Cold radiator - Tried everything I can think of!

[cjt20]

There are two rooms at the front of my house - the bathroom and office. Both have always had luke warm radiators. The rest of the radiators upstairs and downstairs are good.

The bathroom radiator gets hot at the left side valve, but directly after it (the radiator itself) is cold. I suspected a faulty valve, radiator or blockage. I've replaced it with a bigger, high BTU radiator and bi-directional (not TRVs) valves, but the problem remains. The radiator is cold. I've bled it so there's definitely no air in there.

I've taken the radiator off and let the water run out of the copper pipes, looking for any blockage.
Now this is where my plumbing knowledge ends, so forgive me if my assumptions are incorrect here: Water flows from both left and right copper pipes. I was expecting water to flow from the left pipe, assuming it to be an inlet, and nothing to come from the right pipe, assuming it to be the outlet to feed the office radiator.

My guess is there isn't a flow, so water from both pipes is clashing / meeting in the middle?
Do you think I need a directional valve or something?

 

[ALCPlumbing]

Shut all other radiators off so the full flow from the pump is directed to that radiator. If is still doesn't get hot then there's either a blockage or it's been piped up wrong.

 

[cjt20]

Shut all other radiators off so the full flow from the pump is directed to that radiator. If is still doesn't get hot then there's either a blockage or it's been piped up wrong.

Thanks for the reply.
Do I turn the other radiators at both ends or just the thermostatic valves?

Is it normal for water to flow from both copper pipes?

 

[WabbitPoo]

just close one end of the other rads. pipes to both sides of a rad will dispense water onto your carpet if you disconnect the valves as the whole system is under pressure.

 

[cjt20]

I've turned them all off except for the bathroom.
The feeder valve is too hot to touch, but an inch away, on the radiator itself, it's warm rather than hot.

I'm pretty confident there isn't a blockage as I've left the water flow from both pipes for a while. Also I'm using new valves so I don't think they're faulty. The problem existed on the old radiator/valves too, but I've replaced everything with new.

 

[cjt20]

I've turned the pump up a bit and re-balanced. The bathroom radiator is reasonably hot now. I can touch it for a couple of seconds at the most.

It's not perfect, but a vast improvement on what it was before I started

 

[jackthom]

If it is a fairly modern boiler the pump should probably on maximum speed.

 

[cjt20]

Here is a photo of the pump in my boiler.

I've turned the dial in the direction of the arrow. I'm assuming this is the pump speed?
I've turned it up a bit from where it was, but probably not on full.

 

[Agile]

That does not look like a pump in a boiler at all!

In fact it looks like an advert picture from Adlink!

Tony

 

[jackthom]

The pump speed is controlled by the three position switch on the left side of the pump in the picture, assuming your pump is similar.

Have you instead loosened the large screw on the front? If so it may start dribbling water.

 

[cjt20]

The pump speed is controlled by the three position switch on the left side of the pump in the picture, assuming your pump is similar.

Have you instead loosened the large screw on the front? If so it may start dribbling water.

Thank you, I have indeed made that mistake. Corrected now
The pump speed was already on the top setting, so maybe better radiator balancing was the cure?

 

[jackthom]

Did any air come out when that was loosened?

It may be worth slackening it again a little further until only a trickle of water comes out, then retighten it, as any air trapped in the pump doesn't help.

 

[Mountainmick]

Very funny Tony. You really are a laugh a minute.

 

[cjt20]

Did any air come out when that was loosened?

It may be worth slackening it again a little further until only a trickle of water comes out, then retighten it, as any air trapped in the pump doesn't help.

No I didn't hear any hissing. I'll have a look tomorrow