My system has a low loss header, which for effiency I’d like to remove. Currenlty averaging a daily COP of 3.5 to 3.8, which is good but I’d like it to be better. I have a 8k Samsung gen6, however all the installation information from Samsung or Joule says to use a header or buffer. My system map is this, its fairly simple one zone in two bedroom mid terrace.
Those of you with Samsung gen6 HP do you have a system without a header or buffer, my plan was to just remove it and connect up the flow and returns and see what happens. I just want to make sure I’m not doing something catastrophic before its done.
I have an Ecodan with LLH and same pumps. I’ve built a PWM controller to ‘engineer out’ the LLH. When on heating the 2ndry pump tries to achieve a delta T of 5C across the LLH flow and return and the primary pump tries to control the primary delta T to match whatever the secondary is achieving. On DHW, tye primary pump switches to controlling at 5C deltaT.
The issue you might have with removing the LLH is having enough head from a single pump, especially if you need both on max now - might be worth reducing the settings a notch or 2 and see if it causes any problems.
Hi. I ha e a 16kw Samsung and originally it was installed with a plate exchange. I didnt think it was working at its best so changed it to a low loss header which did improve it but now after watching the likes of heat geek and urban plumber i have removed the low loss header and just use it as a volumiser of the return as i altered my downstairs raDs slightly to ensure i got the correct flow around the system to match my heat loss.
I think now it works pretty much as good as it can. I do t have any external monitoring info but it does have a energy meter on the supply to the heat pump
My epc says the house requirea 25 thousand kwh per year for heat and hot water and the energy mon itor says we are using between 4 and 4.5 thousand kwh per year which makes it cheaper than when we were on oil and the house is warm all the time
So i would say as ling as your pipe work is big enough and you use it with everything open it woll be ok you could also fit a bypass valve just for good measure
Regards
My flow rate with both my pumps set to their maximum setting is 26lpm, which is about right for Samsung documentation, although my deltaT is only about 2 degrees, but that is rough as I don’t have great monitoring. If I’ve done my maths right I could have a lower flow rate around 16lpm, so I think pumps would be fine if i knocked them down one setting, although as you suggest I should probably try that first and see what happens.
I think designing my own PWN controller is a bit beyond me if I’m being honest, but sounds like an interesting solution.
You can remove your LLH but you need to do a few calculations first to make sure it’ll work as expected.
Every heat pump needs a certain flow rate to function. Usually 2-2.5x the capacity. So you need around 16-25l/pm in your case. Currently your system can achieve that without issues as the primary pump just circles water to the LLH. Without a LLH you need to make sure you’ll get that flow rate across your entire system. If for example you have TRVs and those close a few rads when the room is hot, you can end up with not enough flow and flow errors.
A proper room by room heat loss calculation will tell you what each radiator needs to output and also what the flow rate should be. Yes you can decrease pump-speed, but that also decreases your heat output.
After you have your calculations, and you’re certain TRVs won’t restrict flow, then you can remove it and see if your primary pump can actually deliver the required flow rate. If yes then all good, if no, then you need to put your secondary back in or maybe upgrade to a higher head primary.
First thing I would do is to monitor the temperature differential at the LLH. I built myself a small unit with two DS18B20 sensors for radiator balancing. These can sit quite nicely against copper pipe, so long as the pins are well covered with heat-shrink sleeving. Mine sit under some offcuts of pipe insulation. The reading may be a bit different from the actual water temperature, but the difference should cancel most of that out.
I believe the Grundfos pump you have has quite a range of flow control options. It may be that changing its settings can give a better balance between ASHP pump and space heating circulation pump. Also see if the ASHP has settings to alter flow rates, and (as another reply says) do some calculations such as working out the energy transfer rate for a given flow rate and dT (there are notes on doing this somewhere on the OEM site).
As I understand it, a balanced LLH will have an acceptable level of loss.
@Rachel I’ve been musing about using PWM but imagined I would use the temperature differences either side of the LLH on each of flow and return. I see you took a different approach so I am wondering about pros and cons. What persuaded you to follow the route of measuring dT between LLH flow and return?
When the LLH is operational i am measuring the DT on the inlet and outlet effectively. The inlet side is monitored before the 3 way valve on the flow and at just after the tee from the DHW cylinder on the return. If i had the sensors on the LLH itself then they wouldn’t give me a DT to control to when the system is on DHW. But when its on the heating circuit its effectively the same temperatures as the LLH flow and return.
