Separate DHW and Space heat monitoring

They’re zero vs. non-zero to indicate when they are on.

You can set up a virtual feed like this to provide the appropriate signal when DHW is on:


Personally I find it easier to use WaterPump2Status (heating) and WaterPump4Status (dhw), although cylinders with coils don’t have that 4th pump.


Thanks, no I only have one pump so can’t use that.
Maybe there could be a feed as well for defrost cycles?

Like this? Appears when you click “Show detail”.

“Show flow rate” moved below the stats table.

That would be lovely!!

Ok I think I must be just being a bit slow… where do I get a ‘If =, skip next’. I don’t see any logical operators in the list of available processes.

Ah - the public instance of emoncms might not have that those operators for virtual feeds.
Does the input process steps have logical operators?

It is possible to do the same thing with arithmetic operators too: (untested)


  1. Add -2
  2. Allow negative
  3. Add 1
  4. Allow positive

Hot Water;

  1. Add -1
  2. Allow negative
  3. Add 1

How are you getting the data out of melcloud? Can you do any preprocessing before posting it to emoncms, creating some extra inputs?

Looks like I have the same options of inputs.
Maybe it would be easier to add to my pymelcloud script as another Emoncms input.


Actually, if you’re scraping data from Melcloud, your best option might be ValveStatus3Way which I’m guessing will work whether you have coil or heat exchanger.

I’d suggest sticking with WaterPump2Status for the heating signal.

Many thanks for this Tim; very nice. I’ve just added the feeds for my system this morning.

One question about the intended usage for the _ch flag when the heat pump is in ‘standby’ (ie. not actively heating either DHW or CH); should that be 1 (since it’s in ‘NOT hot water’ mode) or 0 (since it’s not actively delivering heating either)?

I’ve gone for the latter, so my system spends quite a lot of time with _dhw and _ch both set to 0 and only flips them to 1 when the compressor is running for either one or the other. Is that what you had in mind?

I had intended for the heatpump_ch to be zero when it’s not heating.

The heatpump_ch feed is not (currently) used to determine standby mode (we’re still using the power threshold for that), and is only used to highlight the heating cycles on the chart. It’s purely decorative. The COP for heating is worked out by subtracting the energy from DHW and standby.

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So these are boolean feeds right?

I’ve tried this on my emonpi and still don’t see the new feeds in the HeatPump app.

Yep. 0 for ‘not heating’ and 1 for ‘heating’ for DHW and CH respectively.

Here’s how today’s graph for my system looks after I configured these around 10:00 (so no yellow ‘CH’ shading for the 06:30 heating cycle.

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Which branch are you using? I think only the master branch has these improvements at the moment.

Whatever the default is - I just hit the update button. I’ll take a look.

Need to work out how to create those boolean values as well …

The app considers zero to be off and non-zero to be on, so it might work with feeds that aren’t strictly boolean, so long as they are zero when off.

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If you keep making enhancements like this @Timbones you’ll get to my dodgy app from four years I did before I found EmonCMS:

Next up: little snowflakes icons for defrost :slight_smile:

When that’s working I expect to see seasonal themes:


Did this change happen Tim? I’m not seeing in on

Not yet, just waiting for this pull request to be merged (includes several other goodies).


Looks like it has been merged.

How does this work?

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