Min pipe size for a bathroom

[Shluffer]

I'm updating a bathroom and replacing the old brass water lines. For the life of me I can't get the 3/4 PEX lines up to the bathroom, but was able to up 1/2 inch. Am I asking for trouble if I feed a shower, sink, and toilet branched off a 1/2 line?

For clarity:
1) line from water heater to below the bathroom is 3/4
2) riser to bathroom for hot and cold (25 ft rise) 1/2 inch
3) branch the 1/2 line in the bathroom to the shower, sink, and toilet
4) this is the only bathroom running off the 1/2 inch line. Everything else branches out of the basement in other places
5) I'm using PEX crimp fittings

Thanks in advance for the help

 

[Breplum]

You are not doing it correctly in half inch. Period. You will get serious pressure drop when operating more than one fixture at a time.

 

[Sponsor]

 

[Shluffer]

You are not doing it correctly in half inch. Period. You will get serious pressure drop when operating more than one fixture at a time.

Thanks. I'll try to find another way to get a 3/4 inch pipe through. I'm down to cutting open walls which isn't an acceptable solution at the moment.

In the event I can't find another way, will I have a pressure drop from the multiple fixtures when only 1 is in use?

 

[Sylvan]

You are not doing it correctly in half inch. Period. You will get serious pressure drop when operating more than one fixture at a time.

Not only a pressure drop you will also have a severe volume drop if someone is in a shower without a pressure / temperature balance shower valve the possibility of someone being severely scalded is a real possibility if another fixture is used at the same time

 

[John Gayewski]

What is the minimum static pressure of your water service?

 

[Shluffer]

Are you referring to where it comes in from the street (60 psi) or at the farthest reach of the water line? Tge former can be adjusted upwards. Probably north of 90 but I wouldnt want it above 75. I don't know how to calculate the second. I can put a gage on it if I need to.

 

[Reach4]

I think he is asking the equivalent to the lowest pressure you ever measure when you are not using water.

When water flows, there is a pressure drop. So what is the lowest static (non-flow) that you see if you look. I think measuring at the house, but before any PRV, would be fine.

 

[Shluffer]

I think he is asking the equivalent to the lowest pressure you ever measure when you are not using water.

When water flows, there is a pressure drop. So what is the lowest static (non-flow) that you see if you look. I think measuring at the house, but before any PRV, would be fine

I think he is asking the equivalent to the lowest pressure you ever measure when you are not using water.

When water flows, there is a pressure drop. So what is the lowest static (non-flow) that you see if you look. I think measuring at the house, but before any PRV, would be fine.

60 but I cam increase to 80. I can double check during lunch.

 

[Reach4]

60 but I cam increase to 80. I can double check during lunch.

Are you implying that you only can take pressure readings after the PRV, your PRV is at the street, and you have ready access to the adjustment?

 

[Shluffer]

Are you implying that you only can take pressure readings after the PRV, your PRV is at the street, and you have ready access to the adjustment?

The PRV is imediatly after the water meter, I have access, and I can adjust. My town has high water pressure. I dont remember what this house has before yhe prv. But my last house in the same area was over 100 psi. I also have a tee immediately after the PRV where I can read the pressure. I have a 1/2 inch line run to the bathroom and I can take pressure at that location as well.

 

[John Gayewski]

The PRV is imediatly after the water meter, I have access, and I can adjust. My town has high water pressure. I dont remember what this house has before yhe prv. But my last house in the same area was over 100 psi. I also have a tee immediately after the PRV where I can read the pressure. I have a 1/2 inch line run to the bathroom and I can take pressure at that location as well.

If you can adjust your pressure up a 1/2" supply will likley be enough. I'd have to do some figuring but having a prv gives you flexibility.

 

[Shluffer]

Pressure after the PRV is currently 70. I checked and I can adjust upwards over 100 (but I'm hesitant above 80)

I'm going to connect the gage where the first bathroom fixture will be and add the numbers.

 

[Terry]

I typically run a 1/2" hot line for a tub and lav, and 3/4" for the cold, tub-lav-toilet. Nobody wants to be in a shower if someone is flushing a toilet.
I have been in places where the valves were not pressure balanced before and taking a shower within a 36x36 experienced someone working the kitchen sink while having no place to dodge the water. I wound up cutting out three single handle shower valves and replaced them all with balanced valves.
By code a pressure balance or thermostatic tub/shower valve.
If you have a roman tub faucet, the water needs to be 120 degrees or less. Sometimes there is a mixing valve in the bathroom for that.

 

[Terry]

If you can't fit a 3/4" cold line up there, at least fish two 1/2" PEX lines and give the toilet it's own 1/2" supply line.

 

[Jeff H Young]

If you can't fit a 3/4" cold line up there, at least fish two 1/2" PEX lines and give the toilet it's own 1/2" supply line.

yup that works!

 

[Shluffer]

I would like to start with a thank you. I always find this forum helpful.

Unfortunately the current limitation is 2 half inch pex lines. I'm fishing them by sliding them inside the old brass lines. I did put a camer through and found the issue with pulling the pipes out from the bottom, two unions on each plumbing line.

Plan A is now to cut two holes in a bedroom wall, cut up the Olde pipe. And remove it. We can the push the 3/4 inch pex through.

Plan B is 2 half inch lines and a warning sticker. With this is the only bathroom on the branch and it's infrequent use it may have to do.

I'll post what happens.

 

[wwhitney]

If you can't fit a 3/4" cold line up there, at least fish two 1/2" PEX lines and give the toilet it's own 1/2" supply line.

If you don't care how quickly the toilet refills, a flow limiter on the toilet supply would reduce the magnitude of the pressure effect on a simultaneous shower (while increasing the duration of the effect). Is there a readily available product designed as a toilet supply flow limiter to be installed after the shutoff valve?

Cheers, Wayne

 

[Shluffer]

All - thank you again for the help. Given the advice we opened the wall and removed the pipe 3 feet at a time. It took a while, but we now have 3/4 inch lines for both hot and cold up to the third floor.

Now I get to figure out how to level a tub ....

 

[Sylvan]

If you don't care how quickly the toilet refills, a flow limiter on the toilet supply would reduce the magnitude of the pressure effect on a simultaneous shower (while increasing the duration of the effect). Is there a readily available product designed as a toilet supply flow limiter to be installed after the shutoff valve?

Cheers, Wayne

All globe patten valves are designed for throttling. He can just close the valve slightly and test to see if flushing affects the shower

 

[wwhitney]

All globe patten valves are designed for throttling. He can just close the valve slightly and test to see if flushing affects the shower

And a multi-turn supply stop is a globe pattern valve?

Thanks, Wayne