@derek-m thanks I've seen the videos I'll have a go at weather comp this evening. Can I just check that you think that is best option alongside our system which is ufh bungalow with about seven or eight uponor thermostat controls in different rooms?

I did mention weather comp to my installer when they put the system in but his answer seemed to be that the room thermostats did the same job - ie only ever calling for enough energy to get to desired temp but the conversations on here seem to challenge that view.

If I go for weather comp does that alter how I should be using the thermostats or do I just leave those alone?

Also - interested in your view - their are a couple of areas that we don't heat in the house - I saw some stuff that suggested this might actually be more inefficient and that should just heat the whole area but that seems counter intuitive to trying to keep costs down. I suppose the thing to do is keep tweaking and keep checking the melcloud etc but any thoughts on this pls? 

Thanks for your time

@rv3 thermostats and weather compensation do very different things

Thermostats call for heat until they reach the desired temperature and then then they turn off the heat source - Thermostats work with, or without weather compensation, they don't care about the flow temperature they just call for heat.

Weather compensation changes the water temperature inside the heating system due to the weather conditions outside - Weather compensation can work with or without thermostats, if you get weather compensation correct you can maintain the temperature at whatever your desired setting is i.e. 21 degrees. 

Both achieve the same thing, but go about it different ways

@batalto thanks for this - ok will have a go this evening using the youtube instructions - also just need to try and understand how it is set now so can go back to that if it's not improving etc.

@rv3 its a bit trial and error. Just find your current settings (whatever they are) and make a note of the set points. It'll be something like

55 degrees (water temp) and -2 degrees (ambient)  : this is your max heating water temperature

20 degrees (water temp) and 20 degrees (ambient) : this is your minimum heating water temperature

Weather compensation will vary the heating water temperature between these two points - the lower the water temperature the more efficient the heat pump is (as it needs less energy).

What you can do is then just adjust the points, turn up your thermostats in the rooms to 22 degrees and leave things for a day or two. You are aiming to get the room to hold at whatever temperature you want e.g. 21 degrees. Then its just trial and error. The real goal is to have the heat pump working at the minimum possible temperature to keep your comfortable all the time.

As a start you might want to go for something like

50 @ -2

20 @ 18

@rv3 

Hi RV3,

As Batalto has pointed out, correctly adjusted weather compensation will allow your ASHP to operate at the lowest water flow temperature that meets the present heat demand.

Thermostats, by design, are on - off devices, so have a built in hysterisis, the temperature difference between switching on and switching off. So a typical thermostat may switch the heating on when the indoor air temperature falls to 20C, but will not switch the heating off until the temperature increases to 21C. A 1C temperature difference may not seem much, but can be the difference between feeling comfortable and feeling chilly for some people.

Because you appear to have your FTC controller in a room environment rather than in the airing cupboard, rather than only using weather compensation, I would suggest that you set your system for auto adaptation. This is where weather compensation initially adjusts the water flow temperature dependent upon the ambient air temperature, and then the FTC controller measures the actual room temperature, and then fine tunes the setting of the required water flow temperature, to bring the indoor temperature to the desired setpoint. So if the indoor temperature were to start to increase due to solar gain, the water flow temperature would be reduced slightly to compensate.

To use auto adaptation, you initially need to adjust the weather compensation curve, probably to the values suggested by Batalto, but then rather than leaving your system on weather compensation control, you would then select auto adaptation. Then as Batalto stated, turn all your thermostats up to 22C, and allow your system to stabilise with the new settings. It will probably take several hours for the temperatures to fully settle under the new control scheme, so don't be tempted to jump in and start making adjustments.

As far as the areas that you don't heat are concerned, it is not an easy question to answer without the full details. ASHP's operate differently from other types of boilers in that they extract much of the heat energy from the outside air. How hard they have to work to do this, is dependent upon the temperature difference between the ambient air temperature and the required water flow temperature. The required water flow temperature, is that which transfers sufficient heat energy to meet the demand of the home, the higher the heat demand the higher the water flow temperature will need to be. You may therefore think that by turning off the heating in certain areas of your home, you will be reducing the heat demand, lowering the water flow temperature, and saving energy. This may not be the case, because the unheated rooms will still be absorbing energy from adjacent rooms, this will therefore increase the heat loss and hence heat demand in the adjacent rooms. To meet this increased heat demand in the adjacent rooms will require a higher water flow temperature, which in turn would require the ASHP to work harder to supply this higher water flow temperature.

Once you stabilise your heating system using auto adaptation control, it should then be possible to monitor the operation of your system, with some rooms left unheated, as against heating the full house, and quantify which is more beneficial.

@derek-m Thanks for this.

Our RTC is actually in the loft rather than one of our rooms - does that alter the advice in any way? 

@batalto Thanks this is really useful - I'll give myself a bit of time with this and have a go this evening thanks.

Unless interrupted - just had a call from home to say that the water has been cut off - no idea how this will affect the heat pump but hopefully sorted soon. 

Posted by: @rv3

@derek-m Thanks for this.

 

Our RTC is actually in the loft rather than one of our rooms - does that alter the advice in any way? 

Hi RV3,

Yes, I'm afraid you will not be able to use auto adaptation, but you can still set your system for weather compensation.

Posted by: @rv3

@peterr @kev-m just to contribute as a fellow 14kw ecodan user here are my figures for the same period 1-18th Nov. 533kwh heating, 88kwh hot water.

(Sorry those graphs look small not sure if they'll be a bit bigger when the post goes up, also it is the consumed energy pls ignore misleading title at bottom of page that's for another graph on melcloud)

 

@peterr we also switched from lpg, our installer also used a Telford tank we also have uponor ufh so some more similarities there.

Our room temp sensor actually in loft as installer said system set to just be dictated to by room thermostats - when they call for heat that's what triggers the ashp so they said it served no use in a room and just put it in the loft.

Energy usage pretty high as previously discussed, certainly compared to some others on here. 224 sq metres bungalow with average insulation but nothing that can easily improve now we've done what we could. Not had chance to have a dabble with the weather comp curve stuff yet. Lots of stuff on the forum to think about - will start to have a tinker.

Main objectives for us are much more basic compared to a lot of the much mor esavvy contributors on here. At the moment our concerns are a) will the ASHP keep us warm enough when temp drops - it's gone pretty cold here in North East last few days but so far seems to be ok b) will it be cheaper or at least no more than LPG which was our previous and c) after that can I get costs down as low as possible / things working at best efficiency.

Interested but also fairly boggled by some of stuff on the forum.

Interested that my COP seems to stay pretty much 2.6-ish throughout both milder periods and in this little cold snap - had thought it would reduce when temps dropped. Astonished to see cops of over 5 being reported elsewhere - though that does seem to be an outlier with most reporting 2.5 to about 3.5 I think? Seems to fall short of manufacturer claims but the forum had warned this would be the case remember an article by Mars on that.

As always thanks to all for various comments and advice in the different threads. Helpful stuff. 

 

 

 

 

 

 

 

 

Here is my data for this period (1-18th November) - 420M2 House with UFH and Rads. Both you and the original poster have quite high heating consumption figures. Our house is quite large and the downstairs neo UFH stats are set to 24 and upstairs radiators are set to 21/20 so we have our house quite warm. 

You can spend a lot of time faffing about with the weather compensation or you can just do trail and error with manually setting the flow temp and see how low you can go whilst keeping the house comfortable/warm. For the last few months I've just left it at a flow temp of 40 degrees. I'm trying 38 for the next month to see how it copes. 

(ignore my hot water consumption, its a 500l tank with an inefficient

secondary return)

@george @kev-m @rv3

I now have a full month of figures to work with, and I don't think my energy consumption is quite as bad as it seems from the MelCloud data I posted.

In November we used 1080kWh from the grid, along with 214kWh generated from our solar.  Assuming that we didn't feed any of our generated power back to the grid that gives a total usage of 1294kWh for the whole house.  I have data going back 6 years from when we originally had our solar installed, and typically in November our usage + generated was 560kWh.  For the purposes of my calculations I have assumed that we didn't usually feed any of our generated power back to the grid, which, as we have a solar iBoost is probably fairly valid.

Making the additional assumption that all of the additional usage was for ASHP, which is probably not unreasonable, this gives us a total ASHP consumption for the month of 734kWh, or an average of 24.5kWh per day.  Our current electricity rate is 20.01p/kWh, so that works out at an average of £4.90 per day for heating and hot water.

For November, MelCloud shows that ASHP usage was 1749kWH, which, if you believe it, means that the ASHP consumed 455kWh more than was supplied to the whole house!  Delivered energy was shown as 2156kWh, giving us a measured CoP of ~1.2!!  If the delivered energy is correct and using 734kWh as the consumption would give us a CoP of 2.9 for November.  Our installer is coming back to have a look at the MelCloud kit again!

Thanks for the update. I would be interested to know how the system/melcloud calculates the consumed electricity as without official metering it just says estimated so it would be good if you could ask the engineer when they visit so we can better understand.

@george it'll just be a CT clamp - or that would be my best guess. I would assume its maybe on the wrong cable and is double counting the power use or its a bad clamp (or an old one which doesn't understand direction of flow e.g. import/export). CT clamps are only around 90% accurate anyway, especially at low wattages.

Good discussion here

https://community.openenergymonitor.org/t/accuracy-of-existing-ct-clamps-since-adding-pv-install-do-i-need-an-emon-solution/8737