Scorching hot water

zebedy

How hot should the water coming from the hot tap be?
After about 30 seconds mine runs scorching hot, so hot it burns and you can't touch it.
Sure I can turn on the cold to mix but if you're aiming for lukewarm I can't get it. I have to turn the hot down so low that it cuts out and then I just get cold.
Plumber just serviced my Worcester boiler and changed the thermostat for a DHW (don't know what this means£.
Any suggestions welcome
Thanks

Alex1983

Turning it down slow will make it hotter. Its all to do with flow rates, faster the flow the cooler the water.

Norman_Castle

Can you turn the water temperature down on the boiler. There's normally a dial. Heating engineers often turn these up when servicing but forget to turn them down again.

Grenage

There should be an adjustable setting on either a hot water tank (if one exists), or the boiler on a modern combi.

You don't want it too low, mind you. My hot water tap would be uncomfortably warm if on alone, but that's generally how it's supposed to be.

macman

DHW: Domestic Hot Water. If he's changed a faulty 'stat, then just turn the temp down on the boiler (if a combi) or on the tank (if a conventional boiler).
It always helps to give the make and model...

wantonnoodle

From what I recall when we had the thermostat replaced on our hot water cylinder in our rental last year, the hot water should be at a minimum of 65 degrees. This is to prevent the growth of bacteria in the DHW system, as this is the temperature above which they cannot multiply.

It may be that your previous thermostat was not allowing the water to get this hot, so when replaced and the temperature is correct, it seems too hot.

TheCyclingProgrammer

If you have a combi just turn the temperature down for the hot water.

Alex1983

Not all Worcesters have the ability to turn the hot water down.

Ectophile

Assuming it's a combi boiler...

If the water flow rate is rather slow, then the problem is that the flow rate is too low. Check for any valves turned half-off. Possibilities include small isolators under the sink, or the cold water feed into the boiler.