How large should my hot water cylinder be?

[diynige]

I'm installing a direct hot water cylinder (economy 7 immersion powered), fed by a 200L water tank in the loft (gravity-fed system) into a 3-bedroom house, where typical daily usage would be one bath, and two leisurely pumped power-shower sessions. All of these will be drawing hot water from the hot water cylinder.

I'm trying to size the cylinder correctly so it can happily cope with this usage requirement. Can anyone please offer guidance as to what size of cylinder would meet our modest needs? We've had a heating guy suggest a 96litre cylinder but I have a feeling that may not be enough.

Any replies much appreciated.

 

[namsag]

36 BY 18 inch(standard size) or go for a 42 by 18 should be plenty.

Just re reading your post are you hoping to have enough stored hot water from what you have heated over night without reheating the water during the day

 

[JohnD]

I use a 120litre cylinder (this is fairly typical). It will do one bath plus a bit of washing up provided it is pretty hot and you mix cold with it (a bath uses approx 100 litres). You would not get a shower out of it as well.

A power-shower can easily use 100 litres of water. Squirt yours into a bucket, time it, and see how many litres per minute it delivers. I don't think a power shower is sensible with an immersion heater.

I know someone who has a similar setup to the one you describe, and washes things up individually under the running hot tap, as and when they are used (one cup, one teaspooon, etc) and runs out of hot water by the afternoon

Start saving up for a gas boiler.