Changing gas boiler, condensing or combi?

I currently have a gas Y Plan system fitted in my three bedroom detached house. The system is working ok but the boiler is rather old and getting noisy so I'm thinking of replacing it.

Should I just replace the boiler with a new condensing boiler to get better efficency (my understanding of this is that my two loft water tanks and hot water cylinder would remain the same?).

Or should I go for a combi system (my understanding of this is that the two loft water tanks and hot water cylinder would all go?)

There are only two people living in the house, but we do have overnight visitors sometimes, the house has eleven radiators and two showers. Would a Combi boiler, which I believe can't give hot water and heating at the same time cope with this?

Finally, I assume a straight boiler exchange would be cheaper than taking out the tanks and cylinder?

Any suggestions much appreciated !!

Will not be a straight swop as system will need to be cleaned and possibly HW cylinder replaced. If present is gravity HW, then system will need to be converted to fully pumped (which entails plumbing alterations)

I read your post and understand that your system is already fully pumped.Having said that the most economical plan is simply to replace your existing boiler with a heat only boiler together with a system flush.You may consider replacing the cylinder if your hot water usage exceeds the existing cylinders capacity.
Running two showers off a combi is not ideal.They are designed for single point use.

Sorry to be a bit thick, but is a 'Heat Only' boiler replacing the existing boiler with a like for like, or a condensing boiler?

I'm not clear on what boiler types are now available, if I keep the existing tank (hot water capacity is ok) do I get better efficiency from a condensing boiler?

Thanks

Rod

Simplified a little,
ALL boilers are now condensing.
Heat only boilers are , just boilers, like you have now.
System boilers are also heat only, but have Y valves and pump, & pressure vessel in them for sealed systems, if you want/need to get rid of the small heating header tank. Nowt to do with the big tank.

Combis heat the water only when you turn the tap on.
2 bathrooms - don't have a combi.

Condensing boilers are more efficient than non-cons which are now obsolete/unavailable.

Some system boilers are heat only with a pump but no Y valves.

I would usually prefer a heat only boiler with external pump as thats a generic component and not a manufacturers own part at a high markup.

Tony

It is hard to figure out what the best is from behind a key board.
And even when we can, the most important part can not be sorted this way: the installer.
Best advice is to find a good installer, and follow his lead.