**1. What is the plastic pipe from a boiler?**
The plastic pipe connected to a boiler is typically a **condensate drain pipe**. Modern condensing boilers produce acidic condensate (water vapor byproduct) during operation, which is safely drained away through this pipe. It is usually made of corrosion-resistant plastic like PVC or ABS to handle the mildly acidic liquid.
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**2. Can you use PVC on a boiler?**
**No**, standard PVC should **not** be used for high-temperature parts of a boiler system (e.g., flue gases or pressurized hot water lines). However, some boilers may use **CPVC** (chlorinated polyvinyl chloride) or specific high-temperature plastics for certain low-temperature drainage lines, like condensate pipes. Always follow local codes and manufacturer guidelines.
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**3. What is a boiler flue pipe?**
A boiler flue pipe is a vent that safely expels exhaust gases (e.g., carbon monoxide, combustion byproducts) from the boiler to the outside air. Modern flues are often made of metal (stainless steel or aluminum) or plastic (for condensing boilers with lower exhaust temperatures).
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**4. Do all boilers need a flue?**
**Yes**, all fuel-burning boilers (gas, oil, propane) require a flue to remove harmful gases. Even electric boilers may need ventilation, though they don't produce combustion gases. Older "open-flue" boilers rely on chimneys, while modern "room-sealed" boilers use dedicated flue pipes.
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**5. Why is water coming out of my boiler overflow pipe?**
Water leaking from the overflow pipe (often called the **pressure relief valve pipe**) usually indicates:
- **Excessive pressure** in the system (check the pressure gauge; 1–2 bar is normal).
- A faulty **pressure relief valve** (PRV) stuck open.
- **Expansion vessel issues** (loss of air charge, causing pressure spikes).
- **Filling loop left open**, over-pressurizing the system.
**Action**: Turn off the boiler, call a qualified technician to diagnose and fix the issue.
