"Richard from DPS Heatweb" wrote in message
om...

Heat Banks provide Secondary Circulation
by the usual means, except the return tees
into the mains in (above flow switch). The heat
exchanger pump

Don't you mean the secondary circulation pump?

can be brought on by a
pipe thermostat fitted to secondary return
that will result in circuit being reheated once it
has dropped to stat setting. A clock should
always be used.

Note that Pumps are more reliable, less
vulnerable to grit, easier to service, cheaper,
and provide pressure gain, rather than loss, over
motorised zone valves.

Pumps require a check valve in the circuit. Check valves restrict
flow/pressure, unless the next size up is used, i.e., 28mm on a 22mm pipe.

Where an expensive modulating pump is to be
used, zone valves may be more economical however.