How much hot water (litres)??

[bobby62]

What capacity indirect hot water cylinder/s would be required to serve 15 showers (i believe the showers consume about 12 litres every minute - hot and cold mixed).

There would be 20 people at any one time that could use the showers, i.e. most rooms have a shower en-suite.

I just want to make sure the plumbers don't skimp on the hot water.

Just a rough idea, I believe this isn't an exact science!

Many thanks

 

[RichieHoneybucket]

Bobby mate, if it's showers only, then there's the fact that the temperature of the water used will only be 34-38*C, so if you store it at 60*C you're using roughly half your hot water. Then there's the Summer incoming mains factor, it could be anything up to 15*C, so you'll only need a temperature rise of about 18*C for showers.

If it's a Hotel, then book says 36Ltr per person.

 

[bobby62]

Bobby mate, if it's showers only, then there's the fact that the temperature of the water used will only be 34-38*C, so if you store it at 60*C you're using roughly half your hot water. Then there's the Summer incoming mains factor, it could be anything up to 15*C, so you'll only need a temperature rise of about 18*C for showers.

If it's a Hotel, then book says 36Ltr per person.

There is one basin in each en-suite, but I suppose this wouldn't be in use whilst the shower is in use.

2 x 400 litres cylinders (800 litres) wouldn't be far out then
36 l/person x 20 people = 720 litre

 

[RichieHoneybucket]

There's other factors to consider Bobby, like how quick the cylinders will recover(re-heat), for that number of rooms & HW demand you'd need something dedicated to heat the cylinders. How you heating the water mate??

Nothing worse than staying in some Faulty Towers Hotel that runs out of hot water, so I hope you've got a good time-served qualified Plumber. There's also then the pipe sizing, has he done that??

 

[bobby62]

There's other factors to consider Bobby, like how quick the cylinders will recover(re-heat), for that number of rooms & HW demand you'd need something dedicated to heat the cylinders. How you heating the water mate??

Nothing worse than staying in some Faulty Towers Hotel that runs out of hot water, so I hope you've got a good time-served qualified Plumber. There's also then the pipe sizing, has he done that??

Thanks RichieHoneybucket - I believe the plumber has a good experience with this type of project, and will size the pipework adequately. There is one boiler doing the heating and hot water, the boiler is going to be oversized to allow a fast recovery time i.e. dedicating say half the boiler load to the cylinder(s) say 25kW or so.

 

[cozzmic]

I think you might find that 25kw is not adequate for two 400 litre cylinders. I did a 450 litre one the other day and the coil is about 40kw. Even magaflows are 20kw plus now on a standard domestic tank.

 

[Agile]

There are a lot of variables. Particularly that the HW could be heated during the night while heating is off or on setback.

That 36 li/person is rather out of date compared with what people expect. I use 50 li plus 50 li per person in a home. But higher diversity can be applied in a hotel.

In a hotel I like to take a long shower and most take at least 10 minutes. Alowing for the storage being higher than the 40° at the shower the 100 litres at my shower might only use about 60 li from the cylinder.

I dont understand this, but the diversity factor in hotels is often higher than would be expected but it does depend on the type of visitor and if thats not diversified then it could cause a run on the HW all at the same time.

Just as important is if the source of water is adequate!

There are a lot of factors to be considered.

I would never fit just one boiler in a hotel! I was once called to a hotel with 48 double rooms and just a single boiler ( which had failed ).

Tony

 

[ajrobb]

My single 300 litre HWC can sink all the output from 2x25 kW boilers, you might want a bit more for 800 litre.