I'm in the process of considering an unvented cylinder to replace the existing gravity system. I know that unvented systems are only as good as the pressure/flow rate that supply them, so I'm anxious to make sure these are adequate before I give the go-ahead.
The pressure has been measured at between 3 and 4 bar, which is fine, but the flow rate is what I'm questioning.
The potential installer has measured flow at around 16 litres/min. He thinks this is on the low side for unvented and that a case could be made for a high-end combi as an alternative (the risk with unvented being the loss of pressure in cases of multiple demands for water).
From my own research I can see that 16 l/min is on the low side but my question is how accurate is this, given it was taken by using a tap in the downstairs utility? From what I can see, flow rate is governed by the diameter of the thing the water exits through, meaning that the flow rate from a 1/2" tap would be less than say, the flow rate from a 3/4" tap, given equal pressure.
Googling suggests that your standard 1/2" sink or utility tap will have a 15 l/min flow rate as a maximum. If that's the case, what's the point of using that tap to determine flow, given you're unlikely to see anything over 15 l/min, and how does one measure the 'real', unrestricted flow rate that's coming into the house?
Sorry if this is painfully ignorant, learning as I go by Google!
The pressure has been measured at between 3 and 4 bar, which is fine, but the flow rate is what I'm questioning.
The potential installer has measured flow at around 16 litres/min. He thinks this is on the low side for unvented and that a case could be made for a high-end combi as an alternative (the risk with unvented being the loss of pressure in cases of multiple demands for water).
From my own research I can see that 16 l/min is on the low side but my question is how accurate is this, given it was taken by using a tap in the downstairs utility? From what I can see, flow rate is governed by the diameter of the thing the water exits through, meaning that the flow rate from a 1/2" tap would be less than say, the flow rate from a 3/4" tap, given equal pressure.
Googling suggests that your standard 1/2" sink or utility tap will have a 15 l/min flow rate as a maximum. If that's the case, what's the point of using that tap to determine flow, given you're unlikely to see anything over 15 l/min, and how does one measure the 'real', unrestricted flow rate that's coming into the house?
Sorry if this is painfully ignorant, learning as I go by Google!