With the wave of solar installations in Israel, the question of whether SP piping can be used with a solar system is one of the most common among plumbing contractors. The answer: yes — but only under very specific rules according to Israeli Standard SI 579. The most common mistake is installing SP piping on the roof — which is completely prohibited. This guide explains exactly what is allowed and what is not.
Quick Summary
- SP piping is allowed for connecting an apartment solar water heater
- SP piping is allowed in vertical risers only in a central solar system (SI 579 Part 5)
- SP piping is prohibited on the building roof
- Roof outlet for risers: concealed only — only the end of the metal fitting may be visible
- Pressure and temperature relief valve is mandatory — item no. 770465
- Best-value SP pricing — see below
What is allowed: approved uses of SP piping with solar
✅ Allowed — connecting a thermosiphon solar water heater:
SP piping may be used only for the connection between the heater and the apartment. The connection to the heater must be made through fixed, securely mounted faucet brackets.
✅ Allowed — vertical risers in a central solar system:
SP piping may be used in the circulation system for vertical pipes only (risers), according to the requirements of SI 579 Part 5.
✅ Allowed — connection of the apartment water heater:
SP piping may be used for connecting the apartment’s water heater.
Prohibited: SP piping on the roof
It is strictly forbidden to install SP piping on the building roof.
Risers may exit onto the roof concealed only — in the parapet wall or on the roof surface inside a built column. Only the end of the metal fitting may be visible, to allow the connections to continue.
The reason: roof temperatures in Israel can exceed 70°C in summer — too high for SP piping without protection.
Mandatory rules according to SI 579
Water temperature — mandatory limit:
- Non-circulated system: limit to 55°C by thermostat
- Circulated system: limit to 60°C
Approved limiting methods:
- Thermostat to cut off heat when 60°C is reached
- Mixing valve — controlled and regulated, ensuring water is mixed at the proper flow rate
Mandatory metal connection:
When connecting the piping network to water heaters — it is recommended to connect a metal pipe between the SP pipe and the outlet from the water storage tanks.
Prohibited: installing SP piping between the storage tank and the collectors (the hottest part of the system).
Pressure and temperature relief valve — required in every solar system
SP pressure and temperature relief valve (item no. 770465) is a mandatory component in every solar system and in every hot-water storage tank.
Valve specifications:
- Bronze body — maximum durability and strength
- Stainless-steel spring
- Inlet: ¾" male | Outlet: ¾"
- Temperature relief: 99°C
- Pressure relief: 10 bar
- Compatibility: all pipe types (metal, multilayer, plastic)
When the valve opens:
When the water temperature or pressure exceeds the limits, the valve opens automatically and releases the water. Important: proper drainage must be provided near the valve.
Mandatory annual maintenance
You must test and operate the valve once a year to prevent malfunctions and water waste. A valve that hasn’t been checked for years can seize up — and that is dangerous.
Summary: what is allowed and what is prohibited — SP piping + solar
| Use | Allowed / Prohibited | Note |
|---|---|---|
| Connecting an apartment thermosiphon solar heater | ✅ Allowed | Through a fixed faucet bracket |
| Central vertical risers | ✅ Allowed | According to SI 579 Part 5 only |
| Connecting an apartment water heater | ✅ Allowed | |
| Installation on the building roof | ❌ Prohibited | Without exception |
| Between storage tank and collectors | ❌ Prohibited | Area with excessively high temperature |
| Two fitting systems in the same installation | ⚠️ Not recommended | One type is preferred |
| Without a pressure relief valve | ❌ Prohibited | Mandatory according to SI 579 |
🏆 SP valve and solar products at the best price
The SP pressure relief valve (770465) and all piping accessories needed for solar-system connections are available from us.
You won’t find a lower price in Israel — and if you do, contact us and we’ll make you a better offer. We’re committed to you.
Frequently asked questions — SP piping and solar systems
Can SP piping be installed on the roof?
No. SP piping is prohibited on the roof. The riser outlet to the roof must be concealed only — in the parapet wall or in a built column, with only the end of the metal fitting visible.
What is the maximum permitted temperature for SP piping with solar?
SP pipe can withstand up to 95°C, but according to SI 579 it must be limited to: 55°C in a non-circulated system and 60°C in a circulated system — using a thermostat or a mixing valve.
What is a pressure and temperature relief valve and why is it mandatory?
A P&T valve (SP item no. 770465) is a mandatory safety device that prevents extreme pressure and temperature conditions. It opens automatically at 99°C and 10 bar and prevents damage to the system and piping.
Is SPEX piping suitable for solar systems?
Yes. White insulated SPEX pipe is manufactured according to the requirements of Israeli Standard 1205.1 and is suitable for solar systems and solar water heaters. It can also be ordered in different colors to match the wall color.
Conclusion
The correct integration of SP piping with a solar system — following the rules of SI 579 — is reliable, durable, and safe for many years. The key is knowing exactly where SP is permitted (risers, heater connections) and where it is not (the roof). All required accessories — including the relief valve and a wide range of piping — are available from us at a price you won’t find anywhere else.