Suitable system advice

[sunny]

Hi,

I was recommended this forum to get the advice I am looking for ...

We have a very old hot water system that we are finally looking to have replaced.

I would like the system to meet the following requirements :

- heat 8-10 radiators (on three different floors)
- heat water as soon as possible (max 30 mins)
- provide good amount of pressure to at least two showers and a tap running simultaneously
- maintain good pressure regardless of number of taps/showers

The old system is a back (gas) boiler. There is a cistern in the loft and cylinder in an airing cupboard. I have encountered issues with air locks and the water takes quite a long time to heat up. The mains pressure is 10 bar I think.

I was looking at the following :

- conventional boiler (such as a Worcester-Bosche boiler)
- megaflo cylinder

I have been told that the following could be suitable :

- Worcester Greenstar 15I condensing system
- Santon Premier Plus Indirect Unvented cylinder

I understand that conventional/system boiler is more suitable for my requirements (in terms maintaining pressure to support what I need) than a combi. I have been informed that conventional boilers tend to be more reliable than system boilers, is this true? An unvented boiler can run off the mains and does not require a cistern to be installed. The megaflo cylinder will maintain good amount of pressure and does support indirect hot water as well as direct. Also that a modern system such as this will easily heat water within 30 minutes. Please could you confirm that all of this is correct and would be a suitable solution in your opinion? If so, are there any special requirements? Which models would you suggest?

This may sound stupid but would we also need to get a flue separately for a system boiler? Also is magna clean suitable for this type of boiler?

Thank you!

[solarsmith]

hi sounds fine ...its completly down to you what products you use. there are many good boilers out there, as are unvented cylinders.
boiler wise, system boilers contain a pump and are generally sealed. conventional boilers are not, meaning a new F&E tank would be required (open-vented central heating)..there are ways around this, thats by installin what i know as a 'robokit'.. this contains a EV, filling loop and presure-relief valve & gauge.

you do relise that if you fit an unvented cylinder that the pressure whould need to be reduced.! normally to 3/3.5bar.