New radiator goes cold after an hour

[Andrew Morris]

Hi guys please be nice I'm not in the trade

Fitted two rads yesterday to an existing system one to replace an old one and another one totally new and extended the rad circuit. The issue I have is they warm up perfectly but after about an hour or so one goes cold. The rad isn't the last in last in circuit the other new one comes after it. I've used this rad Kudox Premium Type 21 Double-Panel Plus Single Convector Radiator 600 x 1200mm White with this Drayton RT212 White / Chrome TRV & Lockshield 15mm x ½".
Does the trv have a built in thermostat which is cutting the feed as the room has hit temperature? There is no other room thermostat. I'm thinking this is the issue but was hoping someone could confirm this.

Cheers Andy

 

[townfanjon]

Thats how the trv works , it senses the air temp around it and closes off the flow to the rad , assuming of course the room is up to the required temp as selected by the trv setting , ie 1 to 5

 

[Andrew Morris]

townfanjon thanks for your reply

 

[Riley]

Or is it teed off another radiators feed?

 

[Andrew Morris]

Hope the image explains it. I think I've done what you've said

Imgur

 

[ShaunCorbs]

pic of the rad and pipework

 

[Andrew Morris]

DSC 0531 and DSC 0532

 

[Scott_D]

What size pipe?

 

[Andrew Morris]

10mm scott

 

[Scott_D]

DSC 0531 and DSC 0532

Wow!

 

[Riley]

There’s your answer. My friend 10mm won’t carry enough heat for two rads

 

[Andrew Morris]

Which to a uneducated person is? All the pipe on existing rads in the house is 10mm or is it the fact I've joined another rad to one with which is 10mm i take it should be from a bigger pipe somewhere?

 

[SimonG]

Take your 10mm back to manifold.

 

[Andrew Morris]

Thanks guys and sorry.. So basically find the manifold and connect the new directly to that so the rads aren't sharing the feed and then the rads will get the heat benefit. One last question from what you can see it's not dangerous atm or what I have done could it damage the boiler? Really sorry to bother you guys I really wouldn't ask but if I could afford to get someone I wouldn't have done this.

 

[ShaunCorbs]

theres your reason

 

[Riley]

Won’t cause damage just won’t work

 

[dan_the_plumber]

Should be alright though if you balance the system?
You might also have an air lock in that leg. If it’s on s drop down. Feel the glow pipe running wall. If it’s only hot at the top, it’s an air lock.
Turn all other rads off to get it going, then balance the system.

 

[Riley]

10mm simply can’t carry the wattage for those two rads

 

[dan_the_plumber]

10mm simply can’t carry the wattage for those two rads

How big are the rads?

 

[Riley]

Not huge but too big to be run in sequence splittingbthe heat between the two

 

[Andrew Morris]

Hi again guys funny thing is it cloudve been the trv or balancing. I've done some adjustment to both and the radiator is staying on all the time now and every radiator is running red hot. When looking at the balancing around the house every lockshield was fully open so I'm guessing these rads had no chance really. I really do appreciate the time and effort you his took in trying to help me out I really appreciate it