How to stop water being so hot out of hot water tap?

blackstar

Hello all,

I am trying to stop the water from the taps being so so hot. I turned the dial on the boiler where the Tap symbol is (Please see picture) down which stopped the water being so hot but for some reason the first few seconds of hot water is way to hot then it settles down to a more normal level. Or if I run the tap at a low turn its way too hot until I turn the tap on more and the hot water settles to a more gentle hotness.

http://2imgs.com/a4c7f2d80b

Thanks in advance.

Reece_

This is from the manual for your boiler : DOMESTIC HOT WATER TEMPERATURE
CONTROL
The position of this knob will determine the temperature of the
water delivered at the domestic hot water taps between fully
clockwise and anti- clockwise positions.
By slightly reducing the flow of domestic water from the tap, the
delivery temperature of the water will be further increased. This is of
particular advantage in the winter, for example to increase bath water
temperature and to remove heavy grease deposits on plates, etc. Also
this will provide an added advantage of reducing the delay before hot
water is obtained.

Perhaps turn the temperature down so that the slower flow rate is at the highest you'd want it, then see what full flow is like, you'll probably find it hot enough still.

Myser

Is the flow rate of the cold water significantly higher than the hot?

If you want to regulate the water flowing from the how water tap to a safe level, you can install an anti-scald TMV (Thermostatic Mixing Valve).

Something like this:

http://www.toolstation.com/shop/p18520

blackstar

Myser wrote: »

Is the flow rate of the cold water significantly higher than the hot?

If you want to regulate the water flowing from the how water tap to a safe level, you can install an anti-scald TMV (Thermostatic Mixing Valve).

Something like this:

http://www.toolstation.com/shop/p18520

Thanks all for the replies. Really helpful.

Well the cold water flow is so much faster than the hot water flow.

daveyjp

If the central heating is on the water in the hot water circuit will have been sat in the internal pipework next to the burner.

When you turn the tap on the first flow is all the pre heated water and as you have noticed it is extremely hot.

blackstar

daveyjp wrote: »

If the central heating is on the water in the hot water circuit will have been sat in the internal pipework next to the burner.

When you turn the tap on the first flow is all the pre heated water and as you have noticed it is extremely hot.

Yes the central heating is on, so in that case theres nothing I can do about the extremely hot water that runs for the first few seconds then?
Why is it then when I run the hot tap at a low flow its way too hot until I turn the tap on more and the hot water settles to a more gentle hotness. This is even after the taps been running a while.

Myser

blackstar wrote: »

Well the cold water flow is so much faster than the hot water flow.

That could indicate a scaled up Heat Exchanger. Do you live in a hard water area?

This webpage explains more about what a heat exchanger does:

http://www.lovekin.net/plate-heat-exchanger-faults.html

daveyjp

blackstar wrote: »

Yes the central heating is on, so in that case theres nothing I can do about the extremely hot water that runs for the first few seconds then?
Why is it then when I run the hot tap at a low flow its way too hot until I turn the tap on more and the hot water settles to a more gentle hotness. This is even after the taps been running a while.

If you walk slowly past a bonfire you will feel the heat and it will become too hot. Run past and you have less exposure to the heat so stay cooler.

At low pressure the water is moving slowly through the heat exchanger so receives more heat. At high pressure the water does not spend as long in the exchanger so doesn't get as hot.

Modern boilers cope with this by modulating the burner i.e they supply enough heat to warm the water to the set temperature. Low flow, lower heat, max flow higher burner output.

Seronera

Thats not quite right. Combis go to maximum when a tap is turned on and its the flow rate that dictates the temperature takeup of the water. So on low flow the water temperature is hottest and on high flow its least. You can often adjust the output power of the burner using a dial, but not on all combis (Swiftflow and bottom of range Worcester Junior). The apparent 'modulation' is often the boiler switching off entirely on the overheat stat which indicates either very low flow or a partly blocked hot water plate heat exchanger as its simply cannot get rid of the heat the boiler is making, and that backs up.

Its also worth noting that the water that comes out of your main pipe into the combi is much colder in winter than in summer. Consequently you usually need the boiler power turned up higher in winter to achieve the required temp rise. In either case the water temperature can be all over the place when you first turn a tap on and it will only stabilise when the boiler has reached an equilibrium of heat being made and heat passed through the HW heat exchanger into the cold water. That does take a minute or so. If the water goes "hot/cold/hot/cold" then that is also a symptom of a hotwater heat exchanger that needs either cleaning out or replacing, though occasionally it can be a failed thermistor.

aardvaak

Lucky you! I don't get any hot water out the hot tap!

blackstar

aardvaak wrote: »

Lucky you! I don't get any hot water out the hot tap!

Yes but its annoying when the hot tap is running at a nice warm temperature and all of a sudden its really hot, so I have to adjust the pressure to get the water to be not as hot again....don't really know how to easily and quickly fix the problem.

Dont know if my area is a hard water area, will have to find out.