Choosing a hot water system

[john_g]

This may generate some discussion...

I am building an extension, and am replacing boiler and tank. The choices appear to be:

gravity fed "traditional"

"combi" of some sort

mains pressure system (vented or unvented)

The boiler will feed some radiators and an underfloor heating system. There will be three toilets, 4 sinks, and either 2 baths with showers over, or 1 bath with shower over and an additional shower. I want a really good shower pressure and flow, and don't want to wait forever to run a bath. It has been suggested the water main into the house is replaced, and that can be done if it helps. Due to lack of space one advantage of a mains pressure system was seen as mounting the tank in the loft space. It is intended the boiler will go in the loft space against one of the eaves.

Any thoughts?

John

 

[EliteHeat]

This may generate some discussion...

Why would you think that?

 

[john_g]

because from what i have seen of the forum there seems to be some differences of opinion...

 

[EliteHeat]

OK then I'll bite. What is your mains pressure and flow rate like?

 

[john_g]

flow rate is about 14 litres per minute out of the bathroom tap... no idea what the pressure us, or how to measure it.

 

[Gasman1015]

Thermal store with system boiler, made for your setup.

 

[john_g]

Thanks

So is that the vented one? In which case it doesn't need building regs and specilaist fitting?

they seem a bit pricy? I can't seem to find too many thermal stores online.

i am worried about a) the weight, and b) the clearance in the loft area...

 

[john_g]

take it back about cost... I can get an Ariston Primo Unvented Direct Cylinder 125L for £475 if I buy a boiler from them...

What is a system boiler, btw? And how powerful would it need to be?

I am guessing 125L should do for my set-up, but I may struggle to get it in the loft from the height point of view, as I assume it need a cold header tank to feed the unpressurised section. if thats the case is would mean boiler in the loft, and cylinder on the ground floor, which is quite a run...

 

[john_g]

What an idiot i am ! I need a vented cylinder, presumably. I can't seem to find one online at all... perhaps I'm searching on the wrong keywords...

 

[EliteHeat]

take it back about cost... I can get an Ariston Primo Unvented Direct Cylinder 125L for £475 if I buy a boiler from them....

I wouldn't do that if I were you - you'll have a few teething problems connecting the boiler to the cylinder