Welcome to the OEM Community!

Welcome to the OEM Community!

Author: Sarah Hanson

This site was founded primarily as a forum to discuss and develop open-source hardware/software for monitoring electricity.

In recent years this limited focus has expanded to include a more general discussion on heat pumps. There is a lot that can be learnt from monitoring heat pumps, and with increasing uptake of this technology, it has become a particular topic of interest in the community. Heat pumps are particularly well suited to user optimisation (whereas PV panels inverters and batteries tend to be fit and forget).


1. Start Here Button

The Start Here button has been created to help less experienced users overcome some of the common basic barriers to effective use of the website. In the following notes, you will see information on the effective use of the Community page, and find links to

  • some guidance on frequently encountered terminology,
  • [future] a (qualitative) overview of heat pump circuits and the equipment involved, and
  • [future] a (more quantitative) analysis of heat flows throughout a typical heat pump system, by way of a set of worked examples

The intention is to add other items as time and effort permit. Note that this initiative is deliberately not vendor-specific – if you have questions/insights/speculations on specific equipment, these should be posted in the usual way. Also, please do not feel obliged to plough through all the links – regard this as an available resource if you get stuck, and nobody will criticise you if you miss things here and post your question anyway…

This is work in progress. If you find any errors or omissions, please contact a member of Staff by emailing [email protected].


2. Site Structure and Effective Use

2.1 Background

The OpenEnergyMonitor (OEM) project and website was created in 2009. The website and community forum started as a Drupal website with an integrated forum. The forum was later changed to use the Discourse platform in 2016. If you want a complete introduction to Discourse, you can find it here: Discourse New User Guide - Docs - Discourse Meta.

2.2 User Hierarchy

In order to protect the site from damage (inadvertent or deliberate), and users (from inappropriate behaviour), Discourse imposes a user hierarchy system through which you progress as you gain/demonstrate relevant experience (and good behaviour). A description of the hierarchy, including a summary of permissions and activity constraints at each level, and the necessary actions to progress, can be found in Understanding Discourse Trust Levels. A table showing full permissions against Trust Level can be found in Trust Level Permissions Table (inc Moderator Roles) - users - Discourse Meta.

You can find your current Trust Level on your Home Page.

If you aren’t yet allowed to post enough material to illustrate your problem or query, just add a note asking for help. The moderators read every post and normally upgrade your permissions very quickly.

2.3 Home Page

When you log on to the Community website (you can’t do much unless you do), you see your Home Page. This shows a list of current topics arranged in date order of the latest contribution to that topic (except for the very first – pinned there by the Administrators – which contains guidance on posting). Here are the main features:

  • You can filter which topics are displayed by Category (e.g. Hardware) and Subcategory (e.g. Heat Pumps). Any such filters are retained for subsequent site visits unless you change them.
  • The system draws a “last visit” line below any topics that have had contributions since you last logged on (which helps you avoid re-reading posts).
  • Clicking on a topic expands it to show the whole thread. For any particular post the various actions available to you (e.g. “like”, edit, link, flag etc.) are listed under the post, and you can post a reply to the post author (though it will appear at the bottom of the thread). A similar list of actions is available at the end of the thread and applied to the whole of it.
  • Some topic statistics are shown under the original post.
  • You can set your topic “watch” level using the bell icon lower right.

2.4 Creating a New Topic

Having first checked that no existing topic covers the same subject (see Search below), click on the + New Topic button top right of screen. If possible, choose a topic title that is both concise and explicit, to give readers and respondents a good guide to relevance to them. Then type your post, and hit the “Create topic” button. Your new topic and initial post will appear at the top of the list.

2.5 Creating a Post (or replying to another)

  • You can use any keyboard character, or insert attachments (photos, or Word/Excel files for example), or insert symbols using ASCII characters (more on this below), or modify text appearance using BBCodes (more below), or insert emojis.
  • If you highlight a part of another post you can replicate it in your reply (to give readers a sense of which particular post detail you are referring to).
  • There are a number of reserved characters:
    • + or − or * will create an indented bullet
    • the hashtag (#) will embed a Category link
    • @ (followed by a username) creates an embedded link that causes Discourse to notify the nominated user of your post (even if they are not following the thread).
  • The ASCII character set is available at Complete list of HTML entities - FreeFormatter.com. Most of these characters are available on a standard keyboard anyway, but others (such as the Greek alphabet) are also available if you type &#nnnn; (the above reference gives the nnnn in the foregoing).
  • Some (but not all) BBCodes are enabled in Discourse. A helpful guide is available at How to Use BBCode: A Complete Guide. These typically take the form of [ code ] xxx [ /code ] (but without spaces!) where [ code ] is the appearance identifier (e.g. [ u ] for underline) and xxx is the text to be underlined. Attributes can be nested, thus [ u ][ i ] text [ /i ][ /u ] will result in “text” being underlined and italicised (again, no spaces - I had to include them here because otherwise they would have been activated!).
  • If another user starts replying on a topic while you are composing a reply yourself, a “(username) Replying…” message is displayed, so as to minimise the risk of “crossed posts”.

2.6 Search/Menu/Profile Options

Near the top right of the Home Page are Search (magnifying glass), Menu (gear wheel), and your Profile image:

  • The search facility is very powerful and will find references to your search text not just in topic titles, but also in the body of posts, and by username. It can be used to point you to already-posted answers to questions. (Important - this search is just for our website. The search symbol at the extreme top right of the screen is an Internet search, so is much broader.)
  • The menu (amongst other things) provides statistics about the site, a listing of all your posts, and information about your “badges” – a Discourse feature that rewards users for beneficial activities.
  • Clicking on your profile image gives access to your past activities and your profile details (including your current Trust Level via the Expand button). If you wish, you can change your profile image (by default this is the first character of your username with a coloured background depending on your Trust Level), and add a brief autobiography (the latter is encouraged - it helps others understand your experience level).

3. Useful Links

3.1 Terminology

This link takes you to a list of commonly encountered abbreviations and a glossary of terms, both with a brief explanation against each item, and a list of agreed mathematical symbols for use in posts.

3.2 Heat Pump Circuit Overview (future)

This link takes you to simplified diagrams of a typical circuit (normal and defrost modes, including the Outdoor Unit and indoor equipment), with a brief summary of equipment item purpose and operation.

3.3 Heat Pump Circuit Analysis (future)

This link takes you to a document that summarises the operation of the Outdoor Unit from a (basic) thermodynamic perspective, and the implications of this on optimisation (i.e. minimum running cost) of your heat pump controller settings.