Sundial Y v Sundial S

[DIYedboy]

I'm replumbing my system and would like to know whether one of these has an advantage over the other (forget about the valves and the wiring of them). My system is open vented (when I've fixed that!) and has a suprima 50 boiler in a 30's mid terraced 3 bed house.

 

[kevplumb]

you get better flowrates through an s plan

 

[bengasman]

How does that work Kev?

 

[DIYedboy]

Kev, if I use the S plan I must install a bypass valve, do I need to fit one if I use the Y plan?

 

[Gasguru]

S plan with Honeywell zone valves, Honeywell autobypass valve and a cylinder lockshield everytime.

You must use a autobypass valve.

The majority of Y plans are never wired up correctly (so don't work as intended) and are more difficult to fault find especially with intermittent faults in the valve actuator.

I'd ignore flowrates..the difference is irrelevant on small systems.

 

[matt1e]

s-plan wins every time

s-plan
more wiring options
easier boiler upgrade options (ie 230v or volt free switching)
easier to diagnose problems
better flow
etc

y-plan
er sometimes you dont need a bypass

matt

 

[bengasman]

do I need to fit one if I use the Y plan?

Not if you have 2 lockshield valves in the room with the roomstat.

 

[DIYedboy]

Lads, this autobypass valve............is it normally shut unless there is a problem n then it'll magically open? Do I have to fiddle with the sucker when I install it or is it just a olt n forget job?

 

[matt1e]

do I need to fit one if I use the Y plan?

Not if you have 2 lockshield valves in the room with the roomstat.

presisely
or if you are replumbing any way what is the problem adding one anyway?

matt

 

[bengasman]

do I need to fit one if I use the Y plan?

Not if you have 2 lockshield valves in the room with the roomstat.

presisely
or if you are replumbing any way what is the problem adding one anyway?

matt

It is extra work.
It costs extra money.
If not set correctly it can always let by and reduce the time the boiler works in condensing mode.
It can fail and leak.

 

[DIYedboy]

Ok, an S plan it is, I'll get this autobypass valve...........but can you tell me whether the thing is normally shut n whether I'm supposed to fiddle with it when I install it?

 

[kevplumb]

you should get a data sheet with the valve

 

[D_Hailsham]

Ok, an S plan it is, I'll get this autobypass valve...........but can you tell me whether the thing is normally shut n whether I'm supposed to fiddle with it when I install it?

Yes, it is normally shut. When TRVs close the pressure in the system rises. The ABV opens when the pressure reached the setting and allows some of the water to short circuit back to the boiler. This ensures that the flow through the boiler does not drop below the mfr's required rate. It also reduces the noise in the system and helps the TRVs to work better.

Adjustment instructions come with the valve. You set it and forget it - though you may have to use trail and error to get the setting right.

 

[DIYedboy]

A datasheet? mmmmh, this valve is obviously complicated then?, so to save me the headache , I think I'll go down the Sundial Y route cos the room with the roomstat in don't have TRV's n I can forget the valve

 

[kevplumb]

can you turn a tap on and off

then you can set it

hell its only a sring loaded tap at the end of the day