Heat only (conventional) boiler temperature settings 12 February at 4:19PM in Energy 23 replies 593 views

Sterlingtimes

I am reading up and trying to get to grips with the dynamics.

I have set the boiler heating temperature to 65 degrees, the heating engineer's recommendation, and the hot water temperature, for what it is worth, to 60 degrees, the maximum possible.

Now on this test with a call for heat, the outgoing flow on the pipe is 52.6 degrees and the return flow temperature 45.2 degrees, 8.1 degrees lower. 

The boiler shows a flow temperature of 67 degrees. So the flow at the pipe is far lower than the boiler flow. Why?

Sterlingtimes

Rodders53 said:

I'm an Engineer (E&E) by training and retired... and sometimes enjoy reading manuals.

Your boiler has no way of knowing when HW or CH is demanded 

Thank you again. I spent my earlier career working in a laboratory as a radio systems development engineer, but then I was diverted into law/business. I am now retired and find time to anguish about little technical problems.

I have viewed various schematics and agree with your observation that, as a matter of fact, the boiler does not recognise whether it has a radiator call or a hot water call. The call can come from the hot water cylinder or any one of the 14 iTRVs. In these circumstances, there seems to be no merit in setting separate temperatures for heating and hot water. Perhaps when the heating is switched into summer mode, the boiler defaults to the lower hot water flow temperature.

vic_sf49

oldagetraveller1 said:

vic_sf49 said:

Rodders53 said:

A combi boiler will definitely have separate HW and CH circulating water temperature control.

Hoping not to derail the thread, but my combi boiler (err, Worcester Greenstar 28i junior) has the HW set at 55 degrees, and that can't be changed, says the manual.

Flow temp (heating) can be adjusted by the dial on the front panel.

Page 8, section 3.1.4 of the manual suggests otherwise. Setting hot water temperature, the left hand control knob.

Here's hoping I wrote the correct boiler above...the left, and only knob, changes the flow temp.

The hot water temp on this boiler is fixed at 55 degrees.