Symptoms are low pressure but still hot.

We have two water heaters, one gas 50 gallon and an electric 40 gallon. As far as I can tell they are tied together for hot water output. They are both about 15 years old, same age as the house. We have lived here for four years

When you first turn the tap on there is good pressure but it quickly goes down to about a third of normal pressure

I haven't messed with them very much. A couple of years ago it seemed we were running out of hot water quickly. Pilot light was off, got it on and also drain the tanks some.

Any help is much appreciated

At this point I would replace both. !5 years is a lot of time.
Do you have hard or rusty water?

I may go that route with replacement, maybe even a tankless, we had one at our last house.

No rusty or hard water. Water comes from the County

Aside from replacing both due to age, I'd look at the pressure regulating valve.

As it was said prior, 15 years is a long time for a water heater, depending in use. I like the tankless units but they have there issues as well depending on water quality,etc.. I have replaced many units for friends and family and they are easy to do,especially with Shark Bite or similar products. The Shark Bite pieces are super easy to work with and you never have to worry about cutting pipes again,which in small areas, can be a pain.

Also do you have a pressure tank on your unit(s)? It helps with water hammer and pressure issues.

If you have a pressure tank, knock on the bottom half. Should sound hollow compared to the top half.

quote:

If you have a pressure tank, knock on the bottom half. Should sound hollow compared to the top half.

Is that the same thing as the expansion tank?

If so, what does that have to do with the pressure?

quote:

Originally posted by guinness301:
Aside from replacing both due to age, I'd look at the pressure regulating valve.

Is this the same as the pressure relief valve?

There is not a visible water leak anywhere

Cold water pressure is normal

PRV ... pressure tank "expansion tank" ... both mentioned. Flow is down but actual pressure has not been measured. Could be a lot of things.

In these parts if one has electric and gas, they'll typically run them in series - as opposed to parallel. Cold runs into the electric, tempers and heats the water to about 120˚. Then into the gas WH. You end up with virtual limitless capacity [recovery] unless you've got eight teenage daughters.

If my WHs were working I'd first look at the flow issue.

Is this the same as the pressure relief valve?

There is not a visible water leak anywhere

Cold water pressure is normal

No, the PRV would be at the meter; possibly at the WH but not usually. With COLD pressure normal, if there was a PRV at the meter, that would not be the issue.

The PRV is not the same as the relief valve on the WHs. The PRV prevents a little ka-boom, the TP relief valve protects against a BIG ka-boom.

Probably sediment blocking the line. They need flushed out. And eventually replaced, based on the their age.

Best guess, unhook the piping at the top of the water heater and clean out (or replace) the plugged pipe nipple.

Galvanized piping?

OK, thanks all

I plan on flushing them tonight as well as checking the expansion tank and operating the cold water in valve or valves to possibly knock any sediment loose.

quote:

Originally posted by BigSwede:
I may go that route with replacement, maybe even a tankless, we had one at our last house.

No rusty or hard water. Water comes from the County

Go for it we did, great stuff, endless hot water and you're not funding two tanks Electricity and Gas to have hot water.

We put in a Rinnai RU199 for LP, removed the 50 gallon tank in the garage and put the Rinnai outside. Cleared up lots of room in the garage.

Be sure to go with Gas for the tankless, better heat costs over electric, will save you monthly on the costs of maintaining hot water in two tanks.

Link

For the last few years I have worked a retirement gig with our little local water district. Suggest checking water pressure at hose bib ... testers from big box stores are cheap. If low, check pressure reliet valve. Open, close a few times, actually they should be "exercised' like this every few years. Possible your pressure relief valve is bad. Something else to check.

90 gallons of hot water yet no one has bothered to ask; just how many teenage girls live in your house?

We are down to one teenager, a girl. ANd upon looking yesterday, they are both 50 gal



I did the tank flush and working the cold water valve, water pressure did improve but not what it was. The expansion tank is bad, could that have anything to do with water pressure?


BTW, Woodman. They are in a series, cold into the gas and hot to the electric.

quote:

Originally posted by BigSwede:
We are down to one teenager, a girl. ANd upon looking yesterday, they are both 50 gal

I had one teen girl in the house, she could empty the 50 gallon tank we had easily LOL maybe that's why they kept failing too many rapid heat cycles..

You could do well to drop in a NG/LP tankless water heater....

If the expansion tank is bad, the should be a label on it. Get the same one. Its probably the same age as your water heater and a small investment.

Did one half sound different than the other? When I made my statement I assumed it was hanging. Sometimes they are on top of a water line.

It sounded solid and water came out where air is suppose to

It's a 2.1 gallon, interwebs says I should have a 5 gallon or better on this 100 gallon setup

Lowes only carries a 2 gallon and those were not in stock

The pressure is likely identical between cold & hot. But the hot flow is restricted.

If the expansion tank is shot your TP relief might blow off a gallon or so as water expands. Then again, they may not.

Is hot flow restricted to every fixture?

I’d look for a rising-stem “stop & waste” type valve. With a huge chunk of sediment in it.

Did the issue start suddenly? Maybe after the utilities were cutting a tee into the main?