Megaflo 22mm output

[Fenning]

Hey folks,

It's that damned self builder again.

We have decided to use a 300l pre plumbed mega flow pressurized system for the hot water, however when I calculate the pipe size to supply the 3 en-suites and bathroom the calc's suggest a 28mm pipe, well as far as the bathroom, then it reduces to 22mm. However my point is if the hot water supply from the megaflo is 22mm is it a waste of time installing 28mm.

Hydralics was never my strong point but if it starts in a 22mm should we then not continue with that size of pipe.

Or, perhaps Megaflo / heatrae sadia can supply this size of tank with a 28mm output.

Any advice would be greatly appreciated.

 

[Balderdash]

Why don't you trust your own calculations?

 

[Fenning]

I do trust the calculations Balderdash, it's just the fact that the hot water output is in 22mm and surely that restricts the flow from that point on, so to fit a 28mm pipe would be nugatory.

 

[fatplumber]

Water does not compress, unlike gas. In order to reduce pressure loss over distance we can in fact increase down stream sizes in gas. The effect in water is minimal. You do get pressure loss over distance with water, but increasing downsteam sizes will not make much difference. Your main difficulty is going to be heatloss over distance and water wastage. The longer the dead leg, that is the uncirculated or standing water, the more you will have to draw off in order to get hot water at the outlet. There are strong regulations as to pipe length in domestic hot water. The larger the pipe the shorter the distance. 28 mm would have to be kept to a minimum.

 

[kevplumb]

Why don't you trust your own calculations?

oh look another helpfull post

it's down to flow restriction



there is less flow restriction in 28

so depending what is liable to be in use determines the flowrate you require

a 22 outlet from the cylinder will not make a lot of difference as long as your main is up to it

 

[Balderdash]

Are all northerners so tender? If so, they need to be cooked for longer.

Things were so much easier when they were all made to work underground.

 

[kevplumb]

Are all northerners so tender? If so, they need to be cooked for longer.

Things were so much easier when they were all made to work underground.

go crawl back under your rock and hide

 

[kevplumb]

Water does not compress, unlike gas. In order to reduce pressure loss over distance we can in fact increase down stream sizes in gas. The effect in water is minimal. You do get pressure loss over distance with water, but increasing downsteam sizes will not make much difference. Your main difficulty is going to be heatloss over distance and water wastage. The longer the dead leg, that is the uncirculated or standing water, the more you will have to draw off in order to get hot water at the outlet. There are strong regulations as to pipe length in domestic hot water. The larger the pipe the shorter the distance. 28 mm would have to be kept to a minimum.

depending on the distance sec circulation might be an idea

 

[Fenning]

Thanks Kevplumb, we have about 6 bar pressure on the main so hopefully that will be enough.

I was thinking of pumped secondary circulation, but agin for my own info, does this connect back to the start of the hot water flow or does it go to the return on the boiler?

 

[kevplumb]

back to the cylinder in a loop with a pump

 

[fatplumber]

Thanks Kevplumb, we have about 6 bar pressure on the main so hopefully that will be enough.

That, I take it is standing pressure. How many litres a minute does that deliver?

 

[numpty1]

i would suggest a 32mm supply to the property,28mm from the stopcock to the uv cly combined prv/strainer and balanced 28mm to the points of use
main bath 28mm
en suite 1 28mm
en suite 2 22mm
ensuite 3 22/15mm depending on layout/lenght
if its a large house a looped hot water circuit with bronze pump and thermostat/timer should be fitted to prevent wastage.

these were posted a while back to help the op.i originally thought he had employed a professional plumber my mistake. it would appear cost over performance is the main concern,yes it will work with 22mm but the performance will be adequate rather than impressive.

 

[Fenning]

You are quite wrong numpty1, we are employing a professional plumber, cost is not an issue, and I fear you have missed the point of this thread.

As I said originally, I am researching systems for my own information, to ensure I get what I pay for and the question originated about whether the size of hot water supply from the pre-plumbed cylinder would be sufficient.[/quote]

 

[kevplumb]

You are quite wrong numpty1, we are employing a professional plumber, cost is not an issue, and I fear you have missed the point of this thread.

As I said originally, I am researching systems for my own information, to ensure I get what I pay for and the question originated about whether the size of hot water supply from the pre-plumbed cylinder would be sufficient.

[/quote]

you missed it

it is copyed from another post and the OP wasn't

 

[gas4you]

Are all northerners so tender? If so, they need to be cooked for longer.

Things were so much easier when they were all made to work underground.

Another Big Burner re-incarnation post from a name he has held from last year no doubt