How do you determine flow and return pipes?

Hi, turn the heating on and the pipe that gets hot first is the flow. Switch on your heating from cold. The pipes on the heating circuit that heats up first will the flow pipe, the other wil be the return. The Flow pipe gets warm before the return pipe.

Does it matter which side of radiator flow and return?

Most modern thermostatic radiator valves are bi-directional – so can be fitted on either the flow or return pipe of your radiator. However, it’s always best practice to fit the TRV on the flow pipe that enters your radiator.

Which is the return pipe on a boiler?

A second pipe (called the ‘return pipe’) collects the cooled water from the radiators and carries it back to the boiler for re-heating.

Do radiators have a flow direction?

The new radiator is marked for the direction of flow; through the valve and in at the top of the radiator.

What is flow and return in central heating?

As your boiler heats up water, it’s pumped out and circulated around your central heating system, i.e. all the rads and towel rails. The hot water (not boiling hot — closer to 75°C) comes out of the flow pipe. This water flows around the whole system and returns to the boiler via the return pipe.

How do you calculate flow and return temperature?

Quote from the video:
Quote from Youtube video: So you can press and hold looking. At this top left-hand number there d 39. So there's loads of these you can check out.

How do I know which way my radiator flows?

Check the valve itself and there should be a little arrow near the outlet. If the arrow points away from the valve it needs to go on the return side of the radiator, if it points into the valve it should be on the flow side.

What happens if you get flow and return the wrong way round?

If the pipes are reversed, the sensor will record the lower temperature and could compensate to make up the difference. This can result in unwanted noise, or overheating and inefficiency.

How do I know which radiator pipe is my feed?

Quote from the video:
Quote from Youtube video: Usually runs under the rad or just under the floorboards. And you just have the one pipe going right around the house chain off to the valves. But if you've got like two valves.

Does flow and return matter on a vertical radiator?

Yes. As it is at present the flow runs straight thru the bottom of the rad and out the other side. Water will follow the path of least resistance.

Does it matter which way you plumb in a radiator?

In terms of which side each valve should go, in the majority of cases this should not matter e.g. the lockshield and wheel head or thermostatic valve can go either side of the radiator due to the nature of the system being on a loop however if you are fitting thermostatic valves then generally these go on the incoming

Is the lockshield on the flow or return?


Conventionally, the wheelhead valve is fitted to the flow pipe and the lockshield valve is fitted to the return.

Does central heating pump go on flow or return?

Below is a basic schematic drawing of how a central heating pump sits within a heating system. Please note that the pump can also be installed on the common return.

What is primary flow and return?

The coil, or “heat exchanger” forms part of the central heating circuit, and its water heating abilities are purely a by-product of its main function, which is to heat the radiators. This heating is called the “primary” circuit, the pipes running to and from the boiler are called the primary flow and return.

What should the flow and return temperatures for condensing boilers?

Condensing mode requires a return temperature of 54°C or lower. So maximum system temperatures of 70°C supply and 50°C return are preferable or, to condense continuously, 50°C supply and 30°C return.

What should the flow temperature for central heating?

To maximise efficiency, we recommend setting your radiator dial to 75 degrees and your hot water to 60 degrees. Once you’ve got your boiler running at the optimal temperature, you’ll want to set the timer for when you need heating the most.

What is the minimum return water temperature for non-condensing boiler?


In non-condensing boiler systems, these warm-up loops mix supply and return water in order to maintain at least 140°F feedwater into the boiler. For non-condensing (i.e., standard (85%) efficiency) boilers, this serves to avoid condensation and fouling of the heat exchanger.

What temperature should boiler return?

For natural gas boilers, the dew point is around 55C. In other words, the water in the return pipe needs to be 55C or lower or your boiler will not operate at maximum efficiency and potentially will not even condense. Turning down the temperature on your boiler can help increase its efficiency.

Should radiators be too hot to touch?

A too-hot radiator can also damage furniture, if the furniture is pressed up against it and while not an out and out fire hazard, flammable materials coming into contact with something very hot is not worth risking and is best avoided.

What is the flow temperature of a boiler?

Boilers can commonly operate between 30-80°C flow temperatures. They start to reach their higher efficiency figures at 45°C flow temperature, but that can be too low for older properties.