Short Cycling, any advice?

[JohnMo]

4 minutes ago, Super_Paulie said:

But what advantage would I gain from this increased volume, longer cycle time?

Cycling is part volume and the other more critical is having somewhere to take heat away - the heating system. An example is trying to push low flow temps through small radiators, they just don't have enough heat transfer area to transfer the energy generated to the room. So heat source cycles as that is all it can do. In this situation you would install radiators with about 3 to 4 times the surface area and the system works.

 

Your system is having a first cycle helped by having to heat a bigger volume (volumiser). But you are not really dumping the heat to the house, I suspect the heat loading in the floor is running full, the house heat loss is way smaller than the continuous heat being supplied.

 

The heat flow through your UFH is about 1.2kW per loop. But depending on room heat losses a lot of this will be recycled water, so may not all come from the boiler.

 

So 4x loops at 2.5 l/min, so y

 

8 minutes ago, John Carroll said:

7C dT,

The Salus actuator will target that dT.

 

Suggested action

Leave system as is

Manually switch off boiler or UFH until house cools to about 20, then switch boiler or UFH back on again see what happens. If you get a long run your solution couple simply batch charge the floor - use as a storage heater.

[John Carroll]

42 minutes ago, Super_Paulie said:

Yeah it's dead on 7 lower, the actuators see to that and seemingly work a treat.

 

42 minutes ago, Super_Paulie said:

Yeah it's dead on 7 lower, the actuators see to that and seemingly work a treat.

So, the return temp to the boiler must be 41C, the (boiler) flow temp is 60C, dT, 60-41, 19C, UFH dT, 48-41, 7C, boiler flowrate, 10*7/19, 3.68LPM, so there obviously is HW being recirculated to give that higher return temp, the only downside of this is that the boiler efficiency will be lower at the higher return temp so maybe just look at this, rather than trying to get longer cycle times etc by creating a bigger heat demand or whatever, your system is, IMO, performing very well, why not leave it be.

 

The "picture" below might be easier to understand UFH mixing etc and you can do your own calcs.

UFH Calculations with Bypass Extract Rev0.xlsx

Edited 3 hours ago by John Carroll