Zone valves for unvented cylinders

[Bodd]

Hello All

Can I have some advice please. Im following a schematic for a job I'm doing in London
After the flow comes from the Low loss header it goes to a pump then to a three port valve from there it splits going to the central heating with two zone valves controling four levels and then from the three port going to 2 x unvented cylinders , not showing any two ports on the flow to the cylinders
Does this sound right to you.

Thank you as always Bod

 

[Onetap]

No. A 2-port zone valve is supplied with the unvented cylinder and it must be fitted. The installer should be G3 registered and he should know that. A 3-port valve is not an acceptable substitute since the DHW port usually remains open with the power off; the flow to the cylinder must be isolated when the power is off, to prevent the \DHW over-heating.

 

[Bodd]

I'm the installer. I have qustioned this. What if I fit the two ports (I already have) but still fit the 3 port as well.

Bod

 

[matt1e]

What if I fit the two ports (I already have) but still fit the 3 port as well.

Bod

Why would you fit the 3port?

Matt

 

[Onetap]

You can fit the 3-port as well, but the 2-ports must be fitted. The wiring for the 3-port AND 2-port arrangement is confusing, I think someone was asking about it on here recently. S-Plan is simpler.

 

[Bodd]

What if I fit the two ports (I already have) but still fit the 3 port as well.

Bod

Why would you fit the 3port?

Matt

Hello Matt

I have no idea. The company who designed this system seem to think its ok. This is not the only thing I have questioned.
But this is how they want it.
Vailant have emailed back to this fella and said its ok to fit with the two ports.
Do they mean the two ports zoning the floors or the cylinders, as the revised schematic still does not show two ports on the cylinders.

Bod

 

[Onetap]

Do they mean the two ports zoning the floors or the cylinders, as the revised schematic still does not show two ports on the cylinders.

The 2-port zone valves are a part of the cylinder kit, they are supplied with the cylinders and have to be fitted on the flow to the cylinder coil; see the installation instructions.

 

[Bodd]

What every one is telling. Iknow. I spoke to.valiant they confirmed I need to fit the zone valves. But this is a top London firm what I'm asking is have they got this that wrong. Or do they know somthing I don't.

 

[Dan Robinson]

What firm?

Just because they are a Top firm (Pimlico? ) doesn't mean they know what they're on about.

3 port valves sound pointless from your description.

 

[Bodd]

What firm?

Just because they are a Top firm (Pimlico? ) doesn't mean they know what they're on about.

3 port valves sound pointless from your description.

They are Building services & Environment consultants.

 

[Onetap]

Just because they are a Top firm doesn't mean they know what they're on about.

Second that; it may be a top firm, but the office junior did the design you've got.

I'd suggest you politely query it, attaching a copy of the installation instructions. You can't install it as they've asked, it would invalidate the BBA approval for the cylinder and you, as the self-certifying installer, would be liable in the event of an incident.

You usually get a 3-port AND a 2-port when an domestic vented cylinder is replaced with an unvented cylinder.

 

[Onetap]

They are Building services & Environment consultants.

So am I. They're wrong.

Those that can do; those that can't become consultants.

 

[Bodd]

Im not the best plumber in the world but I'm up with the good ones. I don't know it all that's why I always try to do it by the book.
But this firm have me thinking do I know my job.

This house has 5 levels 27 rads 3 towel rails 2 x 150 litre unvented cylinders . Supplied by a 30 kw system boiler. If II followed the schematic the boiler two fires and a Arger would be supplied by a 22mm gas supply.

 

[Norcon]

Maybe the UV cylinders being supplied are pre plumbed units.

 

[Bodd]

Just because they are a Top firm doesn't mean they know what they're on about.

Second that; it may be a top firm, but the office junior did the design you've got.

I'd suggest you politely query it, attaching a copy of the installation instructions. You can't install it as they've asked, it would invalidate the BBA approval for the cylinder and you, as the self-certifying installer, would be liable in the event of an incident.

You usually get a 3-port AND a 2-port when an domestic vented cylinder is replaced with an unvented cylinder.

I have but they keep insisting they are right. I'll do it to their design as long as I don't compramise the regs..