hot water cylinder capacity

[shouldknowbetter]

I am thinking of reducing the size of the hot water cylinder in the house. Existing cylinder is 1200mm by 450mm. which I believe gives acapacity of 160 litres. Is there a website or calculation anyone could recommend/provide that would allow me to calculate usage v capacity.


Many thanks

 

[ChrisR]

Check the manufacturers' sites for volumes, but there's no such thing as a standard bath..

 

[shouldknowbetter]

Thanks, I'm aware that there are different sizes. I was meaning more in terms of number of occupants and typical litres used per day, against cylinder capacity and reheating capability.

 

[ChrisR]

It depends too much on usage. Eg my cylinder (same size as yours) is emptied of HW by one bath, but it's hot again in 20 minutes.
An old type cylinder might take an hour or more to reheat, but a short, meagre shower would only use 20 litres of HW.

Size isn't everything!

 

[namsag]

If you have a fully pumped system plumbcentre do the centercyl range where a 1050mm by 400m cylinder (120 litres) replaces old style cylinders up to 1200mm by 450m and one at 800mm by 400mm(85litres) that replaces old style ones upto 900m by 450mm . They have a 20 minute recovery time and come with all the fittings and immersion heater

 

[gas4you]

If you have a fully pumped system plumbcentre do the centercyl range where a 1050mm by 400m cylinder (120 litres) replaces old style cylinders up to 1200mm by 450m and one at 800mm by 400mm(85litres) that replaces old style ones upto 900m by 450mm . They have a 20 minute recovery time and come with all the fittings and immersion heater

Very good cylinders

 

[JohnD]

why do you want to reduce its size?

What size is the one youhave?

 

[giblets]

What size is the one youhave?

Errm....

Existing cylinder is 1200mm by 450mm. which I believe gives acapacity of 160 litres

 

[JohnD]

Quite similar to a 4' x 18" one, then.

A smaller one will not fill a bath.

 

[gas4you]

The small 85 litre Plumb Centre cylinder will easily cope with one bath property and the 120 will cope with a 2 bath property as they are fast recovery cylinders, in fact I would say slightly faster than namsag has said. The only time you might suffer with the 85 is if the boiler breaks down and you rely on the immersion

 

[shouldknowbetter]

Thank you all for your comments.
I also found some information on plumbworld.co.uk, copied below.

So I reckon, because we have low usage, I can reduce the size. If the newer cylinders reheat more efficiently than old (and I know that's also down to the boiler), then the loss of capacity will be made up for with the quicker reheat.

Cheers

3) The next decision is to determine the overall size and water storage capacity of the cylinder.

Hot water usage varies with the type of building, it uses and the number of occupants. Occupant usage may vary depending on their level of activity, age, and water usage by appliances etc.
In modern homes hot water usage can vary between 35 and 45 litres per person per day, with hot water at between 60 - 65 degrees centigrade.

A wash hand basin tap will use 0.15 litres per second at 40 degrees C
A Kitchen sink will use 0.20 litres per second at 60 degrees C
An average bath can use 60 liters of hot and 40 litres of cold water
Modern showers can use 11 litres of blended water per minute.

 

[JohnD]

why do you want to reduce its size

 

[gas4you]

If the newer cylinders reheat more efficiently than old (and I know that's also down to the boiler), then the loss of capacity will be made up for with the quicker reheat.

ONLY if you have a fully pumped heating system as namsag previously mentioned

 

[shouldknowbetter]

JohnD - I'm reducing the size because basically I'm heating a large tank of water to use a small amount of it, and especially during the summer when the CH is off, assuming we get warm weather of course!

Dave, thanks, noted.