2 port and 3 port mid on same system

[pauls]

come accross a system (unvented) that has a 2 port to control hot water and a 3 port on the heating side why this configuration of a 3 port? if zoneing off 2 heating zones then 2x 2port valves on heating would be better to use.

just dont understand why that set up.

 

[raymondo68]

Are you saying that there are 2 heating zones in addition to the hot water? 1 connected to port A and the other to port B?

I agree this is a bizarre way to control 2 heating zones.

Raymondo

 

[pauls]

yes ....a 2 port valveon the hot water side and a 3 port on the heating side?????

 

[raymondo68]

If the two port sits between the 3 port and the cylinder coil then it has been put there to work with the thermal cut out and prevent the UV cylinder overheating in fault conditions. I have seen this a number of times and although it is not wrong, it is not my preferred method of installation.

Just to be clear are there a total of 2 circuits 1 heating and 1 hot water? Or are there 3 circuits 2 heating and 1 hot water?

 

[gaspastemania]

Funny how this has come up as i come across the same config last week , Decided not to investigate further as the same cylinder had solar which had soldered joints, the pump was the wrong way round,no benchmark on the cylinder and the pipework was an absolute mess ,
Told the custard to get the installer back on that one !

 

[pauls]

3 circuts 1 hot water 2 heating new install

 

[raymondo68]

OK, just bizarre then!!!

 

[pauls]

dont understand how the 3 port will operate 2 heating circuts. it must need to be linked somewhere to operate independently

 

[raymondo68]

This can work in exactly the same way it does if doing CH and HW provided there are 2 room stats and either a 3 channel programmer or a 2 channel and a separate timer for 2nd heating zone.

 

[oldplumber]

probably an original 3 port system converted to unvented cyl and because you have to use all the parts provided by manufacturer in an unvented set up , the 2 port valve has to be used leaving this over complcated setup, but done iaw mfis.

 

[fuzzy]

come accross a system (unvented) that has a 2 port to control hot water and a 3 port on the heating side why this configuration of a 3 port? if zoneing off 2 heating zones then 2x 2port valves on heating would be better to use.

just dont understand why that set up.

if its on an unvented it needs an additional 2 port as a safety shut off if the overheat stat kicks in or 3 port fails, coz the 2 port is normally shut. i dont see why people use a y plan? if u gota put a two port on anyway just use an s plan!

 

[pauls]

i see fuzzy just bin the 3 port option and use normal 2 port option as old plumber says they have just over complicated the system.