Unvented wiring .

[townfanjon]

Strange request for Easter Sunday lol , its just in my head .
have any of you fine chaps got a wiring diagram for a y-plan with a new 2 port wired in for an upcoming unvented installation.
I usually change them to an s-plan but the boiler is miles away from the cylinder and would cause a load of work getting perm lives to the 2 ports .
Cheers in advance

 

[EvilDrPorkChop]

Creates more hassle than it's worth IMO. Have you checked the wiring, you usually have enough wires to do it anyway, especially if theres already a pump overrun.

 

[Aire]

Can you add a 2 port to a y plan? With the 3 port keeping one zone permanently open, what happens when the 2 port calls for heat? You'll get unwanted heating of a zone.

 

[EvilDrPorkChop]

Can you add a 2 port to a y plan? With the 3 port keeping one zone permanently open, what happens when the 2 port calls for heat? You'll get unwanted heating of a zone.

Yes you can. It's on the HW side, so you can leave your 3 port in situ and have the 2 port for thermal cut out for the Unvented after the 3 port valve. It's doable but for everyone that i've come across it's not worth the hassle and easier just sticking two 2 port valves in.

 

[Aire]

Yes you can. It's on the HW side, so you can leave your 3 port in situ and have the 2 port for thermal cut out for the Unvented after the 3 port valve. It's doable but for everyone that i've come across it's not worth the hassle and easier just sticking two 2 port valves in.

Ok, I get what your saying, but if the 2 port acts only as a thermal cut out, what happens when the cylinder stat on the first cylinder is satisfied but the thermostat on the second isn't? You could end up with unbalanced temperatures.

 

[townfanjon]

Creates more hassle than it's worth IMO. Have you checked the wiring, you usually have enough wires to do it anyway, especially if theres already a pump overrun.

Ancient boiler pal , so no spare wires but just realised there must be a hw off wire , but really need 2

 

[townfanjon]

Ok, I get what your saying, but if the 2 port acts only as a thermal cut out, what happens when the cylinder stat on the first cylinder is satisfied but the thermostat on the second isn't? You could end up with unbalanced temperatures.

I have never done it but a 2 port should be fitted on to a y plan unvented installation, yes a right pita

 

[EvilDrPorkChop]

Ancient boiler pal , so no spare wires but just realised there must be a hw off wire , but really need 2

If you've got a HW off wire then you're sorted. Change that for a perm live, you'll already have Neutral and Earth there, along with HW on and CH on.

It's when you haven't got a HW off wire that's the issue (So when they have to have HW and CH at the same time)

 

[Aire]

I have never done it but a 2 port should be fitted on to a y plan unvented installation, yes a right pita

So your not having 2 cylinders? Why do you have to a 2 port on a yplan when feeding an unvented?

 

[townfanjon]

If you've got a HW off wire then you're sorted. Change that for a perm live, you'll already have Neutral and Earth there, along with HW on and CH on.

It's when you haven't got a HW off wire that's the issue (So when they have to have HW and CH at the same time)

I have not looked , I just thought of it as I was typing

 

[townfanjon]

So your not having 2 cylinders? Why do you have to a 2 port on a yplan when feeding an unvented?

In case it goes *** up , spring return valve closes supply to cylinder

 

[EvilDrPorkChop]

So your not having 2 cylinders? Why do you have to a 2 port on a yplan when feeding an unvented?

Part of the G3 regulations. Must have a thermal cut out, as a 3 port valve is always open in some form that doesn't meet the requirement.

See so many Unvented cylinders on 3 port valves, it's worrying! Had one where the High limit stat kept cutting out, so cylinder must have been about 85/90oc!

 

[townfanjon]

If you've got a HW off wire then you're sorted. Change that for a perm live, you'll already have Neutral and Earth there, along with HW on and CH on.

It's when you haven't got a HW off wire that's the issue (So when they have to have HW and CH at the same time)

Wheres yer GS badge ??? Admin still in the boozer

 

[EvilDrPorkChop]

Wheres yer GS badge ??? Admin still in the boozer

Must be!

 

[Aire]

Part of the G3 regulations. Must have a thermal cut out, as a 3 port valve is always open in some form that doesn't meet the requirement.

See so many Unvented cylinders on 3 port valves, it's worrying! Had one where the High limit stat kept cutting out, so cylinder must have been about 85/90oc!

Good to know, I suppose if I had my g3 I would have known that

 

[EvilDrPorkChop]

Anyway to answer the original question, just looking at a diagram you'd still need a perm live anyway for a 3 port plus 2 port.

 

[townfanjon]

If you've got a HW off wire then you're sorted. Change that for a perm live, you'll already have Neutral and Earth there, along with HW on and CH on.

It's when you haven't got a HW off wire that's the issue (So when they have to have HW and CH at the same time)

I am no sparks , is it acceptable to use the one perm live and split to supply both 2 ports ? Assuming there is one lol

 

[EvilDrPorkChop]

Good to know, I suppose if I had my g3 I would have known that

Many of the 3 ports that i've seen have been left in/fitted that had their G3 qualification.

It's daft really, the Manufactures instructions clearly state that a 2 port is needed, along with them sending one with the cylinder. If it comes with the cylinder then you'd be thinking I have to fit this thing!

 

[Riley]

Wheres yer GS badge ??? Admin still in the boozer

Ha ha

 

[townfanjon]

Anyway to answer the original question, just looking at a diagram you'd still need a perm live anyway for a 3 port plus 2 port.

I cant find one anywhere lol

 

[EvilDrPorkChop]

I am no sparks , is it acceptable to use the one perm live and split to supply both 2 ports ? Assuming there is one lol

Yeah you can use the same live, you don't need separate lives for each valve.

 

[townfanjon]

Yeah you can use the same live, you don't need separate lives for each valve.

Sound , after all this I am praying theres a Hw off wire , assuming yes I will go S-plan , cheers

 

[EvilDrPorkChop]

Here you go.

 

[ShaunCorbs]

wire the port valve into the stat but you need a neutral

 

[EvilDrPorkChop]

wire the port valve into the stat but you need a neutral

Isn't as simple as that unfortunately. As the HW Stat on a 3 port fires the boiler when it's just HW only. If the heating was running on the 3 port (So Live on the Orange wire on the 3 port) , it would back feed and hold the HW 2 port valve open. Therefore defeating the object of a thermal cut out.

 

[ShaunCorbs]

Isn't as simple as that unfortunately. As the HW Stat on a 3 port fires the boiler when it's just HW only. If the heating was running on the 3 port (So Live on the Orange wire on the 3 port) , it would back feed and hold the HW 2 port valve open. Therefore defeating the object of a thermal cut out.

how would it as the 3 port wouldnt be wired to the stat

 

[EvilDrPorkChop]

As the HW Stat is wired to fire the boiler (HW on to Common on stat, then 1 to S/L on boiler). Then the Orange wire for CH only on the 3 port is wired into the boiler at the same terminal (So your S/L on the boiler). So when you wire your additional 2 port into the 1 terminal on the HW stat (So that the 2 port closes when the stat breaks) if there is still a feed on the S/L to the boiler from the heating side the 2 port valve would still have a live feed and stay open.

 

[ShaunCorbs]

As the HW Stat is wired to fire the boiler (HW on to Common on stat, then 1 to S/L on boiler). Then the Orange wire for CH only on the 3 port is wired into the boiler at the same terminal (So your S/L on the boiler). So when you wire your additional 2 port into the 1 terminal on the HW stat (So that the 2 port closes when the stat breaks) if there is still a feed on the S/L to the boiler from the heating side the 2 port valve would still have a live feed and stay open.

no it wouldnt

perm live to stat in

stat out to brown eg port valve open

neutral and earth the same done

 

[EvilDrPorkChop]

no it wouldnt

perm live to stat in

stat out to brown eg port valve open

neutral and earth the same done

Yeah, and the stat out also would have to go to boiler S/L. So if your S/L on the boiler is live from another source, so the heating. The valve would still be live and hold open.

 

[ShaunCorbs]

Yeah, and the stat out also would have to go to boiler S/L. So if your S/L on the boiler is live from another source, so the heating. The valve would still be live and hold open.

No not with a safety stat 3 port doesn’t get wired to the stat

 

[chris watkins]

Every unvented manufacturer will provide a wiring diagram in their instructions for the use of the 3 port mid position valve & the required 2 port that must be installed with it. This is required as under fault conditions there could be an open pathway from the heat source to the cylinder allowing the cylinder temperature to go above 100deg C.

The only exception to this, to my knowledge, is Vaillant who applied & got a dispensation so long as their boiler & cylinders are used together as a package.
Megaflo one below Jon, whats the cylinder?

 

[Coby kenny AGUILAR]

Strange request for Easter Sunday lol , its just

 

[townfanjon]

Every unvented manufacturer will provide a wiring diagram in their instructions for the use of the 3 port mid position valve & the required 2 port that must be installed with it. This is required as under fault conditions there could be an open pathway from the heat source to the cylinder allowing the cylinder temperature to go above 100deg C.

The only exception to this, to my knowledge, is Vaillant who applied & got a dispensation so long as their boiler & cylinders are used together as a package.
Megaflo one below Jon, whats the cylinder?
View attachment 38257

I didnt know about the Vaillant Chris , as far as I knew it was only Viessmann, on the 200’s its just a probe that plugs in to the board and the other end goes into the stat pocket .
Cylinder isn't chosen yet for this job yet , she will leave it up to me . Its just a shame the boilers a mile away from the cylinder .