1.0Gristhttps://grist.orgGrist Staffhttps://grist.org/author/gristadmin/rich600338<blockquote class="wp-embedded-content"><a href="https://grist.org/article/hot-water/">Umbra on solar hot-water systems</a></blockquote> <script type='text/javascript'> <!--//--><![CDATA[//><!-- /*! This file is auto-generated */ !function(d,l){"use strict";var e=!1,o=!1;if(l.querySelector)if(d.addEventListener)e=!0;if(d.wp=d.wp||{},!d.wp.receiveEmbedMessage)if(d.wp.receiveEmbedMessage=function(e){var t=e.data;if(t)if(t.secret||t.message||t.value)if(!/[^a-zA-Z0-9]/.test(t.secret)){var r,a,i,s,n,o=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),c=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]');for(r=0;r<c.length;r++)c[r].style.display="none";for(r=0;r<o.length;r++)if(a=o[r],e.source===a.contentWindow){if(a.removeAttribute("style"),"height"===t.message){if(1e3<(i=parseInt(t.value,10)))i=1e3;else if(~~i<200)i=200;a.height=i}if("link"===t.message)if(s=l.createElement("a"),n=l.createElement("a"),s.href=a.getAttribute("src"),n.href=t.value,n.host===s.host)if(l.activeElement===a)d.top.location.href=t.value}}},e)d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",t,!1),d.addEventListener("load",t,!1);function t(){if(!o){o=!0;var e,t,r,a,i=-1!==navigator.appVersion.indexOf("MSIE 10"),s=!!navigator.userAgent.match(/Trident.*rv:11\./),n=l.querySelectorAll("iframe.wp-embedded-content");for(t=0;t<n.length;t++){if(!(r=n[t]).getAttribute("data-secret"))a=Math.random().toString(36).substr(2,10),r.src+="#?secret="+a,r.setAttribute("data-secret",a);if(i||s)(e=r.cloneNode(!0)).removeAttribute("security"),r.parentNode.replaceChild(e,r)}}}}(window,document); //--><!]]> </script><iframe sandbox="allow-scripts" security="restricted" src="https://grist.org/article/hot-water/embed/" width="600" height="338" title="“Umbra on solar hot-water systems” — Grist" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe>Dear Umbra, I would like to change to solar heating for providing some of our electricity requirements, particularly for hot water. Can you advise me how to go about it? Leela Pienaar Grahamstown, South Africa Dearest Leela, I notice you’re …http://grist.org/wp-content/uploads/2007/06/kid-bubble-bath_h240.jpg