15 or 22mm connections on system boiler

[andyman22]

Excuse the very naive question, but the pipework in our house has been upgraded to 22mm. I've been looking at a few system boilers and notice on the various Viessmann's they appear to have 22mm connections for flow/return, yet on the Vaillants they appear to be 22mm for flow and return but only 15mm for hot/cold connection.

I notice the 440/550cdi's are even 22mm on all water connections.

Is this the norm? And apologies for the extremely basic question here!

 

[sooey]

System boilers don't have hot and cold connections, you've been looking at Vaillant combi boilers, and yes 15mm is the norm for hot and cold

 

[andyman22]

Thanks. Have a feeling the install manual might be for them both. Is 22mm the norm for system boilers?

 

[sooey]

For an average house yes.

 

[andyman22]

If anything, I'm average.

 

[BigSnoopy01]

the appliance connection size should not be used as a guide to the systems required pipe size, the system should be designed as required.