With C14/C13 in an old CLV, one common flue under positive pressure goes into the old inner pipe, with a tee per boiler (semi-CLV). You choose between rigid stainless steel, PZ C14 Star in black PP or PR C14 Flexible.
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Enter the number of appliances and the height above to get the parts list for your CLV.
How C14 and C13 work in an old CLV
The new column goes into the old inner pipe, which stays in place as a casing. Each boiler has a tee in that column. With C14 the air enters through the existing CLV mesh cap, as before, and flows down the jacket in counterflow with the flue gas. With C13 there is also one common flue, but each appliance takes its air separately. Both are approved as one unit with the boiler.
The concentric boiler connection ends open in the jacket. Only the flue pipe passes through the wall of the old inner pipe into the tee. Around that passage goes an ALU sealing collar per boiler, 80/125 or 60/100, so the jacket stays airtight towards the old inner pipe.
Only use boilers approved for a collective flue under positive pressure, C(10) or C(14), according to gas.be (NBN D 51-003 annex E). Each boiler has backflow protection, and the connection has a fall of at least 3° towards the boiler.
Three versions
| Rigid stainless steel | PZ C14 Star | PR C14 Flexible | |
|---|---|---|---|
| Material | Stainless steel 316, IE range | Rigid black PP | Flexible PP |
| Tee | With ø80 branch | With screw-off connection pipe ø60 or ø80 | Connection set per boiler |
| At the bottom of the CLV | Base plate with condensate drain | Support foot and condensate drain | Base set and condensate element |
| Expansion | No separate part | Absorber under each tee | Taken up by the flexible liner |
| Choose this if | The old inner pipe is straight and round and you want stainless steel | The old inner pipe is straight and round | The old inner pipe is not straight or too narrow |
How to build your list, from top to bottom
- Top: cap and cover on the old inner pipe (stainless steel), or terminal with spacers (PZ C14 Star). The existing CLV mesh cap stays the air inlet.
- Pipes up to the highest tee, and between the tees.
- One tee per boiler. With PZ C14 Star an absorber goes under each tee.
- Per boiler a connection set and an ALU sealing collar.
- Bottom: condensate drain and siphon for positive pressure.
- Base: base plate (stainless steel) or support foot (PZ C14 Star).
- For stainless steel: a clamping band on every joint.
For PR C14 Flexible the order is: mounting set at the top, liner, a connection set and sealing collar per boiler, base set and condensate element at the bottom. There must be at least 2.5 m of liner between two connections.
Frequently asked questions
Is C14 the same as a semi-CLV?
Yes. In a semi-CLV a new common flue pipe goes into the existing shaft and the shaft itself supplies the air. That is C14.
What is the difference between C14 and C13?
Both have one common flue. With C14 the air comes through the jacket of the CLV, with C13 each appliance has its own air supply.
What diameter does the column need?
It follows from a calculation to EN 13384-2, with the number of boilers, their output, the height and the size of the old inner pipe. Send us the data and we will check it.
Can the existing boilers stay?
Only if each boiler is approved for a collective flue under positive pressure. That is on the rating plate, or ask the manufacturer.
