I doubt the 25-80 instead of 25-60 will achieve anything. The maths says that you need a pump that will do 10.8m of head at 23l/min which is quite a big one. I think UPML 25-105 can do it just about. UPMXL 25-125 surely can. But those are big pumps, for big systems, commercial size, they cost in the £600-£700 price area, and they will have high electricity consumption. They just shouldn’t be needed for a house your size.
photograph your circuits and draw a schematic. For example, you mention a mag filter. It could be they put in a small size one that’s designed for boiler circuits. that would instantly be killing your flow rate.
don’t you also have a diverter valve to push water to a hot water cylinder? that can also be undersized.
If you used an electric boiler before it would have worked at DT20, so it would be fine with a flow rate of 1/4 what we’re trying to get for the heat pump
@billt Do you have HT quiet version or regular. Do you have data here on OEM ? 2.4@-7C is very good. Before I’ve removed TRVs to fully open the system I was getting around 2.3@-5C. Now I need to check but still I’m bit bellow paper specs. Do you know what is the minimum power input for your unit ? Guys here said around 400W but I’m worried with mine I won’t get under 1KW which will cause some problems in spring.
I have the previous generation, not the quiet version which should perform slightly better than mine. The system was designed by the gospel according to Heat Geek et al, so has one zone with no buffer, high output radiators and a designed flow temperature of 35C at -3C outdoor.
Yesterday was very mild; the output dropped to 2.2kW and input 350W, however, getting input and output this low does seem to depend on flow temperatures (and flow rates). At the moment the WC curve is set to 29 flow at 15 OAT and 35 flow at -4 OAT.This results in a low power output but at the expense of a lot of hunting which may or may not be harmful! If the flow temperatures are set higher than this the power output won’t drop as low and the hunting goes away.
Maybe I’m missing something but I’ve check specs of my pump alpha 25-60 and seems that flow is spot on. They says 16 l/min at 5.63m which is roughly the height where are my 1st floor radiators. So how the hell people are getting bigger flow ? What pumps they are using? In manual for Samsung they say that for 5 - 16KW this pump should be used Grundfos UPMM 25-95 so this would make sense or ?
Wow, those radiators looks pretty good. Mine are running at 38C at 0C but those are only Type 21. 8cm width ones. What indoor temperature it is designed for ? I have this at 22C but I know guys in UK are used to much less indoor temperature. For me almost freezing temps lol
Your COP looks great. I envy you that low input damn it. I guess with HT Quiet it’s 1.0KW which I didn’t know unfortunately but still need to confirm this. But judging they are put same compressor into 12KW and 14KW units I guess I’m screwed here. Those idiots don’t write this anywhere. It’s still around 0C here so I need warmer weather to confirm if it can go more down or switch off. Actually I have flow problems so I need to resolve.
But wait 350W input and 2.2KW output this is well over 6 COP. Really ? What do you mean by hunting ? I’ve noticed that my mump tries to maintain 5C temp difference. Installers forgot to connect PWM cable so pump wanted to lower the flow but it didn’t so the temperature difference was 3 and once reach 2 it shut off the pump for 5 minutes. This is not wanted, I’ve tried to switch PWM regulation in control panel so let’s see if it behaves better. Current flow is max 16 l per minute. Temp is 1C outside.
Also can you tell me how I can create such nice graph ? Thx.
I’m trying to explain this to you, said it 2 times now. the height of your house is an entirely irrelevant number in a circulating system. It could be 20 meters or 2 meters high it wouldn’t matter. gravity is neutral in the maths, same water going up as down.
Meters of head of a pump is an relevant number for actual height if pumping water one way, only upwards, with little or no flow resistance in play. which we aren’t, at all.
what matters is the dynamic (moving) resistance to flow of the pipework and all associated components.
In your setup, we know its needing 5.23m of head to move 16l/min because we can look at the curve of the pump you own.
this allows me (or you, if you look at the same website of engineering maths) to calculate the value of k. which is your system’s defining constant. keeping that constant the same and redoing the maths for 23l/min says that more than 10m of head is needed for 23l/min. Read the engineering websites, but simply , head loss gets a lot worse the faster you go.
That all means your system has got a pretty high head loss for its physical size. which is a flag, that something is restricting the flow , as I suggested in previous message. It could be the mag filter for example.
People are getting better flow by using slightly bigger pumps (I have the UPMM one with a 9m head) but much more importantly, they are engineering their pipework for low resistance.
to drive 10.7m of head at 23 l/min would mean putting a big pump of the types I mentioned. UPMXL at £700, do you really want to spend that, I am not recommending you do that.
for the avoidance of doubt I am recommending, that you assess the components in your pipework for things that could be undersized and restricting flow
I see what you mean, I just don’t understand the graphs of Grundfos maybe ?
Why in those graphs for 25-60 if I look at that height of 5.63m it shows flow 16.01. This is exactly what I have? 5.63 is of course not height of my house but the height on which the top most radiator is connected. Why do you think 25-80 would not help then ? I’ve looked at the graph of 25-80 and for the same heigh it give well over 20lpm. Not saying you are not right, I just maybe not understand those graphs as I said. There isn’t really much which could restrict the flow in the system besides piping itself which is 28mm for main pipe and 22mm to each of the 3 circuits. There is nothing else in the system, it’s really very simple. Current flow is 15.7lpm at 39/35. Outside temperature -1C.
And this “People are getting better flow by using slightly bigger pumps (I have the UPMM one with a 9m head) but much more importantly, they are engineering their pipework for low resistance.”
This is exactly what is said in the manual for pump to use with this HP. I simply think they underestimated the pump for this because they’ve barely looked at the heating itself.
the number is not the height. Its the head loss of the system. it goes up as the square of the flow rate. you will need a 10.5m head pump . please read engineering toolbox.
two obvious things from the picture:
what exactly is the mag filter? product type and partcode.
the flow sensor looks a bit close to the preceding bend. it might be getting reading errors because of this. get them to install it so that the spacing from joints complies with the manufactures install spacings.
You right, I also looked at that flow sensor a bit to close to the bends. I will mention this to them. I think it must be min. 5x diameter of pipe but i will double check.
placement of the flow sensor behind a disturbance has negligible effect on correct measurement so I don’t think this placement is an issue. More over, the flow is always slower right after a disturbance so my flow can be very slightly higher in reality. If we consider there are no obvious obstacles limiting the flow then I would say that simply that pump is not strong enough for this system.
I can do a test though. Since I have still a electric boiler connected into the system which has his own pump installed on the return, I can try to open the valves from the boiler to the system and start it with the pump. I can see if the total flow will increase. Do you think it would work ? If the flow will increase, then it will be clear the acutall pump is not strong enough.
But wait 350W input and 2.2KW output this is well over 6 COP. Really ? What do you mean by hunting ? I’ve noticed that my mump tries to maintain 5C temp difference. Installers forgot to connect PWM cable so pump wanted to lower the flow but it didn’t so the temperature difference was 3 and once reach 2 it shut off the pump for 5 minutes. This is not wanted, I’ve tried to switch PWM regulation in control panel so let’s see if it behaves better. Current flow is max 16 l per minute. Temp is 1C outside.
Also can you tell me how I can create such nice graph ? Thx.
The CoP is unusually high due to the combination of high outdoor temp and low flow temp. It’s not typical - the SCoP since commissioning is 3.8 which isn’t wonderful, due to lots of freezing and low outdoor temperatures over the past 2 months.
Hunting is switching between 2 states and not settling on one continuously, it implies that the control system is unstable under those condition.
The graph is created with the emonhp app. I bought an OEM heatpump monitoring kit (Level 3 Heat Pump Monitoring Bundle (emonHP) - Shop | OpenEnergyMonitor) well before the system was installed and it has proved invaluable in setting the system up. You can use the emonhp app without the heat pump monitoring bundle if you have a source of the necessary data which can feed emoncms.
The pump in this system is a Grundfos UPM-4L variable speed pump Grundfos UPM4.
No, just radiators, mostly T22 with a couple of T21s. Here’s a video of my system
No, flow rate is determined by the size of the pump and the pressure loss of the pipework index circuit. Static pressure also doest effect flow rate, about 1.5 bar of static pressure is fine.
The FSVs (field settings values) can be adjusted in the installer settings on the Samsung controller. This is also where you adjust the Water Law (Samsung name for weather comp) settings, which are the most important settings.
I’m running open-loop (no buffer tank, with just radiators, I don’t have any zones or TRVS, and I’m using the Samsung controller as the thermostat rather than 3rd party controls and I don’t have glycol. I’ve also been tweaking the settings using data from the OpenEnergyMonitor monitoring. Without detailed monitoring, it’s tricky to know exactly what’s going on and see the direct effect of adjusting settings.
Also, from the data I’ve seen the Gen6 that I’ve got seems to be a bit more efficient than the Gen7 HT, the HT seems to be more optimised to provide higher flow temperatures and the smaller models share the same compressor as the larger models. Is your R32 or the new R290?
Thanks Glyn, I will check your video but those numbers are outstanding.
Yeah, seems GEN6 could be a better choice but my priority was noise and here I couldn’t ignore quiet mark certification. I can’t tell if there is any difference between GEN6 and GEN7 in terms of noise but I would say judging from the construction that GEN7 is more quiet. This is last year model with R32 refrigerant. I know there is new version with R290 but it was not in stock here and not sure if this would have a big benefit besides it’s more ecological and can get higher temperatures.
For now I wonder what is the minimum power input of the compressor. Today in the morning it has defrosted for the FIRST time since I had it installed 4 days ago. It’s unbelievable because temse were around 0 all those days but probably was pretty dry air. So today I’ve captured first defrost but what I don’t understand and maybe you can tell me why there are those 2 shtut downs for no apparent reason.
This was happening before when I had my pump to low or two high without PWM regulation when pump had still PWM enabled at 100%. First I’ve increased the flow rate to max. 16 l/m and the intensity of switching off reduced but still sometime it has shut down. Then I’ve disabled PWM controlling in control panel a it was runnig for 12h continously. This morning, however, it has turned of twice in 2h window and from power graph I can see it was running at maybe 1.3 or 1.4KW so there is definitelly the room to lower compressor speed. But for some reason it has shut down for 5 minute. Do you have an idea why ? My only explanation is that maybe flow rate of 16 l/p was too high and dT was very low close to two so the system decided to shut down. What do you think ? I’ve attached the graph.
I could probably increase static pressure to 1.5bar to get a better flow. It’s OK to have it at 40C water outlet temperature ? Do you also use water law on your HP ?
I also have similar setup with no buffer just radiators but all Type 21 so here I can loose some performance. With TRVs the system had flow issues. What is your flow rate in the system ? Mine max 16 l/p so I wounder if I can improve it. The pump I have seems to be a little weak but Ian said there is probably issue with pipework or some restrictions it the system. But it’s really simple, no additional stuff installed so I don’t know. I think the pump is just not enough. My 1st floor radiators are around 5.5m above the pump since it’s in the underground.
Thanks.
UPDATE:
Another turn off for no apparent reason. Do you have an idea ? Simply it’s running and then it will decide to switch off more few minutes. Can’t get this:
I’m using water law so this should heat with no limits or ? Not sure if this setting can have some impact on this but I would like HP to heat continuously. Yesterday it has run for 12h without any shut down and this morning already 3x.
I’m not saying that you won’t ever need a bigger pump. I’m saying that to achieve 23l/min with your current pipework you’ll need a massive pump (UPMXL) which in my opinion is overkill. If you move to a slightly bigger pump without also looking at the pipework, you’ll achieve nothing.
So better to spend time checking your pipework first before you decide which pump to buy.
the TF1 isn’t brilliant, its burning about 0.15m of head at current flow rate (red mark) and would burn about 0.3m at 23l/min (green mark)
whereas a filter designed for high flow rates such as a spirovent spirotrap G11/4 would burn about 0.02m of head at 23 l/ min
but on the other hand those numbers probably aren’t big enough to affect the overall problem.
where does it change to 22? how many rads on each 22? how long are the 22 runs?
Yeah, it’s not the top but how many liters per minute do you think it can lower the flow if I have 16 l/m now ? Could it be there is still air trapped in the system ?
I wonder I have that electric heating parallelly connected to the HP. It has its own pump. Do you think I can open the circuit to the electric boiler and run the pump at max (installed on return). Do you think I will see some change in flow of the heat pump ? I’m not sure because it’s parallel connection so probably I will see nothing ?
What do you mean by 22 runs ? Sorry I’m still new in this so sometimes it takes longer to understand.
Hi Michal,
Ian is asking for more information about the pipe lengths and diameters in your system. by “22 runs” he means the pipe lengths and diameters for the pipework supplying the Type 22 radiators (those with double panel/double fins).
BTW it was the UK Samsung Technical Dept who told me that the 8kW HT compressors have a maximum turndown speed of half full speed, and that accordingly the minimum heat generated is ~4kW (depending slightly on LWT).
Sarah
Thanks for response. Ah I see now. Those 22 connects at those 3 joins I’ve pictured in the screen. So there is a main pipe 28mm around 10 meters running from HP and then these 3x 22mm pipes goes up and 3x down for every circuit. The main pipe from the pump is around 10 meters. I have no idea how long 22mm are but I have a house 160m2 with ground and upper floor. 5 radiators on each floor. Those are Type 21 only though. My heat loss is around 4.2KW at 0C with indoor temperature set to 22C.
This is really unfortunate for this HT units and I had maybe study more before but I thought that because it’s 8KW unit it will have lowest power input pretty low. Now it seems the lowest it can get is 1.0KW because those idiots put the same compressor in 12KW and 14KW - what a stupid design. Well, lesson learned again.
So Sarah, maybe you have the same issue now as me ? I’m talking about short cycling. I can imagine that in UK the temperatures are higher than in central Europe so how you deal with this ? When it was below 0C it worked pretty constantly. I guess the max. flow of 16 l/p is not sufficient for lower temperatures but up to -5C it should be enough, what you think ? I don’t know why it’s so low because there are really no big blockers in the system so I just think this pump is weak. But Ian pointed that maybe not and there is other issue but in my opinion 28mm main pipe and 22mm should be sufficient. I guess this HT has 1" connections.
Do you have some power graphs for your pump ? Do you have 8KW HT quiet mono ?
But today is 5C and it really short cycle open. My LWT is 36 now so this is pretty low and the pump is running at 15L/m. Still, it is cycling every 12 minutes or so. I can’t imagine what it will do when there is 10C outside ?
What I don’t understand why it is off only for 5 minutes ??? I would like in this case that it’s turned off maybe for half an hour but not 5 minutes. This is not good for compressor in long run so how I can fix it ? I use water law by the way. Mabe I should use thermostat regulation instead ?
Here is my power graph, ignore those spikes those are from different devices.
Guys, I need some serious help here. I’m totally desperate.
So yesterday there were temperatures around 0 to -3C. Heatpump operated at 40/35 no issues with 1.2KW input running from the afternoon the whole night. Great.
Today it warmed up outside and temperature was about 7C and here the hell begun. This unit started to cycle like crazy!!! I don’t understand the logic god damn it. At 7C it heats the water to around 36C so input is 31. For the life of me I can’t understand why it stops after 7 minutes of running then stops for 3 minutes and start heat again ??? Whyyyy ? Why it is not waitng 20 or 30 minutes and then run for longer time. This is horrid, what can I do here ? Can’t imagine what it will be doing when there will be 10 or 15C outside…
I even wanted to change it to indoor temperature controlled but I can’t. That damn controller either is set to AUTO or if you switch to heat it want to setup outlet water temperature ??? I don’t understand this.
I’m a beginner in ASHPs (though a practicing Chem Eng back in the day) so treat what follows with great caution .
My setup is different to yours - I have an AE080BXYDEG/EU (so similar to yours), running on 20% glycol, but with a 4-connection 50l buffer tank (I think that you do not have one). My primary loop flow is ~27lpm (Sika flowmeter and Grundfos UPS2 pump). Secondary loop flow (to radiators with a Grundfos UPS3 pump) is unmetered but I’ve put thermocouples on the buffer tank inlets/outlets and can calculate (from heat in = heat out) a CH flow roughly half of the primary (i.e. 10-15lpm).
I only run the ASHP for 14h/day (I have a big setback on the roomstat overnight), so for the first hour each day the ASHP uses lots of power (maybe 4kW at 0degC outside) while it runs at full compressor speed and warms the glycol towards Water Law setpoint. As LWT approaches WL setpoint the compressor slows to ~50% (I can follow this from Q = glycol mass flow * glycol Cp * (Tw2 - Tw1) using the MIM remote display) then stops till Tw2 has fallen to ~2degC below WL setpoint.
Then the compressor restarts (at ~50% speed) until the LWT again approaches WL setopoint, and the cycle is repeated. My cycling is about every 30-40 mins (see the screen dump I posted a long way up this thread) which I accept as tolerable, until the roomstat approaches its setpoint (when there is a somewhat complex interaction with the MIM controller, also reported above).
I suspect that the cycle time I see is a function of the large thermal inertia of my glycol inventory (about 80kg I estimate), so in your case maybe you should consider adding capacity to your circulating fluid volume?
Sarah
Yes, it’s a bit different setup. I don’t have buffer and just 1 grundfos alpha 1l 25-60 which gives me only up to 16 l/m. But please check my graph, I don’t know why it cycles so often really. if I check outlet inlet temperatures it’s within 5C difference but it runs only few minutes and then it switch of.
These 30 - 40 minutes cycles are at which outdoor temperature ?
.