After the thermostat opens, hot water flows from the engine block to the radiator, and from there to the water pump via the lower radiator hose.

What direction does water flow through a radiator?

From the top down or from the bottom up. Believe you find water from the block (which is heated) flows into the lower radiator hose cooling as it traverses upwardly to top of radiator…. cooling as it travels. Back into the block through the top hose.

Does direction of flow matter on a radiator?





Registered. water flow: no difference. air flow: left<->right no difference. up<->down heat rises so most people go up.

Which side of a radiator is the inlet?

Discovering where the valve inlets on your radiator are is fairly straight-forward and is defined primarily by the kind of radiator or heated towel rail that you have. With a heated towel rail, for example, you will normally find that the inlet position is located underneath at the bottom.

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.

Does inlet and outlet matter on a radiator?

Yes it does. They have a baffle or diverter near the flow. So it is imperative that the flow is connected to the inlet port ,and return to the outlet port.

What are the two types of direction of flow radiators?





Cooling Basics – Radiator Type

  • An Automotive Radiator falls into one of 2 basic categories. The difference is the direction the coolant travels across the radiator core.
  • A Downflow Radiator is used in many older vehicles. …
  • A Crossflow Radiator is used in most modern vehicles.

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.

Can you install radiator upside down?

yes as long as the air can escape when filling the rad, ie the pipes are running upwards all the way to an upstairs rad or air vent in the system, FatHands likes this.

What side of the radiator is the lockshield valve?



The lockshield valve, on the side of the radiator opposite the on/off valve, may be adjusted to balance the output of your heating system. The lockshield itself is the plastic cap that covers the valve to ensure that you don’t accidentally change the setting once you’ve adjusted it.

How do I know which is flow and return?

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.

Do radiators have a flow and return?

The flow pipes are connected to one end of the manifold in a number of radiators, and then return to the other end. But both the feed and return microbore pipes are connected to the same end of the radiator.

Does it matter which side of a radiator the TRV goes?



The vast majority of new TRV’s are bidirectional and can be fitted to either the flow or return, but it is always good practice to fit them to the flow side. If a non bidirectional TRV is fitted on the return side it will create a vibrating sound as the water tries to flow though it.

Does a radiator have an in and out?

Every radiator in a hot water system has an inlet and outlet. The inlet is to take hot water in and the outlet is to let the water back out.

Does the in and out of a radiator matter?

Does it matter which port on the radiator is the in or out? Most rads, no. HWL GTX has a preferred in and out port depending which way through it the airflow goes, but that’s fairly unusual.

Should radiator valve be on inlet or outlet?

Many modern homes will have TRVs – Thermostatic Radiator Valves – attached to most of the radiators on the opposite side from the lockshield valves. A TRV should always be fitted to the inlet on the radiator and the LSV to the outlet.

Which valve is which on a radiator?



One valve accounts for the amount of hot water that enters the radiator. The other valve, referred to as the lockshield valve, balances the system by regulating how much heat the radiator gives off. For a more detailed insight, take a look at our Radiator Valve Guide.

Should both sides of a radiator be open?

You should open both of the valves on all of your system’s radiator when you are starting the radiator balancing process. You will most likely need to use pliers to open the lockshield valve.

Why do I have 2 valves on my radiator?

The reason you need two valves generally on all rads is because the system dictates a flow and return. The flow pipework carries the newly heated water from the boiler. The return taking it back at a lower temperature to be reheated by the boiler.

What does the plus and minus mean on a radiator?

The valve on the left in your pic is a lockshield and should not be touched. The other is a wheel head and is used to turn rad on / off. You should have a plus and minus sign to indicate which direction. Clockwise to close ,anti to open.