Model # 3/4 LFX65BU

Internet #203473938

Store SKU #768031

Watts 3/4 in. Lead-Free Brass MPT x FPT Pressure Reducing Valve


3/4 in. Lead-Free Brass MPT x FPT Pressure Reducing Valve

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Product Overview

This 3/4 in. lead free cartridge style water pressure reducing valve is designed to reduce incoming water pressure to protect plumbing components and reduce the water consumption for commercial, industrial and residential applications. It features a lead free brass body, thermoplastic seat cartridge, NPT threaded union inlet and NPT female outlet connections, reinforced diaphragm, and a bypass valve to control thermal expansion pressure. The reduced pressure rating is set at 50 psi (345 kPa). The maximum working pressure is 400 psi (27.6 BAR) and temperature range is 33 to 180°F (0.5 to 82°C).

California residents: see   Proposition 65 information

  • NPT threaded union inlet by NPT female outlet
  • Great flow performance with low fall off pressure
  • Bypass valve controls thermal expansion pressure
  • Sealed spring cage for accessible outdoor or pit installations

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Name 1/2 in. NPT Brass Pressure Reducing Valve 1/2 in. Lead-Free Brass SWT x SWT Tempering Valve 1 in. Lead-Free Brass FPT x FPT Pressure Reducing Valve 3/4 in. Lead-Free Brass MPT x FPT Pressure Reducing Valve
Brand Taco Watts Watts Watts
Ratings (0) (9) (8) (9)
Valve Outlet Diameter (in.) .25 .5 1 0.75
Connection FIP Sweat x Sweat FIP x FIP MIP x FIP
Valve Inlet Diameter (in.) .5 .5 1 0.75
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Product Depth (in.)
Product Height (in.)
Product Length (in.)
Product Width (in.)
Valve Inlet Diameter (in.)
Valve Outlet Diameter (in.)


Compatible Pipe Material
Maximum Pressure (psi)
Maximum Working Temperature (F)
Product Weight (lb.)
Valve Type
Pressure Regulating

Warranty / Certifications

Manufacturer Warranty
Watts (the "Company") warrants each product to be free from defects in material and workmanship under normal usage for a period of one year from the date of original shipment.

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Customer Questions & Answers

How much is the pressure drop with flow?

In the actual pressure regulator I have, the pressure drops almost to zero when I have flow in any faucet. A pressure drop is innevitable, but it must be minimum. Thank you.
Asked by: Luigy
Hope you've resolved the problem by now but, if you haven't you have to troubleshoot the problem. Either the valve is bad, your input pressure is very low or there is a valve or piping restricting the flow in or out of the valve. This valve has plenty of capacity to handle several faucets without appreciable pressure drop. First, I would put a pressure gauge on the input and output of the PRV. Run the water and see what happens to the pressures. Not knowing your input pressures I can only take an educated guess as to your problem. 1.. If the initial input pressure with no flow is low, <50# you don't need a PRV. 2. If the input pressure stays fairly steady with a faucet open and the output pressure drops to almost zero the PRV is the culprit. 3.If the input and output pressure drops dramatically with a faucet open look for a problem with valves and piping before the PRV. EG: the main shutoff valve, usually a gate valve may have a dropped it's gate restricting the flow of water or has stripped threads internally so the gate doesn't fully open. Remember, you can have a high input static pressure with no flow but, low dynamic pressure when you have flow. The manufacturer should have a pressure drop chart or a formula for different input and output pressures at varying flow rates.
Answered by: j135
Date published: 2015-09-20

what is mpt x fpt?

what do they mean
Asked by: h2oalot
MPT = Male pipe thread, FPT = female pipe thread. The piping fitting description for this valve is not correct. This valve has ONLY FPT. The union is also FPT. Union can be installed on either end of the valve or not used at all.
Answered by: j135
Date published: 2015-09-20

What is the lowest adjustable operating pressure of this valve?

Asked by: highpressure
Manufacturer claims the minimum operating pressure is 20#.
Answered by: j135
Date published: 2015-09-20

after installing this pressure valve,it hums when turn on. why?

Asked by: kenn
The humming you hear is the velocity change in the water psi, the psi is controlled by spring tension, which has a harmonic frequency as it adjusts.
Answered by: HavenAcres
Date published: 2015-11-08
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Customer Reviews

3/4 in. Lead-Free Brass MPT x FPT Pressure Reducing Valve is rated 3.1 out of 5 by 9.
Rated 5 out of 5 by from Works As Specified Functions as described in manufacturer's specs. Compared to 20-year old worn out valve it replaced, it 1) Holds pressure at set point overnight in no-usage situation, instead of creeping up to city water main pressure. 2) Does not restrict flow much under moderate-usage conditions--when using water two different places, like someone watering the lawn with a garden hose and someone else using the kitchen sink, there is NOT a noticeable pressure drop. The Home Depot product title as it is listed above at this time is incorrect. It says "3/4 IN. LEAD-FREE BRASS MPT X FPT PRESSURE REDUCING VALVE". It actually has 3/4 in FPT (female pipe threads) on both sides. One side has a union connection. The union connects to the valve by a large brass nut. The female threads inside the large brass nut engage male threads on the valve. I don't know what size those male threads are, but it's not 3/4" MPT. This product has a flexible design. As far as I can tell, the union could go on either side (inlet or outlet). If you take the union off, both sides are threaded the same (3/4"FPT inside the bore, male threads for union attachment around the outside.) Nice. Or if you had another of the union pieces, you could have it with a union on both sides. If I had it to do over again, I'd try to get one of those. That would have made the installation easier, where it had to go into pre-existing piping where there wasn't much flex in the system on either side. The valve I review here is the Watts LFX65BU. They do have a model number for the double-union version LFX65BDU. I don't where the double-union version is for sale.
Date published: 2014-07-01
Rated 4 out of 5 by from works fine The other guy must not have gotten all of the air bled out of his system. Mine does not hammer. I did have to take off the old flange nut and replace with the one that came with the unit. Mine (about 10 yr-old Wilkins unit) had different threads.
Date published: 2013-12-06
Rated 1 out of 5 by from Don not buy Tried 2 different valves of model lfx65bu and the lfn45bu and both pulsated and water hammered. My pipes sounded like a steam locomotive coming through the house . Exchanged for lf25aub-z3 and it solved all my problems .
Date published: 2015-10-16
Rated 2 out of 5 by from Not for every house Our 3 bedroom, 2 bathroom house with CPVC piping needed a new pressure regulator. After installation however, this unit, when using any one water draw like a toilet, shower, or washing machine, had a resonance/pulsing issue. With pressure gauge attached it would oscillate between 30-50 psi at about 3 pulses per second (whoosh, whoosh, whoosh) and the pipes were shaking around. I talked to HD support who said it could be a restriction in the line to the house, which I tested and ruled out. He said to try another unit, which I did, with the same result. I got the Watts 3/4 LF25AUB-Z3 unit and the problem was fixed. I gave the unit two stars, even though it didn't work in my home, because it may work fine in many installations. If you get a pulsing issue, just get the more expensive unit. I can only choose yes/no on recommendation, so I chose no. Others have had good results, apparently.
Date published: 2015-02-14
Rated 1 out of 5 by from Cheep valve Bought 4 of these valves after having a seal blow off at a rental home and then testing all properties. They worked fine at two of the rentals with a supply pressure between 100 and 120 psi. My house at the bottom of a hill and has supply pressure arount 150+psi. Put two different of these valves on and both sounded like a air horn in the basement. Do not trust the 300psi rating. Spent the extra $25 and get the double check valve, it is worth it to not have to redo the pipes twice. We also installed a different $40 watts valve and it failed after 3 days and was rated at 400psi.
Date published: 2015-05-01
Rated 4 out of 5 by from Watts were good Installation was easy as it was replacing an existing PRV whose seat was leaking. Increasing the output pressure above the factory set point created a chattering in the house piping. My input pressure is 140# which may be part of the problem causing the chattering but the old valve never chattered from day 1. Had to settle for 50# output to keep valve from chattering. Aside from this problem there is little pressure drop thru the valve and holds pressure when there is no flow.
Date published: 2015-05-20
Rated 1 out of 5 by from NOISY AND CAUSED WATER HAMMER First time using this model of P.R.V. and it will be my last time! Installation is standard as with all female N.P.T. adapter valves. Factory setting was 50 PSI, adequate enough. The issue was once the water is turned back on. There was water hammer galore. First thought it was an old fill valve that needed to be replaced in an upstairs toilet. After that was done, the noise stopped.... only to return when another toilet was flushed and when the washing machine was used. After adjusting the PSI both up and down (thought the internal spring could be sticking) had to keep it set at 80 PSI. The unit should function normally within the manufacturer's recommended pressure range. It clearly did not.
Date published: 2013-11-02
Rated 5 out of 5 by from Works great! Had lots of banging and hissing in the main inlet prior to installing this. Now there is none. My installation was a bit of a pain but that is the fault of the person who installed the original one. Glad I didn't get one of the plastic ones because I dropped this on the kitchen floor before installation. Pressure is just over 50psi with nothing running, just under 50psi with a faucet and toilet running.
Date published: 2014-11-23
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