The Secon buffer/cylinders have baffles on the inside to divert flow, they also have a dip tube style connection that bends up towards the inside top of the buffer. Allows for good mixing in the buffer, I've only used as a volumiser though.
There is not sufficient residual pump head available to not have hydraulic separation. And not really enough space to add a separate hydraulic separator. If it was a heat pump that had no internal pump then we could supersize the external pump to overcome the problem
@@peterwalton8721 I don't think you can use close couple Tees. With weather compensation the heat source needs to be able to see the temperature of the secondary circuit in order for it to adjust its temperature to allow for mixing at the hydraulic separator. I believe although I haven't proved that the Daikin heat pump sees the temperature in its buffer and was so adjust it's leaving water temperature to correct the temperature in the buffer. So if they can supply a secondary temperature sensor then yes I guess close coupled Tees could be an option
@@andrewmillwardwatford9410 - not sure what temperatures Daikin are monitoring and using for control. If (for example) it was 1 CCT for hydraulic separation then the flow to the secondary would be that from the heat pump, whilst the return from the floor would be subject to distortion if unbalanced primary/secondary flow rates ? So at least you wouldn't have to run the HP at higher flow temperatures so would improve efficiency. I'm no heating engineer so please take anything I suggest with a pinch (or handlful) of salt - but wanting to learn from others. What difference would it make if running in weather compensation mode versus any other operating scenarios ?
They don't want it to the secondary temperature and the pump on the heat pump has a wide modulation range which would lead to issues with mismatched mixing temperatures on the secondary circuit often referred to as distortion
@@andrewmillwardwatford9410 I believe he is referring to the refrigerant circuit (superheat is the degree of heat above change of state just prior to compressor suction, sub- cooling is the temp of the liquid leaving the condenser below the change of state from gas to liquid. That’s if I recall correctly. It speaks to the regulation of refrigerant flow around the system and its efficiency / effectiveness - best heat transfer and ensuring gas (not liquid) returns to the compressor.
@@andrewmillwardwatford9410 I am not sure if it is relevant in terms of heating system design at all, it is for fault finding for sure, I am not sure how heat pumps are instrumented up in terms of sensors on the refrigerant circuit at the key points.
@@normanboyes4983 it's still good to have an in-depth understanding of everything to do with your Design as I'm sure you appreciate being a fellow anorak. I think at the moment I have more questions and answers about heat pumps and the related designs but I find the technical extremely lacking
On a system I've been looking at we see a similar offset, again a squat (50L) buffer in a pre-plumbed cylinder. Hopefully will be reworked as volumiser with different hydraulic separation design for 3 secondary ufh manifolds. Indeed the degree of mixing due to the buffer results in very fast response of the heat pump return temperature. The hp sees this as minimal load and prematurely turns off. To then cycle back up. Looking forward to any improvements Andrew has to offer.
So you're going to use the buffer as a volumizer and and add a different form of hydraulic separation? I think that could be a good idea if you have space.
Rishis admission that "renewables" won't be replacing natural gas any time soon pours cold water on the heatpump meme. "decarbonize at any cost" even if its not fit for purpose nor saves any money, is a cult. I had a heatpump salesman attempt to scare me with claims of increased nat gas taxes 😂 desperate?
Is that buffer supplied by Paul Brimble? Maybe a drawing of the internal pipework showing what is inside of the external connections would be helpful?
It's the existing pre-plan cylinder which includes a buffer manufactured by Daikin or on behalf of Daikin
The Secon buffer/cylinders have baffles on the inside to divert flow, they also have a dip tube style connection that bends up towards the inside top of the buffer. Allows for good mixing in the buffer, I've only used as a volumiser though.
How do you know about this? Do you have any schematics that you could send to me
@@andrewmillwardwatford9410 sure, where do you want me to send it?
Can you make the buffer a volumizer instead?
There is not sufficient residual pump head available to not have hydraulic separation. And not really enough space to add a separate hydraulic separator. If it was a heat pump that had no internal pump then we could supersize the external pump to overcome the problem
Could you go with closely spaced tees if insufficient room for a low loss header ? Alternatively maybe 3 port the buffer could improve it perhaps?
@@peterwalton8721 I don't think you can use close couple Tees. With weather compensation the heat source needs to be able to see the temperature of the secondary circuit in order for it to adjust its temperature to allow for mixing at the hydraulic separator. I believe although I haven't proved that the Daikin heat pump sees the temperature in its buffer and was so adjust it's leaving water temperature to correct the temperature in the buffer. So if they can supply a secondary temperature sensor then yes I guess close coupled Tees could be an option
@@andrewmillwardwatford9410 - not sure what temperatures Daikin are monitoring and using for control. If (for example) it was 1 CCT for hydraulic separation then the flow to the secondary would be that from the heat pump, whilst the return from the floor would be subject to distortion if unbalanced primary/secondary flow rates ? So at least you wouldn't have to run the HP at higher flow temperatures so would improve efficiency. I'm no heating engineer so please take anything I suggest with a pinch (or handlful) of salt - but wanting to learn from others. What difference would it make if running in weather compensation mode versus any other operating scenarios ?
They don't want it to the secondary temperature and the pump on the heat pump has a wide modulation range which would lead to issues with mismatched mixing temperatures on the secondary circuit often referred to as distortion
I’d like to measure the superheat and sub cooling on these systems.
What do you mean by the superheat
@@andrewmillwardwatford9410 I believe he is referring to the refrigerant circuit (superheat is the degree of heat above change of state just prior to compressor suction, sub- cooling is the temp of the liquid leaving the condenser below the change of state from gas to liquid. That’s if I recall correctly. It speaks to the regulation of refrigerant flow around the system and its efficiency / effectiveness - best heat transfer and ensuring gas (not liquid) returns to the compressor.
@@normanboyes4983 I'd like to learn more about this and it's relevance to the system design
@@andrewmillwardwatford9410 I am not sure if it is relevant in terms of heating system design at all, it is for fault finding for sure, I am not sure how heat pumps are instrumented up in terms of sensors on the refrigerant circuit at the key points.
@@normanboyes4983 it's still good to have an in-depth understanding of everything to do with your Design as I'm sure you appreciate being a fellow anorak. I think at the moment I have more questions and answers about heat pumps and the related designs but I find the technical extremely lacking
On a system I've been looking at we see a similar offset, again a squat (50L) buffer in a pre-plumbed cylinder. Hopefully will be reworked as volumiser with different hydraulic separation design for 3 secondary ufh manifolds. Indeed the degree of mixing due to the buffer results in very fast response of the heat pump return temperature. The hp sees this as minimal load and prematurely turns off. To then cycle back up. Looking forward to any improvements Andrew has to offer.
So you're going to use the buffer as a volumizer and and add a different form of hydraulic separation? I think that could be a good idea if you have space.
Yep, that's the plan. When we get round to it is another matter, arguing with original installer at the moment.
Yep, that's the plan. When we get round to it is another matter, arguing with original installer at the moment.
@@peterwalton8721 how will the heat pump know the secondary mixed temperature
Rishis admission that "renewables" won't be replacing natural gas any time soon pours cold water on the heatpump meme. "decarbonize at any cost" even if its not fit for purpose nor saves any money, is a cult. I had a heatpump salesman attempt to scare me with claims of increased nat gas taxes 😂 desperate?
What do you say may or may not be true but we will still be installing he pumps and rectifying issues with poor systems and poor heat design.