The Caleffi 301341 is an angled diverter valve for one-pipe panel radiators, 1/2 in male radiator connection x 3/4 in male conical pipe connection, on 50 mm centers. It diverts 30 to 50 percent of loop flow through the radiator, factory-set at 35 percent, and includes two ball shut-off valves and an integral PPO thermal break device in the return leg.
Best for single-pipe loop systems where each panel radiator is teed off a common circuit, with pipes exiting the wall.
Specifications from Caleffi datasheet 01036/23 NA (replaces 01036/12 NA). Reviewed August 2026.
Key Features
One-Pipe Diverter Operation
On a single-pipe loop the valve diverts part of the circuit flow into the radiator and returns it to the same main, so each emitter can be served without separate supply and return piping.
Adjustable Bypass, 30% to 50%
Field-adjustable with a 6 mm allen wrench under the threaded cap to send 30 to 50 percent of loop flow through the radiator. Factory-set at 35 percent.
PPO Thermal Break Device
A non-return device in the return leg prevents thermo-syphoning up into the radiator from bypassing flow when the thermostatic valve is closed and there is no call for heat.
50 mm Center Distance
The 2 in (50 mm) outlet center distance is the common standard across all brands of panel radiator, so the valve fits the bottom supply and return ports directly.
Serves the Radiator's Built-In Valve
The valve connects to the bottom ports and feeds the thermostatic valve built into the top of the panel radiator through its internal riser.
Chrome-Plated Brass Throughout
Chrome-plated brass body and control stems with peroxide-cured EPDM seals, rated 150 psi (10 bar) and 212°F (100°C).
Technical Specifications
| Product Type | Radiator Diverter Valve |
| Series | 3013 Series |
| Body Style | Angled |
| System type | One-Pipe |
| Radiator connection | 1/2 in male straight thread |
| Pipe connection | 3/4 in male conical |
| Body material | Brass, chrome plated |
| Valve control stems | Brass, chrome plated |
| Seals | Peroxide-cured EPDM |
| Thermal break non-return device | PPO |
| Adjustable by-pass, factory setting | 35% of flow rate |
| Adjustable by-pass setting range | 30 to 50% of flow rate |
| Suitable fluids | Water, glycol solutions (30% max.) |
| Maximum working pressure | 150 psi (10 bar) |
| Max. working temperature | 212°F (100°C) |
| Max. differential pressure | 15 psi (1 bar) |
| Center-to-center | 2 in (50 mm) |
| Body length | 3 in |
| Radiator centerline height | 1-3/4 in |
| Depth | 2-1/4 in |
Documentation
Related Products
- Caleffi 301241 : Straight Diverter Valve, One-Pipe
- Caleffi 301140 : Angled Isolation Valve, Two-Pipe
- Caleffi 449740 : Wall-Covering Plate 40-50 mm
- Caleffi 437516 : Compression Fitting 1/2" Copper
- Caleffi 681503A : PEX Fitting 3/8" Nominal
Frequently Asked Questions
How does the Caleffi 301341 work on a one-pipe system?
On a single-pipe loop the valve diverts part of the circuit flow through the radiator and returns it to the same main, so each emitter can be served without separate supply and return piping.
Can the bypass on the Caleffi 301341 be adjusted?
Yes. Shut the by-pass valve and unscrew it by the number of turns given in the datasheet graph, using a 6 mm allen wrench under the threaded cap. The range is 30 to 50 percent of flow rate and the factory setting is 35 percent.
What does the thermal break device do?
It is a PPO non-return device in the return leg. It stops thermo-syphoning up into the radiator from bypassing flow when the radiator's thermostatic valve is closed, which would otherwise deliver unwanted heat during the off cycle.
How many radiators can be run on one loop?
Because radiators are in series on a one-pipe system, each downstream radiator receives cooler water. Caleffi recommends limiting the loop to three radiators to ensure sufficient heat delivery.
What is the center distance of the Caleffi 301341?
2 in (50 mm), the common standard for panel radiator bottom connections across all brands.
What are the pressure and temperature limits of the Caleffi 301341?
Maximum working pressure is 150 psi (10 bar) and maximum working temperature is 212°F (100°C). Maximum differential pressure is 15 psi (1 bar). Suitable for water and glycol solutions to 30 percent.
- Product Type:
- Radiator Diverter Valve
- Product Family:
- Panel Radiator Valves
- Series:
- 3013 Series
- Body Style:
- Angled
- System Type:
- One-Pipe
- Connection Type:
- Conical
- Connection Size:
- 3/4 in
- Body Material:
- Brass, Chrome Plated
- Max Operating Pressure:
- 150 psi (10 bar)
- Max Medium Temperature:
- 212 deg F (100 deg C)
