Last rad cold at the bottom - bit of an odd one as I don't think its blocked...

[jase158]

have you turned all radiators off and left this one on since you flushed it out?

 

[M7R]

Not yet, I planned on doing that tomorrow, but I don't hold out much hope..

 

[jase158]

I would try that, especially with x800 in system, leave it for about an hour.
If that dont work then blockage in pipes.

 

[M7R]

I don't think it is the pipes, as I can shut the inlet and back drain the rad via the return pipe... I had the bleed valve on the inlet side before today and drained about 5l out of it the other day!

also it's odd the way the first 3 ribs in the rad get red hot, then the next is only warm then the rest just Luke warm at best... Pointing to a lack of water flow alsong the main water run along the bottom of the rad... But it appeared to flush fine... Water flowing in and out pretty fast, I would have expected a slower flow rate if the main water passage was blocked.

ill try the 1 rad open tomorrow and report back

 

[StillLearnin]

If it is an old rad and you suspect it is blocked/dirty, then might be worth considering an upgrade to a more modern rad with fins

 

[M7R]

No that's what I'm saying this is a new rad, it's only 2 years old. There only 2 old rads left one up stairs in the front room as its a curved rad in the bay, and the same down stairs, the curved rad is the one before this rad... But logicly that shouldn't make any odds? Unless its higher water content means more water is going into the bay rad then back into the return loop..

 

[michael c]

Definately sounds like a return restriction, you may be able to drain the return feed but that doesn't mean there are no restrictions. Remember each rad is on individual legs and any restriction the majority of heat will take the easy path. I would bet that the restriction is in the pipe and not the rad. You need a proper flush or it may be cheaper in short term to replace the leg. Its my opinion that your wasting your time keep flushing the rad.

 

[M7R]

Okay, power flush it is then once the new rads and pipe work in the bedroom and dining room have been done... I'm lothed to replace that leg of pipe due to the new floor that was laid only a few months ago... Cheers

 

[michael c]

Okay, power flush it is then once the new rads and pipe work in the bedroom and dining room have been done... I'm lothed to replace that leg of pipe due to the new floor that was laid only a few months ago... Cheers

Is there no way to get under the floor?

 

[M7R]

When the heating was installed the neighbour has told me that in the back room there are a few floorboards which are lose, this is where he got in to the crawl space under the house.. The one hall rad is as far away form there as you can get...

but there is news! This morning I have turned off all the rads, turned down the bathroom rad as much as I can without causing the boiler to lock out after a couple of mins, and with the pump on 3 you can hear the water racing through the hall rad! I have left it running for 20 mins while I do other stuff, and now just turned the boiler up to 70deg, gone down stairs and the hall rad is hot top to bottom all the way along.

i am coming to the confusion that the 2 bay rads are robbing too much water, they have to be neary all the way open to get an even heat and they hold a lot of water! I think this is allowing too much water to short circuit back to the boiler before getting to the hall, and that joined with the fact the hall is a big long rad means the water that is making it there is not enough to heat the full rad. However I will leave it running hot with just that one rad open for another hour or so as it won't do any harm to clean those pipes through