Changing from Y plan to S plan, pipework.

[Deluks]

Doing some maintenance on my heating system.

System boiler>copper tank>F+E tank in loft> Honeywell Y plan>7 rads.

Changing out the old UPS pump for a newer UPS3 (and new pump valves)

Also fitting a Tado V3+ thermostat.

(Would also like to fit a Spirotech MB3 somewhere in the system, can't get it anywhere near the boiler) so would probably have to fit amongst this lot, just before or after the pump)

X400 system cleaner has been in for a couple of weeks.

Whilst system is drained down, I'd like to replace the 3-port valve with a pair of 2-port valves, and leave an extra blanked off Tee for future UFH in an extension.

What's the best way to achieve this with the current set up?

Are there any 'rules of thumb' that need to be followed when Teeing off or adding valves?

Looking at the 3 port valve, the left hand port goes to water, the right goes to rads.

Space on the heating side for a 2 port valve, but the HW side the pipe immediately turns upwards, then a kink in the pipe brings it back in away from the wall.

 

[Madrab]

Are there any 'rules of thumb' that need to be followed when Teeing off or adding valves?

Nothing really special no.

To keep it easy then a Tee in where the 3 port currently is and then 1st available spot on the left vertical leg for the HW 2 port and as you say the closest point on the right for the CH leg.

 

[oldbuffer]

Just be aware that if it is a mid-position valve in the Y plan system, you may need an automatic bypass valve fitted when you change to S plan. With the S plan, you could have the hot water valve closed, and if you have TRVs on all radiators, then the central heating circuit is effectively closed when room temperature is reached. The boiler could still be sending heated water which has nowhere to go.

 

[ericmark]

@oldbuffer has raised the same thoughts I have had, you don't say what boiler, my oil fired boiler uses the DHW to allow boiler to cool, in my case C Plan, but Y Plan with no power the valve is open to DHW, so even with no power to pump, the boiler can cool by heating the DHW.

I was warned against converting to S Plan by my engineer when he came to alter how my boiler was plumbed. As an electrician I am happy with wiring, but leave the plumbing to those who know what they are doing.

 

[Deluks]

I was aware that I'd need a bypass, and will probs make a separate post when I come to fit it. (I should probably fit that first!)

Can't remember model but it's an Ideal gas boiler, pretty standard. Older model with no bells or whistles (and better for it!)

I I have no problem with the y plan setup, apart from that 3 way valve, mine is like triggers broom!
But adding a circuit in the future, it just makes sense to switch to S plan now, whilst changing the pump and while I've got my 'plumbing head' on.

Few more questions, is it worth putting any extra valves in the system to isolate anything?

...and would it be easiest just to replace the 3 port body with a cross like this?

 

[Madrab]

Why would you want to replace the 3 port with a 4 way coupler? They're not exactly a plumbing standard.

No need for extra valves really, that's just more to go wrong/seize up IMO.

 

[Johntheo5]

Some pump settings are not suitable for ABV operation, especially ones like the UPS3 where the constant speed curves are in effect constant pressure, if you dont have TRVs then you could simply install a normally open 2 port valve as a bypass that closes when any zone valve opens and will only open when all the zone valves close.