Optimal combi boiler for rainfall shower head

[gas112]

bernard green is a diyer like yourself
no point having a 36kw combi if you havent got the right amount of water coming into the house .
Standard water pressure in a house then a 28kw combi delivering 12 litres of hot water is more than enough for the size of showerhead your after when mixed with cold

 

[muggles]

As others have suggested, do things in the right order. Start by finding out what your mains can deliver, and use that information to specify both the boiler and the shower. Rainfall heads are not all the same - some (like the one you're looking at) need a very high flow rate & maintained pressure to function correctly, others require much less. For example, the VADO Aquablade will work down to 6l/min / 0.2 bar.

 

[bernardgreen]

bernard green is a diyer like yourself

I am a DIYer who self built a house including all the design and installation of electrical, plumbing and heating services. I am now renovating an ancient cottage so a lot of experience and knowledge acquired over many decades.

Never forget that a DIYer will be living in the house for many years whereas a professional will not be living in the house. Because of this a "professional" installer may not give as much care to the design of the system as a competent DIYer will. A professional's design philosophy maybe biased by what system gives the most profit for the least work.

 

[muggles]

Never forget that a DIYer will be living in the house for many years whereas a professional will not be living in the house. Because of this a "professional" installer may not give as much care to the design of the system as a competent DIYer will. A professional's design philosophy maybe biased by what system gives the most profit for the least work.

You've used this line before. It was total rubbish last time you used it, and it remains so now (unless you're employing the absolute dirt-cheapest most hairy-arsed installer you can find)

 

[bernardgreen]

unless you're employing the absolute dirt-cheapest most hairy-arsed installer you can find)

So you accept that there are hairy-arsed installers. Some of these do have a particular skill, the skill of convincing potential suckers clients that they are not hairy arsed.

So the line is not total rubbish but is a valid reflection on an industry where the majority of clients lacking the necessary knowledge can be mislead by profit seeking tradesmen

 

[gas112]

I am a DIYer who self built a house including all the design and installation of electrical, plumbing and heating services. I am now renovating an ancient cottage so a lot of experience and knowledge acquired over many decades.

Never forget that a DIYer will be living in the house for many years whereas a professional will not be living in the house. Because of this a "professional" installer may not give as much care to the design of the system as a competent DIYer will. A professional's design philosophy maybe biased by what system gives the most profit for the least work.

And failed straight away on the most basic of questions on how a combi actually works

 

[bernardgreen]

And failed straight away on the most basic of questions on how a combi actually works

What are those questions ?

 

[gas112]

What are those questions ?

You jumped straight in with, get a 36kw combi.
absolute basic mistake

 

[bernardgreen]

You jumped straight in with, get a 36kw combi.
absolute basic mistake

Yes I did say ""With a high flow rate rain shower you would need a combi of 36kW or more to have a good shower.""

I did not say get a 36kW combi, in fact I advised against getting a combi

An opinion that I base on the experiences of several owners of high flow rate showers that are ( or were ) fed from a combi.

Confirmed by a basic calculation for a large rain fall shower with no flow restrictor

Flow Rate (Ltrs per Minute water ) 15

Temperature Rise (Degrees Celsius) 35

Heat absorbed 36 kW

 

[gas112]

Yes I did say ""With a high flow rate rain shower you would need a combi of 36kW or more to have a good shower.""

I did not say get a 36kW combi, in fact I advised against getting a combi

An opinion that I base on the experiences of several owners of high flow rate showers that are ( or were ) fed from a combi.

Confirmed by a basic calculation for a large rain fall shower with no flow restrictor

Flow Rate (Ltrs per Minute water ) 15

Temperature Rise (Degrees Celsius) 35

Heat absorbed 36 kW

Still getting it wrong they wouldn't need a 36kw combi a 28kw combi would be perfectly sufficient not an opinion I base on second hand information such as yours but from decades of experience and also having the exact same set up in 3 of my houses at present.
And why are you quoting 15 litres a minute does it not also have cold water mixed with it?

 

[fixitflav]

does it not also have cold water mixed with it?

No, not if you have 36kW available, and you want a temperature rise 35K.

 

[gas112]

No, not if you have 36kW available, and you want a temperature rise 35K.

I would like so see you stand under a shower with no cold mixed with the hot

 

[fixitflav]

I would like so see you stand under a shower with no cold mixed with the hot

Mains water at 10°C, rise 35K, shower at 45°C would be about right.

 

[gas112]

Mains water at 10°C, rise 35K, shower at 45°C would be about right.

Be higher than the 41 degrees maximum for showering safely for an adult and 37 degrees for youngsters recommended by the chartered institute of plumbing and heating engineering

 

[fixitflav]

Be higher than the 41 degrees maximum for showering safely for an adult and 37 degrees for youngsters recommended by the chartered institute of plumbing and heating engineering

Alright, make the mains water 6°C