Dear all,
In the quest of reaching the higher CoPs, and to better harness the inertia of my under floor heating, I made an experiment last night.
FSV 2093 = 1, WL min = 40
No cycling, although the CoP is not the best it averages around 4.1.
So clearly yes, the 2093 setting has a real fat impact on how to avoid cycles. I just added an automation to stop the zone 1 heating when ambient temperature raises of 0.2 (to try to cope with the high inertia of the underfloor heating).
Cheers,
fsv 2093 can be 1 or 2 or 3 or 4:
Samsung documentation (DB68-08470A-15_IB_EHS_Wired_Remote-Control_Kit1_EU_Boook_EN_231117-D01 page 29/60) says:
Remote controller room temperature control
••Control by room temperature sensor (Service mode)
‒‒ If set to #2093 1, the compressor can be turned on or off only by Room temp sensor.
‒‒ If set to #2093 2~4, the compressor can be turned on or off by Room Temp. sensor or according to the
WL discharged water temperature.
(#2093 2, WL Thermo off → Water pump off, #2093 3, WL Thermo off → Water pump on, #2093 4,
WL Thermo off → Water pump 7min off → 3min on →.......).
I’ve tried many of the values, I could also tries the 3 and 4 and make graphs, but I’m not sure the water pump schedule wouldn’t change much.
Actually they both are set to 0. I just checked to be sure.
I’m not using the MWR remote neither but I wished to rely on 2 different water laws for ufh and fcu, and more importantly I didn’t want to install more wires to control both zones!
Hope that’s helpful.
Cheers
[Use signal only ON/OFF]
The compressor will slow down to min speed when WL set point is achieved but not stop until room thermostat / temperature is satisfied. The primary circulation pump is operating as long as there is a demand from the room.
The Compressor and the primary circulation pump will stop when the WL set point is achieved and then restart when the PHE temperature drop, as long as there still is a demand from the room.
3.
The compressor will slow down when the leaving water temperature approaches WL set point but not to min speed, then stop when WL set point is achieved. The primary circulation pump is operating as long as there is a demand from the room.
4.
The compressor will slow down when the leaving water temperature approaches WL set point but not to min speed, then stop when WL set point is achieved. The primary circulation pump will Stop when WL set point is achieved but restart after 7 minutes and operate for 3 minutes out of 10 as long as there is a demand from the room.
Thanks @Tim_Bailey, and a great first post!
There’s a Table in the Installer’s Manual (p135) that adds a little additional information:
This Table doesn’t directly address compressor speed (only primary circulation pump operation), but my observations suggest that, irrespective of #2093 setting, compressor speed does reduce to minimum as WL target is approached, starting at ~2degC below target (apparently non-linear - seems to be an exponential reduction in speed based on LWTtarget - LWTmeasured). Whether the compressor stops or not depends on the setting - if #2093 = 1 it keeps going at min speed until the roomstat is satisfied; if #2093 = 2-4 it stops when LWTtarget is met but the circulating pump operates according to the Table (off/on/cycling as you note).
Thanks again for the insight…
Sarah
Thanks @SarahH We’re working on a project in Oxford where we now have 26 Heat Pumps installed. Last winter we set all as “1” because most were on the Cosy tariff; but this winter they are on a different (but cheaper) flat rate trial tariff so just wanting to find out whether setting 3 or 4 might be more efficient. At the moment I’ve set them to 3 so will monitor as we go into the winter. I guess 2 to 4 lead to more cycling but higher efficiencies as it won’t overshoot the LWT?
Yes I believe that’s correct - you cannot disable weather compensation in Samsung heat pumps (except for the special situation where there is no roomstat, in which case you can apply an LWT target directly).
I’ll be very interested to hear the outcome of your tests - it’s far from obvious to me that “low and slow” (i.e. minimised LWT for 24 hours per day) costs less to run than a warmer LWT for only part of the day, even if it indicates a better CoP when it is running.
Thanks. Yes will keep you updated; although - because of the way the project was funded (we couldn’t fund additional monitoring from the project funding) - we don’t have heat metering - only onboard monitoring plus data from the Samsung installer cloud Samsung EHS Cloud Service | UK
We do have one person who is ignoring our advice and just turning his heatpump on for a few hours a day - so going for an on/off approach. So will be interesting to see how that performs as it gets colder.
The other thing we’d like data on is how an “underheated” gas heated home performs when switching to a heat pump. For example we have someone who currently uses only 4,000kWh of gas a year who wants to switch to a heatpump. But she only currently heats two rooms downstairs and says that a curtain “keeps the heat downstairs”. We’ve told her that a heatpump will probably cost her more than a gas boiler if she runs it in that way; we could install one and we’d guarantee the min system volume from a volumiser; but we don’t have data on how it will run. Do you know if anyone has run a heatpump to “underheat” their home?
I think that a big risk for the industry is that a lot of people don’t heat every room in their house to a constant 21 degrees, so the current cost comparison calculators won’t be accurate.
Yes, me . I normally just keep the (large) living room warm at 21degC 16 hours every day (18degC the remaining 8 hours), plus shower room ~4 hours per week, plus kitchen ~2 hours per week. Don’t normally heat bedrooms/hall/stairs. I run DHW for just 1 hour per week (in a few short bursts). Year-to-date figures taken from controller display are heat consumption 6118kWh, time in use 1175h, power consumption 1977kWh, so a poor SCoP of 3.09, but that’s a running cost (21p/kWh) well below £500 so far in 2024 which I’m quite happy with
This basically describes us. We have a 1990 3 bed end terrace, circa 80m2 in central Scotland, insulated as built with new double glazing. Now heated by a 6kW Daikin monobloc with new pipework and radiators throughout replacing a gas boiler.
We are 11 months into having a heat pump and have produced 4,200kWh of heat for central heating consuming 1,320kWh of electricity (in built monitoring figures rather than MID). I’d expect our 1 year usage to be just below 5,000kWh of heat / 1,500kWh electricity.
DHW is 1,000kWh of heat / 420kWh of electricity on top of that.
When designing the system we aimed for a balance of comfort, energy usage/CO2 & Cost with none of them being an overriding factor. We don’t heat the house when we are away from home, and when we are at home we heat the rooms we are using + bathrooms + hallway. We have a 14C night time setback. We are both intermittent work at home so there’s someone in the house during the day generally 3 days a week.
We have smart TRVs on all of the radiators in the main rooms, which is about 75% of the heat emitting capacity. We use these to turn off rooms we aren’t using and as a limit temperature as the north & south sides of the house are very mismatched due to solar gain.
Despite going against much of the perceived wisdom this setup is working well for us. We have felt warm, and consumed relatively little energy. We do have issues with minimum outputs & cycling once things are up to temperature if we are only heating some of the rooms.
Fortunately running cost wasn’t a major consideration for us and we could have tolerated a system that was more expensive than gas. However it has worked out very cheap to run. We used circa 5,000kWh of gas prior to the heat pump, the house is now significantly more comfortable for a roughly equivalent energy cost. In reality we also have solar, battery and a time of use / export tariff that has brought our net energy cost right down. Its worth noting that for a low user the £100ish/year of gas standing charges that can be saved by having the gas supply removed is a significant saving that narrows the electricity vs gas price differential.
I think they key to running an intermittently heated house with a heat pump is to have some headroom on flow temperature and be willing to bump the flow temperature to achieve a faster heat up when necessary.
Thanks @SarahH . There had been a post on here saying that the calculation of SCoP from the controller data is: (energy consumption + energy generation)/energy consumption. Because the definition of energy generation was the additional energy extracted from the air outside. But the post has been deleted so maybe @glyn.hudson no longer thinks that is accurate. Samsung 5kW Gen 6 Air Source Heat Pump Installation with monitoring - #10 (the original post location)
Thanks @Jonathan this is very useful. I guess the way to calculate the required weather compensation would be to do a design - setting the temperature of unheated rooms down very low - so then the required heat in the heated rooms will adjust to allow for the flow from the heated to unheated rooms. Although heat loss calcs are not very accurate in older properties; so better to run experiments when the system is in place. I think we can give this feedback to the person considering the heat pump. And if she goes ahead we will remotely test to find the lowest weather comp curve which gets the heated rooms to her desired temp. Obviously the updated design and settings would just be for the current resident. The unit size and radiator outputs will be capable of heating the whole home to 21 for when someone else lives there (as required by MCS).
From your figures 1920kWh of electricity compared to 5,000kWh of gas prior to heat pump. SCoP of 3.125. So given current price cap and assuming 85% boiler efficiency previous cost wth gas = £367 and with heat pump £470 So with the £108 standing charge removed it’s about equal. Then obviously would be cheaper on a special tariff.
Doesn’t this description need some additional qualification? This behaviour with settings 2-4 only applies if the emitters cannot match the minimum heat output from the heat pump which tends to happen at lower LWTs when mild outside. If the emitters are outputting more than this minimum heat output, then the compressor does not stop when target LWT is reached. It continues at that LWT and can do for many hours. At least that is how my 12 kW Gen 6 Samsung works. Perhaps it is different with the Samsung R290.
You can add me to your list. The minimum electrical power used by the ASHP is around 750 W, so in colder months, I would expect the low and slow approach to use a minimum of 18kWh per day and yet I rarely ever use that much.
@Topaz Referring to the first post in the thread: one thing I’m curious about, what are the average COPs for each situation here? Do you have that calculated?
I hadn’t had a look at it since my global CoP has not yet stabilized (it’s my first fall). However I do have all the required data, I’ll dig a bit and see what are the numbers.
Lately I’ve also played with #4051 = 2 (limit pump pwm to 70%) as I was observing that only the compressor got reduced to maximise CoP but the pump pwm didn’t change that much. (also played with #4052 and #4053)
Cheers
. I normally just keep the (large) living room warm at 21degC 16 hours every day (18degC the remaining 8 hours), plus shower room ~4 hours per week, plus kitchen ~2 hours per week. Don’t normally heat bedrooms/hall/stairs. I run DHW for just 1 hour per week (in a few short bursts). Year-to-date figures taken from controller display are heat consumption 6118kWh, time in use 1175h, power consumption 1977kWh, so a poor SCoP of 3.09, but that’s a running cost (21p/kWh) well below £500 so far in 2024 which I’m quite happy with 