gas boiler left on while on holiday...

Pincher

There's lagging, and then there's the sprayed on foam that the cylinder comes with already. To have a bare copper cylinder standing there is a scalding hazzard your plumber will probably refuse to work on.

st999

I can't see how it could possibly work without a timer

Why?

It is on all the time.

The water gets hot, the gas turns off, water cools down, gas turns on, water used, gas turns on.

Simple.

My hot water usage in kWhs of gas is approx 18 kWh of gas a day and 3 kWh of that is the pilot light.

And it even works without any electricity at all, except for the pedantics amongst you I mean mains electricity, the thermocouple produces a small amount.

Cardew

The loss from hot water cylinders is much lower than some people envisage.

They are tested to a British Standard and when filled with water @ 65C the heat loss is typically 2kWh in 24 hours.

So in the OP's case I would think the cost would be between £1 and £2.

Cannot understand what the OP means about having no thermostat to turn off boiler! Tank thermostat? or boiler?

ShilohGreen

Thanks, Ollski. Based on what you say and my gas rates, it comes to about £6.50. Not too bad.

DUTR, - good point! It's just so old, with no visible thermostat, but of course, what you say is right.

About the timer, Humphrey, yes there is one but I've never used it.

jd87 - yes, I'm not happy with the agents and will speak to them.