Heating but no hot water. Why?

[mckenzie]

We have a Gloworm mega flow.
Heating working fine. Hot water was fine last night and for me first thing but DH complained that there was no hot water when he tried to shower.
I've turned timer off and put hot water on constant but still nothing.
Emersion heater going on has made no difference either.
Any ideas gratefully received.
TIA

the immersion heater will take an hour or more to make much difference. When did you turn it on?

Is there a neon indicator on the immersion switch?

If you go and look at the electricity meter, does it speed up and slow down when you turn the immersion on and off?

When you set your boiler to CH constant, does it fire up?

Megaflos are made by Sadia, boilers are made by Glow Worm. What colour is your cylinder?

No-one has fiddled with the water thermostat? Check that it is up high enough.

(veteran of small fingers twisting knobs around so the hot water doesn't fire up!)

Bless you piglet john, I seem to recall you helping me with something like this before. It's not mega flow, my mistake. It's white, glowworm.
The flame ignites when the heating goes on and the rads are all nice and warm.
I turned the emersion on about 20 past 7.

if you set central heating "off" and hot water to "on" does the boiler fire?

do the radiators get or stay hot?

Ch off and hw on makes no difference.
Rads are lovely and hot.

You say the radiators are hot even when you have turned the CH off?

Then it will be a fault in your 3-port valve. The heat that should be going to the cylinder is instead flowing round the radiators. If you turn all the radiators off at their knobs the cylinder will possibly heat up, depending on the fault.

Call your heating engineer unless you are very fond of DIY plumbing.

Sorry PJ, I got confused. No, if I turn heating off then rads are cold.
I've got a guy coming at 10 (I hope). If it's the diverted value, could it fix that myself do you think?

no.