Hot water not staying hot

[Matt]

Yesterday afternoon my mother noticed a problem with her hot water - it wasn't hot, it was stone cold. Soon after that the boiler came on and the heating and hot water were fine (note: whenever her boiler comes on the heating and hot water heat simultaneously - it's one of those boilers where you can't ONLY turn on the heating (manually or via the timer) instead you need to turn on the hot water first THEN the heating a split second later)).

All was well this morning, but she's been out during the day and came back in to find the hot water is stone cold again.

This is not normal - there is usually some hot water left in the tank and, as mentioned, this only started yesterday.

I can't check it myself as I live a few hours drive away.

No taps are on or dripping, there's apparently no sign of any damp patches on the ceiling.

My gut instinct says it's perhaps a leak underneath the floor somewhere (she lives in a house with a ground and upper floor, plus an attic). But she hasn't had any really really hard frosts in her area (unlike some) and even if she had I can't imagine pipes with warm water in them freezing that easily.

But what else could it be? It's rather worrying.

Thanks

[John Rumm]

It could be the cylinder thermostat cutting out too soon (if there is one!)

Need to know more about the arrangement of valves etc, or if the water is heated just by a gravity circulation loop.

[Matt]

Afraid that I haven't a clue how it's all plumbed in - it's a gas-fired boiler on the ground floor. I do know that you can't just turn the heating on, you need to turn the hot water on first and then turn on the heating. Not sure if that's a clue or not?

What would determine how it's plumbed in? I think (from memory) that there's a red wheel valve on one of the large pipes to (or maybe from) the boiler, but I'm not 100% certain.

Thanks for your help.

I'm rather concerned that there's a leak somewhere to be honest, but I'm hoping it's something far less serious and easier (and cheaper!) to repair.

[Phil L]

A leak is probably the cheapest job to repair...now if it's a faulty boiler....

That said, it's highly unlikely to be a leak - she had hot water this morning, and if it was a leak, the boiler would be fired up almost continuously, heating the replacement water lost from the cylinder

[Matt]

True, but not if some damage as been done to the property (depending on where the leak is).

Yes, true, but I doubt if she would notice if it's firing continuously when it's on.

[The Natural Philosopher]

does she actually HAVE a hot water tank?

[Matt]

Blowed if I know. :-)

However, she managed to get the plumber in and the problem was ........ a dripping hot water tap in the bath!

She hadn't noticed that it had a fast drip (plumber says it was losing about a pint of water every few minutes) so he's replaced the washer.

So that's that I hope! Thanks for all your help folks. :-)