Having been presented with large Electrical demands from my Supplier , Shell, I have tried to calculate my approximate REAL COP.
My gas consumption on December 21 was 888 kWh with an electricity consumption of 174 Kwh.
My Electricity consumption on December 22 was 620 Kwh. Gas having been disconnected.
Assuming my electricity consumption remained the same over both years.
Then , My Heat Pump has consumed 620 - 174 = 446 Kwh.
With my Gas consumption on December 21 of 888 Kwh.
MY REAL COP will be , allowing for all the vagaries about
REAL COP ( circa) = 888/446 = 2
I fully appreciate the annual temperature differences but , I have the strong suspicion that the Real COP is much lower than that calculated from the Heat Pump readings!
This figure is way below the Electricity to gas price ratio!
Could anyone else present their figures comparing the actual Gas consumption against the Heat Pump Energy Consumption.
When it’s cycling here, have either radiators in your house turned off due to TRV settings? or is the secondary pump on the radiator side of the heat exchanger turned off?
It looks to me like the secondary side of the heat exchanger is not being loaded sufficiently and so you are seeing relatively rapid cycling at that point, what changed between the period proceeding that were it seems to be running more consistently?
For another comparison Ian, ours does 5 or 6 over a 4 hour period, obviously only when it’s cold.
On the cycling you are seeing, are you sure that the ASHP is defrosting and not as @TrystanLea suggested oscillating because a thermostat is oscillating around it’s set point. In our system, there are 3 zones. 2 large ones with 4 or 5 UFH loops, the other is v small with only 2 loops. If the small one is about at temperature, I can see the temperatures from the ASHP oscillating a bit. When a defrost cycle is happening there is a LARGE change in the temperatures.
I calculate the total electricity consumption for defrosts on a 0C outside day to be around 0.9 kWh electrical on my system, that’s about 6% of the total electricity consumption by the heat pump in that day. Two thirds of the 0.9 kWh is for recuperating the heat energy lost from the radiator system, 0.3 kWh is for pumping the heat to the evaporator during a defrost.
My Heat Pump has , again, failed to control the Flow Temperature , with the Flow temperature again rising to an unacceptable 65 C for 4 hours.
The Absolute Flow Temperature rises to 65 C !!
The Power surges
The Energy surges ans oscillates
I have now hit the panic button , removing power.
WHO IS RESPONSIBLE FOR SAFETY.?
My “installer” has been STRUCK OFF TWICE .
The MCS,NIC and the RECC “reluctantly” advise that I consult a lawyer!!.
WHO IS RESPONSIBLE FOR SAFETY OF HEAT PUMPS.?
This yet further “instability” occurred , again, when using "Weather Compensation ".
This should NOT be possible! The overload/over temperature safety SHOULD have fired!
My opinion is , again, that either there is something amiss with the Temperature Compensation Control OR the External "Air Thermistor " is intermittently failing.
My former “installer” expressed "concern " about the Samsung Weather compensation controls Field numbers 2091,2092 and 2093.
I have switched the Heat Pump ON again , it again is failing with excessive temperatures.
I have NOW switched Weather compensation OFF by switching OFF field bit 2091.
I have also started the HOT Water tank in Hysteresis mode to stop the Hot Water system from switching ON / OFF too frequently. The HOT WATER thermostat being my other suspect.
My concern was , up until now the very large, for me , Electricity consumption taken by the Heat Pump during December and January.
The Bottom line is that , for whatever reason my electricity bill has risen to ~£240 for December.
Given that my December consumption in 2021 was £86.40 with my current December bill at £243 this gives a 280% increase when the cost per kWh has risen from 20.39 p per kWh to 33.9 p per kWh , or,
166 %.!
We could argue until the cows come home, but, this increase , almost certainly caused, in part, by the Heat Pump, for me, is unaffordable!
To put this into perspective, your heat pump has consumed ~700 kWh in December, which is not particularly high. My own system consumed 750 kWh during the same period, so my bill would be greater at £250. I can point to several other heat pumps with even higher consumption; one of them would have a bill for £460!
The amount of gas you would have needed to burn to get the same amount of heat would likely have cost about the same, especially as the ratio between gas and electric prices has become smaller in recent years.
There’s clearly signs that your heat pump is maybe not running optimally all the time, as we’ve senen in this thread, but I don’t think that it’s costing significantly more than other systems. Once the problems with weather compensation and defrost cycles can be resolved, I reckon it will work quite well.
It seems that the Samsung may be underestimating COP by as much as 30%, as per one of Glyns posts. I will have some good data in about 2 weeks time, once I get proper probes in the pipe work and will let you know what I find.
To do that comprehensively and accurately you will need the modbus module. Without that you will be going through the PDCA cycle and probably never stop.
Investing in the modbus module (and some other bits eg screened two core, a USB module and something to log this data such as emonhub) should give you more data than you can throw a stick at and likely the tools to analyse it.
MCS Installer has ceased trading during the workmanship warranty period: the insurance policy will cover the cost to put right installation faults during the warranty period (between 2-10 years).
If you would prefer to get professional advice and remedial help rather than try to get to the bottom of it yourself with the input that we are trying to give here, then it’s probably best that you get an engineer in somehow.
What was the heat pump doing during this period? was it doing space heating? or hot water? was the secondary pump running on the radiator side of the heat exchanger? how many radiator TRV’s where open?
From a quick look back it looks like your high flow temp issue occurred 7 days ago, along with the time which it started this morning being out with your normal schedules, this suggests to me that it may be trying to attempt a weekly legionella cycle? What temp is your DHW normally set to and do you know if it was much hotter out the tap this morning?
Did you get anywhere with arranging a visit from a Samsung engineer? If you’re struggling getting this arranged through your installer then you may have more luck going to Samsung direct and explaining your issue.
I agree that monitoring equipment would be the way forward, with at least temperature probes and CTs both connected to an emonBase/ emonTx. I have a combination of sensors in pockets and sensors strapped to the pipes and don’t find them to be vastly different in readings, the pocket sensors will be more accurate but are more expensive. Ideally you would have a heat meter to accurately measure the COP, but this can get quite pricey
I have also become convinced that the Over-temperature problem is caused by the Hot Water cycle.
The problem is that the Legionella Temperature is set for 60C for a maximum time of 1 hour.
As I speak the Heat Pump is still stuck in Heating the Hot Water from the outdoor unit in my garden.
The Hot Water temperature is above the set , demanded, temperature of 50 C but the Heat Pump is still stuck in supplying electricity to the Hot Water system!
I have now forced the Hot water Temperature down to 45 C , and, mercifully ,the Hot Water cycling has stopped!! Return to sanity!
This may not be legionella misfiring it could be the standard Hot Water system not stopping at the upper tank Temperature temperature. The Hot water Tank Temperature sensor?
Many thanks Colin , you have made me experiment and think!
What your graph says is that the HP flow temperature is 55 degrees, not that the hot water temperature is 50 degrees. The sensor in the tank could be reading 50 degrees, so the HP thinks the tank still needs more heat. Can you access the temperature as read by the sensor? Could you graph that against the HP flow temperature?
Getting an Engineer has proven to be another nightmare.
I asked the original companies who quoted for the installation to quote for repairs or upgrade.
One company quoted a price “without Warranty” or a price of £5k with warranty. The company demanded £96 for their advice. No thanks. .
A second company, wanted to entirely remove not only the Heat Pump but the pipes and the Radiators, saying that the radiators and pipes were too small. An excellent company but no. !^K is too much.
The third company proclaimed that “i Was to blame for choosing these cowboys”.
The Engineer of the third company had two groups of letters after his name, pretending to hold Learned Society membership. The Learned societies turned out to “City & Guilds”. Again , no thanks.
I am in no doubt that the only people who can fix this are Samsung and Telford.
I have twice been promised a visit from Samsung, but, my Installer described the Samsung bill for travelling from Wigan for three days as “ludicrous”.
As to the problem with the Heat Pump It looks like the Hot Water was called , increased the water temperature but failed to stop reaching 65 C without protest.
It looks like the Hot Water thermostat this time.
My previous problems with the Weather compensation, were also probably caused by the air Temperature Thermistor. The Weather compensation seen to rise and fall unexpectedly.
A case of too many thermistors!
Many thanks for your help. I am getting tired, after 8 months of heat pumps.
I don’t think you can get the elec consumption - but you can get a bunch of other stuff including things like compressor frequency or similar data. See this thread. I have some other renovation jobs to focus on this week (thermal solar, and waste water heat recovery for the shower) but will get back to the modbus stuff soon after.
The Hot Water temperature was above 52 C , the Hot water system , with a maximum temperature set to 50 C ,should have stopped demanding energy from the heat pump.
The High Flow temperature shown on the graphs does not show the actual Flow temperature of 65 C.
My K type sensor is only fitted across the pipe not the water within the pipe.
I forced the System out of Hot Water pumping by lowering the Hot Water Temperature to 46 C.
