I think my interest in heat pumps began after reading the late David MacKay FRS’s Sustainable Energy without the hot air in 2008 https://www.withouthotair.com. Then it was meeting @johncantor and seeing the data from his heat pump that convinced me to install one at home rather rather than going down the biomass heat route.
That’s quite a large range but certainly worth testing. Have you explored setting a hot water timer so that the hot water is heated in longer batches? e.g once at 2am another at 2pm… Or perhaps even a single heat up, if that’s sufficient for your hot water requirements.
I just had a look at what my system does when defrosting, and it doesn’t use hot water from the tank at all, it circulates the water from the heating system. During this 5 minutes, it consumed between 311W and 1451W, but mostly around 1000W, 0.065kWh total.
This reduced the flow temperature from 39.8 to 26.3, and the temperature of a radiator I’m monitoring went down from 33.6 to 29.3. It then took 17 minutes running the heat pump to get the radiator back to 33.6.
I don’t know the answer to your question but I think it may be cheaper overall for you to use water from the heating circuit than hotter water from DHW, to do your defrosts.
My Heat Pump, manufactured in 2021 , was later fitted with a Buffer tank under instructions from Samsung.
The Specific reason that Samsung asked for the fitting of a Buffer tank was de-icing.
As now configured my Heat Pump is filling the Hot Water system with energy during a 2 to 4 hour period in the early morning.
The Hot Water burst in the morning consumes upward of 2 KWh of energy.
******************************* BUFFER TANKS OR HEAT EXCHANGERS *****************
Buffer tanks or Heat Exchangers have been installed for three different reasons.
Heat Pump protection using Buffers or Heat Exchangers
If a Heat has only one pipe circuit , containing a Heat Pump , a water pump and a series of Radiators , the Heat Pump would have it’s Water flow cut OFF should the user switch OFF ALL of the radiators.
To protect the Heat Pump either a Buffer is used or a Heat Exchanger can be used.
A) Heat Pumps protected by Buffers
A buffer tank is inserted across the Radiators to present a Volume of water that the Heat Pump can supply if the all of the Radiators are shut.
Kensa have produced an excellent description of this kind of tank
B) Heat Pumps protected by a Heat Exchanger.
A heat Exchanger is inserted into the water circuit , cutting the single Water circuit in two.
The Heat pump is totally protected from the Radiator circuit by the Heat Exchanger…
2) Heat Pumps fitted with buffers for Cycling reduction
If a Heat Pump is heating a small volume of water , the Heat stored in the water will quickly dissipate, causing the Heat Pump Thermostat to be asked to produce more energy .
The Period of time taken to dissipate the stored energy is called the Cycle time.
The Larger the Volume of water , the larger the Cycle Time.
To increase the cycle time a Volumising tank is installed.
A Volumising tank is only a buffer with a different purpose.
MCS have produced a good article on the size of tank for this kind of “Volumising Buffer tank”
Reducing the Hot Water by reducing the Hot Water Starting point Field bit 3023
AND / OR
reducing the Hot Water Stopping point Field bit 3022
still consumes lots of energy!
Stopping the Hot Water system using Field bit 3011 interferes with Energy storage during De-icing.
**To Switch the Hot Water System OFF, switch the front panel control OFF.
I have only now discovered why my Samsung heat Pump fails to produce enough energy during the Winter.
My “installer” installed a 5 KW Samsung when the MCS calculations show a 8KW heat pump was required.
I received three quantitations to install the heat pump
Quotation no 1 from the "installer " whom I chose to install the Heat Pump specified a **
** Warmflow A501-R32 with a power specification of 8 KW.
** My “installer” installed a 5 KW Samsung.**
Quotation No 2 was designed using the MCS design sheet for a Medea MHC-V8 8 KW Heat Pump.
Quotation No 3 was designed for a Mitsubishi Daikin with a MCS specified power of 8 KW.
I have a 5 kW heat Pump installed to meet a 8 kw demand.!
My “installer” , on asked why the heat Pump was made available so quickly , commented that the Samsung had been made available by their supplier .
No one will accept responsibility for this fiasco .!
All of the “regulators” , MCS,NIC and RECC advise Legal action.
Legal action is Impossible, “I would win the case but would be made Bankrupt in the process”.
{ a retired ,former QC at the Court of session , Edinburgh }
You need to check what your Invoice/receipt says. If you paid for an 8 kW unit and got a 5 kW, it looks like fraud to me. If you were quoted an 8 kW unit and were invoiced and paid for a 5 kW, you should have checked when it was installed.
If you are a victim of a fraud, then it might be worth a call to your insurance company to see if you’re covered.
Many thanks for your comments about my Heat Pump .
My “installer” has now been "Struck OFF " twice by the MCS,NIC and RECC regulators.
The NIC have said that , with the removal of the company from NIC,MCS and RECC “accreditation no further action is possible by any regulator.”
The Regulator’s power only consists in the threat to remove accreditation. Once accreditation has been removed , the regulators have no further leverage.
The Power supplied by the Heat Pump is is not immediately apparent from the technical descriptions…
An explicit description of the power of the Heat pumps is not provided…
My installer described their selected heat pump as a Warmflow A501-32.
A second company chose a Medea MHC-V8 heat pump.
A third company chose a Mitsubishi Daikin Ecodan.
All three companies actually quoted for 8 KW Heat Pumps.
My installer installed a 5 Kw Samsung Heat Pump under the name AE050RXYDEG .
All of the numerous pages of guarantees and insurances have not been checked, but the Regulators , NIC and RECC are very sceptical .
The Hot Water tank is still, however,continuously topping up the Hot Water boiler , interrupting the Room heater radiators, and consuming lots of energy, and money.
My Heat Pump
First Takes energy from the Volumising tank
THEN
Second takes energy from the Hot Water Cylinder.
THEN
Starts the Heat pump to replenish the energy stored in the Hot Water tank.
A functioning Hot Water system is required for de-icing, at all times.
When OFF , the Hot water tank is still called but, becomes uncontrollable, reaching a flow water temperature of 65 C.
I keep my hot water system ON , at all times.
Are you using a Backup boiler ?
Have you noticed the very low, 10 ma current supplied by the Backup boiler control on B$/B% of TB-B ?
Surely 10 ma on a 240 VAC supply is very low for a relay?
All of the controls on TB-B seem to have very low operational currents ?
Am I getting old , or are mains relays operating with 10-22 ma currents?
This sounds very wrong to me but I only have experience of my own system.
I’m not using a backup boiler and I have no idea about the other questions you asked about currents.
Do you know who actually supplied your heat pump to your installer? Do they have their own installation manual? Mine was supplied by Freedom Heat Pumps who provide their own manual to be used instead of the Samsung tomes which as you have said don’t read well.
Honestly, if I had your problems I would reset the Samsung settings to factory default and start again with a basic configuration from the Freedom manual.
Might be worth spinning this off into a separate thread. I too have four connections and can’t work out if the Kensa two connection design would benefit or not.
I have , on several occasions , reset the Field parameters to their defaults.
Neither my “installer” , nor Telford , nor Samsung provided any documentation or test results with this Heat Pump.
Telford , the tank manufacturer now says that my Heat Pump , manufactured in 2021 is “Too old”, and that they do not keep documentation for “old Heat Pumps”.
Telford also says that "any questions should be directed at Samsung who “designed” this system.
So, I have no paperwork to show the results of the “manufacturing tests performed on this Heat Pump and Cylinder”.
********************************** DE-icing loss ***********************************************************
The relatively warm outside winter temperatures of 10 … 11 C have not provided any evidence on the energy consumed during De-icing.
I have , however kept the Data from 31 st Jan until today 12 th Feb.
DE-icing incident no 1
A very large De-icing incident occurred between 4 am and 8 am on the morning on 1 Feb 2023.
The incident consumed 3384 Wh of energy
3384 Wh represents (3384/11842) x 100 = 28 % of the Total Daily consumption.
The Samsung records the COP as 3.2 on 31st Jan and 2.6 on 1st Feb.
The decrease in COP to 2.6 does record the FALL in Energy Generated.
The Samsung is recording the energy consumed during De-icing.
DE-icing incident no 2
A very large De-icing incident occurred between 4 am and 8 am on the morning on 10th Feb 2023.
The incident consumed 3563 Wh of energy
3563 Wh represents (3563/10608) x 100 = 33 % of the Total Daily consumption.
The COP of 3.5 does NOT record the FALL in Energy Generated.
The Samsung is here NOT recording the energy consumed during De-icing.
The Samsung records the COP as 3.5 on both the 9th and 10th Feb.
Conclusions
1) De-icing is consuming about 30 % of my normal daily consumption.
The Energy shown as generated by the heat pump sometimes includes the Energy consumed during de-icing.
3) A 30% addition to the Energy consumption during de-icing is unacceptable.
*********************************** Water Law graph in use ********************************
I have tested the Water Law Temperature Compensation on my Samsung Heat pump using the Water Law graph.
Testing Weather Compensation on Samsung Heat Pumps.
Stop the Hot Water system, using the front panel control.
Get the outside Temperature.
enter the Outside Temperature into the X coordinate of the Water Law graph.
Look up the Y coordinate , The Flow Water Temperature , from the Water Flow Graph.
using the Water Compensation Display on the front panel of the Samsung enter a Zero offset into the Thermistor Offset.
|666x500](upload://zAARVbQaNFXuOHUfR4jz1ss2GyL.jpeg)
Over a period of perhaps 30 minutes the Flow Water Temperature, displayed on the front panel will rise and fall by about +3 C.
record the LOWEST temperature that the Thermostat falls to.
The Lowest value should be equal to that obtained from the Water Law Graph.
record the period , or Cycle time ,between these Lowest readings.
I have now bought a stand alone Digital K Type thermometer.
With this device I have extended my measurements to include the Radiators.
After stopping the Hot Water system I discovered the following Temperatures.
Flow Water Temperature, correctly generated by the Weather Compensation system on the Samsung
to be 42 C .
The Temperature at the Heat Exchanger port had dropped to 37 C.
The Temperature at the Heat Exchanger output had fallen to 31 C.
The Temperature at the principal Radiator was 32 C.
The Radiator , A Stelrad K3 when fed with water at 32 C will reduce the operating factor by 0.505.
The K3 at 50 C produces 2900 W, and 1.5 Kw at 32 C.
The Room has a conductance of 77 W per C, at an outside temperature of 11 C and a required room temperature of 21 C, the Radiator would have to supply 700 Watts against a supply of 1500 Watts.
The Room will be warm with something to spare.,
However,
When the outside temperature is -8 C and a room Temperature of 21 C is required , the Radiator would have to supply 2233 Watts against a supply of 1500 Watts.
The Room will be cold, very cold.
Conclusions 1) The Flow Water Temperature drop of 10 C between the Heat Pump and the Radiator is excessive.
The principal cause of this drop is the Heat Exchanger, but, both motors , the piping and the flow switch contribute nearly as much.
3) The Pumps and motors will have to be upgraded to supply a greater temperature to the Radiators.
Hello @iantelescope catching up here. Read your last few posts.
You mention some confusion about the kW rating of the heat pump supplied. Do you have the MCS calculations for your house by any chance? If you get 3 quotes for a heat pump it can be quite normal to receive two at e.g 8kW and one at 5kW. Some installation companies will tend to oversize out of caution. The question is which one is correct!? I’ve done my own heat loss calculations which is a worthwhile exercise, see my blog posts here: https://trystanlea.org.uk/roombyroomheatloss, and here: https://trystanlea.org.uk/roombyroomheatloss2. This blog post by @Zarch is also a great resource: What Size Heat Pump? | Energy Stats UK
Great, interesting results there, those are large temperature differences across the heat exchanger, lots to improve on there! You want to get those temperature drops to be a degree or two at most!
All three of the companies who initially quoted for my Heat Pump initially quoted for 8 Kw Heat Pump.
Because of the difficulties in procuring the 8 Kw Warmflow heat pump my eventual "installer " reduced the specification to a 6 Kw Warmflow .
The 6 kW Warmflow being unavailable , my “installer” then provided with a “special” 5 Kw Samsung by his supplier.
The 5 Kw Heat Pump arrived and was installed and fired up without water in the primary Water loop.
My “installer” was “not aware of the Heat Exchanger” until 14 days later , when My objections finally forced the installation of a Expansion tank,PRV and a third attempt at installing a flow switch.
The “designer” had no knowledge about the Heat Exchanger fitted to the tank.
Joule have issued a warning that in "winter conditions down to -3 C , the Samsung will only provide 4.35 Kw…
How much power the Samsung actually provides at -6 C … -8 C is anybody’s guess, 3.5 Kw ?
Finally, my second choice for installer , volubly objected to the Calculations by my eventual installer, saying that , if installed he would “rip out , not only the Samsung, but the Radiators and the Pipework.”
My eventual installer, was however," quietly confident in his calculations."
My Second installer has since restated his case that the % kW is too small , as is the size of the Radiators.
The Water Temperature Drop across the Indoor is an underestimate being based upon only the Indoor unit itself. Also I am , as usual measuring the Temperatures on the outside of the pipes.
