Problems with Hot water

[bigbluebus]

I posted in Chat looking for Piglet John and someone told me I would find him over here.
Would really appreciate any advice from someone who knows about hot water tanks.
www.mumsnet.com/Talk/_chat/2566262-Is-Piglet-John-around-Poor-DD-just-had-a-cold-bath

Thanks

According to DH it's most likely to be the diverter valve. If bit was boiler related then you'd be having heating problems too, not just got water.

*If it

Thank you pisspot. DH with his very very limited knowledge has concluded it's something to do with a valve on the tank (although he didn't give it a name) Don't understand why this has happened at night a few times though and yet the water has been hot in the morning. DH's only explaination is that it is an intermittent fault that has got worse.
Definitely not the boiler as that has been serviced and completely overhauled recently to sort out another intermittent fault that kept causng the boiler to lock out but would then restart and work properly for days before doing it again.

What colour is the hot water cylinder?

If you put your thumb over the spout of the hot tap, can you stop the flow? How about the cold tap?

Have you got any mixer taps, especially ones with a joystick controlling on/off/temperature?

Hot water cylinder is green.
So many taps in this house piglet. We have 3 bathrooms plus a downstairs loo, a kitchen and a utility room.
All the taps are mixer taps and 5 lots of them are the swing lever type whilst the rest have individual hot and cold knobs with the water coming out of a single spout.
Don't fancy putting my finger over the tap to stop the water at them moment as DH has put the immersion heater on and the water is now hot from that.

From memory though, the immersion only heats part of the tank - it is left over from the days when we had all electric heating and they left the immersion in for times like this. We have an oil fired Worcester boiler now.

DH also thinks your programmer may have gone.

pisspot The programmer will only programme the heating and hot water for the same times - so both come on in the morning and then again in the evening at exactly the same time. The lights are showing that both the heating and hot water are on. The radiators are hot but the water is not - so I don't think it can be the programmer.

Oh OK. In that case he sticks with original thoughts. Diverter valve, otherwise known as zone valve. May be worth investigating - DH would normally charge about £200 to replace one, just so you have a figure to work to if he's right!
Disclaimer, I only have half his attention so I'd pay lots of attention to pigletjohn!

You have a green cylinder, which is insulated, vented and about 30 years old. You have a power shower so the hot water, at least, is low pressure, but the cold might be high pressure.

You say the HW and the CH have to come on together so the cylinder is probably unpumped. You might have a 3 port valve but it sounds unlikely.

The immersion heater is probably in the top of the cylinder so it might heat about 40 litres, not enough for a bath. An immersion heater takes about one minute per litre. It has a thermostat inside so unless faulty should never be scalding.

I understand that after running the boiler for some hours, there is not much hot water in the cylinder.

Are the radiators getting "too hot to hold" on the top?

If the cylinder is upstairs, bleed the highest radiator in the house. Does water squirt out forcefully and without dying away after some seconds?

Oh - and turn the radiators off at their knobs. The cylinder will most likely heat up, whatever the fault.

The following day, open the knobs and turn the heating off at the wall stat, not the timer.

Does the cylinder get hot and the rads stay cold?

Piglet Pretty sure the hot water tank is 11 years old as we think it was replaced when we switched from all electric to oil central heating. If not then it will be 23 years old.

Radiators don't seem to be too hot to hold and also don't seem to need bleeding atm - although will get DH to check tomorrow.

Don't know if the cold water is low or high pressure - the cold tank is in the loft, the hot tank is in the airing cupboard on the landing (1st floor). The control panel is also in there.

We had the power shower fitted in our en suite when we had it re-fitted as the electric one we had before, that the builders fitted, was pathetic. The main bathroom has a fairly new electric shower though and works fine. DD's bath has a thermostatically controlled tap which has it's own pump, although you can over ride the thermostat setting - but not much use if you've only got cold water. The pump in necessary because of the thermostat on the tap - not because of the water pressure. We previously had a bath with normal taps in her bathroom with no pump and taps worked fine.

You are correct in thinking that the hot water had been on since 16.30 and when running a bath at 19.30 there was not enough hot water - even though we had hardly used any previously and the hot water was still on.

the bleeding of the highest radiator so it squirts, is to verify water in it and higher than the cylinder, not because it needs bleeding.

The top of the radiators, depending on type of boiler, should be 60C or higher, otherwise it will not be able to transfer enough heat to the water in the cylinder, which will always be cooler. Without a thermometer, "too hot to hold" is a fair guide. The bottom of the radiators, and the return pipe from them, will be cooler.

Your thumb on the bathroom tap will tell you if the cold pressure is high or low.