Unvented System....system or regular boiler ?

[topgazza]

looking at the Worcester /Bosch website they suggest a system boiler for my house because it contains an expansion tank built in ..yet I have an unvented pressurised system so wouldn't I need just a regular condensing boiler ?

The site only mentions a 1 year warranty as well, extended to two if you return the reg card withing 30 days...

 

[mikej2005]

'System' boilers are used on unvented/pressurised systems (like yours) and 'conventional' or regular boilers are used on vented systems (where you have an expansion tank in the loft)

 

[mikej2005]

P.S. Some unvented systems utilise separate expansion vessels, so by the sounds of it WB are implying that you could do away with that if you chose one of their system boilers, as they they are inbuilt.

 

[topgazza]

Thanks Mike...that makes sense...not sure if I have an expansion tank as there are two "vessels" attached ..one is the pressure tank that I top up from time to time but there is another above the cylinder.

I guess whoever comes round to do the job can decide but I wouldn't want to remove something...extra work/cost/potential problem.....so I'd probably go for the regular as the system wouldn't give me any extra....

 

[mikej2005]

I'd probably go for the regular as the system wouldn't give me any extra....

As far as Worcester Bosch's usage of the terms go, a 'system' boiler can only be used on a sealed/pressurised/unvented system and a 'regular' or 'conventional' boiler can only be used on an open/vented system.

If I've understood this correctly and your current system is pressurised, then you'll have to have a system boiler.

If an inbuilt expansion vessel is the only difference between the two, then I don't know whether a conventional boiler can be used on an existing sealed system in conjunction with a separate expansion vessel though - I doubt it instinctively, but that's probably one for the pro's, that one !