New boiler needed - which type?

Owain_Moneysaver

heating-eng wrote: »

Please don't mis quote and mislead people.
You would not normally need to update the cylinder, you may wish to but it is not normally required.
Also part L is not new.

Domestic Heating Compliance Guide: http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_DOMHEAT.pdf

Table 1 Row C. Minimum provision for replacement system in existing dwellings.

You can work from the Central Heating Standard Specification but that is derived from the Compliance Guide and is intended for new build.

Part L dates from 2002 but is new in that applies to existing as well as new buildings, and most systems getting replaced are going to predate it.

heating-eng

Owain_Moneysaver wrote: »

Domestic Heating Compliance Guide: http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_DOMHEAT.pdf

Table 1 Row C. Minimum provision for replacement system in existing dwellings.

You can work from the Central Heating Standard Specification but that is derived from the Compliance Guide and is intended for new build.

Part L dates from 2002 but is new in that applies to existing as well as new buildings, and most systems getting replaced are going to predate it.

Maybe you should read it again.
If you are changing or updating a boiler ,you are not replacing a system.
This is were people like yourself that don't no what there talking about can make problems by trying to read up on it.
Please leave it to RGI and they will advise on your own system what is required.

Regards.

Leif

Owain_Moneysaver wrote: »

In terms of efficiency, with a stored hot water system there are small thermal losses from the cylinder, but with a combi you are burning gas every time you turn the hot tap on, and you have to wait for the boiler to heat up even if you only want to wash your hands. (You can get boilers with a pre-heat function but that's the same as storing hot water.)

Combis are really useful in small flats where the cylinder takes up an otherwise useful cupboard.

In houses you can put the boiler, and the cylinder if it's mains pressure, in the loft if you want to save space.

A combi boiler with a pre-heat system is not the same as a traditional boiler with a hot water tank because the hot water tank stores significantly more water, and hence thermal losses will be greater in the latter system simply because you have a large tank of hot water, albeit lagged, radiating heat. I cannot give figures for the typical cost per year lost via the hot water tank.

A combi also has one less tank in the loft, though that is probably insignificant for most people.

heating-eng

Leif wrote: »

A combi boiler with a pre-heat system is not the same as a traditional boiler with a hot water tank because the hot water tank stores significantly more water, and hence thermal losses will be greater in the latter system simply because you have a large tank of hot water, albeit lagged, radiating heat. I cannot give figures for the typical cost per year lost via the hot water tank.

A combi also has one less tank in the loft, though that is probably insignificant for most people.

If you have a combi you wouldn't have any tanks in loft. (normally)

Aquatronixjenny

The reason the cylinders cost so much is because they have a lot of copper! The cylinder itself (depending ono the size) will set you back between £150 - £400. You then need to buy all the fittings as you won't really be able to re use the old ones, and you will need a new element. Then you will probably find that the tappings for the heating coil on the new cylinder are spaced differently from the old ones so the surrounding pipe work will need to be adjusted to fit. On a good day, I can fit a new cylinder in 3 hours as long as it drains quickly. On a bad day where it drains slowly and the tappings are in a completely different place, and the customer is peering over your shoulder every 2 seconds it can take a lot longer.