Received: from PCH.mit.edu (18.7.21.50) by mail.efplus.com (192.168.0.8) with Microsoft SMTP Server (TLS) id 8.3.485.1; Tue, 29 Jun 2021 16:42:57 -0700 Received: from PCH.MIT.EDU (localhost.localdomain [127.0.0.1]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 15TNX8Su018518; Tue, 29 Jun 2021 19:33:55 -0400 Received: from outgoing-exchange-5.mit.edu (OUTGOING-EXCHANGE-5.MIT.EDU [18.9.28.59]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 15TNX7jr018513 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 29 Jun 2021 19:33:07 -0400 Received: from w92exedge4.exchange.mit.edu (W92EXEDGE4.EXCHANGE.MIT.EDU [18.7.73.16]) by outgoing-exchange-5.mit.edu (8.14.7/8.12.4) with ESMTP id 15TNWd3n007570 for ; Tue, 29 Jun 2021 19:33:07 -0400 Received: from w92expo9.exchange.mit.edu (18.7.74.63) by w92exedge4.exchange.mit.edu (18.7.73.16) with Microsoft SMTP Server (TLS) id 15.0.1497.18; Tue, 29 Jun 2021 19:32:02 -0400 Received: from w92exhyb4.exchange.mit.edu (18.7.71.74) by w92expo9.exchange.mit.edu (18.7.74.63) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 29 Jun 2021 19:32:41 -0400 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (104.47.57.173) by w92exhyb4.exchange.mit.edu (18.7.71.74) with Microsoft SMTP Server (TLS) id 15.0.1497.18 via Frontend Transport; Tue, 29 Jun 2021 19:32:41 -0400 Received: from BN9PR03CA0418.namprd03.prod.outlook.com (2603:10b6:408:111::33) by SN6PR01MB4911.prod.exchangelabs.com (2603:10b6:805:c6::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4287.21; Tue, 29 Jun 2021 23:32:39 +0000 Received: from BN8NAM11FT052.eop-nam11.prod.protection.outlook.com (2603:10b6:408:111:cafe::da) by BN9PR03CA0418.outlook.office365.com (2603:10b6:408:111::33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4287.21 via Frontend Transport; Tue, 29 Jun 2021 23:32:39 +0000 Received: from mail-lj1-f182.google.com (209.85.208.182) by BN8NAM11FT052.mail.protection.outlook.com (10.13.177.210) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4264.18 via Frontend Transport; Tue, 29 Jun 2021 23:32:39 +0000 Received: by mail-lj1-f182.google.com with SMTP id p24so568339ljj.1 for ; Tue, 29 Jun 2021 16:32:39 -0700 (PDT) From: RussellMc To: Microcontroller discussion list - Public. Sender: "piclist-bounces@mit.edu" Date: Tue, 29 Jun 2021 16:32:25 -0700 Subject: Re: [EE] HVAC filter efficiency and energy consumption Thread-Topic: [EE] HVAC filter efficiency and energy consumption Thread-Index: AddtQH1jW2bQ007hSqCPxHXiN66aiA== Message-ID: References: <60DA6883.23190.2A016236@brent.eds.co.nz> List-Help: List-Subscribe: , List-Unsubscribe: , In-Reply-To: Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of gmail.com designates 209.85.208.182 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.208.182; helo=mail-lj1-f182.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=P60T13aMRv9KSCYxED8Gg49spOhvsjppGs7Z2cwnbC4=; b=kL/VnJX2Shq8zXS6uKdIqRYqMsxd9gHFkL1pFnoLj+TZZswUJlvOTV+FWnISUUB/XY 6RO/tPjolQURqtozRyBDSv+ejp/0TbrOTMgMvaoFuu8B/tgQcEoNvKs6go58N3mwLr2A /uXIlT7qfMw2UxtWhIB9/y4UQYVTx2m1oX+HbWAjZOV5yMUJFRcajP0if3mYdIkS/KHT GolDnVwiJhd0yC4gySgjNi6asxLCHVRwt0i9WAUEBxci/lRZEgu549auGtDO7XQxa2sN WhL6IF6kYqFmGx2BbOWLmcQtz8ZZ3y+SEg1x4lyFyhLm/v3LsOkY8+CQ3+phxlyk9Qrc bBwA== authentication-results: spf=pass (sender IP is 209.85.208.182) smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified) header.d=gmail.com; mit.edu; dmarc=pass action=none header.from=gmail.com; errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a05:651c:1501:: with SMTP id e1mr5769340ljf.87.1625009558205; Tue, 29 Jun 2021 16:32:38 -0700 (PDT) x-topics: [EE] x-content-filtered-by: Mailman/MimeDel 2.1.6 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 You can do a very unsophisticated but useful visual test by using a partialy water filled flexible tube and placing the ends before and after the filter. Even if you "jammed one end around the edge of the filter" it should suffice as long as there was some flow possible. A single exterior hole would suffice - possibly from temporarily removing a screw. You now have a U tube manometer with difference in fluid levels showing you the pressure. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .