AJH wrote:
On 9 Mar 2006 14:05:11 -0500, wrote:
Derek Broughton wrote:
"Those guys" show a system that is reliable as long as that valve opens.
Aha. I've been thinking drainBACK, as in "the water drains back when the pump
stops, by gravity, with no valve."
Yes this was my assumption, the water header being sufficient cross
section, and within the insulated area of the house, that once the
pump stopped it just filled up a bit. The only drawback I could see
was that the pump would always work against the head from the header
tank up to the panels. In a sealed system the pump only circulates
against the friction in the system.
I realised this isnt so. Once the panel circuit fills with water, the
pump is only pumping against the running friction, and not the head.
The panel output piping is filled with water after a second or 2, so
gravity has the same effect on both sides, so no extra pumping
resistance.
NT