Problem with bathtub taps

[Mr. Mike]

I turn on the hot water tap for my bathtub, giving it maybe half a turn, leaving it until the water is hot. I then turn on the cold water tap, and only have to turn it a fraction of an inch or so before the water is warm. If I turned it as much as the hot water tap, the water wouldn't even be warm, it would be cold. What is the problem and how can I fix it? (It's been like this for ages, and the distance you have to turn the cold water tap before the temperature is optimum is getting less and less.)

[Dave]

What is the temperature difference between pure hot and pure cold water?

[AZ Nomad]

Newsflash: you have two taps so that you can adjust them independantly.

Who the f*ck cares if they are opened unequal amounts?

[Mr. Mike]

I don't know offhand what the temperature of the hottest water is, but you would not want to stand in it in the shower (it is not scalding hot). Similarly, you would not want to stand in the cold water either.

These are taps which turn in a round fashion counter-clockwise, by the way.

[Mr. Mike]

It would seem to me that if you have two taps, one hot, one cold, and you turn the hot tap a certain distance like 2" counterclockwise in a circle and the cold tap a fraction of an inch so it is barely "on" to produce warm water, that something is wrong. There is virtually no variation in the temperature of the water, it's either hot or cold other than in a very limited range.

[AZ Nomad]

No. It means that you're using the tap to set a desired temperature.

If it wasn't meant to be adjustable, you'd have just one tap handle and it would despence the hot and cold together equally and too bad if you don't like the resulting temperature.

[Jeff Wisnia]

Your hot water feed path may be more restricted than the cold one which can produce the kind of results you are seeing.

Put an empty bucket under the bath spout and time how long it takes to fill it with hot water with the cold tap closed and the hot tap fully open.

Empty the bucket and repeat with the hot tap closed and the cold tap fully opened.

If it takes significantly longer to fill the bucket with hot water than with cold water you've located the problem.

Fixing it is another (and likely rather expensive) matter.

HTH,

Jeff

[Joe]

You don't really have a problem. Your cold water is coming in at about

45 F and your hot water at 140 F or more. If you must have equal turns of the taps, then cut down the cold water piping size a whole lot, like to 1/4" pipe and even add a restrictor of some sort, like an inline pressure regulator. Replacing the controls with a single handle type will eliminate your worries, but you may get sticker shock over the $$ for the change.

Joe

[bob haller]

the comfort of our single handle temperature control valve was worth every penny it cost and the miserable install job it was........

its used on our tub shower, tubs dont matter much but wild temp swings on shower is horrible

[SteveBell]

Let's look at some hypothetical data. Assume your hot water is at 130F, your cold water is at 45F, and your desired temperature after mixing is

110F. Further assume that both knobs allow the same amount of water to flow through when opened the same amount and each allows 2 gallons per minute (GPM) flow when fully open.

Open the hot knob half way. You now have 1 GPM at 130F. Open the cold knob half way. You now have 2 GPM at (130+45)/2 =

87.5F--way too cold.

Although the physics is probably not this simple, you can see that you'll never get the temperature you want by opening both valves similar amounts.

Others have pointed out that physical conditions in your water system can effect the temperature, maybe more than the mixing temperatures.

I would start by replacing the washers. It's easy and cheap, and it probably needs to be done anyway. Maybe it'll help, maybe not, but you'll be out less than a buck.

[mm]

Expensive it may well be. But if one of the valves in the path has never been fully opened after the last time it was closed, it might be cheap.

OP, your faucet works the way mine does. Once I learned that I could control the temp with the cold water valve, it was actually simpler than it was somewhere else I lived. I use the hot to set the volume of water I want, and the cold to adjust the temperature.

If it the adjusting range is so small you can't get the right temperature, that's a problem, but you seem to be bothered by more than that, like the fact that they're not open the same amount. If they ever are like that, it's a fluke.

[sligoNoSPAMjoe]

It is very possible that the hot water supply is clogged somewhere between the heater and the tap. If there is some kind of strainer on the hot water, cleaning it may help. If the pipes are partly closed off, they may be cleaned or they can be replaced. A partly clogged hot water will reduce the amount delivered.

Then again it may be simply a matter of the temperatures of the cold vs hot water.

[Dave]

While you're in there, replace the seats as well. If they are corroded/eroded you can end up with the symptoms you're seeing.