the water at a tap.
If everything is tight(no leaks) the pressure will start to rise from thermal expansion from the hot tank.
Often quite dramatically, enough to cause the pressure releif valve to release at the hot tank.
You can purchase an small surge fixture that will take up the expansion. They are sold more to stop water hammer but will work for both. Only a few dollars at a plumbing supply store.
Then set the pressure as high as you want in the house.
65-70 PSI is what I find people are most happy with.
Good luck
1 The relief valve leaking due to a back flow preventer and no expansion tank.
Well, we don't know if that is the case because he han't responded to your earlier query.
BTW, you may or may not know this, but the requirement for backflow prevention is a State/Municipality requirement, not a code requirement under any of the varying codes adopted throughout the country.
The city of Seattle doesn't require them, but if you drive across the bridge into Bellevue you'll definitely need one.
If he does have a backflow preventer on his system, then a malfunctioning check on his double check, or the remote possibility of both checks malfunctioning would certainly explain the surging and the failure of the T&P's.
Quote:
2 Low water flow due to construction debris somewhere in the system. %0 psi. should be plenty.
Construction debris is always a possibility -- And if he has a backflow preventer installed without an inline wye strainer, then debris may be lodged in the seat(s) of his backflow preventer -- If the municipality is going to require backflow prevention, then they should also mandate protection for the backflow preventer in the form of a wye strainer -- But of course the don't.
Quote:
3 A plumbing company not seeing and correcting the above. I do admit that a few years ago it took Tom and I a while to catch on to needing expansion tanks with the back flow preventers. As more and more public systems add them, it seems to me that practicing plumbers should have caught on to them by now.
The problem is that Plumbers are only required to know the letter of the code when sitting for their competency exam -- Understanding the 'WHY', IOW, the engineering behind the 'WHY' never enters into the equation.
I do the best I can in the code compliance classes I teach, but 2 hours a night twice a week for six weeks leaves a lot of questions unanswered -- They know what a vacuum breaker is and when one is required, but have no idea whatsoever what it does.
Also, the municipalities requiring backflow prevention haven't thoroughly thought through the requirement -- Most of the municipalities simply require a double back check, which offers no relief whatsoever for the domestic side of the equation.
A much better device for protecting both sides of the equation would be a Reduced Pressure Backflow Preventer -- This device would protect both sides without causing surging and pressure buildup on the domestic side.
Quote:
It is ludicrous to think those little plastic flaps are going to hold much pressure. I still have the nipples that came with the water heater I installed last year. I just tried blowing through them. I can easily blow through them in both directions. Since Tom says you don't need dielectric unions, I had thrown them in my junk box without looking at them. With some of the posts I am seeing here, that may be the best place for them.
Well, there's the rub, there are a number of different manufacturer specific heat trap nipples, and there are a number of different ways of manufacturing them.
The kind you speak of, with hinged plastic flaps are only one example.
Some use machined seats and machined balls matched to the seats and rely solely on pressure and back pressure, while others use machined seats and balls and springs to return them to the seats.
If it weren't a warranty issue, as it so often is, I would yank them out and throw them in the trash -- But it isn't in my best interest to invalidate the warranties of the fixtures and appliances I provide and install.
Quote:
They may slow down little convection cells saving a certain amount of energy, but I wonder how much? I do have the pipes insulated on my tank.
Frankly, I think they're crap -- But part of my success and my longevity in the trade is based on not invalidating the warranties of the fixtures and appliances I provide.
Not sure what growler's problem is. Maybe he spilled coffee on his lap and is a bad mood.
From what you said in your original post my advice is accurate and correct.
I have been a trouble shooter in a large municipality for 27 years and have come across this problem many times.
The trouble with plumbing terminology is that different terms have different meaning all over the country.
I would rather use a generic term that you can use at a plumbing supply store.
I don't know how to post a link but if you google water hammer you can see what a water hammer arrester looks like.
This will cure the problem if water expansion is causing your pressure relief valve to blow.
Linear Mode
