Radiator half hot other half cold, issue for 3 years

[Nik538]

Hi guys,

I have problem here for several years on one of the living room radiators and I happily found this forum. I live in The Netherlands for 6years, but bought house 3yrs ago and have this issue with the central heating. The dutch problems requare dutch solutions :).

On the photos is shown aprox. what the situation is. The radiator on front of the living room about 3m long and 1/2m high is not heating fully. Only when I crank up that radiator to 23 degrees its starts to heat up completly but not even. From the other side of the wall there is radiator for the coridor and have no issue atm. I think the problem is with that drain valve it might be cloged and the cold rethurn water is coming up to that valve.

Any other issue might happening in the system like malfunction pump or TRV broken, radiator full with slug or corrosion.

I have already emptied the system 5 times and cleaned the radiator with a water hose under pressure.

CV ketel is Remeha Avant probably from 2009.
I have 9 radiators in whole house which 6 are with smart termostat and the others with regular radiator valve. There is not voetvalve or chuckvalve on any of the radiators. I have TADO smart system with central control On/Off and an internet bridge.

Please let me know what you think about this issue.

 

[The headhunter]

The radiator with the hot returns get to much water the ones with the cold return to little.

Check the valve sometimes they get stuck halve way.

 

[Nik538]

You mean the TRV can be stuck half way?

 

[The headhunter]

Not the TRV itself, the valve behind it.
Remove te TRV, yuo will see the valvebody.
You see a small pin, that pin actuates the valve in the body.
This pin can be pushed in ca 3mm en should return by itsself in the starting position.
Pushed in the valve is closed, released the valve is open.
If it does not return you can get it unstuck by hitting the valve BODY, never hit or pull the small pin!
Without TRV the radiator should warm.

 

[Nik538]

I have this valve on the photo just the straight version, I do not use the analog thermostatic knob instead I use the tado smart knob. That doesn't matter, the only thing concerns me is the inside rubber blind or a metal blind, maybe it's broken or maybe it's not fully open.

I have checked the pin goes up to to 3mm inside and retracts without a problem.

I saw that this valve is not adjustable for the flow, the other valves have that feature like the black valve on the photo.

 

[The headhunter]

Ok valve, works correctly.

What happens when you remove the TRV and close all other radiators in the house?
This way all water should flow trough this radiator and should it get hot.

 

[Nik538]

Yes thats correct, but I want a balanced system not all hot water to go only thru that one radiator in the living room. I will try to replace the valve and to see whats happening.

 

[The headhunter]

Your problem is indeed a problem in the balance of waterflow.

You should restrict the flow of de Radiators that do get hot.

 

[Nik538]

Indeed, this system doesent have any footvalve or chocking valve to balance each radiator. The only thing are those TRVs and they used to be classical radiator valves, but I had to replace them due to leakage.

 

[Hharbers]

Am I right that you can restrict flow also with some brands TRV valve body bij adjusting the 6-side nut ?
On the picture of the valve body you see numbers 1-7

I'm not a specialist but someone gave me this advise when is had to restrickt a radiator in my house without foot valve

 

[Nik538]

Thats correct I did not thought about that when I was planning to change the valves. After research I think is better that you can calibrate the TRV for the flow. The uploaded picture on the right the black TRV has that feature. I wanted to buy brand item like Danfoss or Comap, but its a hassle to set up TADO Smart knob on it since doesent have the 32mm thread.