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Discussion Starter · #1 ·
Does anyone know if the Watts 1” N45B is compatible with the 1” N45B M1?

I tried the Wilkins NR3XLR and the threads on the side before the regulator was slightly smaller than the existing union. So I had to put old regulator back on. In the mean time I'll order the N45B M1 but I'm trying to check if it has all of the same dimensions first.

The nice thing about the N45B M1 is that it has an integrated pressure relief valve so I no longer need an expansion tank...
 

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The nice thing about the N45B M1 is that it has an integrated pressure relief valve so I no longer need an expansion tank...
The thermal expansion feature in a pressure regulator just allows downstream pressure to be bypassed back into the source pressure when the downstream pressure exceeds the source pressure by about 10 psi. So if your source pressure is 120 psi, then your home's pressure will only be bypassed when it exceeds about 130 psi.

HRG
 

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Discussion Starter · #3 ·
Ah. So I take it I'll still need the pressure relief valve before the line gets to the water heater?

Still wondering about the compatibility though. I plan on calling Watts tomorrow to see what they can tell me.
 

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Ah. So I take it I'll still need the pressure relief valve before the line gets to the water heater?

Still wondering about the compatibility though. I plan on calling Watts tomorrow to see what they can tell me.
There's no pressure relief valve on the N45B M1 pressure regulator. It just has an internal thermal expansion bypass that bypasses water back to the source when downstream pressure exceeds source pressure. There should be a pressure relief valve on your water heater already so you shouldn't need to install one. Look for a flip lever thingee above your water heater.

You may need to install a thermal expansion tank depending on what your source water pressure is. If there's an anti-backup valve (backflow preventer) in your supply line then you probably should install an expansion tank regardless of the source pressure.

HRG
 

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Discussion Starter · #5 ·
That's what I thought. My water heater has a pressure relief valve but I had a plumber tell me I needed another one after the regulator but before the water heater in order to be up to code. He said the part is only about $20 but his minimum labor charge is $125. The pressure relief valve didn't make sense to me so I opted not to do that work. My source pressure going into the regulator is about 125 psi.
 

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That's what I thought. My water heater has a pressure relief valve but I had a plumber tell me I needed another one after the regulator but before the water heater in order to be up to code. He said the part is only about $20 but his minimum labor charge is $125. The pressure relief valve didn't make sense to me so I opted not to do that work. My source pressure going into the regulator is about 125 psi.
It would be worth it to verify what your plumber said and install one after the regulator if that's the code in your area. All I know is that it's not code in my area and just one above the water heater is all that's required.

HRG
 

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Discussion Starter · #7 ·
I confirmed that there is a difference between Watts and Wilkins. I ended up using the N45B M1 DU S pressure regulator and it fit perfectly. Too bad Watts and Wilkins can't have the same 1" threaded standard...I understand though and it worked. I returned the Wilkins and picked up the Watts...
 
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