# Water Pressure



## Raindem (Sep 2, 2009)

We've got those plastic water lines (with copper fittings) in our new house.  We also have a well and the pressure tank is currently set at 50 psi which has resulted in low water pressure in the house, which has caused problems with our tankless water heater, but that's another story.  I'm thinking of having the well pump installer come back out and adjust the pressure but I'm wondering...

Question #1: What is the normal range of water pressure at a residence?

Question #2: What is the maximum pressure those plastic water lines can handle?

Thanks in advance for your help.

Curt


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## Speedbump (Sep 3, 2009)

I don't know about the plastic pipes and their max pressure.  The Plumbers here do.

Most people set their pressure switches at 40/60.  I sometimes go higher, depending on the situation.  What is better than that is a constant pressure valve.  You set your pressure switch at, say: 40/60 and the valve at 50.  When you use water the pressure will go down to 40, the pump will kick on, come up to 50 psi and stay there as long as you are using at least 1 gpm or more.  If someone uses more water, the pressure stays the same 50 psi with more water running by the valve.  This prevents cycling of your pump motor which is very harmful and gives you constant pressure.  You can read about them here:
- PumpsAndTanks.com


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## majakdragon (Sep 3, 2009)

I think you are referring to PEX pipe. It can hold any pressure you can produce from your well pump. Hopefully, you are not talking about an old  home with Poly pipe in it. This pipe was installed the same way as PEX but the pipe deteriorated over time. Big lawsuits at the time. It is no longer made.


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## Raindem (Sep 3, 2009)

Speedbump said:


> I don't know about the plastic pipes and their max pressure.  The Plumbers here do.
> 
> Most people set their pressure switches at 40/60.  I sometimes go higher, depending on the situation.  What is better than that is a constant pressure valve.  You set your pressure switch at, say: 40/60 and the valve at 50.  When you use water the pressure will go down to 40, the pump will kick on, come up to 50 psi and stay there as long as you are using at least 1 gpm or more.  If someone uses more water, the pressure stays the same 50 psi with more water running by the valve.  This prevents cycling of your pump motor which is very harmful and gives you constant pressure.  You can read about them here:
> - PumpsAndTanks.com



I believe ours is at 30/50.  I didn't understand what that meant until you explained it.  The tank shows a max possible pressure of 125, and the guage goes up to 100.  So you think we'd be OK going to 50/70?

Majakdragon, yes it must be PEX pipe because this is a brand new house. Glad to hear it can take the pressure.


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## Nestor_Kelebay (Sep 3, 2009)

Raindem:

     Before you start fiddling with the water pressure on your bladder tank, I'd check the aerators on your faucets.

     Is there low water pressure in ALL of your faucets, or only certain ones?


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## Raindem (Sep 3, 2009)

Nestor,

When I mentioned in my OP that the tankless water heater was "another story" that wasn't quite accurate.  The water heater is _the_ story and the reason why I'm messing with the pressure.

We have those aerators on all our faucets including the laundry tub.  If I run hot water at any faucet in the house it takes a long time to get hot water and then it is only luke warm. If I take the aerator off I get hot water a bit quicker and a bit hotter.  So my tankless water heater seems to be very sensitive to water flow.  My complaint therefore is not about the water pressure per se, but about getting enough water flow to cause the tank to provide adequate hot water.

Here's how ridiculous my situation is.  To take a hot shower we have to run another faucet in the bathroom (after removing the aerator) the same time as our shower in order to get hot water.  So much for the water-saving shower head!

So I will probably need to change to a different type of water heater, but I was hoping that a slight tweak in my water pressure might be enough to solve the problem since my pressure seemed to be on the low end of the scale.


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## Speedbump (Sep 4, 2009)

> So you think we'd be OK going to 50/70?


Yes, you would be fine.  Whether it will help the tankless heater or not, I don't know.  The constant pressure valve has helped in these situations I've heard.  I don't know much about the tankless units except that there seems to be a lot of talk about them both good and bad, so apparently they aren't perfected yet.


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## Raindem (Sep 4, 2009)

I changed the pressure to 40/60 and it didn't really help, and I doubt 50/70 will be any better, so I'll just leave well enough alone on the  pressure. I don't know if the constant pressure valve will help but I might put one in anyway to help out the pump motor.

Thanks for all the help.  I wanted to be all green and modern but I think tankless units are overrated. I'll be swapping mine for an old fashioned hot water tank.


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## majakdragon (Sep 5, 2009)

I didn't see any mention of the name of your tankless heater. All I can say is, they are not all created equal.


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## Raindem (Sep 5, 2009)

It's an eEMAX whole house unit.  It has 4 coils of which some or all are supposed to come on depending on how much water is being used.  Price wise it was in the middle of the pack. I have another eEMAX in my workshop. It is a single point of use unit that doesn't work either.  On that one they tested the water flow rate and determined that it wasn't enough to trigger the unit.  It needs 1.5 GPM and the faucet is less than that.

Speaking of which, is water pressure concurrent with GPM flow rate?  In other words does increasing the pressure increase your GPM?


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## Redwood (Sep 6, 2009)

Raindem said:


> It's an eEMAX whole house unit.  It has 4 coils of which some or all are supposed to come on depending on how much water is being used.  Price wise it was in the middle of the pack. I have another eEMAX in my workshop. It is a single point of use unit that doesn't work either.  On that one they tested the water flow rate and determined that it wasn't enough to trigger the unit.  It needs 1.5 GPM and the faucet is less than that.
> 
> Speaking of which, is water pressure concurrent with GPM flow rate?  In other words does increasing the pressure increase your GPM?



Ah electric tankless that explains a lot...


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## Speedbump (Sep 8, 2009)

Yes, if you increase pressure, you will increase water flow.  It's not identical though.  It may take a lot of pressure to make much of a difference in flow.


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