Posted by: @derek-m

↑

Thank you for providing a redacted copy of the raw data, I am always amazed at how trusting humans can be.

Without giving away any state secrets, could you please identify when the compressor, primary water pump and secondary water pump, are actually operating?

Can you provide an estimate of how much of the DHW thermal energy may have 'leaked' out, or been 'released', within the thermal envelope, and how much was 'flushed' down the drain, so to speak.?

It's not you I don't trust, it is any human being (me included), as it is impossible not to see the data in the file! 

The fan speed might be a proxy for the compressor, I'll check and let you know. Both the primary and secondary pumps appear to run continuously whenever the heating is on and calling for heat, ie they run all the time except during the setback. The evidence for the primary pump is that there is always (E&OE) a flow rate above zero except when in setback, for the secondary pump it is eyeballing the pump's LEDs.

The DHW tank is a bit of a mystery, it loses temperature at about 10 degrees per 24 hours even with minimal hot water use. It is a standard Telford Tempest ~200L heat pump model, and all the heat released from the tank is released within the thermal envelope (airing cupboard). 

Posted by: @cathoderay

↑

Posted by: @derek-m

↑

Thank you for providing a redacted copy of the raw data, I am always amazed at how trusting humans can be.

Without giving away any state secrets, could you please identify when the compressor, primary water pump and secondary water pump, are actually operating?

Can you provide an estimate of how much of the DHW thermal energy may have 'leaked' out, or been 'released', within the thermal envelope, and how much was 'flushed' down the drain, so to speak.?

It's not you I don't trust, it is any human being (me included), as it is impossible not to see the data in the file! 

The fan speed might be a proxy for the compressor, I'll check and let you know. Both the primary and secondary pumps appear to run continuously whenever the heating is on and calling for heat, ie they run all the time except during the setback. The evidence for the primary pump is that there is always (E&OE) a flow rate above zero except when in setback, for the secondary pump it is eyeballing the pump's LEDs.

The DHW tank is a bit of a mystery, it loses temperature at about 10 degrees per 24 hours even with minimal hot water use. It is a standard Telford Tempest ~200L heat pump model, and all the heat released from the tank is released within the thermal envelope (airing cupboard). 

 

If you just show when the Amps are zero, that should indicate that the compressor is not operating.

The specification for the hot water cylinder should indicate a standard rate of heat loss.

Posted by: @derek-m

↑

If you just show when the Amps are zero, that should indicate that the compressor is not operating.

The specification for the hot water cylinder should indicate a standard rate of heat loss.

I've added a column, comp_on, 0 for off, 1 for on, based on amps > 0 or not. Note the htg_on_off and dhw_on_off columns are based on the three port two way valve position, and are used to detect when the heat pump is heating the DHW, not whether the heating itself is on, as the valve can be in the space heating position, but the heating is off. However, when it is in the DHW, and the compressor is running, then it is heating the DHW. Revised data attached below. 

Incidentally, this is what causes one of the hourly data anomalies. The DHW takes less than an hour to heat, typically 30-40 mins, leaving 20-30 mins in that hour that will be used for space heating, making that hour appear to have an oddly low heating energy in value, seen as the below the line outliers in the scatter plots. I usually discard these values as they are small in number, and they distort the picture (an hour's data needs to contain an hour's worth of energy in).

According to the manual, the DHW tank I have has a standing loss of 2.04kWh/24h.

@cathoderay

Can you please confirm that your secondary water pump does indeed continue to run when your heat pump goes into an 'off' cycle.

I think some time ago you provided details of the temperature reduction across the PHE. Could you please confirm those values and that you are happy for those values to be used. I feel certain that you are aware that variations in the DT across the PHE and deviations in the OAT readings will negatively impact the accuracy of the results produced by the spreadsheet.

I would have thought it quite a simple matter to take daily readings from your main electricity meter, daily readings from your heat pump electricity meter and do the simple maths to get the daily house use excluding the heat pump. Maybe you could make an effort and try.

@cathoderay

Could you please provide details of the WC curve settings, and also confirm the your AA mode is still limited to +/- 3C around the calculated WC value.

Are there any maximum and minimum limits set for LWT, and if so what are they?

@cathoderay

There is one further question. The hourly average LWT derived from the minute data can be obtained in two alternative ways, one way is to sum all the minute values and divide by 60, the alternative being to sum the minute values for only when the compressor is running, and divide by the appropriate value.

Which method did you use?

Posted by: @derek-m

↑

Can you please confirm that your secondary water pump does indeed continue to run when your heat pump goes into an 'off' cycle.

I think some time ago you provided details of the temperature reduction across the PHE. Could you please confirm those values and that you are happy for those values to be used. I feel certain that you are aware that variations in the DT across the PHE and deviations in the OAT readings will negatively impact the accuracy of the results produced by the spreadsheet.

I would have thought it quite a simple matter to take daily readings from your main electricity meter, daily readings from your heat pump electricity meter and do the simple maths to get the daily house use excluding the heat pump. Maybe you could make an effort and try.

No need to get sarky again.

As far as I have been able to ascertain, the secondary pump always runs when the heating is on, as in the thermostat is calling for heat, so it does carry on running throughout normal cycles. There appear to be three states (bearing in mind the room stat is actually used as an on off switch:

1. room stat not calling for heat = heating off (as in setback periods and over the summer (secondary pump is off)

2. room stat is calling for heat and compressor is producing heat = heating is on and heating (secondary pump is on)  

3. room stat is calling for heat but compressor is not producing heat = heating is on but not heating (however secondary pump is on). This is the state during a LWT/RWT cooling period in normal running.

Getting valid measurements for the PHE temps is as I have said before problematic. I suggest you use the ones I provided earlier with this caveat (they may be out) borne strongly in mind. That said, the values aren't absurd.

I already record those readings, but not quite in that format. For example:

Main house meter use over most recent Mon to Mon week: 278 kWh

Heat pump meter use over same period: 234 kWh      

Average daily non-heat pump use: 6.29 kWh   (seems reasonable for late December).

Posted by: @derek-m

↑

Could you please provide details of the WC curve settings, and also confirm the your AA mode is still limited to +/- 3C around the calculated WC value.

Are there any maximum and minimum limits set for LWT, and if so what are they?

WCC settings: baseline is 56 @ -4 / 34 @ 15, AA mode variation is still limited to +/- 3C.

I am not sure if the LWT itself has limits itself, but the endpoints for the WCC, which sets the LWT, do: 25 - 60C.

Posted by: @derek-m

↑

There is one further question. The hourly average LWT derived from the minute data can be obtained in two alternative ways, one way is to sum all the minute values and divide by 60, the alternative being to sum the minute values for only when the compressor is running, and divide by the appropriate value.

Which method did you use?

This has to do with energy out, not energy in, meaning I don't use it for the observed vs expected calculations, which only look at energy in. That said, I use the former, all minutes are included whether the compressor is running or not, on the grounds heat is still being delivered if there is a flow rate and a LWT/RWT delta t, even if the compressor has temporarily stopped running ie it accommodates the transition phase. If the delta t gets very low, very little heat is actually delivered, and when it gets to zero, none is delivered, even if the flow rate remains above zero.  

I doubt ye will ever be able to conclusively agree on the interpretation of the data. Could it be that yes fabric of house cools a bit but the real feel is all that matters and that the fabric is always recovered quite quick to the a degree that it wont affect real feel. Currently with setback from nov5-jan5th, im trending at35% less usage then last winter. That is the difference from 7 zones to 1 and not using stat on/off. Its constant running from 11am-9pm nowadays. I know running 24/7 costs me roughly 30kwh, running from 11-9pm is 14-16 both include dhw. Think kev-m also reported energy saving. So 3 people are indicating setbacks save energy. Yes running24/7 has bit more comfort but not by that much. I will have to see how my setback works in next cold snap as i was in Scotland for the last snap.

@newhouse87 - I agree, the few people who have reported their findings (very much to their credit, if only others would, then we would have a better overall picture!) have all suggested there are measurable savings to be had, yet the 'theorists' always seem to think what you see is not what you get. Perhaps the truth will lie somewhere in the middle. I am awaiting @derek-m's predictions for my recent energy in based on his model with interest, because it will provide a test of the model's predictive capabilities as tested against the real world.

I also think you are right about the feel, ie what we perceive in the way of comfort. We are not digital thermometers with a LCD readout, but rather complex beings that take many subconscious inputs and end up with a summary conscious output: we do or don't feel comfortable, and even then, when we are comfortable, we probably aren't explicitly conscious of it most of the time, we only register it when we are not comfortable!  

Posted by: @newhouse87

↑

I doubt ye will ever be able to conclusively agree on the interpretation of the data. Could it be that yes fabric of house cools a bit but the real feel is all that matters and that the fabric is always recovered quite quick to the a degree that it wont affect real feel. Currently with setback from nov5-jan5th, im trending at35% less usage then last winter. That is the difference from 7 zones to 1 and not using stat on/off. Its constant running from 11am-9pm nowadays. I know running 24/7 costs me roughly 30kwh, running from 11-9pm is 14-16 both include dhw. Think kev-m also reported energy saving. So 3 people are indicating setbacks save energy. Yes running24/7 has bit more comfort but not by that much. I will have to see how my setback works in next cold snap as i was in Scotland for the last snap.

Could you clarify how you assess that you are achieving what would appear to be a 50% reduction in electrical energy use?

Posted by: @cathoderay

↑

@newhouse87 - I agree, the few people who have reported their findings (very much to their credit, if only others would, then we would have a better overall picture!) have all suggested there are measurable savings to be had, yet the 'theorists' always seem to think what you see is not what you get. Perhaps the truth will lie somewhere in the middle. I am awaiting @derek-m's predictions for my recent energy in based on his model with interest, because it will provide a test of the model's predictive capabilities as tested against the real world.

I also think you are right about the feel, ie what we perceive in the way of comfort. We are not digital thermometers with a LCD readout, but rather complex beings that take many subconscious inputs and end up with a summary conscious output: we do or don't feel comfortable, and even then, when we are comfortable, we probably aren't explicitly conscious of it most of the time, we only register it when we are not comfortable!  

I doubt whether anyone is going to post on the forum that setbacks are actually causing them to use more electrical energy, even if they knew that to be the case. It is human nature to brag about wins, and conveniently forget about defeats.

Posted by: @cathoderay

↑

@newhouse87 - I agree, the few people who have reported their findings (very much to their credit, if only others would, then we would have a better overall picture!) have all suggested there are measurable savings to be had, yet the 'theorists' always seem to think what you see is not what you get. Perhaps the truth will lie somewhere in the middle. I am awaiting @derek-m's predictions for my recent energy in based on his model with interest, because it will provide a test of the model's predictive capabilities as tested against the real world.

I also think you are right about the feel, ie what we perceive in the way of comfort. We are not digital thermometers with a LCD readout, but rather complex beings that take many subconscious inputs and end up with a summary conscious output: we do or don't feel comfortable, and even then, when we are comfortable, we probably aren't explicitly conscious of it most of the time, we only register it when we are not comfortable!  

I doubt whether anyone is going to post on the forum that setbacks are actually causing them to use more electrical energy, even if they knew that to be the case. It is human nature to brag about wins, and conveniently forget about defeats.