Posted by: @vcosmin

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Hello, i just watched some youtube videos and also i saw in pump manual that Samsung Monobloc R290 has a built it water pump with pwm. 

My current layout for a newly installed heat pump is - flow sensor > primay pump (fixed speed no pwm) > buffer > secondary pump (no pwm again and this pump is controlled by room thermostat) > radiators (upgraded k33) . 

I am pretty new to this, but i did some checking and it seems pretty far from ideal . COP during this time around 2.7 - 2.9. Right now i am playing with weather compensation ( i changed it form the default thermostat controlled setup) 

What i was wondering is that if the ASHP has buit in pump with pwm modulation, this will control the flow much better that and probably just removing the buffer (60l) will improve the the COP as well. I have more than enough water volume for defrost . 

I attach a pic, sorry for my english 

That looks like a tiny buffer plumbed with 4 ports and no temperature sensor to allow the heat pump to equalise flow rates, as well as quite a lot of uninsulated pipework!.  If my interpretation of the photo is correct this is probably giving you an efficiency penalty of 15% or more.

Its very probable indeed that the system would work more efficiently without the buffer and using a single pump.  Did the installer give any reason for doing it this way.

It sounds like you know already that the objective is to adjust the weather compensation (water law in samsung-speak) curve to the lowest possible consistent with keeping your house warm, all TRV and thermostats set well above the target temperature.  This may take a few iterations and you really want a few cold days to do it!

Posted by: @jamespa

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Posted by: @vcosmin

↑

Hello, i just watched some youtube videos and also i saw in pump manual that Samsung Monobloc R290 has a built it water pump with pwm. 

My current layout for a newly installed heat pump is - flow sensor > primay pump (fixed speed no pwm) > buffer > secondary pump (no pwm again and this pump is controlled by room thermostat) > radiators (upgraded k33) . 

I am pretty new to this, but i did some checking and it seems pretty far from ideal . COP during this time around 2.7 - 2.9. Right now i am playing with weather compensation ( i changed it form the default thermostat controlled setup) 

What i was wondering is that if the ASHP has buit in pump with pwm modulation, this will control the flow much better that and probably just removing the buffer (60l) will improve the the COP as well. I have more than enough water volume for defrost . 

I attach a pic, sorry for my english 

That looks like a tiny buffer plumbed with 4 ports and no temperature sensor to allow the heat pump to equalise flow rates, as well as quite a lot of uninsulated pipework!.  If my interpretation of the photo is correct this is probably giving you an efficiency penalty of 15% or more.

Its very probable indeed that the system would work more efficiently without the buffer and using a single pump.  Did the installer give any reason for doing it this way.

It sounds like you know already that the objective is to adjust the weather compensation (water law in samsung-speak) curve to the lowest possible consistent with keeping your house warm, all TRV and thermostats set well above the target temperature.  This may take a few iterations and you really want a few cold days to do it!

 

The installer added this buffer (60l) , for defrost reason i believe. I'll try and do a bypass on that buffer as it pretty easy to do. 

What's the target delta T for radiators (k33) , still 5 degrees as the pump like ?

Also, the monbloc pump has a built in PWM pump (inside the external unit) , it's possible to use only that pump ? and remove the other 2 as i have a straightforward layout, only 7 radiators, only one level etc. 

Cheers

you will need to set the buffer up as a volumiser for the defrost if the installer has said it needs it for defrost and also make sure you have at east one open circuit or a bypass after the volumiser to ensure flow at all times. Then you can attempt a one pump installation. Before you do this, ask the installer for the full design, index circuit calculations which will allow you to research the pump curve to make sure it is powerful enough. Assuming you need a volumiser it will mean the Monoblock is very close by to the 3 port valve or you have a low volume heating system, assuming the index circuit is not unreasonably high resistance you can attempt to run the whole system on the monoblock pump alone, set the water law, TRV's and so on to see if all improves.

@ashp-bobba I'll try that, to be honest the installer did not made any calculation or explained anything. 

I calculated water volume and is around 100l without buffer , so for my 8kw it should be enough. 

I think that most installer are going for the more expensive and generic way for this, without tailoring the install for each specific house. 

I really dont'see the the need for 2 extra pumps / 60l buffer / relay for secondary pump etc for a simple layout. 

@vcosmin Many people here will agree with you on that design issue.

I watched the video and if they have 7 or 9m pump you should be well covered.