Open vent DHW - calculate recovery time

[Desktop987456]

What would be the heating time for this (indirect) vented cylinder? Rated coil = 14kw
Is it 96 litres x 4.2 specific weight x 40 (dT) ? How do I calculate the heating requirement of the boiler to heat this cylinder.
Secondly, they are simpler to install as opposed to unvented type but what are the advantages they have over their unvented cousins?
Thanks in advance for guidance.

 

[fowlerboi]

Not sure but my old college books all say allow 3kw for the cylinder

They have no advantages over an unvented. You would only fit a vented one if you didn't have means of getting a relief pipe out, the plumbing in the house is Rubbish or the water pressure and flow are not adequate

 

[ShaunCorbs]

to heat 96l at dt40 your coil is only 14kw so around the 20-25mins mark

 

[ShaunCorbs]

eg

20mins x60 second =1200 seconds
4.2 x96x40 / 1200 = 13.4kw at 20 mins

 

[Desktop987456]

eg

20mins x60 second =1200 seconds
4.2 x96x40 / 1200 = 13.4kw at 20 mins

Thank you both of you.

 

[Desktop987456]

Not sure but my old college books all say allow 3kw for the cylinder

They have no advantages over an unvented. You would only fit a vented one if you didn't have means of getting a relief pipe out, the plumbing in the house is Rubbish or the water pressure and flow are not adequate

Pls check your message, I have sent a PM

 

[John.g]

Thank you both of you.

The coil rating is possibly based on a 80C boiler temperature and a flowrate of maybe 30LPM which may not be the normal running conditions so maybe average coil rating of 8 to 10kw, still only a problem if you are programming the reheat time, maybe allow say 30/35 minutes in the summer and 40/45 minutes in the winter.

 

[Desktop987456]

The coil rating is possibly based on a 80C boiler temperature and a flowrate of maybe 30LPM which may not be the normal running conditions so maybe average coil rating of 8 to 10kw, still only a problem if you are programming the reheat time, maybe allow say 30/35 minutes in the summer and 40/45 minutes in the winter.

Thank you Sir.