S plan layout question

[sdc-911]

Hi,

I'm about to swap out our 15 year old vented indirect hot water cylinder for a more up to date vented indirect cylinder and as part of the upgrade I'm considering changing the current Y plan layout to an S plan layout for improved reliability.

One question I have, is in relation to how the 2 x two port valves should be physically connected into the system.

I've seen some diagrams that show the valves connected either side of a tee from the pump after the ABV (Automatic Bypass Valve) and another that showed the valves connected as a stack, each tee'd off the pump output: ABV, then valve for cylinder coil, then valve for CH circuit.

Ideally I'd like to be able to connect the valves up as shown in the diagram below, as the space in the airing cupboard is tight.

Any guidelines or comments appreciated, as I want to ensure everything gets installed as optimal as possible.

Steve.

 

[SimonJohns]

to aid air seperation from the water try to make the upstands going to the AAV as long as possible

add another gate valve on the way back down after the ZV this will aid service of the valve should it fail and avoid having to drain down, also this will aid balancing

Dont forget you will need to remove the head off the ZV should it fail

Dont use the 1/4 turn pump valves, use the gate valves

pay attention to the direction of flow for the ZV incorrect installation can cause banging when closing

 

[Simon F]

you seem to have researched your topic well, just a small point the flow to radiators if that came down from the tee it could be vented through the one vent, just set both valves manually open to vent

 

[xpertbert]

I wouldn't do that way, if boiler lower eg downstairs , I would go up with flow to airing cupboard then continue it up to heating tank for vent. Put a tee in higher than cylinder flow. Go horizontal then put a 22 15 centre tee facing down. Loop cold feed under then in. Elbow or bend down. Tee off for bypass, then other tee one into hot water flow with valve, other down to heating flow with valve. That way as long as it all rises no air vents needed, self vents. Heat won't travel up cold feed. Does not suck no air in. Put a 22 gate valve on cyl return so you can balance everything spot on including all rads and auto bypass and pump speed. Once system is settled you will get no bother. Done hundreds and hundreds. Hope that helps

 

[stevetheplumber]

beat me to that simon one vent would be fine make the tee the high point and valves on the drops to heating and cylinder you also need a gate (actually it should be a lock shield ) valve on cylinder return to balance the flow through cylinder

 

[xpertbert]

If boiler higher then I would take them off top boiler , still loop cold feed. Vent return.

 

[Halesowen1]

Fitting an aerjec aint a bad idea for any open vented system, I always fit them, you get no problems with air then.

 

[sdc-911]

Thanks for all the replies, really helpful advice. I've updated the design below.

 

[SimonJohns]

Another bit of advice is.
Vent should be 150mm +40mm for every 1 meter head

This is from the book. I don't know in practice. Only ever fitted one ov system