Came across a few notes from a thread on here, a while ago,re a Telford 300L TS.
The gist of it was that a old fixed 17kw (gas) boiler runs almost continuously when heating the TS, the cylinder stat is in the "bottom" of the TS, set to 65C, it switches in at 60C, a hysteresis of 5C, the boiler runs with flow/return temps of 72C/60C using a grundfos Alpha2 set to max CC3 curve. By calculation, 17kw output wiyh a dT of 12C = flowrate of 20.3LPM, 1.22m3/hr which the 6M Alpha2 will deliver at a 4.5M head.
The boiler flowtemp is set to 80C to avoid the boiler cycling as it reaches 70C as soon as the stat cuts in at 60C.
Suggest you increase the boiler SP to 80C and see if the boiler ramps up. Also check setting of the circ pump as the boiler Hx may have a fairly high pressure loss and requires a high head to get a high flowrate and dT.
The gist of it was that a old fixed 17kw (gas) boiler runs almost continuously when heating the TS, the cylinder stat is in the "bottom" of the TS, set to 65C, it switches in at 60C, a hysteresis of 5C, the boiler runs with flow/return temps of 72C/60C using a grundfos Alpha2 set to max CC3 curve. By calculation, 17kw output wiyh a dT of 12C = flowrate of 20.3LPM, 1.22m3/hr which the 6M Alpha2 will deliver at a 4.5M head.
The boiler flowtemp is set to 80C to avoid the boiler cycling as it reaches 70C as soon as the stat cuts in at 60C.
Suggest you increase the boiler SP to 80C and see if the boiler ramps up. Also check setting of the circ pump as the boiler Hx may have a fairly high pressure loss and requires a high head to get a high flowrate and dT.