Pop-Off Valve Replacement

Take it out by unscrewing. Take it to your local big box or plumbing supply store, buy a new one. Take it home and screw it in.

X2

Fairly easy to do.
Yes, just simply unscrew the old one. It may take a good size wrench to get it loose.
You can get a replacement at most hardware stores. There should be a tag on your old one that shows the temperature and pressure spec.
Get some Teflon tape for threads.

What the others have said......

However, does it really replacement, or is it just dripping when the water is hot? If it is dripping, it could be a sign of a lack of airspace inside the water heater.

If no over temp or over pressure condition exists, a healthy TPO will not drip even if covered in water.

They are easy to replace as others have said.

If it drips occasionally when first heating water, it is normal. An RV has a closed water system. When the water is heated, it expands and increases pressure in the system. A house normally has an open water system so the pressure does not build.

Easy to replace is relative........

Old rusty will be hard to unscrew
Access can be very tight due to location and exhaust venting in the way

Camco makes a wrench for them


The T&P valves are just like ones in home water heaters. Just need to get the correct size (Thread) Sensor probe sits in water.
210*F/150# (Full pop open values)

Weeping can be due to build up on valve disc/seat.....open/snap close couple times with water on and cold. Stand back it will spray :B

Weeping can also be due to loss of air pocket (designed into tank)
As water heats it expands....air controls the increase in pressure due to expansion (air can be compress/water can't)
So if air pocket is gone...water heats/expands....pressure increases...T&P will weep.
Re-establish air pocket------weeping should stop
Turn water off..open faucet...open T&P until water stops flowing...let T&P snap close.....turn on water/close faucet

Simple thermal dynamics

Excellent illustration, Biscuit! Mine drips a little only when it is heated. Apparently from what is said above, it is supposed to do this.

Many thanks for those above who provided this information. Saved me a lot of work.

Mike