water heater recovery

Hey all you plumbing experts. How do you test the recovery time on electric and gas water heaters? I check the water temperature with a laser thermometer at the kitchen and baths. But it seems like it would be real easy to miss a bad heating element or bad dip tube. Any advise?

I was not aware that anyone checked the recovery time. Interesting. I’ll be interested in responses.

Never did … Never saw the need too

You can always check the elements if you feel it’s necessary. Of course, you could check a lot of things with your multimeter if you wanted, where do you draw the line?

Well it sounds like nobody checks the recovery time… This is interesting because bad heating elements and bad drip tubes are very common. So the buyer moves in and take a shower, the hot water only lasts for 10 minutes, and they are pissed off.

I use Kenton Shepard’s narratives, and I couldn’t find where he addresses it either.

As I enter the kitchen I will usually turn the hot water on at the sink and let it run for 3 or 4 minutes and then take the temperature with a laser thermometer. And I do the same in the bathrooms. Maybe if there is a significant difference in temperature I should recommend evaluation by a licensed plumber?

Or maybe I should just disclaim it. Something like…due to the amount of time and expertise required to test recovery time it is beyond the scope of the inspection, and let to a licensed plumber. I really don’t like this, because the buyer could be buying a bad water heater and is expecting us to discover it for them.

Hum… I can’t believe that somewhere one of my InterNACHI brother doesn’t have a goo idea on this. This may be the first time ever that I’ve stomped all the InterNACHI experts…

Interesting can you supply a place to confirm this information
( " This is interesting because bad heating elements and bad drip tubes are very common. ")

Thanks … Roy

Hey Roy,

Thanks for the post.

No Sir, I don’t have any documented source that speaks to heating elements and drip tubes being common failure items. Just my personal experience.

The lower electric heating element usually fails before the top one, because as the hot water rises in the tank the top element may not turn off/on as often, but the bottom one will due to the cold water in the bottom of the tank.

The drip tub delivers the in coming cold water to the bottom of the tank. When it breaks off at the top, the cold water comes in at the top and when the hot water is turned on, the cold water moved directly to the hot water outlet pipe. You get cold water in and cold water moving directly to the hot water outlet pipe.

I’ve seen these a number of times.

They had bad tubes for 3 years 93 to 96 .
People need to flush their tanks get rid of the slush frequently
Water pressure should not be over 80 LBs. ( Brighton Ont where I live is about 115 Lbs ) . I have a regulator set at 50 Lbs

More info is found at


But the recovery rate can be affected by so many variables, such as the temperature of the water going into the water heater. Here’s a good chart for electric water heaters, including a recovery rate formula for manual calculation.


Of course, the whole question of recovery rate is moot if one installs a tankless water heater!

No, not really. You just asked the question in a way that didn’t get you the right answers - not that I consider myself a “plumbing expert,” but we don’t check “recovery rate.”

A broken dip-tube is pretty easy to diagnose in a gas-fired water heater. In many of the cases where I find this issue, the water heater is turned up to maximum heat capacity and the unit produces scalding hot water for a minute or so. After that, the water remains luke warm almost indefinitely.

An electric water-heater with a bad element will produce similar results, but diagnosis may be difficult when trying to differentiate between a bad element and a broken dip tube.

So rather than checking “recovery rate,” we’re checking for “functionality.”

Very easy to tell if both elements will operate on a electric WH Start HW running in a bath tub and while you have the dead front off the electric service panel check the amp draw on the WH breaker. You must allow enough time for the water in the tank to be drawn down in temp for the top element to active

Never did test the elements .
Never had a claim for a bad one If I did I would buy a new element and put it in . Little cost ,No big deal… Roy

Easy to install in a tank like this

Tired Tank.jpg

No one knew they were bad until after your vehicle tail lights disappeared down the road then it was to late:p

You have one of those fancy thermometers, why don’t you just check the temperature where the elements are located after you run the water during normal testing for a while?

Same thing for a drip tube. But my other question is why can’t you see water coming out of it in the first place?

If you want to test recovery time of the water heater you have to know from what temperature you start at, to what temperature your trying to achieve. You must determine the wattage capacity of the water heaters and the actual voltage/amperage being drawn.

You convert your amperage to wattage. You convert your wattage to BTU’s. You weigh the amount of water in the water tank. The number of pounds of water is equivalent to the number of BTUs to raise the temperature of 1 pound of water 1°F. You multiply this by the weight of the water your heating and convert it per hour and you will know how long it will take to recover.

You need to determine the standby heat loss factor for the particular unit for this period of time it takes to recover because you have losses as soon as you have temperature gain.

If someone flushes the toilet during the process you have to start all over again…

Are you a home inspector?