Cylinder query?

[steve26]

I recently had an extension on the property and added 2 more bathrooms, I reused my existing 250 unvented and gas boiler (some time ago I had the boiler and cylinder installed with the extension in mind which is why I have kept them).

The main issue is the fact that the same boiler and cylinder setup used to reheat the cylinder in say, 10 mins or so.... now it seems to take about half an hour or more, this is with the heating off too.

Can anyone explain why this may be, its the same equipment?

Thanks

Steve

 

[holty]

depends on demand ,10 mins to reheat is very quick.average is 30

 

[doitall]

Lateral thinking required

If I use 100 Ltrs of water and it takes 10mins to re-heat, How long would it take if I use 3 times much

 

[Agile]

To reheat 100 litres of water by 45°C in 10 minutes would require about 34 kW boiler output.

However, the heat transfer would only be at a maximum for some of that time, longer if its a condensing boiler.

Practically you could allow 15-20 min per 100 litres of water with a 32 kW boiler.

Tony

 

[doitall]

But, you wouldn't heat 100Ltrs by 45°C, you would be heating 250Ltrs by say15°C.

Now for the complicated bit.

If I was to do that 3 times, would it be reasonable to assume I would need to heat 250Ltrs by 45°C. So it would also be reasonable to assume it will take 3 x longer.

Wouldn't it

 

[steve26]

Thankyou for your comments, I do take on board the fact that there is likely to be more demand on the cylinder now there are more bathrooms.

However, I had a closer look at my cylinder and boiler set up today and think I may have found what may be causing the problem. The boiler flow temp was set at 70 degC and the HW storage temp on the cylinder stat was set at about 65degC. Upon closer inspection, I think I have a faulty cylinder stat.

I put the HW on for a good hour, however when I turned the cylinder stat down slowly to see what temp it 'clicked' it kept clicking at around 40degC, so I suspect the stored water was never getting any higher than this (although the boiler was set far higher). I assume that would be the main problem why we were running out of hot water so quickly, as it took hardly any cold water to mix it down?

Any thoughts would be welcome.

Thanks.

 

[doitall]

Yes, it's possible the stat is faulty, or not making a good connection.

With any unvented cylinder I always query the way it's connected and wired.

It has to be by the book and by a holder of an unvented qualification G3