Hi, i intend to switch my current Samsung 8kw mono layout to open loop in order to improve my current low COP (2.5) , using water law right now.
I’ll remove the buffer, secondary pump etc. I am not sure if i can relay only on the built in pump , in external unit which i suppose is a pwm one and can modulate the flow as needed ? Also is there need for the secondary flow sensor as well ? like in pic ?
Cheers
Hello @VIERICIU_COSMIN and welcome to the forum.
Assuming that you have the Gen7 Integrated model, the on-board UPM4K25-75/130 is designed (flow, head) to supply the whole emitter circuit (without buffer) and is PWM speed controllable.
Personally I am not convinced that a 4-nozzle buffer tank system reduces the CoP very much, provided the secondary circuit flow is close to the primary flow. There is lots of experience on this forum on the subject if you search “buffer tank”, so it might be worth doing a bit of research before spending too much money.
Let us know what happens to your CoP if you do modify your setup…
Hi, thanks for reply.
I am sure that a buffer if setup correctly will not affect to much.
I am more concerned about getting in sync 3 different pumps on a small layout (5 radiators - 80 sqm) 2 without PWM and different speeds etc. Also i am not sure why i have 2 flow sensors ? i can rely on the built in (external unit) i presume?
Cheers
I surmise that a second flowmeter (in the secondary circuit) is to allow you to equalise the flows in the primary and secondary. (Equalised flows minimise short-circuiting in the buffer tank and maximise average emitter temps for any given LWT.)
I have actually installed a Sontex heat meter on my secondary circuit which has allowed me to 1) roughly equalise circuit flows, 2) verify the accuracy of my primary meter (the one on the heat pump outlet), and 3) evaluate the heat actually entering the heated envelope (i.e. the ability to ignore external heat losses and heat gained from circulating pumps).
The Outdoor Unit flowmeter should be satisfactory for control (and calculating CoP if your controller doesn’t do it for you), but it may not offer Class 2 accuracy.
Edit: If you do abandon the buffer tank, you will need to ensure that radiator TRVs don’t constrict total circuit flow below the heat pump minimum requirement. One of the benefits of a buffer tank is (almost) guaranteed flow through the heat pump.
Hello, just routed the return around puffer for a test. It’s better cop around 3.1
PWM connection coming soon.
I cant’ seem to get the water law to work correctly,
I have 50degres for -5 outside and but even if the temperature are going down the water temperature does not increase … Are there any other settings ? Cheers.
Possibly. Can you post a list of your FSV settings #2011/2, #2021/2, #2031/2, #2041, #2091/2/3?
I know that Water Out temperature are high but this is just for testing…
Hmm those look OK.
What is your current LWT at your current ambient temperature?
The WL you have set up is LWT(degC) = 45 - Ambient(degC). Does your LWT roughly correspond?
I am afraid not, at -1C outside o have 41 LWT, maybe is not linear ?
Is there a way the see the externel temperature read by HP sensor ?
The WL figure is a target figure, not the actual, so at the time of reading your LWT may have been still heating up towards the target. (Wait half an hour to see if it’s still rather low…) It is linear BTW (at least on my HTQ controller).
The external temperature is visible on the remote display (the one split into “Zone” and “DHW”) - small numbers, top left corner, above “Zone”.
WL is dispayed on my Samsung Smart Thinks, and on display, it did not increase significantly, i’ll check the outside temp sensor.
I’ve heard reports that it (the outdoor sensor) isn’t necessarily accurate (e.g. somewahat susceptible to cold-air recirculation, effect of rain etc.), but that shouldn’t affect its control of LWT - if it thinks ambient is -1degC (even if it’s not) it should try to get your LWT to 46degC (with your WL settings). Something else must be going on here… 
(To exclude the obvious) is it possible that your roomstat setpoint has been reached so it quits heating before your WL target temperature is satisfied?
Thermstat is disabled, still the room temperature is bellow thermstat set point. No external temperature here
Go back a screen (the reversing arrow) and you should see it.
Yap, you are right. It seems that the waterlaw is working but it takes a while to react. Thank you .
Yes this does occasionally happen. Don’t bank on it, though…
Just connected the pwm cable to my main pump, (WITA OEM4) it does not seem to work. Just to doublecheck the pwm connection on controller side. 1 is signal, 2 ground. ?
I tried the inverter pump limit etc , but the pump just dont get into pwm mode…
