Tankless water heater TPRV

I was standing near this tankless water heater when I heard the TPRV make a little spurting noise, I looked over and there was a drip of water coming out of the discharge pipe. (I had already been in the house and the hot water was functional.) Is this a normal discharge for a tankless water heater?

Most likely a PRV, not a TPRV. Did you check?

Ok, thanks, PRV. The question still is : why did it emit a puff of water. I have never seen one do this. The house was vacant and the utilities were on.

That’s what they do when the temp or pressure exceeds the ratings;-)

So maybe the unit needs adjustment?

Replacement.

It may need an expansion tank, was there a one way valve or pressure regulator at supply valve area?

These units require regular flushing/cleaning but almost never are. That may be the cause.
Cheers

Usually there is two obvious or inconspicuous reasons that the T and P (Temperature and Pressure) valve will leak one is that the pressure is to high and thus causing the T and P valve to leak . 2. Check the incoming pressure to make sure it isn’t to high . You check with a water heater](http://jonsguide.org/best-top-ao-smith-water-heater-reviews/) test gauge by screwing on to the Hose bibb. When the pressure is above say maybe 80- 90 + Lbs. it will cause wear and tear on the plumbing fixtures. Like the toilet Flush valve or what is called the Fluid master in the toilet tank. Another factor or problem thus caused by excessive pressure is that the shower valves and or the faucets can wear out faster and would need to be changed or replaced much more frequently than if you have it at 55 - 60 lbs. which the normal water pressure…