Potatoman Posted December 18, 2024 Share Posted December 18, 2024 Hi, can anybody tell me what the flow rate from my 9kw LG ASHP should be given a 5.8 KW heat loss and using glycol, thanks Link to comment Share on other sites More sharing options...
JoeBano Posted December 18, 2024 Share Posted December 18, 2024 Good video on how to work it out. Don’t know glycol heat capacity, someone will know here. Link to comment Share on other sites More sharing options...
ReedRichards Posted December 18, 2024 Share Posted December 18, 2024 You're never going to have a fixed 5.8 kW hot loss, though. Link to comment Share on other sites More sharing options...
PhilT Posted December 18, 2024 Share Posted December 18, 2024 On 18/12/2024 at 06:37, Potatoman said: Hi, can anybody tell me what the flow rate from my 9kw LG ASHP should be given a 5.8 KW heat loss and using glycol, thanks Expand This is the formula with a few example numbers. Set up a spreadsheet and model the variables to get your flow rate, or whatever parameter you want. Formula for Energy Delivery M x Cp x ΔT = Q flow rate coefficient temp diff output l/s water/glycol degC kW 0.35 x 4.085 x 4.00 = 5.7 litres/minute 21.00 litres/hour 1260 Water Cp 4.18 Fernox HP-5c @ 20% 4.085 -2.3% Link to comment Share on other sites More sharing options...
Potatoman Posted December 18, 2024 Author Share Posted December 18, 2024 That's great, Thanks Link to comment Share on other sites More sharing options...
akjos Posted December 19, 2024 Share Posted December 19, 2024 Your heatpump needs around 2-2.5x the capacity in flow rate in l/min. So 9kw unit you’ll need 18-22l/min for the unit to work. Otherwise you’ll get flow rate errors. Not the individual rooms or UFH loops you can calculate by the heat output formulas gives above. But you heatpump overall needs the high flow rate to function. Link to comment Share on other sites More sharing options...
JohnMo Posted December 19, 2024 Share Posted December 19, 2024 I just leave every as open as possible and the the heat pump controller sort out what it wants to flow at. Most the time my 6kW will flow around 18 to 20 L/min. Bigger the flow the smaller the dT, so more output for a given flow temp. Link to comment Share on other sites More sharing options...
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