Help understanding why I'm not getting enough Hot Water for a full bath

[martygturner]

its got a removable black cap which would point to it being a combination cylinder....

 

[Bouy]

He's got a thermal store.

Not a cylinder.

That sends my ideas out the window

 

[JohnD]

I heard from someone with a bigger thermal store that it was preferable to run the CH first, to get the house up to temp and the rads hot, then heat the store to max, before running a bath.

With an ordinary cylinder you usually heat the HW before the CH because there is no other load on it so it will stay hot.

I've never had a thermal store so wouldn't know.

 

[JonathanM]

On a side note - I tried a little experiment when running the bath last night. Instead of using the bath tap, I used the over- bath shower instead. It took a bit longer to fill but the water was warmer than from the tap below. Before anyone asks, it definitely is not an electric shower . Can anyone think of a reason this might be the case, or is this a tangent not worth exploring at the moment while I fiddle with other things?

Do you mean the overall bath temperature ended up warmer, when you had finished filling it? Maybe, because it took longer to run the bath, the thermal store had more time to be replenished with hot water from the boiler, so you had more heat to play with overall. You could achieve the same by running the bath tap more slowly.

Do you know the power of the boiler, or its model number? It looks like an Ideal Classic, but these come in different power outputs.

I have now set it to 70c, lets see if this makes a difference . I have also increased the boiler heat from 4/6 to 5/6. As mentioned previously, this is not a setting I have touched since moving in so I am a bit wary about setting to max 6/6 in case it wastes energy (please correct me if I am not thinking about this logically and I would be better setting it to max.

I think it is logical to take it in steps, like you are doing. You can always turn the settings up a bit more later.

I measured my cold mains water temperature today and it was 7C. Back in the summer it was 18C. That makes a big difference to how much hot water you can produce with your thermal store. It would take almost 50% more energy to raise the temperature from 7C to say 45C, than it did when it was 18C. So it is probably going to be necessary to really maximise the use of the thermal store.

I think the most important thing, as others have suggested, is to make sure the thermal store is fully hot before you start running a bath. That will almost certainly mean turning off the central heating for a period beforehand, and just having the hot water on. It probably won't need very long, but that depends on the power of the boiler. And then leaving the central heating off for a few minutes whilst you run the bath, so that all the heat from the boiler goes towards heating the hot water, not the radiators.

 

[mjgreen81]

An update with some good news....

After increasing the cylinder temp to around 72c I had plenty of HW for my daughter's bath this afternoon. This was after taking a quick shower myself a couple of hours before.

Brilliant, thanks guys I am pretty sure we have the solution here .

Just a couple of queries remain in my mind which I would like to clarify if possible:

1.) Do I definitely have a thermal store? Increasing the temp seems to have resolved the issue but I just want to make absolutely sure that it is not another type of cylinder that I now have the temperature too high.

I have checked for labels on the cylinder and can't find anything. How can I be certain this is a thermal store?

2.) I'd still like to try and confirm whether I am better off programming the system to keep the thermal store at temperature 24/7, or if I am better off just programming it to be up to to temperature during waking hours.

Thanks again all

 

[stem]

The two pumps are the clue to it being a thermal store, one circulates water from the boiler to heat the thermal store, it will run whenever the boiler is on, the other pump pumps the water around the radiators and will run whenever the radiators are on.

An internal coil heats the mains water as it passes through the thermal store.

THERMAL STORE