Changing from vented to unvented

[peterf83]

Hi, we’re close to completing on a new house. We think we have a vented system. There is a Potterton Profile 50e boiler downstairs. There is a cold water tank in the loft and a cylinder in an airing cupboard in the first floor.

Our home buyer survey suggested that the system is old and needs updating, also there was no cover over the cold water tank which means crap is getting into the water supply.

We’re thinking we’ll upgrade the system to an unvented system such as a megaflo or similar. We’re also considering having this installed in the garage instead of the airing cupboard. Whilst we’re doing this we’re planning on installing a slimline water under floor heating system to the whole of downstairs which means we can lose the radiators.

Does anyone know if the boiler that is installed is compatible with this new set up or would we need to upgrade that too? If we have to upgrade are there any recommendations.

In case you need to know there is currently only one bathroom upstairs but we’re planning on extending next year so that we have an additional two bathrooms upstairs. There is also a downstairs toilet.

 

[oldbuffer]

1. Before going un-vented (or combi) you need to know the incoming mains water pressure, and the static (no tap running) and dynamic (one cold mains fed water tap) water pressures. You need 2 bar pressure and 20 litres per minute for unvented. You might get away with a bit less for a combi.

2. The existing boiler is compatible, but it is quite old and you should be thinking of a replacement in the near rather than the distant future. If you are extending you need to do a whole house heat loss calculation on the new size to see if the boiler has the capacity to heat the property and do the hot water.

3. To run three bathrooms, then if you want simultaneous showers you'd need to:
3a. Go unvented
3b. OR: stay vented and run one or more shower pumps. Probably have to increase the size of cold water storage cistern and hot water cylinder for this option.

 

[Mottie]

We had an unvented Potterton Profile 60e system and had that converted to an unvented system. Boiler was around 25 years old but worked that system fine until it needed repair so we changed the boiler for a Vaillant Ecotec plus 418.