Options for new extension and loft conversion heating

[mravant]

Hi All,

Let me first apologise for me making up new technical terms as i go along

Im in the middles of have a side extension build to my current 3 bedroom semi, which will house a new lounge and two new bedrooms (measuring 3.1m x 3.3m each) and the new lounge will be 7m x 4m).

We currently have a conventional boiler (Ideal Ikos) which was only replaced a couple years back and does the job perfectly. Our hot water cylinder is in the airing cupboard with a backup electric immersion heater.

This is where is get complicated. We may now also have the loft done at the same time giving us another bedroom and bathroom (giving us 2 bathrooms in total). We are now not sure what to do:

1) do we just leave the current system and install a small combi boiler just for the loft?

2) Do we change the whole system to a large combi and run everything from it?

Very confused, the builder for ease is recommending just a large combi to run everything.
I would be grateful for your view and input

 

[Whitespirit66]

3) Change current hw cylinder for an unvented one.

(As long as you have minimum 1.5 bar pressure and 20 L/Min flow on incoming cold water)

 

[mravant]

Thanks.

Please correct me if I'm wrong but to check the flow I just bucket marked in Litres and opened the cold kitchen tap and timed how much it fills in a minute?

I did this and i only get 13L per minute. Did i do it right?

 

[Whitespirit66]

Your technique is right.

Make sure all stop taps are fully open, as well as an isolation valve under the tap.

Try the outside tap if you have one.

 

[mravant]

Just checked all and still getting 13L / m.

Is there any systems that can work with that flow rate?

 

[bengasman]

As your current cylinder appears to be a vented model ( yuck ) and your boiler is a piece of junk, you might as well rip the lot out and stick a big combi in.
Your mains flow seems rather limited, so an unvented cylinder would be a waste of money.
And make sure this time it is not an Ideal.

 

[Norcon]

If its just a shower and basin in the bathroom then fit an electric shower and an electric (point of use) water heater.

 

[mravant]

I also need to heat the loft along with the rest of the house and new extension.

I think i may just opt for a small combi just to run the loft.