Solar Thermal Pipe Fittings – K-FLEX Twin Solar System
Find the complete range of brass fittings and accessories for K-FLEX Twin Solar pre-insulated stainless steel pipe systems. Whether you're connecting solar collectors to hot water cylinders, extending a pipe run, or completing a domestic renewable heating installation, this collection covers every connection point in the system.
K-FLEX Twin Solar fittings are engineered for fast, tool-free assembly with reliable metal-to-metal sealing — significantly reducing installation time compared to traditional copper pipe systems.
What's in This Collection
- Compression Couplings — external and internal thread, DN16, DN20 and DN25
- Straight Fittings — DN16, DN20, DN25 in Ø18mm and Ø22mm
- Double Couplings — for joining or extending pipe runs, DN16 to DN25
- Olives — replacement compression olives, DN16, DN20, DN25
- Copper Connection Sets — stainless to copper transition, 15mm and 18/22mm
- Accessories — flange tools, tube clamps, gaskets, split rings and oval pipe supports
Buying Guide – Choosing the Right Solar Thermal Fitting
DN16 or DN20? DN16 is the standard size for most domestic solar thermal installations. DN20 is suited to larger systems or commercial applications with higher flow rates. DN25 is used in high-capacity commercial installations.
External or internal thread? External thread couplings connect to female-threaded ports on collectors and cylinders. Internal thread couplings connect to male-threaded ports. Check your collector and cylinder connection specifications before ordering.
Connecting to existing copper? Use the Copper Connection Sets, which include a clamping ring for a secure stainless-to-copper transition in either 15mm or 18/22mm copper sizes.
Frequently Asked Questions
Are these fittings compatible with all K-FLEX Twin Solar pipe?
Yes. All fittings in this collection are designed specifically for K-FLEX Twin Solar pre-insulated corrugated stainless steel pipe in DN16, DN20 and DN25 sizes.
Do I need special tools to install these fittings?
No. K-FLEX Twin Solar compression fittings are designed for quick, tool-free assembly. The flange tool (available in the Accessories product) is required only for forming pipe end flanges before fitting compression couplings.
Can these fittings be used with glycol solar fluid?
Yes. All fittings are suitable for use with glycol/water heat transfer fluid circuits as used in solar thermal systems.
What is the difference between a straight fitting and a double coupling?
A straight fitting connects Twin Solar pipe to a fixed connection point such as a manifold or cylinder port. A double coupling joins two sections of Twin Solar pipe together, used when extending a pipe run or making a repair.