I am having my system boiler replaced with a combi and I have had 2 engineers around to give me quotes and 1 has said that he would leave the pumps in place and 1 said you don't need them, whic one is right? I have about 15 rads and it's a large house so I don't want the end of the house where the pumps currently are to get cold. Any advice on this?

He said he would leave the pump in place - he didn't say it would be used? Or did he? Post not clear Probably can't be bothered to remove it and old pipework???

the pump should be removed. the combi should have a pump already incorporated in it if you are concerned about areas being cold you should look into breaking it down into zones with zone or motorized valves. personally i wouldnt put a combi into a large property especially if you have 2 or more bathrooms