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This just doesn't make sense.
The OP says he has an Ultracom 24 hxi boiler, which has a 24kW output; but the App says the energy consumption is 29kWh. Is that the current rate or the total since the pump was first installed?
1. Why are you using a flow temp of 65C? It will reduce the rad output considerably.FYI, here are some numbers I took yesterday when trying to manually balance with the pump on:
- I think the system had been heating around 10/15 mins, I didn't note it down, I can't remember which pump setting I had it on, possibly CC at 65%, I would need to repeat to be 100%.
View attachment 37039
2. How, and where, are you measuring the temperatures? The drop of about 20C from boiler to rad seems excessive.
3. The Ultracom is designed for a 20C differential. An 11C differential will result in a pressure loss through the heat exchanger of nearly 6 metres, compared to 1.8m with a 20C differential. This is at max output.
You say, in another post, that the boiler continually short cycles. This is probably due to the boiler being oversized. (24kW for approx 12kW of rads.) The boiler's logic says that, every time it restarts it does so from max output and then modulates down if necessary. Unfortunately it doesn't modulate fast enough so the temperature rises very quickly, the boiler overheats, shuts off, and the whole cycle starts again.
The reason for over-sizing the boiler is: Hot Water. The system "designer" assumes that the HW cylinder is being heated at the same time as the CH is running flat out. The solution is simple - heat the cylinder when CH requirement is minimal or non-existent. (Modern HW cylinders retain their heat for a very long time.) Installations with Weather Compensation have to be configured so that HW takes priority over CH. If it didn't, the flow temperature might not be hot enough to heat the cylinder. Although you don't have weather comp, you could sill adopt the same principle and give HW priority over CH.
It might be possible to reduce the max output of the boiler using parameter d.0 (See the installation manual).