I have looked at the Service Menu and noted that the Pump speed is 5 and flow rate 19 l/min, I have dropped it down to 3 giving 16 l/min...................I noticed that on my commissioning document they have noted the pump speed as 3 but I have never altered it until today.
Yesterdays figures which was a cold day are fairly concering at 31.1 Consumed and 39 Delivered = Cop
1.25 ??? (See attached)
I looked back on melcloud to a similar period in january 2020 when I was running on auto adapt mode with timer schedule and you can see that cop was around 3 at that time..........I have never adjusted any settings prior to this exercise other than timer schedules and DHW temperature....I have it serviced yearly so the engineer could have tweaked
things...........not been able to get through to Mitsubishi yet.
I would imagine that the FTC figure for Consumed energy should be fairly accurate as metered input but imagine the delivered energy is less accurate due to the way it has to calculate ??
Based on my records HP Consumed has come out at 2819,3688,3776 & 3819 for last 4 years, last years is lower as it was a generally warmer year, corresponding overall cop figures are 2.19, 2.48, 2.69 & 2.73 (all inclusive of DHW and Heating) you can see the decline (2018 cop for Sep to Dec when installed was 3.11).
Based on your heat loss, it's very unlikely that 39kWh would keep your house warm for 24 hours. From your numbers, I think it'd be more in the 80-100 region on a day like yesterday. 31kWh consumed sounds feasible; 39 delivered doesn't. That's about 1.5kW to heat your whole house.
Thanks Kev.....A simplistic approach is probably always the sensible one..........as you say its obvious to me now 🙄 that Melcloud is the issue or the data reaching it is...............I have a smallish 3 bed semi half 1865 and half 2000, solid walls to 50%, over the trial period the whole house has been @ 20 to 22c dependant on rooms for 24/7 (No setback) so stick a 1.5W electric heater in there just wouldn't do it..................
So I think I can feel satisfied & sleep at night that the cop is not correct and a spend of around £9.50 a day (Yesterday was 29KWh consumed 39 Delivered??) for the above performance is reasonable in todays energy market.
So..........it was queried yesterday why my Delta T was showing around 1C so reduced pump speed to 3 and now getting around Delta T of 2C ( See attached showing pump speed reduced at 15.00 hrs.
Again just thinking in basic terms for the above duty (9 radiators) would the temperature drop expected to be higher??.................Could this be indicative of a sensor on the return giving false readings to Melcloud?
What is the ideal Delta T ?........I have read elsewhere that 5 is acceptable with heat pumps but if Melcloud is correct then I would have to slow the pump down so much to achieve 5 that I would be running at a flow rate below ecodans recommendation.
Interested in yours or anybody's thoughts before I get onto Mitsubishi or original installer.
At least I seem to have refined the WC curve as to achieve the figures above I am on a 36@-5 and 25@20C Curve, the dilemna now is to see what auto adapt mode does for the spend and comfort levels with a small setback at night.
Thanks Kev.....A simplistic approach is probably always the sensible one..........as you say its obvious to me now 🙄 that Melcloud is the issue or the data reaching it is...............I have a smallish 3 bed semi half 1865 and half 2000, solid walls to 50%, over the trial period the whole house has been @ 20 to 22c dependant on rooms for 24/7 (No setback) so stick a 1.5W electric heater in there just wouldn't do it..................
So I think I can feel satisfied & sleep at night that the cop is not correct and a spend of around £9.50 a day (Yesterday was 29KWh consumed 39 Delivered??) for the above performance is reasonable in todays energy market.
So..........it was queried yesterday why my Delta T was showing around 1C so reduced pump speed to 3 and now getting around Delta T of 2C ( See attached showing pump speed reduced at 15.00 hrs.
Again just thinking in basic terms for the above duty (9 radiators) would the temperature drop expected to be higher??.................Could this be indicative of a sensor on the return giving false readings to Melcloud?
What is the ideal Delta T ?........I have read elsewhere that 5 is acceptable with heat pumps but if Melcloud is correct then I would have to slow the pump down so much to achieve 5 that I would be running at a flow rate below ecodans recommendation.
Interested in yours or anybody's thoughts before I get onto Mitsubishi or original installer.
At least I seem to have refined the WC curve as to achieve the figures above I am on a 36@-5 and 25@20C Curve, the dilemna now is to see what auto adapt mode does for the spend and comfort levels with a small setback at night.
As a trial, I would suggest dropping the pump speed to 1 for a period of time and see if the DeltaT improves. The Ecodan is designed to control the DeltaT at 5C.
Thanks Kev.....A simplistic approach is probably always the sensible one..........as you say its obvious to me now 🙄 that Melcloud is the issue or the data reaching it is...............I have a smallish 3 bed semi half 1865 and half 2000, solid walls to 50%, over the trial period the whole house has been @ 20 to 22c dependant on rooms for 24/7 (No setback) so stick a 1.5W electric heater in there just wouldn't do it..................
So I think I can feel satisfied & sleep at night that the cop is not correct and a spend of around £9.50 a day (Yesterday was 29KWh consumed 39 Delivered??) for the above performance is reasonable in todays energy market.
So..........it was queried yesterday why my Delta T was showing around 1C so reduced pump speed to 3 and now getting around Delta T of 2C ( See attached showing pump speed reduced at 15.00 hrs.
Again just thinking in basic terms for the above duty (9 radiators) would the temperature drop expected to be higher??.................Could this be indicative of a sensor on the return giving false readings to Melcloud?
What is the ideal Delta T ?........I have read elsewhere that 5 is acceptable with heat pumps but if Melcloud is correct then I would have to slow the pump down so much to achieve 5 that I would be running at a flow rate below ecodans recommendation.
Interested in yours or anybody's thoughts before I get onto Mitsubishi or original installer.
At least I seem to have refined the WC curve as to achieve the figures above I am on a 36@-5 and 25@20C Curve, the dilemna now is to see what auto adapt mode does for the spend and comfort levels with a small setback at night.
I suspect your flow and return temps are not accurate. I doubt 36 degrees with radiators would heat your house in the current weather. Are the rads hot or just warm? 36 is just warm, think baby bath temperature. Do you have a thermometer you can test the rads with?
If the flow temp is under-reading by a few degrees this would make the energy delivered an underestimate. Do you know where the flow and return the sensors are? It's very easy to install them, badly; if they aren't in purpose made pockets (and they probably aren't) they should be firmly attached to a copper pipe and covered with insulation.
Mine were originally poorly installed and under-read by about 4 degrees. Fortunately they were both equally bad.
Mine were originally poorly installed and under-read by about 4 degrees. Fortunately they were both equally bad.
I think we may have a bit of a false reading on ours… I’ve fitted 2 bezel thermostats closer to the heat pump (for visual curiosity) and they show regular 5 to 8 c Ta whereas the electronic measurement on the controller shows 2 or 3 C differential. @Kev-m do you know if the COP calculation relies on Ta readings?
@sunandair I have MMSP so my COP calculation uses the heat meter and consumption meters that came with that. For a standard Ecodan or other ASHP I don't know. I can't see how else it could measure heat produced other than using the volume of water heated and temperature raised. I think it will either (1) use the delta T and its own estimate of flow rate or (2) use lookup tables based on ambient temp and LWT. Neither is going to be very accurate.
I dropped the pump speed to 1 running at 10 l/min and Delta T increased to about 2.5 / 3 c on Melcloud, I had two clip on thermometers which are of dubious quality and they are showing reasonably close to what temperatures are being indicated on melcloud and the delta t above. The attached shows flow and return temps where speed was 2 for first half the day and 1 second half, can see marginal difference in Delta t
I don't know if its a coincidence but the indicative energy consumption on melcloud has fallen in line with the pump speed being reduced in increments over similar days temperatures.
My query now is should I keep running it at the low speed or back up to a maximum (5) as it was installed or go for 3?
Not sure if I have a buffer or low loss header tank, I know up there in the loft there are two expansion type vessels of similar size?..........both uninsulated.
Im thinking they may look un-insulated but the insulated ones have an outer shell. If they have a product plate you may be able to check their serial number... would have thought they will be insulated. Typically 2 expansion vessels needed on a dual heating circuit.
Update on our installation; we have just had our faulty ftc6 controller replaced.
So that I can try to create a mental picture of your system, the pump whose speed you have been changing, is it located inside your heat pump or external?
If your system is happy running with a pump speed of 1 and it improves efficiency, then I see no reason to change back, unless you wish to carry out a trial to see if the efficiency again reduces.
It would be useful if you try to draw a schematic of your system. If there are items that you don't recognize then either find the manufacturer's nameplate and Google the model number, or provide a photo and we can see if we can locate the details.
Im thinking they may look un-insulated but the insulated ones have an outer shell. If they have a product plate you may be able to check their serial number... would have thought they will be insulated. Typically 2 expansion vessels needed on a dual heating circuit.
Update on our installation; we have just had our faulty ftc6 controller replaced.
I have an Ecodan with 2 expansion vessels and I definitely have no buffer or LLH.
@sunandair, good news on getting the FTC6 replaced.
Im thinking they may look un-insulated but the insulated ones have an outer shell. If they have a product plate you may be able to check their serial number... would have thought they will be insulated. Typically 2 expansion vessels needed on a dual heating circuit.
Update on our installation; we have just had our faulty ftc6 controller replaced.
Just managed to get in the loft and look at this.
I do have both expansion tanks but I also have the low loss header which is part of the packaged cylinder unit....definately no buffer tank.
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