Hot water scoldingly hot

[Nudy]

I wonder if any of you guys could help an amateur try and work out what is happening with his hot water.

I have recently found that my hot water is getting unbearably hot. I understand the principle of modern systems, making use of a cylinder stat to tell the boiler and controls to stop heating water. However my system does not have one of these. I have located the pump, room stat, motorised valve (2 port) and programmer. Can you explain how the boiler would know when to stop heating water?

The system is well over 20 years old is that makes much difference.

Yours,

Ned

 

[breezer]

as i understand it, the room stat is only to control the rads, the overall temp is via the boiler stat, so i suggest you turn this down, or it (the stat) has a problem.

try turning the boiler stat down first

 

[ChrisR]

All too common on older simple systems I'm afraid, but it shouldn't be too difficult to add a cylinder thermostat, and convert what you have to a "C Plan" system. This assumes your HW heating is done by gravity circulation from the boiler.
um, errr, here

http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.1 C Plan.pdf

It doesn't satisfy building regs for new installations, which require them to be fully pumped - but its a heck of a lot better than what you have.

 

[wilhelm]

bear with me, cos im not sure, but surely if you ve got a motorised valve you must have a tank stat, ? i would say your motorised valve has packed in. trace the wires from the valve, and one of em must go to a tank stat...... ?

(im assuming this is a really early c plan, with the mot valve not wired to a wiring centre, a valve with separate 240v and controlled by tank stat.)

 

[ChrisR]

Could be. Wouldn't be the first time I'd gone to fit a tank stat only to find a perfectly good one scudding around under disintegrated insulation on the floor