For air conditioning. They were the first ones to really get variable refrigeratnt volume (VRF / VRV) nailed.
“Take an AC condenser and botl a heat exchanger onto it” doesn’t quite make a heating optimised monobloc though!
I agree for major discrepancies.
If you know the electrical input and you know the radiator sizes/temperatures and these are in “steady state” then you can imfer the heat output to within say +/-20% with ease.
Vaillant brought sensible control logic (a lot of the boiler logic does read across in terms of dgeree-minutes, weather compesnation, load compensation, maximum starts per hour etc) and matched that with a purpose made (heating optimised) design.
Viessmann are perhaps even nicer but £££.
Then folks like Lambda with very quiet / efficient units. sCOP 4.5 even on the 55C cycle and 5.7 on the 35C cycle.
They are far from cheap though!
Daikin are much closer to the cheap and cheerful end of the market.
I see, but what if you have -10C or -15C ? I’ve calculated my size to be able to run at -15C and this gives 7KW. I also have average temps in January max. -2C but sometimes temp can spike to -15C at cold nights. It’s not very often though. Maybe I should have take some 6KW unit but 4KW would really be small to me.
I think they’ve calculated 7.5KW at maybe -15C so that’s why maybe 7.5KW ? I don’t know. Mine house takes around 7.5KW at -15C. You could put 4KW unit on the age when you have freezing temperatures, I guess the best is if the pump is running at it’s nominal power. I don’t know how much is it. 60% or 70% of compressor speed ? Also make sure that the unit you buy has your needed output at the temperature you need. I saw with many pumps they say it’s e.g 8KW but it’s 8KW at +2C and then the output is going down so at -15C you have only 5KW pump running at 100% - noisy.
So you are replacing 9KW Daikin with 8KW Daikin ???
Yes, with closed conservatory you should be fine. Without you may struggle few days a year. But who knows, what if an Ice age strikes soon ?
You can set overshot ?? I’m missing such setting in this Samsung unit. I can’t control it at all I guess.
I think you are just hunting COP like crazy. Cop 4 or 5 does matter to much to be honest in global. Let’s say you mneed 6000KW electricity a year. With scope 5 vs 4 you save 300KW. Is it worth the hastle ? My house itself without heating eats 750KW a month! To me these 300KW saved per year not a number. It’s 45 eur here.
I’m looking more to rentability and comfort than hunting COP. Really cycling the pump, let indoor temp vary is not very good for me.
I think you must be pretty obsessed about this man. You have electricity for free and you still hunting COP
50% of what ? Electricity ? How many of these solar panels you have ? Sounds quite a lot.
Crossing the fingers anyway. Let us know how this new Dakin is.
Yeah, could be. But didn’t they change the compressor already ? They are using ones from AC. I know this Samsung has scroll compressor but before they’ve also used type which were used in AC units or ?
Yeah, it’s possible like this. But the pump has energy monitoring integrated. How do you think it counts energy generated by pump? I guess for input power it has this power meter so this must be precise +/- few percents at most. But how does it count energy generated ? Do you think it has some sort of heat meter installed on flow pipe or somehow extrapolate from water inlet/outlet temperatures and flow ? Don’t know.
Never heard of this brand. It’s and Germany brand ?
You know, maybe I will give a chance to this Homely box. They are saying they will optimize the run of a heatpump as best as possible by using weather forecasts and monitoring indoor temp, humidity and lighting. Sounds interesting and could work, maybe it has better login than Samsung’s algorithms. What is your opinion ?
Agree, but I’m sure this is only temporarily. World got mad after covid and this war on Ukraine with electricity and gas prices. Do you think it will ever return to normal ?
Them I really don’t understand why Samsung limit min. temperature to 10C and max. temperature to -20C for weather compensation. If it’s unlimited it could save me lot of troubles.
The Samsung HTQ unit in Cambridge with very “average” performance is running on a Homely unit.
The control logic that works for one brand, one model, and one type of plumbing is not guaranteed to work as well with another.
The Homely logic tries to run “long and low” and whilst that might work on other units on this Samsung HTQ unit that doesn’t appear to give the best performance.
I would try to make what you have work with as few external things to go wrong as possible.
Fair.
Cooler than “warm” winter England but it’s not what you’d call cold as a central or northern European.
The sticky humid 20C+ (over day and night) summer is where their expertise is IMO. That and air based heating and cooling expertise rather than radiator/underfloor based. (as you can’t dehumidify with those)
They don’t use scrolls in their residential AC. This is specific to this (new) heat pump. The previous units all used rotary compressors.
If you take a look at the vaillant range (as they publish full datasheets) you’ll see that their small rotary compressor units (5, 7kW) have better “turndown” range and worse high temperature performance than their larger scroll compressor equipped units. (10, 12kW)
It wouldn’t be a surprise if this high temperature optimised Samsung unit with a scroll had similar turndown limitations.
This is also speculation; but it also wouldn’t be a surprise if Samsung recycled their air conditioning control logic, where they do things like deliberately slowing down the fan to increase the temperature of the evaporator to increase load on the compressor, just so that it can keep running. Why? In an air to air system it is very uncomfortable if the heat cycles on and off as the compressor cycles on and off. The same isn’t true of a radiator system. (as the water temperature doesn’t change quickly) Why might they do this with the monobloc? To avoid people complaining when it refuses to run the compressor when they ask it to (instead of when it chooses to based on degree minutes etc). To allow them to get away with basically one design for houses from 0-14 kW; as long as they can make it run ok at the loads it is tested at? Don’t know.
It’s definitely all new in compressor type and vapour/liquid injection etc compared to their old units. A fairly major R&D leap from the “AC condenser with a plate heat exchanger bolted on” of before.
You mean to ask “do you think we will see a repeat of the last 20 years, whilst energy prices in Europe were artificially low as they life-extended old assets whilst failing to invest in any nuclear or renewables or the distribution grid and relying completely on free gas from Russia and cheap to build gas plants?”
We are back to normal.
30-50 cents/kWh for the next 20 years; depending on how many of these Deutsch-Lira Germany needs to print.
so you can choose: either run with COP that is lower, but the power input is low, so accept it, its running in steady state at a low power input , thats a good state to be in , and the energy cost overall is nothing to be worried about. Or, run at the higher temp, then the room temp sensor will cycle as the house warms to it set point . you can always experiment with a slightly higher WT to see at what point it cycles on the room stat, you don’t have to go all the way to 40.
If you’ve got yours down to stable state of 2kw output I’d be very pleased, others with the 8kw unit haven’t got close to that.
I don’t have too much heat. I have a large house that has not brilliant insulation. 3.7 to 4kw in 10C weather is only slightly too much, the house will cycle on the room temp stat sometimes, but its does not happen excessively.
FYI I’ve found my system doesn’t behave nicely with the water lower than about 35.
This is how it is with my Mitsubishi. Overall, I’ve had better performance and comfort since switching to using room temp sensor. I don’t find the 1°K hysteresis be particularly noticeable.
It does appear that a number of units are happier at 35C than at 25C or 30C.
It would be enlightening to be provided with extended performance maps from the vendors here. It isn’t (or shouldn’t be) a large part of the overall space heat load delivered at these kind of temperatures but could still be material.
What is it average performance ?? What type it is ? Mono R32 ? How many KW? I’m little bit afraid of homely because I fear there is not much settings I can change. Maybe I will drop them a message and kindly ask if they can provide me some registry address when flow temps or outdoor temps are set.
You said it tries long and low this is what I already have until it is so low than it cannot go lower. Wonder if Homely is able to change parameters on the run. E.g. if it sees that power is to low and it is cycling too much, can it increase LWT a bit ? I don’t know.
I have to say I’m pretty impressed with mine. Today it was pretty hot (average temp until now 8.7C) and this this is running all the time with minimum water temperature 33C. Indoor 23C running constantly! Saw it running at 600W min. completely silent operation. Returned home and thought it’s not running. Had to walk 1m from it to hear it. Pretty impressed.
Granted, COP is “only” 3.2 on 8.7C average but the comfort is great.
Don’t know what happened before 9 to be honest. Looks like it was so hot it couldn’t go lower as sun was shining? That stop cycle is pretty short. Guess I need to increase a water temperature a bit. But otherwise it is running whole day.
But again this 3 minute off cycle! My brain can’t process it Why it is so short ??? Anyone knows ? So it was running again for 20 minutes and then thermostat shut down the pump and it was off until 16:00. But it was really hot.
There is high probability you are right. I would say they’ve took everything from gen6 and probably tweak some paramters because this water law mode works really strtange for me. And you right, the fan can run deliberatelly slow and seems it goes to it’s limits just to hold target water temperature. Really saw it running at 600W with water temp 33C. Wish I can use flat until 0C…
I would not say they were artificially low but we had a Russian gas Then Germans closed their nuclear plants so should we be surprised ? The best is that Europe is trying to save the world why US, China and other big countries completely ignore this climate crisis.
Don’t scare with 30 - 50 cents. Then I would need to hunt fro a COP as Mat. Buy new radiators and install solar panels all over the roof lol
You are very right. It’s really interesting how you can play with COP. Today it was very hot like 12C and saw it it cycled once but the water temperature was really low - 33C.
This 8KW I guess completely shut off the fan but it was not able to maintain such low output. I don’t know exactly what was the power output but it must be lower than 2KW. I need to increase water temperature a bit. I’m really sad I can not set it up in two steps. From 0C and above like 38C flat. And then from 0C and bellow with water compensation curve. Seems without modbus and some programming I won’t be able to to that. And it’s only because engineers in Samsung set a limit of 10C for warm weather and I cannot get lower. If they would not limit it or allows 0C then it would solve all my issues. Can’t get why they did this
Yeah, so my pump would be ideal for you
Seems it’s not very stable on mine as well at lower than 35.
I also had to switch to room sensor. In water law it was not stable at all for some reason. Seems it this mode is programmed to run as best efficiency so it has never lower the fan speed. Need to observer more here but I’m pretty fine with room sensor. 1C hysteresis I can register because in fact I have a feeling it’s more.
I have to 2nd this. Samsung provides only max. heating capacity which is quite useless. I think they are doing this intentionally because numbers in low range would not be that impressive
Never mind, I will but DWH tank to increase my efficiency little bit more. Now I have electric boiler. Then loser COP at higher temps won’t hurt me that much
What if you detected the compressor stopping and then remove power from the heatpump until [0,20,40] minutes past the hour so the compressor can only start 3 times an hour?
Thank you. Seems I can achieve better SCOP without Homely so not sure if it would give me some benefit. I guess I will program something with modbus.
Btw, do you know what setup this user is using for all those measurements ? It’s pretty impressive.
Compressor on this unit can start every few minutes. Saw it starting at least 6x per hour. It is always 3 minutes off for some reason. I guess it’s because I have probably low water volume or there is some issue with pump. I’ve noticed that pump stops when compressor turn off so could be that water in unit losses heat to fast. I thought it should circulate the water. I don’t know but I have to observe this behaviors. However, this was only in water law mode.
Not sure what do you mean exactly but the compressor was running all the time at minimum input - you can see it from the graph. Only the fan was barely spinning.
Have a timer that turn the power on at 0 minute, 20 minute and 40 minute past the hour and that turns the power off when the compressor stops. The would prevent the compressor starting more then 3 times an hour.
Yes, but would be pretty uncomfortable and really not good way how to control the pump. Conditions are changing constantly and you can’t rely on this schedule.
The idea here is to detect when the compressor turns off at the end of a cycle, and turn off the power so that it doesn’t restart after 3 minutes, allowing for the water in the whole system to cool down a bit. Then, after some reasonable length of time (10 minutes is decent), turn the power back on.
This was explored more fully in this topic I mentioned before:
Solution can be done with hardware, as Ringi and John proposed, or possibly via Modbus. I did something similar via Mitsubishi’s cloud service.
Ah, like this. Now I got it. Yes, this is interesting idea. Yes, there are many ways how to do it, probably will check something but now seems there is no issue with it.
Anyway, my plan is to buy modbus and make a java application which will run on Raspberry Pi and constantly monitoring parameters read from modbus. After evaluation I will program logic to set the weather curve flat when temperature is +5C and above. Either 40 or 45C. This will give me much better COP than keep it running on minimal power with fan barely spinning. And probably I will integrate some weather provider API to change the curve when there is a sunny day.
I can’t agree with this statement. This is truth only if you have well dimensioned pump which can cover your heat needs across all weather conditions and best with floor heating. Especially when freezing this is ideal, yes, but…
…I’ve clearly proved that in warmer climate, with radiators… to let it run constantly is inefficient. My COP at +12C is the same as COP at 0C. The only advantage is the thermal stability but that’s it. And very silent work of the outdoor unit which maybe not good for fun at the other hand. Even running the water at 50C would be more effective than this. I would expect at least COP4 at 12C…
Rather then having a fixed minimal “off cycle” length, I think setting the “of cycle” to be longer if the “on cycle” is shorter would be more stable. I question if there is ever a need for more then 3 “on cycle” per hour.
If the water pump can be kept running then it would be improved by increasing the water volume in the system with a inline volumizer, so the radiators remain warm while the compresser is forced to be off.
(Shame there is not a standard design to bypass a volumizer until dt reduces to about 6c, so the volumizer does not slow down the heating of the building until the heatpump has catched up with demand.)
Yes, this is a good idea we have discussed here with marko. Volumizer should really help to prolong cycles. The only question is why this pump behaves differently in “water law” mode and differently in “indoor” thermostat mode.
In indoor this pump can lower its performance as lowest as 2KW by decreasing the power input of compressor to minimum and limiting the fan of outdoor unit to bare minimum. Not very efficient but helps maintain pump on as long as possible.
What I don’t understand that if the pump is not able to do this anymore, then it will switch off but is stopped only for 3 minutes and then starts again. Really the water temp decrease that much it has to kick in again? Volumizer would be good idea here maybe.
Yeah, I’ve seen Glyn did this so at least I can get some registers from it, but I’m not very keen in python. I’m mostly java developer so it would be easier for me. I saw some java libraries for R485 USB converter so this should be possible. I also need to records values from pump somewhere into database so I can evaluate them and do some actions on the pump.
I said this several times. In Water Outlet mode, the ONLY thing its using as a control input by default is the temperature of the outlet-side water in the outdoor unit. it is NOT the water in the radiators, or a volumiser or buffer.
As soon as it goes to an off part of the cycle, this water cools down. because its outside, it cools quickly. So then it detects the drop and restarts, after not long. It is an entirely useless mode unless you have some other control input as well. Such as a 3rd party thermostat, or a modbus controller.
If you have the coding skills then you could run in water outlet mode, and use modbus to adjust the water outlet setpoint dynamically based on whatever rules you desire to code. Drop the outlet water temp right down. Or just simply turn CH off via modbus - there is an on/off register for that.
This is basically what homely does, but they are doing it as a service.
I strongly suggest you don’t do a relay to actually power down the unit, thats a really bad idea IMO. turn it off in software.
