Summary

JG Speedfit, Wavin Hep2O, and Polypipe Polyfit all manufacture push-fit pipe and fittings to BS 7291, which standardises the outside diameter at 15mm, 22mm, and 28mm to match copper pipe sizes. Because the OD is identical across brands, any fitting will physically accept any brand of pipe. The critical issue is the internal diameter — wall thicknesses vary between manufacturers, meaning pipe inserts are not interchangeable. John Guest officially states that Speedfit fittings "are compatible with Hep2O pipework as long as the correct manufacturer's pipe insert is used" but adds that they "cannot guarantee the specification of other manufacturers' pipe" and do not advise mixing. In practice, the professional approach is to pick one system and stick with it throughout an installation. If you must join two systems, a short section of copper pipe is the safest transition method.

Key Facts

  • All UK push-fit pipe is manufactured to BS 7291 with standardised outside diameters (15mm, 22mm, 28mm) matching copper pipe sizes
  • Outside diameters are identical across brands — fittings will physically accept pipe from any manufacturer
  • Internal diameters differ — Hep2O, Speedfit, and Polypipe each have slightly different wall thicknesses and bore sizes
  • Pipe inserts are NOT interchangeable — a Speedfit Super Sleeve forced into Polypipe can over-expand the bore and compromise the seal
  • Hep2O uses a "Smart Sleeve" insert; Speedfit uses a "Super Sleeve" or standard insert; Polypipe uses its own insert — always match insert to pipe brand
  • No manufacturer warrants cross-brand use — mixing voids the warranty on both the pipe and fitting
  • Copper pipe needs no insert — it is rigid enough to maintain its shape inside push-fit fittings
  • Push-fit fittings cannot be used with chrome-plated copper or stainless steel pipe — only plain copper and plastic

Compatibility Matrix

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Fitting Brand JG Speedfit Pipe Hep2O Pipe Polypipe Polyfit Pipe Copper Pipe Notes
JG Speedfit fittings Yes Yes* Yes* Yes (no insert needed) *Use Hep2O Smart Sleeve / Polypipe insert with their respective pipe. Speedfit officially "does not advise" cross-brand use
Hep2O fittings Yes* Yes Yes* Yes (no insert needed) *Use the correct brand insert for the pipe. Hep2O In4Sure visual indicator will not function with non-Hep2O pipe
Polypipe Polyfit fittings Yes* Yes* Yes Yes (no insert needed) *Match insert to pipe brand. Speedfit Super Sleeve is too tight for Polypipe pipe — do not force it
Compression fittings Yes (with insert + copper olive) Yes (with insert + copper olive) Yes (with insert + copper olive) Yes (brass or copper olive) Always use a copper olive (not brass) on plastic pipe to avoid crushing

Key: Yes = manufacturer-supported combination. Yes* = will physically work but is not warranted by either manufacturer. Always use the pipe manufacturer's own insert.

Detailed Guidance

Can I mix Speedfit pipe with Hep2O fittings?

Yes, it will physically work. Both Speedfit and Hep2O pipe have a 15mm or 22mm outside diameter, so the pipe will push into either brand of fitting and the O-ring will seal. However, you must use the Speedfit insert (Super Sleeve) inside the Speedfit pipe, not the Hep2O Smart Sleeve — the bore sizes are slightly different. John Guest's official position is: "JG Speedfit fittings are compatible with Hep2O pipework as long as the correct manufacturer's pipe insert is used. However, mixing JG Speedfit with Hep2O is not advised." No manufacturer will honour a warranty claim on a mixed installation.

In practice, if you are extending an existing Hep2O system and only have Speedfit fittings to hand, it will hold. But for a proper job, either match the brand or use a 100mm stub of copper pipe as a transition piece between the two systems.

Do I always need pipe inserts?

Plastic pipe: always. Every push-fit connection to plastic pipe requires a pipe insert (also called a pipe stiffener or liner). The insert prevents the pipe wall from collapsing under the grip of the grab ring and ensures the O-ring seals against a perfectly round surface. Without an insert, the pipe can ovalise over time and leak.

Copper pipe: never. Copper is rigid enough to maintain its shape. Fitting an insert into copper pipe is unnecessary and not recommended.

Insert types by brand:

  • JG Speedfit Super Sleeve — one-piece stainless steel insert, stays in place once pushed in
  • JG Speedfit Standard Insert — brass, traditional style
  • Hep2O Smart Sleeve — plastic insert with a distinctive blue or white collar, designed for Hep2O's specific bore size
  • Polypipe Polyfit Insert — plastic or brass, matched to Polypipe pipe bore

Critical rule: Always use the insert supplied by or specified for the pipe manufacturer, not the fitting manufacturer.

How do I connect plastic pipe to copper?

There are three reliable methods:

1. Push-fit fitting (simplest) Push the copper into one end of any push-fit coupler, and the plastic pipe (with its correct insert) into the other end. Deburr the copper thoroughly — a sharp edge will cut the O-ring. No insert is needed on the copper side.

2. Compression fitting Use a standard compression coupler. On the copper side, use a brass olive as normal. On the plastic side, you must use a copper olive (not brass — brass olives will crush the plastic) and fit a pipe insert. Tighten by hand plus one full turn with a spanner; do not over-tighten.

3. Solder ring / end-feed to push-fit Solder a short copper tail, let it cool completely, then push the plastic fitting onto the copper tail. Never apply heat near push-fit fittings — the O-rings will melt.

What's the difference between barrier and non-barrier pipe?

Barrier pipe has an aluminium or EVOH (ethylene vinyl alcohol) layer bonded into the pipe wall. This layer prevents oxygen from permeating through the plastic into the water. All three major brands (Speedfit, Hep2O, Polypipe) offer barrier pipe versions.

When barrier pipe is required:

  • Sealed central heating systems — oxygen ingress causes corrosion of steel radiators, boiler heat exchangers, and steel/iron components. Building Regulations and manufacturer warranties require barrier pipe on heating circuits.
  • Open-vented heating systems — barrier pipe is strongly recommended but the system is already exposed to oxygen via the feed-and-expansion tank.

When non-barrier pipe is acceptable:

  • Cold water supply (mains and distribution)
  • Hot water supply from the cylinder to taps (not heating circuits)
  • Some open-vented gravity systems (check boiler manufacturer requirements)

If in doubt, use barrier pipe everywhere — the cost difference is marginal.

Can I use push-fit on heating systems?

Yes. All three major brands are approved for sealed central heating systems when using barrier pipe.

Operating limits:

Brand Max Continuous Temp Max Pressure (at 82 C) Max Short-Term Temp BS 7291 Class
JG Speedfit 82 C 3 bar 114 C (safety) Class S
Hep2O 82 C 3 bar 110 C (safety) Class S
Polypipe Polyfit 82 C 3 bar 110 C (safety) Class S

All three systems are rated to BS 7291 Class S, which covers both hot and cold water supply and central heating. Modern condensing boilers typically operate at 60-70 C flow temperature, well within the rated limits. The short-term temperature ratings exist to handle thermostat failure scenarios without immediate pipe failure.

Testing requirements: All push-fit plumbing and heating installations should be pressure-tested before commissioning — 2 bar for 10 minutes, then 10 bar for 10 minutes, checking for leaks and pressure drop.

Frequently Asked Questions

Can I use Hep2O fittings underground or in concrete?

Hep2O fittings can be buried in screed or plaster, and the pipe can be run through concrete floor slabs inside ducting. However, no push-fit joint should be directly buried in concrete without access — use continuous pipe runs through slabs with joints at accessible points. For underground external pipework, use MDPE (blue pipe) with appropriate fittings, not push-fit.

Does the pipe colour matter?

No. White, grey, and blue Hep2O pipe are all the same polybutylene material and specification. The colour is for identification only (white for hot/cold water, grey for older stock, blue for cold water mains in some ranges). Similarly, Speedfit white and grey pipe are the same material. Barrier and non-barrier pipe may look identical — check the print line on the pipe for the barrier marking.

How far does the pipe need to go into the fitting?

Each fitting has an insertion depth marked on the pipe or in the manufacturer's documentation. As a general guide: 15mm fittings require approximately 25mm insertion depth; 22mm fittings require approximately 28mm insertion depth. Always mark the pipe before pushing in and check the mark is flush with the fitting face. Hep2O In4Sure fittings have a visual indicator that confirms full insertion — this only works with Hep2O pipe.

Can I reuse push-fit fittings?

Fittings can be disconnected and reconnected a limited number of times. JG Speedfit fittings use a collet (grab ring) that can be released with the Speedfit disconnect tool or by pushing the collet back. Hep2O uses a similar demounting clip. In theory, fittings can be reused, but inspect the O-ring for damage before reconnecting. If in doubt on a heating system, replace the fitting.

What about Tectite and other copper push-fit brands?

Tectite (by Pegler), and similar copper push-fit fittings (Yorkshire Pushfit, Conex Cuprofit) are designed for copper pipe only. They use a different internal grab ring design and do not accept plastic pipe. Do not confuse these with plastic push-fit systems.

Regulations & Standards