gas rating heat input

[tamz]

Hi Graham

Here is the duotec mi's page



As you can see the CH input is less than the HW

The CDi's are the same although the 27 has both the same.



Generally, especially on bigger combis the CH input is less than the HW.
If you fire it at full rate using the commisioning button it will fire at its maximum.
CDi's put the output to water and heating when in service mode so it is a good idea to run the taps while checking it to keep it running.

One to watch for.

 

[amy]

Hi,
When I was learning this in class, we spent a couple of hours reading through MI's on several different boilers, putting them in full mode via reading through pages & pages of literature and pressing multiple buttons on some boilers......THEN, our tutor told us to just turn the tap on full rate to get exactly the same effect, this is how I have tested for months now and always get a spot on reading,,,,, I take it this is ok to do.

 

[Toddyplumb]

Of course its Ok to do . When you work on a particular make (or 2) of boiler using the inbuilt max rate function does become second nature though

 

[tamz]

So what do you write on a benchmark when filling out gas rate for CH?

 

[Toddyplumb]

I just log flow and return teperatures , and for the gas rate write " Modulating "
Obviously I do the max rate in the HW section