Low Hot Water Pressure; Cold Water Fine
 

A few days ago it felt like someone turned our water off mid shower. Now, given that I try to make a habit of paying bills, I knew that it couldn't be due to delinquency. Oddly, the cold water isn't affected at all, but the hot water runs at about half of its old pressure Upon further Googling, it seems that when such issues arise it is often due to a blockage in the hot water heater, often due to sediment.

The question is "What do I do about it?"

My knowledge of plumbing is low, although I can at least fix a running toilet.

I've read that draining the water heater is recommended, but the success rate seems fairly low. One guy recommended putting a dime over the only running spout to create back pressure to blow out the sediment. I'd rather not turn a shower head into a mortar shell, so I'm laying myself prostrate in front of your collective home repair acumen.

Call a plumber is my first thought, but other cheaper and quicker potential fixes that don't damage the integrity of the tank or pipes would be greatly appreciated.

Does your heater make like a knocking or banging noise when it kicks in?

Nope. Sounds perfectly normal.

Heater is a Ruud 67 Gallon capacity. Manufactured in October 2004. The house is seven years old. Copper pipes.

Bypass your water heater and see if the pressure on the hot is fine. Hook the cold inlet flex up to the hot water outlet pipe.
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I'd try flushing it out first. If that doesn't work it could be the pipes themselves but try trouble shooting the water heater first thing.

I'm assuming you have already googled this topic and searched YouTube on this ? I have saved myself a lot of $$$ doing this. Both have been very good especially YouTube.

HA! What is this supposed to accomplish??? Blocking a running tap would be exactly the same as just turning it off.

OK .. have you checked to make certain that the hot water pressure is low throughout the entire house?

Have you checked the cold line into the heater to make sure it has adequate pressure?

Those are the two easiest things to check first.. next it gets a bit more complicated. You'll want to flush it and check for sediment or bits of plastic. After that, check the dip tube and make sure it is in good shape. The dip tube is the tube INSIDE the tank that carries the water from the cold inlet to the bottom of the tank.

My prediction is that you'll mess around with it for a couple days and end up buying a new hot water heater.

The time for flushing is before it clogs, IMO.

are you suggesting he backflush the water heater? interesting idea. i guess if a chunk of sediment is blocking a line, blast it backward out the tank drain.

I would guess its more likely the shower valve or cartridge.....Do you have 1, 2 or 3 handles on your shower? I have dealt with many problems such as this...if your kitchen faucet still has decent hot pressure, it is most likely( 99.9%) a simple valve or cartidge issue.

Go Tankless.. You will not regret it..

I think he's suggesting hooking the the hot water outlet the the cold water lines, then if he has decent pressure, the blockage is in his hot water lines AFTER the water heater. Saves a guy from replacing a perfectly good water heater. I could be wrong though.

you probably did this, but take your shower head off and check the hot pressure without the head on, 1st thing....

A pressure relief valve or cartridge is my bet that has gone out.

http://www.youtube.com/watch?v=sJe1R7SRXZ8

http://www.youtube.com/watch?v=2yhH86GccWI

This is good but you'll need an extra bit of tubing with two male connectors to make this happen.

Sounds like sediment build up to me. Not much you can do at this point but attempt to flush it out. If that fails you might be looking at having to buy a new one. 8-10 years is usually about the time the anode rods start to fully dissolve which will quickly cause that sediment to build up.

yeah, if the pressure returns with the head off and you still have pressure issues elsewhere in the house then you have sediment that has lodged in all of your various outlets. This can be a one time deal or it can be a disintegrating dip tube. You can clean out each outlet (the little screen on faucets and such) and hope the problem is gone but if it's the dip tube it will come back eventually.

+1 rinnai gas
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Close, bypass the water heater and it will tell you if its the pipes, connect your city pressure cold line to your domestic hot side, run the faucet. It will blast cold water through your hot lines if you have full pressure then the problem lies in you water heater. You can also try to blast the hot outlet of the water heater but that really won't do anything.
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Sadly now a days even top of the line water heaters rarely make it 10 years. If you do end up getting a new one I'd definitely get a plumber out there to give you an estimate on a tankless system.

If you're only experiencing this at the shower, then it's the probably the shower valve and you'll likely have to replace it. This was a common problem at a property I used to work at.

I obviously wasn't clear enough. I noticed it first in the shower, but it is systemic throughout the house. Kitchen faucets, tub spigots, shower heads all blast cold water, but hot water just seeps out, barely enough to initiate the shower head.

The tank was built at the same time as the house. I'm assuming that it's just a builder grade quality. I've never ****ed with this except to light a pilot, so I'm out of my element, but I can try a few of these suggestions on Tuesday.

Thanks guys.

The hamas I know would have tried fixing it while drunk.

I did that with a bike once. I just ended up taking it apart piece by piece, spray painting each piece black, and then throwing the pieces into the woods behind my apartment.

Did that fix the problem?

ok, it still could be sediment that came from the tank and now is blocking each outlet. Easy check for that is to just remove the shower head (super easy) and see if the pressure returns at that one spot. Assuming it doesn't, my next step would be to shut off the cold water into the tank, disconnect it and put it in a pitcher, turn it back on and see if the cold water coming in to the tank has pressure. If so, you pretty much know the problem is in the tank.

OH, one last thing. When you flush the tank just connect a hose to the tank then run it to a drain/sink but I would recommend putting a fine strainer in the sink so that if there is sediment you can see exactly what it is. Will make the next steps much easier if you know.

And of course you should shut off the gas to the heater to be safe.

wanting to see what happens here.


thinking that there is a black spray painted bike in the hot water heater??

Any list of trouble shooting (before calling a plumber) on a Water Heater that goes cold quickly?

It sounds like you need a new hot water heater. The sediment slowly fills up the bottom of the tank. Over time, you'll find less hot water available and the need to turn up the gas in order to properly heat the water.

A soft-water system can reduce the amount of minerals in your water line making the amount of sediment and build up much less over time. I've looked into a system but it's not feasible due to the placement of the hot water heater.

For what it's worth, I've been through two 60 gallon hot water heaters in less than 10 years. The water is that bad out here.

Good luck!

I started draining and flushing mine once a year and it seemed to help a lot. It's going on 10 years on the current tank, despite our really hard water.

electric or gas?

Gas, without question.
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Interesting, thanks!

The first hot water heater was defective (GE). GE offered to pay for the parts but not the labor and since it was not working too well anyway, I chose to replace it for not much more than the cost of the labor.

This last summer, we noticed that the hot water wasn't lasting as long, so I turned up the heat and it's been fine since. But my contractor of ten years believes it's just a quick fix due to sediment buildup since replacing it in 2007.

I'll look into a flush, although it may not be feasible to due to the drain emptying onto a flagstone patio with a polyurethane finish. I'd be concerned the sediment and whatever might stain or remove that finish.

Are they better now? I looked into having a couple installed back in 2007 and everyone I spoke to advised against it.

drain it straight into a clean out, using a garden hose

I hook a garden hose to the drain and run it out into the yard. I look for the place with the most weeds to dump the scalding water on. :)

My HWH went out in 2011 I bought another tank, I wanted an electric tankless but the guy who installed advised against it... I am wondering the same thing... Sure would love to claim that closet space in the laundry room

I've put in over 100 over the last 4yrs without a complaint yet. My boss and predecessor have put in multiple hundreds going back 10 years, in 4 years I've maybe worked on 15 of them probably less. That's in a pretty harsh climate as well. All Rinnais. I've repaired a shitload of bosch/poloma/myson/rheems/etc and there's not many of them sold here and none by us.

If you go Rinnai, you'll be very happy, another brand who knows.
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Also pay a bit more to purchase from an authorized retailer, the extra hundred is worth it to make sure you're not getting a refurb or one that was reported "destroyed".
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Thanks for the info!

:thumb:

If the heater is over 8 years old, you may as well buy a new one since it's at the end of it's life expectancy. Otherwise, buy a rebuild kit that includes both elements and T-stats, TURN THE POWER OFF, drain the heater and swap out the parts, re-fill the heater then (and only then) turn the power back on. Done deal...

This. Also if you have older pipes, they could be blocked with sediment. I had this exact problem. Replaced my lines under the sink with new ones and put a new faucet in. That was 5 years ago, and I'm still on the same hot water heater without problems.

It's about 11 months old.

What's the temp set at? Have you had any power surges lately?

Typically the hot side has rusted shut when this happens and is first noticed @ the shower since it has the most draw. Disconnect the hot pipe and use a screwdriver to break free any rust in the hot opening on the heater

If it were me, I'd buy a quality standing water heater. I have a State Industries unit that was installed in 1992. It's still going strong (40 gallon, gas). They aren't one of those companies that use cheap components (like crappy dip tubes).

I'd stay away from tankless for now. Way too inconsistent as far as reliable hot water and require yearly maintenance.

Our engineering group received a white paper from a company that has developed a tankless system that will rock the world. It will be pricey, for sure.

This deffinatly applies to electric models, however Navien makes a high quality gas heater that is 99% efficient & consistantly gives you the endless supply of hot water so, even with the annual maintenance it's worth the investment. Installing a softener or descaler such as the NUVO will help keep the system running smoothly. Of course, as with anything else, as they become more popular, they will get cheaper

Had to replace my hot water heater. Scale buildup was awful. Every time i would unclog my lines it would just clog right back up. I had to cut my lines and take an air compressor to them and buy a new hot water heater.

If you do buy a standing, buy the cheapy version (shortest warranty) and replace the anode. The only difference among same brands is the length of the sacrificial anode determines the warranty period.
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This x 1 billion

If I remember my chemistry and physics, low pressure means that either temperature is low or volume is low since Pv/T is a constant. I think this means that you either need a new hot water heater, or your hot water heater is developing an endothermic reaction that will eventually result in the development of a black hole.

Got another question. If you shut off water when you are gone for a few days or a week or so is the unit safe with this scenario?

That second possibility doesn't seem right, but I don't remember enough from my physics classes to dispute it.

Huh? Why would you shut off water anyways? All replacing the anode does is make it take longer for stuff to attack the tank's lining. Similar to the idea of zinc anodes on a boat/motor.
If you close off your hot lines and your heating elements fail and stay on you get a bomb. If you close the cold feed and your tank runs out of water and is still on, that's bad too.
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I'm hoping it's just the hot water heater.

You want to shut off the water to your house to prevent you coming home to a river flowing from your front door


The T&P valve prevents this from happening in ALL modern water heaters

Our Noritz tankless has been great.

Although, if I was to get another tankless heater, it would be a Navien with built in recirc system.

Just be aware that it requires a recirc line to function properly

True, however T&P valves fail more often than elements staying on.

I've never heard of anyone shutting off their water during vacation, but I guess that makes sense. Murphy's law and what not. Good way to have a bunch of busted pipes up here in winter.
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Yeah, I am well versed in water heating.

This is bull crap. Gas tankless are completely reliable, extremely efficient, and DO NOT require annual maintenance.

It is "recommended" to flush the heat exchanger yearly with vinegar to remove scale build up, but absolutely NOT required.
Warranties are still valid without doing this.
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We had our heat exchanger flushed a bit more than 1 year after purchase. There was no scale build up yet. Our water isn't terribly hard though (7 grains / gallon) and it's just the wife and I in the house.

Large families with heavy usage and hard water would be advised to have the heat exchanger flushed annually.

If you don't follow the maintenance instructions from the manufacurer, then yes, they can fail. In 22 years of plumbing, I can honestly say that I've NEVER seen an exploded water heater. I've have seen the aftermath of burst pipes too many times to count

I don't have anywhere near 22yrs plumbing but I have never seen an exploded w/h either. I have come across a dozen or so failed t&p. Tankless just use a pressure relief w/o temp valve, so I guess in theory a person could accidentally put one in a standing w/h.
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Hey Hamas did you experience any shrinkage?

Sounds like the hot & cold lines were reversed which is the only way sediment from the bottom of the tank could be pushed into the hot supply. If so, the fix is only temporary. When the sediment starts to build up again, it will start happening again

:hmmm: Never seen a pressure only relief valve either. Every tankless heater I've ever installed comes with a T&P valve

When a T&P fails, most times it starts to leak eventhough the WH is working as it should. When elements go bad they tend to super heat the water then blow out causing less or no hot water. 99% of the time the water does'nt get hot enough to set the T&P off

I'll take a closer look tomorrow, but I'm 90% sure they are only pressure, they install directly into the piping (I put isolation valves in and install the PRV into them).
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Did some research and found that there are pressure only relief valves, my bad. It's code to have T&P valves here which is why I have not seen any of them.