<html><head></head><body>None of the TRVs I've looked at use a spring, relying instead on the gearbox and motor to act as a passive break on the pin actuator. As below, I'm not sure there's enough standardisation or energy saving to justify the increased design and manufacturing costs. I suspect you'd get better returns from improved gearing or tweaks to the software\wireless protocol (but I won't try to prove that!).<br><br><div class="gmail_quote">Thomas Hood <jdthood@gmail.com> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre style="white-space: pre-wrap; word-wrap:break-word; font-family: monospace">On Thu, Mar 28, 2013 at 2:27 PM, Stuart Poulton <stuart@poulton.org.uk> wrote:<br />> On 28 Mar 2013, at 12:19, Thomas Hood wrote:<br />>> On Thu, Mar 28, 2013 at 12:56 PM, Jack Kelly <jack-list@xlk.org.uk> wrote:<br />>>> The pin on the base of a TRV is spring loaded, isn't it? I wonder if<br />>>> there's a way to reclaim some of this energy when we release the pin.<br />>><br />>> The radiator valve insert is spring loaded. If the TRV is well<br />>> designed then it is also spring loaded so as to balance the insert<br />>> spring; then the actuator only needs to overcome friction plus I<br />>> suppose some dynamic hydraulic pressure. Is this not how the motorized<br />>> TRVs are actually constructed?<br />><br />> I don't believe there is a spring, I'll try to deconstruct my TRV<br />> over the weekend. It simply
relies on the gearing to prevent the<br />> pin from returning.<br /><br />Hmm, well I suppose you can only include a spring if you know what the<br />minimum possible tension on an insert spring is, otherwise the TRV<br />spring will hold the valve closed. And perhaps you don't know that<br />because there are so many makes and models of inserts.<br /><br />In any case, a spring efficiently implements the idea of storing<br />energy delivered by the insert pin and returning it later when needed.<br />If the spring pushes with 10N and the travel is 3mm then the energy<br />stored is 30mJ. Maybe that isn't enough to warrant building in a<br />spring. An AA battery stores about 10⁴ J.<br />-- <br />Thomas<br /><hr /><br />OpenTRV-dev mailing list<br />OpenTRV-dev@lists.opentrv.org.uk<br /><a href="http://lists.opentrv.org.uk/listinfo/opentrv-dev">http://lists.opentrv.org.uk/listinfo/opentrv-dev</a><br /></pre></blockquote></div></body></html>