Hot water too hit

[Pinklemon]

Hi all, having some plumbing problems at the moment. I've noticed that the hot water is too hot. When tap is on, the initial flow is warm but then after a while it gets very hot. It has always been like this and I thought it is normal since it is hot water coming from the hot water tap. But some say it should only be warm?

[Pinklemon]

Sorry, title should say hot water to hot.

[Betty5313]

is there a temperature ccontrol on your boiler? you might be able to turn it down?

hope someone more knowledgeable can help!

[TallulahBetty]

Yep, turn it down on the boiler.

[Pinklemon]

Boiler, not the hot water cylinder? What should I set it to and where is the thermostat on the boiler?

[PigletJohn]

What is the actual temperature of the water in degrees centigrade?

If you have got a hot water cylinder it will (should) have a rectangular thermostat strapped to the side, you don't use the boiler thermostat to adjust the tap water.

Do you have baths or showers?

What colour is the cylinder?

[Pinklemon]

Hi pigletjohn, cylinder is green. The thermostat is set on 50c on the cylinder. We have bath and shower. The plastic dial on the thermostat is damaged so although it is set on 50c, it might actually be higher.

[PigletJohn]

if the water coming out of the tap is 50C, that is not especially hot, but IMO about hot enough for a bath. You ought to test it with a thermometer if you think it is excessively hot. A cylinder stat is not at all expensive. Less than 50C and it is possible for some bacteria to live in the cylinder.

The hot pipes that go into the cylinder and the boiler should all be insulated with Climaflex or similar stiff plastic foam lagging, this will prevent heat loss and save money. The pipes will probably mostly be 22mm diameter. This may help the first gush of water to be nearer the temperature of the rest.

There is a faint chance that your cold water tank, probably in the loft, is overfilling due to a fault which can cause cold water to get into hot pipes at a mixer tap. Try to have a look at it one morning before you have started to run the taps, and see if the level is above the old tide mark.

[Pinklemon]

Thanks for you help, pigletjohn. You've replied on my other thread regarding vibrating pipe when hot tap is run. Could all this be connected? Could it be due to faulty ball valve?

To recap: recently, when we run the hot tap, the pipe linking to the kitchen hot tap vibrates and makes this humming noise. It happens intermittently, especially if hot taps have not been used for while. Only hot taps, not cold taps, shower or central heating. If I run the kitchen hot tap for a few seconds, the vibration and humming noise stop.

Maybe all connected?

My husband and I have no idea at all regarding plumbing. I appreciate your advice.

[PigletJohn]

is the kitchen hot tap a mixer, and does it have ceramic discs (a joystick, or knobs that only go a quarter turn from on to off?

Does the sink have one tap-hole, or two?

[Pinklemon]

Both bath and kitchen sinks are a mixer with one tap hole. Kitchen with ceramic discs, I think. The plumber said with this tap there is no washers but only cartridges. But the bathroom taps have washers.

[Alwayscheerful]

Are you talking about the immersion heater? If so, and piglet john will correct me, I think they have 2 thermostats, an internal one and an external one strapped to the cylinder.

Our cylinder is close to the bathroom and the taps run cold for a short while. It is much further away from the kitchen and the tap runs cool for some longer. Our thermostat is set fairly low but the water comes out scalding, our electrician said the strapped on thermostats are very unreliable, and likely to need to replacing.

[Pinklemon]

Alwayscheerful, I will ask the plumber to change the check the thermostat when the boiler is service.

Pigletjohn, I went up to the loft, it seems the water is below tide mark. Ball valve seems to be working fine, too.

[Alwayscheerful]

There is a DIY question In the times newspaper today about noise such as yours, I will try and cut and paste the answer late , (on my phone now) I think they recommend replacing the ball cock in the water tank.

[PigletJohn]

Good point, it might be the ball cock in the loft causing the vibration (it will not affect the water temperature)

If you can go into the loft and either hold the float up with your hand while someone runs the taps, or tie it up with a bit of string under tension so the float cannot drop when water is used, see if the noise stops.

A ball cock is usually at its noisiest when it is almost closed. Though if you have recently had a plumber in the house he should have recognised it.

[PigletJohn]

Cheerful

The immersion heater is the smallish electrical device which has its own internal thermostat to control the electrical heating only. Only the round plastic cap is visible. The internal thermostat is a replacable part. Hiwever it has no effect when the boiler is in use. You only use the immersion heater when the boiler is turned off or broken. I have come across a 50 year old immersion heater in use.

The hot water cylinder is the large thing that holds the water, typically a metre high. The strap on thermostat controls only the boiler heating the cylinder. These thermostats are I would say very simple and reliable, however they control a (usually) three-port valve which is a moving part and will wear out, usually between ten and twenty years old.