New boiler - connecting pipes

[Paraig]

I have had 2 different opinions from gas engineers.

To replace my old conventional boiler with a new combi boiler, it seems the connecting pipes are the wrong size (too small). Not sure if this is gas or water pipes.

One engineer says pipes need to be replaced, the other says not. What are the possible issues with just connecting the pipes to bigger diameter pipes?

Property is 3 bed house.

Thanks

 

[stani]

More likely it's the gas, which now has to be sized correctly,
A. To make the boiler work efficiently
B. The manufacturer will void the warranty if it's undersized.

 

[Gareth Harris]

Agree with @stani but may also need to consider the size of the cold water pipe, may also need to be upgraded to give adequate flow rates depending on existing system.

Definitely need to clarify - or get a 3rd opinion.