Calculate ROI for a custom Unvented Indirect Heat Pump Cylinder???

[MNW67]

That just looks like two coils connected in parallel? but doesn't show the flow/return.

The flow goes in the top like normal. I have absolutely no idea what he means by "reverse return". In the video he says "and that means the first port to go in will be the last to come out and that will ensure even flow across both coils".

 

[MNW67]

What is the mass? well what is the volume! interchangeable....So a volume (which = a given weight) flow at a speed = mass flow rate...the mass(volume) how do you measure the flow rate...or is this just another guess?

But the mass of water in a given volume changes dependant on temeprature. Which is why l/s is technically wrong for mass flow rate.

Although for the purpose of domestic heating calcs I'm also very guilty of interchanging them

100 kgs of water at 4.35C is almost exactly 100 liters.
100 kgs of water at 60C is 101.7 liters or 1.7% greater so reasonably acceptable to use liters for these type calculations.

Thanks guys. I only made my original comment because I was a bit concerned that the OP was getting slightly confused, in various ways, by the terminology of velocity and flow rates, and I was hoping to simplify things. It was when he quoted from Wikipedia:

Mass flow rate can be used to calculate the energy flow rate of a fluid:

where

is the unit mass energy of a system.

And I thought I would just try to make it simple and say forget about mass flow rate, just call it "flow rate". I wasn't really wanting to trigger a wider debate. I agree that it doesn't really matter for the purposes of central heating.

 

[ScottishGasMan]

Looking at it the reverse return is just for even flow through both coils.

Where it enters the cylinder one pipe goes straight and other elbows off, so most flow would go straight.

So at the bottom the higher flow coil has an elbow and visa versa, to even out the resistance and flow

 

[MNW67]

Great. Makes sense now!

 

[old duffer]

But the mass of water in a given volume changes dependant on temeprature. Which is why l/s is technically wrong for mass flow rate.

Although for the purpose of domestic heating calcs I'm also very guilty of interchanging them

for this calculation there is a limited range of temperatures. The heating flow will be at best 70 degrees...so the volume (not mass) is negligible for calculations

Liquids - Volumetric Expansion Coefficients

Volumetric - or cubical - expansion coefficients for common liquids.

www.engineeringtoolbox.com