Viessmann 4 pipe onto vented cylinder

[spikewt]

Hi all,

Quick question as I'm quoting a boiler install.

Has anyone installed a Viessmann system boiler on a vented hot water cylinder and piped as a 4 pipe using the hot water thermostat probe cut into the foam insulation.

As i understand you wont need a 2 port valve as the hot water is vented and the probe sits in the same position as any other stat would. Run it through a time clock and then job done.

Iv done a couple of Viessmann 4 pipe system with their unvented cylinders and really like them but iv yet to put one on a vented cylinder which i have been told can be done, but this was by your typical know it all plumber in the merchants.

He got me thinking tho!

Opinions would be great.

 

[SafeGasInstall]

why not fit a heat only boiler then with y plan

 

[AWheating]

whats it say in the manufacturers instructions?

 

[spikewt]

whats it say in the manufacturers instructions?

Taken from the MI's

DHW heating with DHW cylinder
If a Viessmann Vitocell is connected, a
cylinder temperature sensor will issue
the heat demand (accessory). The cylin-der temperature sensor is connected to
the boiler control unit. A 230 V cylinder
temperature controller is not required.
If a different DHW cylinder is connected,
the cylinder temperature sensor (acces-sory) may also be used on this cylinder.
Alternatively, a 230 V cylinder tempera-ture controller should be connected via
the cylinder demand junction box (part of
the boiler standard delivery)

Thats about as much as ya get!

 

[GasManMike]

I've fitted a few worcester's system boilers with an integral diverter. Same as CDI combi but hot and cold become flow and return to cyl. Is this similar?

 

[spikewt]

I've fitted a few worcester's system boilers with an integral diverter. Same as CDI combi but hot and cold become flow and return to cyl. Is this similar?

Sound like it because the viessmann system is just a combi with the hot water parts removed.

 

[SafeGasInstall]

Simple just run your cable to oiler and conect stat where its say to conect it !
MI have fitted lots viessmenn combos and heat I only but never system ! I would have to e for a any heat only boiler with y or s plan ! Keep it to the traditional way !
Just my opinion

 

[GasManMike]

I ran into problems linking the worcester with an unvented cylinder. All the worcester controls are low voltage but Gledhill state they want a 2 port on the flow to the cylinder. Couldn't find a way of getting the 240v 2 port to work with the low voltage worcester Intelligent controls.

 

[SafeGasInstall]

Should have gone for wb with wb cylinder with integral diverter or traditional way wb heat only /system with s and y plan + Honeywell twin Chanel 7 day programer and
Happy days !
MI am coming of wb boilers and will fit baxi from now on ! Local rep has taken out my name of there accredited installer list just to sign in someone else , so they can go ......you know where

 

[spikewt]

Keep it to the traditional way !

I like to mix it up abit. :tongue:

 

[spikewt]

I ran into problems linking the worcester with an unvented cylinder. All the worcester controls are low voltage but Gledhill state they want a 2 port on the flow to the cylinder. Couldn't find a way of getting the 240v 2 port to work with the low voltage worcester Intelligent controls.

The viessmann come with a control box for that which converts the voltage. I guess with worcester they like to make it difficult tho.

 

[GasManMike]

Cylinder was already in, in the end like you said, s plan. Happy days.