bagaceratops
Banned
Hi,If all rads are producing their rated output then rad demand ~ 9.4kw.
UFH, 8LPM? at say a dT of 8C= 4.45kw. total, assuming no DHW = 13.85kw.
But, by calculation, boiler output at a flowrate of 1.42m3/hr @ dT of 12C, (70-58) is 19.82kw, 1.42x16.67x60x12/860, so again something not adding up, I suspect the pump is not now providing the correct data as one, its head at 3.7m can hardly even overcome the boiler Hx loss and two, by calc, the pump at those values is running at a efficiency of 54.85%, seems unlikely IMO, so again maybe reduce d.0 to a few kw below what your present calculated demand is, from pump flow&boiler dT and the flow temp should fall a bit below its SP, this will show up something.
I have gone through all of my radiators and their output is 9.4kw at Delta 50, 7.5kw at delta 40.
My underfloor heating has in total 7 loops manifold 1 and 6 loops manifold 2. They are all configured for flow rate of circa 2 litres per second. I believe this gives 7.2kw with dT of 8 degrees, but they are probably running at 10.
Assuming I use delta 50 figure this gives me 16.6kw plus the hot water take - How to calculate that - 250 llitre tank, fully steel enclosed and cold to touch on outside.
My system if un vented, with the condensing boiler which is circa 2007.
I set the boiler to d0 21kw and it appears to be behaving better - Is this due to my load being no where near 30kw?
I have tried to balance the radiators with a 20 degree difference, although should it be 20 or lower?
Many Thanks for your continued responses and help
Andrew