Posted by: @Anonymous

↑

Posted by: @uk_pete_2000

↑

That means I only start and run the compressor once, not 2 or 3 times a hour.

In the grand scheme 2 or 3 starts an hour is good. It's what it's designed to do. During the cycle it just maintaining floor temp.

If you never let it cycle you will never get WC to work, that's maybe why you make the sweeping statements that WC can work.

Mine is currently cycling about twice per hours and it's just doing what they are designed to do.

I find it faintly amusing that nobody ever worries about a heat pump cycling more or less continuously when it's their fridge, but gets extremely concerned when their heating cycles for some of the time

I was looking at electricity usage the other day and the heat pump dryer was on, that cycles also.

My dryer cycles, one day of sunshine at least once a year got to love Wales!

Posted by: @jamespa

↑

I find it faintly amusing that nobody ever worries about a heat pump cycling more or less continuously when it's their fridge, but gets extremely concerned when their heating cycles for some of the time

Difference is I’m actively encouraging as much cycling as possible on our dreadful Samsung fridge in the hopes it gives up completely, so we can finally justify replacing it with something decent.

Posted by: @jamespa

↑

Your original statement, to which I responded, was essentially that WC doesn't work, period

Correct and I still stick by it as this is a discussion on automation and getting control of the HP to respond to circumstances.

In the end all a WC is a table of what the flow temp should be for a given temp outside, with no consideration about what happens inside. People adjust the WC to get the internal temp right and then do things like setback to correct the overheating that WC will introduce, overtime and cycling is one of those symptoms.

Now I understand cycling may be normal in a fridge, but have you monitored the spike in energy when it starts up. Now do the same for a HP and suddenly you are using 2/3/4kw more spike every time the compressor starts (yes some can have soft start now).

Anyway going back to WC, most HP only respond with 1/2 or 1° difference and depending on your curve it could take 2 or 3° outside temp change, before the HP changes flow temp. 

Also bear in mind that even using a set flow temp, the HP will change its behaviour to changes in outside temps to maintain that flow.

By using internal temp and just flow temp, you can get the system to respond too changing internal circumstances, which is what we all respond too. Like a good WC this can be done on a trend basis, but now you can respond with 1/10th difference (though I would still set it a about 1/2°)

It also means that when you do a setback, the flow temp is decreased to match the internal temp and increased when turning the temp up. Something which the WC does not do (though again some new models are introducing this), without switching to another curve (if it has one)

We both talk about residual heat and I think we can agree that both WC and internal temp will suffer from it, regardless. For me this is where a 2nd table come into play that builds up a picture of residual times and takes this into account when making changes. The system can then anticipate what you want to make those adjustments beforehand 

Posted by: @uk_pete_2000

↑

also means that when you do a setback, the flow temp is decreased

With UFH that does not happen - the heat pump will cycle off for many hours

Heat pumps are controlled on delta T and return temperature, even though you set a target flow temperature. As soon as you set a lower target flow temperature, the heat pump will try to modulate output down to reduce return flow temp AND while trying to maintain dT. But within a minute or so it will shutdown. Then will be subject to a restart permission based on return temp. Your low heat loss house will respond exactly the same as mine, heat pump goes to sleep on setback. Mine has been asleep for the last 11 hrs based on a change in flow temp demand.

Posted by: @uk_pete_2000

↑

where a 2nd table come into play that builds up a picture of residual times and takes this into account when making changes. The system can then anticipate what you want to make those adjustments beforehand 

Good luck doing anything better than a low hysterisis thermostat. That knows what is happening real time, my room sensors can be configured to any hysterisis you like (if I used them), so can be set to zero if you want. Then as soon as you move from target temp, the heat pump fires up, as soon as over set point HP shuts down. No dependency on iffy weather forecasts, or anything really. Closest I have seen to working is in a Salus SQ610, which is designed for only UFH heating systems. Not that is great in high inertia UFH systems either.

Set your fixed flow temp, set your thermostat hysterisis and target set point, walkaway find a real issue that needs fixing.

Posted by: @uk_pete_2000

↑

By using internal temp and just flow temp

It's called room compensation, your controller for the heat pump can do that out the box. Most decent boilers and heat pump do that. But they all say don't use it with UFH because the inertia is to great. I did try it, it was awful had big temperature swings as the system slowly goes into meld down. Basically controller says room temperature is dropping add more heat, still dropping add more heat. Soon gets to max temperature, big room overshoot is the final outcome. Then massive underwing repeat. Radiators it's fine, UFH heating no doesn't work.

Will watch with interest, to see how your system responds to your automation. But will bow out of further contributions to this thread. I have said enough.

Posted by: @jamespa

↑

Posted by: @jamespa

↑

Your original statement, to which I responded, was essentially that WC doesn't work, period

 

 

Correct and I still stick by it as this is a discussion on automation and getting control of the HP to respond to circumstances.

...

Sorry, @uk_pete_2000, but I don't see that position as tenable. This forum is littered with posts from homeowners who were set up with or have switched to using WC and now sing its praises. That's a lot of people saying their real world experience is that WC DOES work. Any suggestion otherwise is simply not letting the evidence get in the way of a good theory.

That is not to say that pure WC without supplementary moderation is the ideal for all homes in all circumstances but that's not what anyone is trying to state. However, even for homes that need some further tweaking of parameters, WC is a proven good foundation on which to build and the army of satisfied homeowners is pretty difficult to argue against. I hasten to add that I'm not just talking about the satisfied homeowners posting on this forum but also the masses who provided the evidence that convinced several European countries to push WC as the default setup for any new fossil fuel installations for many years hence.

Posted by: @jamespa

↑

Posted by: @jamespa

↑

Your original statement, to which I responded, was essentially that WC doesn't work, period

 

 

Correct and I still stick by it as this is a discussion on automation and getting control of the HP to respond to circumstances.

If your statement were 'WC doesn't work in your house' then it might be true.  As it stands, apparently intended to be generally and widely applicable, it is definitely not true and is, unfortunately, seriously misleading.  That doesn't mean that some supplementary level of control in addition to WC isn't sometimes useful.

Like @johnmo i will not contribute further to this discussion unless it gets to the point where there is a serious risk of misleading others. If this happens I will intervene in my role as a moderator.

I wish you luck with your control experiments.

Posted by: @majordennisbloodnok

↑

That is not to say that pure WC without supplementary moderation is the ideal for all homes in all circumstances but that's not what anyone is trying to state. However, even for homes that need some further tweaking of parameters, WC is a proven good foundation on which to build and the army of satisfied homeowners is pretty difficult to argue against. I hasten to add that I'm not just talking about the satisfied homeowners posting on this forum but also the masses who provided the evidence that convinced several European countries to push WC as the default setup for any new fossil fuel installations for many years hence.

This is very much where I am coming from, I am  happy with WC and at the moment I am just tweaking one parameter (the max flow temp) and it is working pretty well, maybe I will get to the stage where I find that sweet spot by the end of next heating season who knows, however the inner geek/tinkerer/breaker of things in me can't resist looking at this and seeing if I can make something cool that works for me and share my findings.

I am going to look at implementing the second set point as @johnmo suggested, I hadn't even considered it as I only have one circuit so completely ignored any settings for zone2, but I like these cool little work arounds. I also haven't bothered looking at the low tariff modes either as when I get my battery installed this will be les of an issue.

Cheers for everyone's input.

Posted by: @grantmethestrength

↑

@jamespa I have an Ecowitt weather station so this is in my plan. I am also building the system locally so no internet required and so that it fails safe so it can easily be controlled by the EPH dumb controls if anything goes wrong.

Given the Ecowitt weather station itself can be configured to send its data directly to an endpoint on your local network (e.g. a Home Assistant server) and the Ecowitt HA integration is a standard one (not HACS) I'll be very interested to find out your experiences with it.

@majordennisbloodnok The ECOWITT integration is useless (or maybe I am as I couldn't get it to work!) I use an API call to get the data from my weather station. In my configuration.yaml I have the following:

  - platform: rest

    name: ecowitt_weather

    json_attributes:

      - code

      - data

      - msg

      - time

    resource:  https://api.ecowitt.net/api/v3/device/real_time?application_key=“YOUR_KEY”&api_key=“YOUR_KEY”&mac=“YOUR_MAC”&call_back=all 

    method: GET

    value_template: "OK"

Then in my sensors.yaml file I have created templates for each data stream:

      # Home Assistant configuration for Ecowitt Weather Station
      # Outdoor sensors

      - name: "Outdoor Temperature"
        unique_id: ecowitt_outdoor_temperature
        unit_of_measurement: "°F"
        state: "{{ states.sensor.ecowitt_weather.attributes.data.outdoor.temperature.value | float }}"
        device_class: temperature
        state_class: measurement

You need to connect your weather station with the Ecowitt website in order to create the API key and ID get the MAC address from your device and you are up and away. Also the formatting is off in this post so you would have to get the indentation correct for it to work. If you want the full list of sensors I am happy to provide it.

That's interesting, @grantmethestrength. I'm a little surprised you couldn't get the Ecowitt integration to work (and suspect it's the integration, not you), but I'd also have thought your quest for independence from broadband failures would've had you rattling Ecowitt's cage incessantly until it was fixed.

I'm not thinking at the moment about getting one of their weather stations but I must admit it has piqued my interest. If I do, I'll let you know how I get on.