Such a refreshing approach, the race for the highest scop is distorting the big picture, overall system efficiency and longevity. Love the easy to understand logical explanation. Thanks
My view. Yes. I run a 2000litre buffer and never pay for electricity for heating other than when we have 2-3days inclement weather. Solar provides most of my needs. In those conditions I can charge buffer on ECO7. Any time shifting helps avoid peak periods.
Very interesting video. I understand that adding system volume can reduce (although not eliminate) cycling. The other option is to increase flow temperature hysteresis and/or energy integral (where these settings exist e.g. Arotherm Plus). The drawback of this is that flow temperature is increased (and reduced) for part of the cycle.
@@JohnBrophy-z1c correct those settings either extend the off time and overshoot the flow set-point. Most units will have both these settings and as you say they’re there to help reduce cycling. If you have correct system volume alongside correct parameters cycling will be limited. 🙂
Great content 👍 How do you calculate the correct system volume rather than the minimum volume for defrost? I guess it's too complicated to include in this video. I'll do some research online 👍
I’m so busy I don’t have time to do slick videos with full on descriptions 😂. However I am planning on doing separate videos in the class room with a whiteboard and marker so watch this space. Appreciate your support and I too love watching your videos…🙂
@@Rowlysrenewableroadshow Thank you! I'm trying to help spread reassurance through my experience of living with a heat pump. I'll keep watching your stuff. I'm always eager to learn more from people like you who know a lot more than I ever will!
Key Factors Heat pump capacity Minimum output of the heat pump Desired start/stop frequency Flow rate requirements Calculation Method 1, Determine the heat pump's nominal capacity and minimum output. 2. Calculate the minimum flow rate: Typically, heat pumps require a flow rate of about 3 liters per minute per kilowatt of capacity 3. Calculate the hourly flow rate: Hourly flow rate = Minimum flow rate (L/min) × 60 minutes 4. Determine the desired start/stop frequency per hour: Lower frequencies (e.g., 2-3 times per hour) are preferable for system longevity and efficiency 5. Calculate the required system volume: System volume = Hourly flow rate ÷ Desired start/stop frequency Example Calculation Let's use a 7 kW heat pump as an example: 1. Nominal capacity: 7 kW Minimum output: 3.14 kW (assuming 45% of nominal) 2. Minimum flow rate: 7 kW × 3 L/min/kW = 21 L/min 3. Hourly flow rate: 21 L/min × 60 min = 1,260 L/hour 4. Desired start/stop frequency: 2 times per hour 5. Required system volume: 1,260 L/hour ÷ 2 = 630 L In this case, the correct system volume would be 630 liters Scraped from the web using Perplexity
Great summary. As you say in some situations ('some' in bold), then a buffer/volumiser can be designed out, but it can be risky/tricky. Seems to me that many systems are over capacity, so even more need for need for system volume since they spend a lot of time below minimum modulation.
What's the biggest risk of designing out a buffer tank John? I think volumisers serve a purpose, but see very little need for a 4-port buffer in a heat pump design.
@@MyHomeFarm if its a big-ish place, and not fully occupied, then the owner might turn quite a lot of radiarors off/down. The system could then spend too much of its time cycling. A buffer tank should at least increase the time spent at efficient steady-state running. Whilst I would always recommend calculating the emitter circut properly so that the heat pump gets a steady load (flow-rate enough, and/or water temperaures dont rise too quickly). However, A buffer can mean the emitter design does not have to be quite so exacting. All that said, we have seen on HPM where the buffer tank is introducing inefficiecy. e.g. radiators getting say 35c, but HP flow has to be 38c to achieve this. Remove the buffer, and the heat pump should now have the same flow temperature. (35c at HP, 35c at radiators). I prefer 3-port buffers (or very well-optimised 4-port) since this issue can be minimised. Finally, If radiators are automatically opening and closing, then the return temperature to the heat pump will be varying up/down. This can 'irritate' the heat pump.... it can rev-up/slow-down, stop and start. if the heat pump return is drawing from a volumiser or buffer tank, it can make for more stable opetration. That said, manufacturers build in time delays with sensors to smooth all this out. There are a lot of variables, so no easy answers.
As an end user, it's nice to see some installers aren't superglued to a flow temp of 25 ! Also great to see self driving in operation. What vehicle is that ?
Using a Volumiser like that, in the return, should be the norm. Sadly, most of the time both the installer and the manufacturer will insist on having a "Parallel" buffer in the system. Now, there is a middle ground here, which would be putting a "T Junction" in the System Flow that essentially diverts part of the water into the buffer in case the house doesn't currently have enough Flow Volume. Unfortunately it is really hard to find reliable info on thie method and it would be nice if someone could maye share some Info or make a Video about it...
@@rolandrohde yea sure we do a 3 pipe configuration as you describe if the direct approach isn’t possible. I will do a video on it soon. I also still use 4 pipe if the customer can’t upgrade the pipework and or they are having a hybrid system. 4 pipe does reduce efficiency but if it saves the plant from premature failure and the customer gets the quoted run costs IMO that’s ok. Manufacturers have to start somewhere I guess and for them 4 pipe protects their equipment.
@@Rowlysrenewableroadshow Thanks for your reply. I am in Germany, and was lucky that my Installer at least gave me a small buffer (45l). Others are often saddled with huge 200+l Buffers with 4 Pipes. Installers here seem very much adverse to putting the Buffer on the return side or even doing the 3 Pipe install, mine wasn't even aware that it is an option...🤷♂️ So yes, a Video on the Topic would be fantastic so we can show our Installers that it is possible...😉
@@rolandrohde We would assume the Germans know best 🤣 like I say in the video reliability is almost as important as overall efficiency and I guess that is the driver towards 4 pipe buffers from manufacturers and long term installers. There is no single solution other than a well considered one. 🙂
