Hot water distribution

Where "hot water distribution" begins and ends

Distribution is the piping from the boiler outlet (hot water supply point) to every fixture: kitchen sink, bathroom sink, shower, bathtub, washing machine (if connected to hot, rare in Israel). Pipework before the boiler is cold-water supply — a separate task.

Typical DHW draw-off points in a 3-room Israeli apartment:

• Kitchen — sink mixer, sometimes a dishwasher.
• Bathroom — basin, bathtub/shower.
• Separate toilet — usually cold only.
• Balcony — occasionally a washing machine with a hot inlet (rare).

Two main distribution layouts

Tee (series)

A single trunk line runs from the boiler, with a tee branching off to each fixture. Cheaper and faster to install, requires fewer meters of pipe.

• Pros: pipe and fitting savings, easier to route through finished walls.
• Cons: simultaneous use of two points causes pressure drop (turn on the shower — kitchen goes lukewarm). A failure on one section takes the whole line offline.

Manifold (radial)

A single pipe runs from the boiler to a manifold (distribution comb); from the manifold, each fixture has its own dedicated pipe. More materials, more complex to install, but fundamentally better in use.

• Pros: stable pressure under simultaneous use, each fixture has its own shut-off at the manifold, leaks stay local.
• Cons: higher cost, requires a niche for the manifold (or a plumbing cabinet).

In Israeli new builds, manifolds are increasingly placed in a niche behind an access panel, sometimes combined with the cold-water manifold and the boiler connection.

Materials

Cross-linked polyethylene (PEX / PEX-AL-PEX)

The de facto standard in Israeli new builds for the last 20 years. Red pipe (for hot) or black with a red stripe, 16–25 mm diameter for apartment distribution. Flexible, hides inside floor screed or a wall chase.

• Service life — 50+ years.
• Working temperature — up to 95 °C (peak 110 °C).
• Joints — press fittings or brass compression.

Multilayer (PEX-AL-PEX)

Comparable to PEX in spec, but joints are often elbow-and-nut, which can loosen over time.

Copper

Premium material in old and high-end homes. Soldered with a gas torch or press-fitted. Reliable (70+ years), but expensive and requires skilled labor.

Polypropylene (PP-R)

Usually rigid lengths joined by heat fusion. Less common in Israel than in Eastern Europe, but present.

Galvanized steel

The "Soviet" option, found in 1970s Israeli homes. Threaded joints, rusts from the inside over the years, narrows the bore. Usually replaced with PEX or copper during renovation.

Dud shemesh (solar boiler) specifics

95% of Israeli apartments have a combined solar boiler: collector + 120–200 L tank on the roof + electric element. Important points for distribution:

• DHW flows top-down — from the roof down the riser. Riser integrity and insulation quality matter (or the water cools before reaching the tap).
• Thermal expansion. Heating up to 80 °C (and higher in summer sun) expands the pipes — expansion loops or a floating bedding are needed.
• Check valve on the boiler's cold inlet — mandatory, otherwise hot back-flows into the cold line when pressure drops.
• Trunk insulation in unheated areas (balcony, stairs) — otherwise 20–30% of heat is lost en route.

What the plumber does during distribution

1. Drawing or sketch. Mark draw-off points, manifold position, pipe routes in screed/walls. At this stage, coordinate with the electrician so runs don't cross wiring.
2. Chasing / laying in screed. In Israel, pipes often run in the floor screed — safer against freezing and noise, but more expensive to replace during renovation.
3. Trunk line installation from the manifold to each fixture, with slack for final connection.
4. Manifold installation with a shut-off on each outlet.
5. Pressure test at 8–10 bar — every joint checked for leaks over 24 hours.
6. Sealing up after a passing pressure test.
7. Fixture connection (mixers, appliances) at the finish stage of the renovation.

Pricing in Israel

• Full DHW distribution in a 2-room apartment (tee, PEX) — 2,500–4,500 ILS material + labor
• Manifold distribution in a 3–4 room apartment — 5,000–9,000 ILS
• Replacing old galvanized with PEX (incl. demolition) — 3,500–7,000 ILS
• Custom copper distribution — 12,000–25,000 ILS for a 3-room apartment
• Adding a single DHW point (extending the line to a new basin) — 600–1,500 ILS
• Manifold + shut-offs + assembly (hardware only) — 600–1,500 ILS

Prices depend heavily on route complexity (meters of run, path, whether concrete has to be chased), the material, and the brand (PEX Rehau is twice as expensive as a no-name).

Common mistakes

• No insulation on hot trunks in unheated areas. Saving 200 ILS on insulation means a 5–10 °C temperature drop at the fixture.
• Abrupt step-down from a large to a small diameter. Pressure is lost at the tees. Best practice — max diameter at the manifold, slightly smaller toward each fixture.
• Joints buried in the screed. Even PEX joints must not be concealed — any fitting must remain accessible. Only continuous pipe goes inside.
• No pressure test before screeding. Skip it and you'll find a leak under tile later — the repair costs more than the original distribution.
• A shared trunk without isolation valves. A single-point repair shuts off the whole apartment — inconvenient.

Timeline

• Full distribution in a 2–3 room apartment (incl. chasing) — 3–5 working days.
• Replacing the trunk without chasing (along the ceiling / behind a false panel) — 1–2 days.
• Extending a single line — 2–4 hours.