Flow and return to radiator

[Triode]

Hi

I have just fitted a new rad in my utility room. Due to the location I cannot have both the flow and return entering the bottom of the radiator.

I put (what I thought was) the flow to the bottom left connection (with a Pegler Terrier TRV) and the return to the top left connection, the radiator was gettiing hot from the top downwards. I concluded from this that the flow and return were reversed so I swapped the pipes around. Now is does not get hot at all.

The flow pipe gets warm as far as the TRV, but the rad stays cold. The little arrow on the TRV is pointing towards the rad so the flow should be correct.

Any ideas please?

Thanks - MArtin

 

[doitall]

It would have worked fine as it was.

Is the trv stuck

 

[Triode]

Is the trv stuck

No, it's a new one and the pin moves in and out easily.

Martin

 

[doitall]

Have you opened the lockshield valve then.

Nothing else can stop it, if the flow is hot up to the valve you must have some circulation.

Best to check the rad port isn't blocked as well.

 

[TicklyT]

I would expect the flow to connect to the top of the radiator, as you originally configured it. Gravity circulation within the radiator will keep the hot water in the rad. until it gives up it's heat, cools and sinks to the bottom.

With the return at the top, the gravity circulation will let the hot water whizz straight up the first vertical column and out the return without heating the rest of the rad.

 

[Triode]

Have you opened the lockshield valve then.

Nothing else can stop it, if the flow is hot up to the valve you must have some circulation.

Yes the lock shield is off so the valve is open. I have just taken the rad off and checked that nothing else is blocked. There is no iar in the rad, but it still wont get hot. It takes about 15 minutes for the flow pipe to get warm, and it is only warm at the TRV, that suggests that noting is moving to me. I am going to have to swap the pipes back to where they were before, even though I can't believe that there can be anything stopping the flow. I'm totally mystified...

 

[twgas]

Yes the lock shield is off so the valve is open

So is it off (closed) or open (on)?

 

[Triode]

Yes the lock shield is off so the valve is open

So is it off (closed) or open (on)?

There is nothing on the valve, I took the white cap off, which I assume is the lockshield, and the stat is off as well, so the TRV valve is fully open.

 

[Triode]

I would expect the flow to connect to the top of the radiator, as you originally configured it. Gravity circulation within the radiator will keep the hot water in the rad. until it gives up it's heat, cools and sinks to the bottom.

With the return at the top, the gravity circulation will let the hot water whizz straight up the first vertical column and out the return without heating the rest of the rad.

OK I got my flow back, it was an airlock in the return pipe, but as you quite rightly say the hot water is shooting up the first columns. The rad now gets hot from left to right instead of top to bottom, seems I just can't win!!

Anyway thanks for the replies. I know whats happening now.

Martin

 

[D_Hailsham]

There is nothing on the valve, I took the white cap off, which I assume is the lockshield, and the stat is off as well, so the TRV valve is fully open.

The whole valve is the lockshield; the white cap just protects the adjuster.

Remove the white cap and you will see a spindle. Use a pair of pliers or spanner etc to turn this spindle anti-clockwise about a half turn. This will open the lockshield valve and let water out of the radiator. If it does not get hot enough, open the valve another quarter turn.

As you have added an extra rad to your system you should really re-balance the system. This is done by adjusting the lockshield valve on each radiator so they have the correct flow. This is checked by measuring the return pipe temperature so it is lower than the flow pipe. If you don't have a thermometer you can do this by feeling the pipes. Check the flow and return pipes at the boiler to find out what the difference should be. If the temperature is too low you open the LS valve (anticlockwise) if it is too high you close the LS valve (clockwise).

How to balance a heating system