Your furnace would not run properly if the pipes were not sized properly. Is your furnace giving you problems? The installation manual will have a sizing chart in it. Every manufacturer is different. For the brand that I install, the size seems right.

Most ppl erroneously believe their line starts at the meter, but that is not correct. When we install a new gas service the gas company will inform us where our final connection to the "gas main" will be located. Normally the property owner is then responsible for installing a line from the structure to within a specified distance from the main, usually on the utility easement on the front of the property, about 4' to 5' from the municipal main where they will install a "Curb stop valve". The curb stop is the point of demarcation between the gas company line and the homeowners line. The gas company will also inform us where the meter is to be located. It may be near the street, adjacent to the exterior of the building or is may be inside the structure, such as in a basement or utility area. An exception to that may occur if the gas companies line has a higher pressure and they install a pressure reducing valve at the meter, in which case the homeowners line may begin at the meter. For the purpose of sizing line we must measure the "TDL" (Total developed length) of the line from the designated point of demarcation to the furthest gas appliance or demand. TDL is determined by adding the actual physical length of the line plus the "Fitting insertion loss" of each fitting on the line. To find the fitting insertion loss we have to consult a "fitting insertion loss table" for the specific type of pipe being used. The table will list each type of fitting and express the loss as an equivalent length of straight pipe, by example it might say a 45el has a fitting loss of 0.4ft and a 90el might be 0.7ft. Under most codes they will allow us to compute TDL by multiplying the actual physical length by 1.20%. Example, if you have a total of 100ft from the point of demarcation to the furthest demand the line length would be 100' x 1.20% = 120ft. We would then compute the total load in cf/hr and check the table for the load and TDL to determine the correct line size. In regards to whether you can install a union in your crawl space, you will really have to check with your inspector. Normally if the crawl space is open to atmosphere there would be no problem, but, if your crawlspace has a skirting around the house with an access door that would normally be considered a concealed location. The concern is that you could have a gas leak and the gas would collect under the house unnoticed and potentially create an explosive hazard.

Good morning all. I am plumbing a new bath in my basement and have some questions regarding size of distribution/supply pipes. The following is existing: (1)DWV system is in place (2)water supply is a private well (3)Water enters house via a 1" rubber hose and connects to a 1"brass pipe and anti back-flow device (4)this 1" line goes to Amtrol pressure tank and exits tank via a 3/4" copper distribution run with a whole house filter close to the beginning of this run (5)the 3/4" pipe runs approx. 12' towards the center of the house and then starts to branch off to kitchen, 1 bath, laundry, boiler, hose bib, AND doubles back to water heater all with 1/2" copper and exits the water heater also with 1/2" copper and supplies hot water (obviously) to fixtures requiring it (6)house is small - 24x30' (7) new bath is 29' from water supply entry point into house and also 29' from water heater. OK. Now my questions. (A) Shouldn't the line to and from the water heater be a 3/4" distribution size (as is the cold)? If so, should I upgrade it to 3/4 or leave it as is? (B)Should the distribution pipe from the existing 3/4" cold run to the new bath also with 3/4" and then go to 1/2" branch lines or should I use 1/2" branch lines all the way from existing to new bath? Whatever is done with the new cold (3/4" or 1/2") will be done with the new hot run. (C) I assume that running branch lines down from ceiling to new fixtures (via 1/2") is OK and won't adversely affect water pressure to a significant degree (D)I plan to run new supply line first to shower then branch of it to sink and toilet. Is this OK? (E)Finally, when complete, farthest run from entry point/water heater will be 30' as the crow flys and a total of approximately 70' total pipe run each hot/cold (not including hose bib or boiler) and will service 2 vanity sinks, 1 kitchen sink, 1 tub/shower, 1 shower only, 2 toilets, 1 washer, 1 hose bib, 1 boiler. Will this work? Appreciate any advice you can give me. Hope I've given enough info (probably too much)

Far too often people get one of those silly little pressure gages that have a female hose thread adapter and attach that to a hose bib or laundry faucet and blindly assume the pressure they see is the actual working pressure of their system but such is not the case. When you attach one of those gages to a faucet then open the faucet to take the reading the gage is blocking the outlet thus for all intents and purposes they are still recording the pressure in a closed system. The basic laws of physics state that the pressure will remain constant at all points in a closed system however, the moment that we open a faucet and allow water to flow the pressure throughout the system immediately drops to "Dynamic Head Pressure" or more commonly stated as "Working Pressure." Dynamic head or Working head pressure is Static Head pressure minus "Friction Head Loss" and "Vertical Static Head Loss". Water physically weighs 0.434lbs per vertical inch column therefore to compute vertical static head loss we must measure the actual vertical rise from the point where we measure the pressure to the point of demand. As an example; let us assume a two-story house where the water line enters the basement near the floor and the shower is on the second floor. Typically we would have an 8 rise to the ceiling plus 1 for the floor joists and flooring material on the first floor, 8.5 to the ceiling and another 1 for floor joists and flooring material to the second floor and finally a 5.5 rise to the showerhead for a total vertical rise of 24Â. The vertical static head loss from the main water shutoff valve to the showerhead would then be 0.434psi x 24 = 10.4psi loss. Now assume that we measure the pressure at the main water shutoff valve and we get 45psi. This means that the absolute maximum pressure at your showerhead would then be 45psi minus 10.4psi = 34.6psi. From this we would then need to subtract friction head loss to determine the actual pressure at your showerhead. In the original post they stated that the pressure and volume is fine when only one faucet is opened but it decreases rapidly as two or more demands are opened. That is because "Friction Head Loss" increases dramatically as the velocity of flow increases. By example, let us continue to examine what happens if just the shower is used. Let us assume that in addition to the 24 vertical rise there is a 10 horizontal offset from where the supply line enters the basement to where it rises up to the shower therefore the total length of the line inside the house from the water main to the shower is 24 vertical plus 10 horizontal for a total of 34Â. (Technically we would need to also add in the fitting insertion losses but for now we will disregard them). The post states that they have a ¾" supply line that is 200 long. Let us assume the line to the shower to be a ½" line 34 long and the shower is rated for a flow rate of 2.5gpm. We measured 45psi at the main water shutoff valve and as was previously stated the pressure is constant at all points in a closed system so it then stands that the pressure at the prime mover (municipal main) is also 45psi however when flow begins friction head loss also begins at the prime mover. The post states that the existing supply line is ¾" and let us assume it is continuous roll PE-SDR pipe (black poly-which has one of the lowest friction loss factors). Consulting the PE-SDR friction loss table we find that at 2.5gpm the loss is 1.5psi/100ft and we have 200 so the loss is 3psi from the municipal main to the main water shutoff valve. Assuming the ½ line to the bathroom is copper we then consult the type L copper pipe friction head loss table and find that for the 34 run from the main to the showerhead we have a net loss of 0.118psi/foot x 34 = 4.02psi so at 2.5gpm the total friction head loss is 3psi + 4.02psi = 7.02psi (round off to 7psi) The static head pressure was 45psi and dynamic head pressure is static head pressure minus vertical static head loss + friction head loss so the actual pressure at the showerhead is 45psi  7psi  38psi. That is not bad pressure if we could be assured that no one would turn on any other fixture while we are taking our shower however the plumbing code requires that when we design a water supply system it must be capable of maintaining certain minimum pressure standards in a worst-case scenario where all the demands in the structure are open simultaneously. Under the UPC we would use the FU (Fixture Unit) method as I described in my previous post whereas under the IRC we use a minimum gpm rate for each fixture. Both methods will ultimately arrive at the same solution so for simplicity let us use the IRC demand rates here. Bob sent me an email stating that he has the following fixtures: 4 sink faucets 2 toilets 2 bathtubs 1 shower 3 hose bibs outside When I examined the list I was a bit confused. With 2 toilets I am assuming he has two bathrooms and one of the sinks is obviously a kitchen sink so I am guessing that he has a master bath with both a tub & a shower and perhaps 2 lavatories but on the other hand one of the sinks could also be a laundry sink. From IRC table 2903-1 we get the following minimum pressure and flow rates to each fixture. BathtubÂÂÂÂÂÂÂÂ.4gpmÂÂ8psi Shower (temp controlled)Â3gpmÂÂ..20psi LavatoryÂÂÂÂÂÂÂ..2gpmÂÂ.8psi Kitchen sinkÂÂÂÂÂÂ.2.5gpmÂ.8psi Water Closet(tank type)..Â3gpmÂ....8psi Laundry hookupÂÂÂÂ..4gpmÂÂ8psi Hose bib #1ÂÂÂÂÂÂ.5gpmÂÂ8psi Hose Bib#2ÂÂÂÂÂÂ.5gpmÂÂ.8psi TOTAL LOADÂÂÂÂ28.5gpm Although not mentioned, if he has a dishwasher that would add another 2.75gpm. Now let us examine the Friction loss table once again. With a flow rate of 28gpm the velocity of flow through his ¾" PE-SDR line is 16.82feet/sec or more than 4 times the maximum allowable 4ft/sec and at this rate the line will exhibit severe pipe wall and fitting erosion resulting in premature line failure and the friction loss is 59.41psi/100 of pipe. Given that his line is 200 long @ 28gpm the total friction head loss is 2x 59.41psi = 118.82psi thus the friction head loss is more than twice the supply pressure of 45psi and with all fixtures open at best he would barely get a trickle of water and no noticeable pressure. Even increasing to a 1" line would still result in a 36.5psi friction head loss from the municipal main to the main water shutoff at the house. On the other hand if the line from the main to the structure was increased to 2" the friction head loss through the supply line would be reduced to 1.36psi and the resultant pressure at the house main shutoff valve would be 45-1.36= 43.64psi which remains slightly above the code minimum supply pressure of 40psi.