Derek,

from what I can see the meter is receiving and recording data; flow rate, flow and return temps and kWh.  Just not the right data and the temp sensors are definitely wrong at the moment. I'll see if I can record some real time numbers and I'll also have look at the (non-MMSP) sensors. 

@kev-m 

Hi Kev,

For clarity, could you please identify which readings you think are incorrect, is it the ones on the MMSP or the FTC controller? A set of readings from both would be useful. It could be that the FTC controller has not been correctly configured to match the signals coming from the heat meter and/or electricity meters. I have seen this time and time again in the past when I have been commissioning industrial systems.

Hi guus

How do I work out relative heat loss/ usage based on m2? I'm wanting to work out whether my house insulation is performing well or not

Thanks 

Posted by: @hr_3

Hi guus

How do I work out relative heat loss/ usage based on m2? I'm wanting to work out whether my house insulation is performing well or not

Thanks 

Hi HR_3,

I'm afraid it is not quite as simple as watts per m2. Your heat loss will probably vary from room to room, rooms with larger window area will have a higher heat loss than rooms with a smaller percentage of glass. There is a spreadsheet that can be downloaded from MCS, that will help you to calculate the heat loss room by room.

@hr_3 do you know your current heating use in kW? You can just divide this by the total area of your house and that's your w/m2. However this will vary depending on the temperature outside - so you would need to do it at multiple temperatures to generate your own heat loss estimations.

Posted by: @derek-m

@kev-m 

Hi Kev,

For clarity, could you please identify which readings you think are incorrect, is it the ones on the MMSP or the FTC controller? A set of readings from both would be useful. It could be that the FTC controller has not been correctly configured to match the signals coming from the heat meter and/or electricity meters. I have seen this time and time again in the past when I have been commissioning industrial systems.

I've just had a look. The MMSP heat meter is showing 37C flow, 33C return.  I think the flow is correct; it corresponds to my reading from the inlet to a radiator that is a few feet away from the heat meter flow temp sensor (this one is correctly installed in a pocket).  The return sensor isn't installed correctly but it shouldn't be far off as it's taped to a copper pipe. 

Melcloud, which gets its info from the Ecodan, is showing 31/27 (ish).  I think therefore it's under-reading by 6C or so - at the moment.  So I think when my compensation curve asks the ASHP for 31C, it heats until it reaches what the sensor thinks is 31C, except it's really 37C.  I also don't know whether the under-reading is linear; i.e. if it's the same % at different temperatures.  

it's good that my house is nice and warm at 37C flow/2C ambient but it makes it quite hard to control the system using flow temps. It really needs to be sensing them correctly.  I could have go at fixing this but I want to speak to the installers first.  Having said all of this, I'm still very pleased with the system. 

Posted by: @derek-m

@kev-m 

Hi Kev,

I think that you said before that you don't have a buffer tank, but do you have a low loss header?

Do you have any pumps in addition to the one inside the ASHP?

For the sensors that are zip-tied to the pipework, once we find out what type they are it may be possible to either ask for them to be replaced by your installer with pipe clamp type or the installation of thermowells. First it is necessary to find the best location, so that they are providing both accurate and consistent measurements. See if there is any writing or labels on the sensors connected to the FTC controller to identify them. They could be a PT100 or PT500, which can easily be sourced at quite reasonable cost.

No buffer or low loss header. Two additional pumps. 

The Ecodan sensors would be a 300mm to the right of the heat meter on the same pipe run on this diagram. 

@Kev-M - I am pretty sure that within the service settings of the FTC there is one for adjusting the thermistors, which I presumed to be to allow for the fact that they might not be reading true.

@hjd ,

thanks, yes there is, I saw that yesterday.  You can adjust the flow and return up/down by 10. I'm not sure whether to tinker with that or leave it to the installer.  Wouldn't do any harm I suppose and I can always put it back.  

@kev-m 

Hi Kev,

Having ambient air temperatures around 2C is not very good for ASHP operation, because it will increase the number of defrost cycles.

Adjusting the calibration setting of the temperature measurements probably will not improve efficiency, and could make matters worse. Calibration of a measuring system involves making an adjustment at the lower end of the range (zero), when testing against a known standard. A further adjustment would then be made at the upper end of the range (range) against the same standard measurement device. Since there may be interaction between the 'zero' and 'range' adjustments, this process would be repeated until both measurements are correct without further adjustment. The overall calibration would then be checked at 20% steps over the full range. Making adjustments to a systems calibration to correct for poorly installed sensors is not the correct way to resolve the issue.

To reduce overall energy consumption to the absolute minimum requires correct operation and optimisation, rather than just offsetting readings.

What are the settings of your weather compensation curve? Do they match those shown in the modelling tool after allowance for incorrect temperature indications has been made?

Reduce the indoor air temperature to the minimum acceptable level, using the weather compensation offset.

Consider lowering the indoor air temperature by 1C overnight.

Lower the DHW tank temperature to the minimum acceptable level, and set the controller to heat the water during the mid to late afternoon period, when the ambient air temperature is probably at a maximum for the day.

Derek,

that was my worry about just offsetting the thermistors; it might correct it at one end but not the other.   

My weather comp curve says 33.3C at 0C.  I've got it offset to -2, so that's 31.3C at 0C.  Melcloud was showing exactly that last night.  The model suggests I need 39C to heat my house to 21C and will use c. 2.2kW.  That's close to what I'm seeing. 

I suppose it doesn't really matter that the sensors are under-reading as they are still doing a good job of controlling the room temperatures. 

I've now got the curve about right on an offset -2 so I'm happy enough. As you suggest I may bump it down a notch overnight and see what happens.  If all is OK I'll recalibrate the curve it so it runs with zero offfset. 

I do need to look at the HW timer as it's coming on at random times.  It could also come down a bit as 50C is a bit hot.   

Kev  

@kev-m 

Hi Kev,

One further area were it may be possible to reduce energy consumption by a few percent, would be by tightening the 'heat pump thermo. diff.' setting during the Winter period. I mentioned the upper and lower settings before when you were concerned about the cycling during milder weather conditions.

If you look at your MELCloud graphs showing the water flow temperature, you may see that the temperature goes above the required weather compensation value and then falls below for a period of time. If this is the case, then lowering the upper setting and increasing the lower setting should reduce the variation, and may improve efficiency. I may be wrong, in that when the ASHP is running continuously during colder weather, the water flow temperature is controlled and does not reach the limits.

I would be interested to see that graphs and also the frequency and effect of the defrosting cycles.