Help hot water is luke warm

[ophiotaurus]

For the past month or so the shower hasn't been as hot as usual. Neither is the hot water from the taps.
If I run a bath at night there isn't enough hot water in the morning to have a shower.
Does anybody know what this could be?
We have a hot water tank in the attic. The shower isn't an electric one it just comes from the tank.
Any help appreciated.

[Spanglecrab]

Is the hot water tank heated via a gas boiler or via an electric element? What type of heating do you have if any?

[PigletJohn]

What colour is the hot water cylinder?

Can you see the overflow pipes? Are any dripping?

Have you recently fitted any new mixer taps or showers, especially ones with a joystick?

[ophiotaurus]

We had a bathroom in 7 years ago so I don't think it's that.
Sorry to be dense but which part is the cylinder? There is a big cylinder in my son's room which is covered in some kind of yellow foam. Is that it? I think the tank is in the loft.
It's a warm air heating system with a gas boiler which also heats the water as far as I know.
Thanks so much for replying and trying to help me!

[PigletJohn]

the yellow foamed cylinder is the hot water cylinder, so the tank in the loft is the cold-water cistern.

Observe the loft tank. You will see it has a noticeable tide mark, which should be a few inches below the water-inlet valve and the overflow pipe. Is there any sign that the water has risen above its usual level? This may be slow, and only noticeable when no water has been used for several hours, for example at night.

A photograph of the cylinder would be useful, especially the large pipes going into it near the bottom and about half way up, and any wires or cables connected to the cylinder.

[ophiotaurus]

I will get dh to have a look at the loft tank. He's at work just now. I will go and take some pics of the tank.
Really appreciate your help.

[ophiotaurus]

Here is the whole tank

[ophiotaurus]

Other more close up pics

[ophiotaurus]

The right hand side

[ophiotaurus]

I'm off out to collect the dcs from school but I will check back later thanks again.

[PigletJohn]

thanks. Looking at your pics of the LHS, I see a fat pipe near the bottom, and another about half-way up. Those would be the circulating pipes that bring heat from the boiler into a coil sealed inside the cylinder. When your boiler is running on a HW timing, those pipes should be very hot.

I am not familiar with warm-air systems. Feel the pipes, one of them should be "too hot to hold" and one of them will vary between cool and very hot, depending how hot the cylinder is. It will get hotter as the cylinder warms up. the hotter pipe is flow from the boiler, and the cooler one is return going back to the boiler to be reheated. They will not be hot enough to burn you, more like touching a teapot.

the yellow insulation shows it is an older cylinder, and might take an hour or so to heat up. Longer in winter when the incoming water supply is colder. Do you have a timer that put on the boiler for HW at least an hour before you get up? If your boiler is not very powerful it may have difficulty heating the house and the cylinder at the same time. This is usually mitigated by heating the cylinder first.

If you feel the horizontal pipe coming out of the top of the cylinder, it should always be hot, unless you have used up all the hot water. If you ever find it to be surprisingly cold, it suggests you have a faulty mixer tap allowing cold water to run into the cylinder. This will also cause the loft tank to overflow down a pipe that probably comes out under the eaves.

You can improve the insulation of the pipes and cylinder a bit, but that is not an urgent job and will not be your main problem.

[PigletJohn]

what do you reckon, spanglecrab? I'm thinking either primary flow or temperature, or mixer letting by.

[ophiotaurus]

Thank you so much Piglet John I will show this to DH and let him investigate and report back.

[ophiotaurus]

Hi I have shown this to dh he said to add that when we turn the bath (mixer) tap to just hot to run a bath, it takes about ten seconds for any water to actually come out of the tap. Could this be anything?

[PigletJohn]

suggests that air is collecting in the pipe. I see you have a shower pump which might be relevant if it is needed to pump water to the bath, but usually the bath taps are not pumped.

[ophiotaurus]

No the pump is for the shower. We had to replace that last year.

[Spanglecrab]

I would think two separate issues. Assuming that the heating is working an that the warm air unit heats the water, a problem with the warm air unit is unlikely.

The most likely cause is a lack of circulation on the circuit from the warm air unit to the coil inside the hot water cylinder.

Possible causes would be the pump which is probably next to the warm air unit (different from the shower pump) common manufacturers include grundfoss and wilo. If you can find this pump is it a lot hotter than the pipe work connected to it?

Also the circuit in question would be fed by a header tank in the loft. It's possible that the ball valve is stuck allowing this tank to run dry. If you want to look for it it's much smaller than the large storage tank.

[tobysmum77]

Have you had your heating on less as it has been mild? Only we've had an issue twice where the valve that allows the hot water to heat without the central heating being on has seized. So it only heats when the ch is on and hasnt clicked off at the thermostat. That doesn't do much for water temperature!

[ophiotaurus]

Thanks for these suggestions. I haven't been back to the thread until today. I will pass this on to dh.