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Hi all,
So did some additional thinking based on messages from yesterday. Wanted to share and get thoughts based on people's input so far.
- Achieving that 25 litre per minute reheat capacity on two cylinders (12.5 litre per min * 2 cylinder) will require an upgrade of boiler from current proposed 50kw to 100kw
- But this would effectively double my monthly gas heating bill assuming I'm using boiler for same amount of time but its consuming 100kwh instead of 50kwh :O
Therefore, I did some thinking around how to lower flow rate demand through the pipes and from cylinders:
MID CASE DEMAND (MOST REALISTIC)
I'm taking a guess here but based on lower re-heat capacity of 12.5 litres per minute (6.25 litres per min x 2 cylinders) - what boiler size would I need? Could I get away with 65kw?
- 7 bathrooms (not 8) to be used during peak times for av. 10mins
- each shower will have flow rate of 9.5 litres per min instead of 11.5
- Litres per min used: 66.5 (9.5 x 7 showers) (total demand over 10mins = 665 litres)
- At 600 litres cylinder capacity, house will run out of hot water in 9 minutes
- However if boiler is able to re-heat two cylinders at 12.5 litres a minute (6.25 l x 2 cylinders), in that 9mins, an additional 113 litres of hot water would be available due to reheat capacity (9 mins * 12.5 litres per min reheat)
- This gives a total capacity of 713 litres of hot water (600 litre core capacity + 113 litres reheated over 9mins)
- NOTE 1: the 600 litres in 9 minutes indicates a flow rate of 66.5 litres per minute from the cylinder - Would this also require installation of a pump to support that kind of flow rate out?
- NOTE 2: At 66.5 litres per minute from cylinder + 12.5 litres per minute recharge capacity = 79 litres per minute flowing through the pipework
- NOTE 3: The above takes no account of radiators, toilets being flushed or sink basins being used. Should I factor more for this?
- NOTE 4: Assumes the 8th bedroom which is a staff room will not use the shower during peak periods
post 2 should help you out with most of that