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

Good video on how to work it out. Don’t know glycol heat capacity, someone will know here. 

You're never going to have a fixed 5.8 kW hot loss, though.

4 hours ago, 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

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%

That's great,   Thanks

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.

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.