On Fri, 24 Sep 2004 11:45:05 +0100, "IMM" wrote:

A cheap plain direct cylinder can be used. One with a shower tapping on the
side for the flow from the boiler, and have two tapping at the bottom (Range
have these mostly as standard) One bottom tapping for the return to the
boiler and one for the return from the plate. the draw-off at the top is the
flow to the plate. Have two strap on cylinder stats to prevent boiler
cycling. The top stat set to approx 65C and the bottom to approx 70-75C. A
relay is required using these and latching is required. When starting from
cold the store heats up and the boiler is cut out when the bottom stat is
75C. The store cools as water is being drawn-off. Only when the water at
the top is below approx 65C does the boiler cut in. Then it heats the whole
store all in one long efficient burn. No boiler cycling on a few degrees as
with one stat.

Hi,

Would that only be OK for a vented system? What pressures can sealed
systems and direct cylinders operate at?

Also I wonder if it's possible to put a blending valve in so that
primary water from the boiler is used by preference, with water from
the heat bank used when necessary.

cheers,
Pete.