From Gravity System to Unvented Indirect Hot Water Cylinder

[Madrab]

Not relevant, read my first post to what was my question.

I did and your 2nd post - I appreciate you were originally asking about expansion vessels and the ability to use an open vent which the answer to both was yes.

I understand I need expansion vessel for the unvented cylinder to get main pressure hot water of max 3 bar

You then went on to explain that there was a measurement of the mains taken @ 4bar and a pressure of 2bar @ a PRV, hence the question asking to clarify whether that was a single outlet and whether there were proper flow figures taken. Can't understand why those basic questions should be met with such an abrupt response.

What I was trying to explain is - at the moment, given the information that was relayed to us - it is unknown whether that cold water main will delivery even the min that an unvented needs to offer a half decent HW supply to the property. If as has been suggested there is a dynamic pressure of 2 bar (is that will multiple outlets running?) that 15mm pipe will struggle to flow enough to sustain an unvented cylinder properly.

To offer an example - a 15mm copper pipe (13mm ID) @ 2 bar dynamic will flow ~ 14L/Min through a straight 5m length, no bends/valves/fittings/etc, that are always be found in a house. Whereas a 22mm copper pipe (20mmID) @ 2 bar will flow ~ 38L/Min over the same distance. I know what one I'd want with an unvented cylinder.

I know the rest, done my homework on these elsewhere inc manufacturer

Unfortunately - given the info we have here which granted, may be incomplete - the homework isn't getting a passing grade I'm afraid. Most manufacturers of UV cylinders I've worked with (and that most of them TBH) ask for a 22mm supply @ 2 bar dynamic @ 20L/min and even then they will caveat to say @ those levels, that HW output will be significantly reduced if more than 1 outlet is used at a time.

 

[yartin]

I did and your 2nd post - I appreciate you were originally asking about expansion vessels and the ability to use an open vent which the answer to both was yes.

You then went on to explain that there was a measurement of the mains taken @ 4bar and a pressure of 2bar @ a PRV, hence the question asking to clarify whether that was a single outlet and whether there were proper flow figures taken. Can't understand why those basic questions should be met with such an abrupt response.

What I was trying to explain is - at the moment, given the information that was relayed to us - it is unknown whether that cold water main will delivery even the min that an unvented needs to offer a half decent HW supply to the property. If as has been suggested there is a dynamic pressure of 2 bar (is that will multiple outlets running?) that 15mm pipe will struggle to flow enough to sustain an unvented cylinder properly.

To offer an example - a 15mm copper pipe (13mm ID) @ 2 bar dynamic will flow ~ 14L/Min through a straight 5m length, no bends/valves/fittings/etc, that are always be found in a house. Whereas a 22mm copper pipe (20mmID) @ 2 bar will flow ~ 38L/Min over the same distance. I know what one I'd want with an unvented cylinder.

Unfortunately - given the info we have here which granted, may be incomplete - the homework isn't getting a passing grade I'm afraid. Most manufacturers of UV cylinders I've worked with (and that most of them TBH) ask for a 22mm supply @ 2 bar dynamic @ 20L/min and even then they will caveat to say @ those levels, that HW output will be significantly reduced if more than 1 outlet is used at a time.

Honestly, not reading the above even if you pay me as really don't have time. How do you "pros" find time for such!
Move on.

 

[Madrab]

Honestly, not reading the above even if you pay me as really don't have time. How do you "pros" find time for such!
Move on.

Ah well .... Fine - knock yourself out and crack on.

The galling thing is when DIY'ers that think they know everything come onto forums like this to ask basic questions and then show their ignorance and arrogance when given straightforward and helpful advice. The ironic thing is though, that's what keeps all those numpty rip off installers in business and then they blame these very installers when they end up with a $hit system.