Originally Posted By: rmoore This post was automatically imported from our archived forum.
David…
To expand on Larry's post...
When you attach your pressure guage to the hose-bib how many turns do you open it to get a reading? Probably only about half a turn right? But to open it fully for full flow would require 3 or 4 full turns. This means you are getting a full pressure reading even through a small orifice. Kind of like reading your tire pressure through the valve stem. Pressure in liquids or gases will equalize, given time, either side of an open restriction.
You could, in fact feed a house with a 1/4" icemaker line and still get a full pressure reading. Just don't be in the wimpy shower when someone flushes the toilet.
-- Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
Originally Posted By: Guest This post was automatically imported from our archived forum.
Don’t confuse pressure w/ volume. A static pressure reading will be the same anywhere in a contained sytem. Flow or volume is factored by line size and the force behind it.
Originally Posted By: jpeck This post was automatically imported from our archived forum.
I see where everyone has assumed that David measured pressure with a pressure gage.
How about considering that David ran the water and said 'Looks like good pressure here to'?
You can have good flow with no pressure (think stream) and (as explained above by others) good pressure and not much flow, however, you can have a good pressure / flow combination from any size pipe.
Originally Posted By: rmoore This post was automatically imported from our archived forum.
Jerry?
If David did, in fact, use the word pressure when he meant flow, then he needs to change his terminology. It is confusing here and would be in a report. If he did indeed mean pressure then?well, either way, the above posts made valid points.
As for ?you can have a good pressure / flow combination from any size pipe?. Granted?but if it took 200PSI to achieve acceptable GPM from an undersized pipe then that wouldn?t be ?good?.
David...
To answer your original question...
I would report the 1/2" line as being "less than required by modern standards and that it may result in less than adequate flow when multiple fixtures are operated". The size of home, number of bathrooms, occupants, the static pressure, etc will determine how much of a problem this might be.
-- Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
Originally Posted By: Lew Lewis This post was automatically imported from our archived forum.
Good point Jerry,
Prople ask me all the time if I am going to measure the water pressure. I tell them that I could measure it, but the number is meaningless in an inspection report. I tell them I will run fixtures simultaneously to get a realistic idea of the water FLOW under actual conditions.
David, I also see 1/2 inch service to older homes, and the flow seems to be OK. Usually these are smaller houses with only bathrooms. Now try to imagine the interior diameter of those 75 year old galvanized water service lines!
Originally Posted By: Guest This post was automatically imported from our archived forum.
Lew,
To answer just your question and make no assumptions about what method you used to measure pressure, or if in fact you're talking about volume when you said pressure and the planets are in alignment when you take the reading to account for that little extra gravitational pull...
1/2 inch supply would probably be adequate for any one discharge device.
(I can't think of words other than faucet or spigot, but didn't want to have them pointed out to me)
If you opened two or more discharge devices simultaneously, flow would probably be adversely affected and possibly be inadequate. 3/4 or 1 inch would be better.
To flood by 3/4 is nice,/ but often done 1/2 will suffice.
(apologies to Robert Frost and anyone who likes a nice concise answer)
Originally Posted By: rmoore This post was automatically imported from our archived forum.
Lew…
What about excessive pressure? While pressure alone is no indication of functional flow, isn't it also our job to report on pressure that might damage or burst fittings such as clothes washer lines? Anything above 80PSI requires a regulator. How do you judge this without taking a pressure reading?
I'm surprised that the SOP doesn't require this.
-- Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
Originally Posted By: dvalley This post was automatically imported from our archived forum.
but pressure is the terminology I?ve been trained to use when testing the bathrooms. I turn on the shower and the basin faucet simultaneously then I flush the toilet. If the ?flow? (hey, I used the word correctly this time) doesn?t change at these points, I inform my client that the pressure is fine. But from today, here on in, the word ?flow? will be used instead of ?pressure?. Pressure can only be tested with a gauge.
As for the ? inch piping at the main, I?ve always informed my client that the piping at the Water Main appears to be inadequate for the fixtures that are being supplied. Even when the flow (wow, I did it again) seemed adequate, the report states ?undersized piping after the main. Recommend ? inch piping if problems arise?.
Originally Posted By: tgardner This post was automatically imported from our archived forum.
Interestingly enough, a 3/4 L copper pipe will flow 4 times as much (20 vs 5 gpm) than 1/2 " L copper at 20 psig pressure drop. But that’s through 100 equivalent feet of pipe. Elbows and valves have some extra values in terms of resistance to flow but equate to some value of feet in head loss per gpm of flow.
If there is only 50 equivalent feet of pipe or less, many well designed homes could be serviced by 1/2" copper at 8 - 10 gpm (typical well pump BEP capacities). Especially if the service pressure is 50 -60 psig or above. ( but less than 80).
Rare though.
That said, seldom does one run more than two fixtures at once without getting yelled at by the one in the shower.
Originally Posted By: jpeck This post was automatically imported from our archived forum.
David,
Don't change to quickly or too far.
It IS 'pressure', but it is also 'flow, or, as some might say, it is 'flow, but it is also 'pressure'.
Ever seen one of those waterfall lavatory faucets by Kohler? Very good "flow", but absolutely useless with no pressure behind it. You have to stick your hand right up under the spout as the water "flows" off it.
I'd much rather have some pressure behind it, and let is stream out from the faucet some.
For a shower, you need good flow, but more importantly, you need good pressure, to spray the shower out into the shower area.
Thus, when you say 'that's got good pressure' you are correct. If you said 'that's got good flow', that might also be correct, but without pressure, you'd have to stand right under it to be able to use it.
Thus, 'that's got good pressure' might be the more correct way to describe it when the shower is acceptable.
Originally Posted By: dbowers This post was automatically imported from our archived forum.
Lets cut to the chase and quit beating around and talking it to death. Tell your client it used to be commonly done but is no longer recommended and the seller needs to replace it if they want to sell the house. That will impress on the local realestators that you’re a no-nonsence type of guy, and they’ll tell all their other realestator friends about you - so you’ll make lots of money from the big increase in your business.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
David,
No I don't see 1/2 inch copper to often for the main but I still do see it on occasion.
Just because you have 1/2 inch does not mean you will not have adequate flow, or whatever else you want to call it. The theory on pressure is correct, no matter what size pipe you have the pressure should equalize in time, given any pipe size.
Most of the newer fixtures are water conserving fixtures, so flow rates of 1.5 GPM and 2.5 GPM is typical. What that means is that you can run the shower, the sink and flush the toilet and you will still have adequate flow to take your shower.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
is a volumetric rate (usually measured in gallons per minute or gpm), while water pressure is a force per unit area (usually measured in pounds per square inch or psi). They are not interchangeable.
Good water flow is a function of both good pressure [that can also be maintained over time ... called "residual pressure"], and adequate pipe size (or more correctly unrestricted pipe opening) without to many fittings or excessive length. While it is true that low pressure will result in poor water flow, having good pressure does not mean you will have good water flow. Undersized piping and corrosion inside pipes (particularly if ya have older galvanized pipe prone to corrosion) can restrict the water flow, even if you have good pressure.
Water flow is hard to measure unless you have special equipment, so most just get an indication of this by turning on two fixtures (like a shower and faucet) and then flushing a bowl. You can also get fancy and set the shower water temperature to like 105F, and then re-check the temperature after flushing the bowl to make sure it doesn?t go over like 120F which can cause scalding.
Water pressure is fairly easy to measure, and is good to know particularly if a low water flow situation is suspected. However, be careful reporting both water flow and water pressure as they will vary somewhat depending on the time of day and demand on the municipal system. And if you are just hooking up a gauge to a hose bib or something, you are really measuring "static pressure".
Note that some consider 1/2? service pipe at 30 psi static pressure a minimum, but that is usually only marginally adequate for like two fixtures running at the same time in a smaller home. Many consider 3/4? service pipe at 40 psi static pressure a more reasonable minimum for a typical home (along with an 80 psi maximum), and that is what?s required by the IRC for new homes (IRC P2903.7 & P2903.3). But I think pipe size without deterioration is the most important thing.
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: Lew Lewis This post was automatically imported from our archived forum.
Robert,
I don't use those fancy tools like a magnet.  One scrape of the screwdriver is all I need to tell the difference, and the fact that one metal is usually rusted and the other is usually pitted.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Lew Lewis wrote:
One scrape of the screwdriver is all I need to tell the difference
Very true ... as long as ya don't hit that pitted area that is ready to let go ... 
Lew Lewis wrote:
I don't use those fancy tools like a magnet. 
Some of the folks here would actually bust my chops for crossing my own "line in the sand" and recommending anything other than a flashlight and screwdriver ...
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
