Option 2 the heat pump doesn't actually know the heating water temp, which may or may not matter. Thats what I assume anyway, I may be wrong!
The leaving water temperature is constantly displayed on the wired remote controller, irrespective of whether the compressor or the water pump is on or off. Therefore, the heat pump is always aware of any fall in LWT, indicating that it needs to restart. Whether the water pump is on or off makes no difference to the monitoring, but may cause the LWT to fall more or less rapidly.
The leaving water temperature is constantly displayed on the wired remote controller, irrespective of whether the compressor or the water pump is on or off. Therefore, the heat pump is always aware of any fall in LWT, indicating that it needs to restart. Whether the water pump is on or off makes no difference to the monitoring, but may cause the LWT to fall more or less rapidly.
I accept its always displayed however with static water in the pipes the temperature at the sensor wont in any represent the temperature of the actual water, other than at that point in space. Samsung isnt unique in having a 'sniffer' mode, chofu does too, and expressly calls it that. Quite possibly others do also.
This post was modified 8 months ago 3 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
This is how I would interpret the various options for fsv 2093.
Option 1 means that the heat pump is being controlled by the room thermostat.
Option 2. The heat pump is being 'enabled' by the room thermostat, but is normally being controlled by the Samsung controller with reference to the LWT. The water pump runs on for 1 minute to extract the remaining thermal energy from the PHE inside the heat pump.
Option 3. Similar to option 2 but the water pump runs continuously.
Option 4. Similar to option 2 but the controller periodically checks the LWT by running the water pump as stated.
The actual affect upon the heating system will depend upon a number of factors. The location of the LWT sensor and how quickly it cools once the water stops flowing. In option 2 the LWT reading should gradually fall until the compressor restarts, thereby cycling the heat pump.
In option 3 I would expect the LWT reading to fall at a slower rate than option 2, since thermal energy will be passing back from the heat emitters.
In option 4 I would expect the LWT reading to fall then increase slightly when the water pump runs, though the overall trend will be downwards.
I agree that option 4 would appear to be the most advantageous.
Locking the Thermostat to a Temperature 2 C above that required , while adjusting the Samsung Water Law for the required Temperature in an attempt to avoid Thermostat "Short Cycling".
On setting my Thermostat to 24 C I reduced the Samsung Water Law Offset by -1 C resulting in a reasonably stable working Temperature of 22 C .
All appeared to be working, with a stable Temperature of 22 C .
However , on examining the power consumed during this test , the Power was still, unfortunately Thermostat "Short Cycling".
The first power group was using the Temperature set by the Thermostat.
The Second power group was using a -1 Setting on the Water law control Display.
The band width of the close approach Honeywell Themostat algorithm is apparently more than Two C!
I will try again , with the maximum Thermostat set to 25 C and the Water Law set set to -2 C.
The concept works, producing a resulting temperature of 22 C , but does not reduce Thermostat "short Cycling".
My Thermostat is set to exactly produce a cycle time of 20 minutes.
Clearly, my Honeywell Thermostat is still Cycling .
OK. If its still cycling at desired temp plus 2, its absolutely useless both as a temperature limiter and as a temperature controller and will need to go. For now turn it right up to desired temperature + 10C then to (hopefully) take it out of the loop entirely (for now) just to find out what the heat pump is doing! Just to be absolutely certain change the thermostat cycle time as well to check that the cycle time of the system changes.
This post was modified 8 months ago 3 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
Sorry James , I cannot set the Thermostat to a Temperature greater than 25 C . 25 C is Maximum.
I will try again, later tonight, with a Themostat Temperature of 25 C , setting the Weather compensation, Water Law Offset to -2 or -2.5 C.
I will set you know the result, tomorrow.
I have, until now, for the last 18 months been using the Thermostat , set to my desired Temperature, with the Water Law offset adjusted to reduce Electricity consumption by reducing the pipe Water Temperature.
Sorry, if I sound like a traditional Scots Skeptic, too much David Hume reading!
Sorry James , I cannot set the Thermostat to a Temperature greater than 25 C . 25 C is Maximum.
I will try again, later tonight, with a Themostat Temperature of 25 C , setting the Weather compensation, Water Law Offset to -2 or -2.5 C.
I will set you know the result, tomorrow.
I have, until now, for the last 18 months been using the Thermostat , set to my desired Temperature, with the Water Law offset adjusted to reduce Electricity consumption by reducing the pipe Water Temperature.
Sorry, if I sound like a traditional Scots Skeptic, too much David Hume reading!
Sorry but if you now want to get your current system, which is sub optimal as regards the plumbing, running as best as it can then you need to stop fiddling with the WC values at the current time, its the thermostat that is the current problem and you assure us is causing the cycling, and you need to fix it. Once that is fixed you can see what the heat pump is doing take the next step. I have absolutely no interest at all in the result of you adjusting the WC curve until the thermostat problem is fixed so we can see the wood from the trees, so if you post any result where the thermostat cycling has not been stopped, please do not quote me in the post.
Returning to the issue: according to the spec the set temperature on the Honeywell can be up to 35C
However, if the spec is wrong and your thermostat cant be set to 10C above desired temperature, and since it cycles at smaller offsets, to you need to short it out so that, for now, the secondary pump is running continuously and you can see what the heat pump is doing.
Its now clear that your thermostat is totally unsuitable for use with a heat pump so it needs to go or be taken out of the loop. Setting it high or shorting it out takes it out of the loop. It can be reinstated later if necessary and useful.
Sorry but this needs to be approached systematically. If you aren't prepared to do this then I cant help further; you are on your own or will have to find another fool who is prepared to persist in trying to help whilst you ignore all suggestions/advice given.
This post was modified 8 months ago 2 times by JamesPa
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
Sorry James , I cannot set the Thermostat to a Temperature greater than 25 C . 25 C is Maximum.
I will try again, later tonight, with a Themostat Temperature of 25 C , setting the Weather compensation, Water Law Offset to -2 or -2.5 C.
I will set you know the result, tomorrow.
I have, until now, for the last 18 months been using the Thermostat , set to my desired Temperature, with the Water Law offset adjusted to reduce Electricity consumption by reducing the pipe Water Temperature.
Sorry, if I sound like a traditional Scots Skeptic, too much David Hume reading!
Sorry but if you now want to get your current system, which is sub optimal as regards the plumbing, running as best as it can then you need to stop fiddling with the WC values at the current time, its the thermostat that is the current problem and you assure us is causing the cycling, and you need to fix it. Once that is fixed you can see what the heat pump is doing take the next step. I have absolutely no interest at all in the result of you adjusting the WC curve until the thermostat problem is fixed so we can see the wood from the trees, so if you post any result where the thermostat cycling has not been stopped, please do not quote me in the post.
Returning to the issue: according to the spec the set temperature on the Honeywell can be up to 35C
However, if the spec is wrong and your thermostat cant be set to 10C above desired temperature, and since it cycles at smaller offsets, to you need to short it out so that, for now, the secondary pump is running continuously and you can see what the heat pump is doing.
Its now clear that your thermostat is totally unsuitable for use with a heat pump so it needs to go or be taken out of the loop. Setting it high or shorting it out takes it out of the loop. It can be reinstated later if necessary and useful.
Sorry but this needs to be approached systematically. If you aren't prepared to do this then I cant help further; you are on your own or will have to find another fool who is prepared to persist in trying to help whilst you ignore all suggestions/advice given.
Ian, should you decide to short the thermostat contacts as suggested, please be aware that 240v ac is present at the room thermostat terminals. Ensure that you switch off the heat pump mains supply before carrying out any work.
Ian, should you decide to short the thermostat contacts as suggested, please be aware that 240v ac is present at the room thermostat terminals. Ensure that you switch off the heat pump mains supply before carrying out any work.
Fair enough advice, which is why my first advice was to turn the set temperature up to 10C above desired temperature. Apparently this is impossible (although that is at variance with the spec), so shorting it out is (apparently) the only option to find out what the heat pump is doing and take this thermostat out of the loop for now.
@iantelescope please note @derek-m s safety advice, but you have got to get this thermostat out of the control loop for now by some means so you and we can see what the heat pump is doing and, until you do, Im not prepared to comment further.
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