Best way to get 3 bar / 20 l/m shower experience?

[shaft120]

My 35 yr old boiler is about to bite the dust, and I've been advised to fit a combi (Intergas Xtreme 36).

I have a cold water pressure if 14l/m, and I currently get 13l/m on the hot tap in the bathroom basis.

I have a direct cold water mains supply with noh hot or cold tanks. I have a mixer shower, and a further electric en suite, which I want to swap for a mixer. I'd rarely use 2 at a time, so I'm fine if I can only get the pressure I want on the shower when being used on its own.

What are my options? I understand the combi will supply between 14 - 20 l/m. I'm presuming this is only above 14 when using the mini storage tank in the combi (presume it has one?).

Will I be able to get what I want as is, or could I fit a pump to boost the mains pressure? Would this then take the boiler rate up to 20l/m?

I'm being quoted about £3k for the total install.

Ideas appreciated

 

[Madrab]

Firstly, the only way to increase your mains supply is if your supply pipe is restricting the flow and the district mains is running higher, if so then you would need to increase the size of your mains supply pipe. You need to get your water company to tell you what the district mains is running at.

Only then is it worth while looking at how you would heat that flow, even the largest storage combi would struggle to get that high a flow.

If your mains cannot be increased then the only way to get 3bar @ 20L/Min would be to have a pumped hot water supply with it's associated cold water cistern.

 

[shaft120]

Firstly, the only way to increase your mains supply is if your supply pipe is restricting the flow and the district mains is running higher, if so then you would need to increase the size of your mains supply pipe. You need to get your water company to tell you what the district mains is running at.

Only then is it worth while looking at how you would heat that flow, even the largest storage combi would struggle to get that high a flow.

If your mains cannot be increased then the only way to get 3bar @ 20L/Min would be to have a pumped hot water supply with it's associated cold water cistern.

Thanks

I've actually managed to get it up a bit at the mains by properly opening the stopcock. It's now a shade under 16 at the bathroom cold tap when no other taps running, and just over 14 when another cold tap is running in the kitchen at the same time.

Guess I'll just take my chances and hope the new combi works out ok.

1 further question about the showers. I have a thermostat cartridge controlled mixer shower. I don't actually know how this mechanically works, and how it would impact flow rate with say a combined 14 l/m hot and 15 l/m hot feeding into it? Presume this would be dependent on the pressure in the respective HC feeds? My question is if a straight mixer head, with separate hot and cold taps would provide a better combined flow rate compared to the cartridged thermostat (tmv) ?

 

[Madrab]

A thermostatic mixer always restrict the flow of any mains supply to a certain degree, each one has a different throughput, usually design and size of the waterways dependent. The better the dynamic pressure though the less impact there will be to the actual noticeable performance.