Usually getting it out is more important than saving the head. You can replace it. However, destroying the head before you have it out is counterproductive. Some screws will not yield to a proper fitting, quality screwdriver. Heat works well on iron and steel. Even with them, I find hammering on things is often more quick. The trick is to hit stuff hard enough to distort it, but it still springs back without staying bent or breaking. When it moves, it breaks apart the rust, corrosion, lime, etc. holding it. A little spray lube helps too. I like silicone oil. I can use the same can to remove stuff and to lubricate things I don't want to gum up. It also doesn't swell rubber. The hammering opens up the joint long enough for the oil to wick in. You can put a good screwdriver with a tough plastic handle in the screw head and hammer on it. Often after a few minutes of that, the screw will back out. There are little hand impact tools that work great too. They take a bit or socket at one end and you hit the other end with a hammer. They twist when you hit them. Provides both the impact and the twist. If the head does strip or twist off without it coming loose, you can switch to a punch. Work at the edge pushing it in the way it unscrews. If the head twists off, you should be able to remove the knob. Then you can unscrew the assembly and carry it to your shop for further work if it is worth salvaging. A good hardware store is a better place for it. Match it to a new one. Note, hot and cold are not interchangeable. If the knob is worse for the wear or just old and shabby, they have new ones. It would gaul me to go through all that in a rental.

The above techniques will work on shower heads too. From your more recent posts, that sounds like where the problem is.

Turn the thurmastat on bottom of watter heater up to wite line

TRY RUNNING THE TAP AS WELL AS THE WATER HEATER noramlly the more flow the more the system pounds out the how water it could just be that the hot water system has like a ten litre capasity and won't work

Along with the bad spelling,( we do have a spellcheck you know) she already stated she tried turning up the temperature in her post number three.
Pimpin, are you the same pimberman that I had to correct the two posts you put up in this page? If you are, I want you to know that your posts are being monitored by the mods for content. Check your posts for accuracy before hitting the send button. While "off the wall advice" my float in other pages such as relationships bad advice on this page can cost the asker big bucks and will not be tolerated. Having said that let me give you my take on why Inz can't take more then a three minute shower before the hot water runs out.
As a rule the lower element would fall under suspicion but since this is a new installation I can see only one explanation and it's not the water heaters fault.
What I thinki happened is that instead of using brass nipples or heat traps the installer soldered in 3/4" male adapters directly to the inlets of the heater and piped from there instead of soldering a piece of copper pipe to the adapter before installing it. This put heat on the cold water inlet causing the flare on the plastic dip tube to melt allowing the tube to slip off the cold water inlet.
This allowed cold water to enter the upper part of the heater and begin to mix with the hot water instead of being diurected to the bottom where it would get heated. The longer she showered the more cold water got drawn up into the hot water line until that was all that was left after three minutes of draw.
The solution would be to remove the pipe coming out of the cold water inlet and replace the dip tube using the correct method. I've heard a bunch of reasons for "the three minute shower" but I don't think the shower head or the shower valve have anything to do with the problem. A bad lower eleiment or a failed dip tube is the only explanation and my bet's on the dip tube. Regards and pimberman/pimpin, you're being watched for content. Tom

Wow, speedball, you sure caught me by surprise. I think you may be right. I assumed that since a plumber installed the heater it must have been done correctly. I can't believe I missed that one. It seems so obvious too.

But this happened twice to two different tanks?

What are the odds of that happening?

If you read the initial posting, you'll see that the problem was present even before the tank was replaced.

If it were me, I would start with replacing the hot stem on the shower valve -- Some of the older Price Pfister stems were of a type that turned down a stainless steel sleeve with multiple o-rings that acted as guides and seals, when the o-rings finally went points up they would bunch up at the seat and seat washer and restrict the flow.

But this happened twice to two different tanks?
What are the odds of that happening? ( I'd say pretty damm good if the same plumber installed both of them. Betcha didn't thing of thawt!)

"If you read the initial posting, you'll see that the problem was present even before the tank was replaced. (I read it)

If it were me, I would start with replacing the hot stem on the shower valve -- Some of the older Price Pfister stems were of a type that turned down a stainless steel sleeve with multiple o-rings that acted as guides and seals, when the o-rings finally went points up they would bunch up at the seat and seat washer and restrict the flow." ( And then magically reset themselves for the next three minute shower)
I still say open up the cold water inlet and at least check the condition of the dip tube. Regards, Tom

Use extreme care when turning up the temperature. This can result in a very costly electric bill if other problems exist.

On original post... But then he said he was able to fill the bathtub before the hot water ran out so there is no problem with the water heater... may not be the dip tube

Hi Doug...

I don't think we'll ever know the answer here. As you know, this post goes back to 2007! Would be nice if LNZ returned, but doubtful... ;)

How have you been? Keepin' busy?

MARK

Please, Install Low Flow Shower Head (2.2 gln/m ). Have the plumber to recheck his installation. Unless you do so, this thread will go on, and on, and on...

In 2 or 3 days the installation will be past warranty (assuming the installer offered a warranty).

Had most of this week off, but was real busy for about 4 weeks. Enjoyed the break but rather have the work. Atlanta seems to be starting to recover but many are struggling bad. In my county, 500 businesses went bankrupt in 2008. I am just outside atlanta. The mood here is very cautous. [looking fer that spellcheck speedball was talking bout]

In my area: if my tenant doesn't have enough hot water to take showers - he will withhold the rent. Then, landlord jumps and solves the problem in no time.

Sorry to hear that, Doug. Situation is the same in my area...

I just read this entire thread from beginning to end (I know... I need a life). This is a good one with a lot of good information. The little tip about how to properly install the water heater (don't solder right at the inlet) is worth remembering for us amateurs.

BTW, spelll check workss automatically... underlines the misspelled wordds as you type.

Things have slowed down a bit for us as well -- We're staying busy with some of the larger projects that were already in the pipeline, but the days of having our dance card filled up to six months in advance are pretty much a thing of the past.

I'll say one thing, though, competitive bidding has sure come back with a vengeance.:)

If you want to know how long the water should last according to the laws of physics use this page.
http://crazycalculations.com/water_tanks/index.php
Either the mains water is very cold, the hot water is not hot enough, the tank is too small or there is some weird problem with the hot and the cold mixing at the wrong point.

Sounds like a problem I've had recently. The problem turned out to be an issue with the diverter stem (the middle handle).
I replaced the diverter stem for my client and that solved the problem.

In response to Milo's answer even if you had a shower head that was a 5 gal.per min. head which is unlikely you would still get about an 8 min. Shower. Try replacing the diverter stem. You don't even have to shut the water off to the apartment. Just make sure the hot and cold are turned off in the shower.Remove the handle, trim piece, and stem. Take it to home improvement store, get another one and reverse your steps.