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

[M7R]

The last rad in my system, the down stair hall rad, seems to be showing signs of being blocked... but I don't think it is.. heres the info...

The system was installed by the neighbor in the late 60s early 70s, (neighbour still loves next door, they have been in since the house was built in 56!)

it did have a Baxi Bermudia back boiler system, we still have the fire but about 4 years ago while the last owner was in she had a new Vitedons W100 boiler fitted in the bathroom..she had it fitted due to being a pensioner so got it on a grant I believe.. at the same time the boiler was fitted the back boiler was by passed next to the boiler, and the bathroom rad was put on its own loop.

when we moved in 2 years ago I removed all the rads bar the 2 curved ones in the bays (which are going this summer to be replaced by 2 doubles on the other wall as getting 2 curved rads is stupid money!) and replaced them with rads from Wickes, along with adjustable and fixed length adapters to convert the imperial length old rad spacing to slightly smaller metric rads.

I dont know if it has been like this from day one, but certinally for the last 6 months, the hall rad which is the last on the loop and a new rad seems to have the issue of the hot water coming in, going up the first 2 water jackets, and the top being hot, and thats it.. the middle is warm, and the bottom is pretty much room temp, even only 3" from, the inlet!!! (the outlets never red hot either!)

Last weekend I cleaned out the header - see my other post for the mushroom farm I had gown in less than 2 years in there!!! - and filled the system with Sentinal X800 cleaner, which has had a week to work its magic! the rads used to bleed clear, but after I messed around with the system they started to bleed charcoal...emptied, refilled the system and added the x800, and over then today with a mate I dried the system again, wiped down the header (charcoal water but no rust bits etc in there..) and then took off the hall rad, flushed it through with the hose, via the bottom inlets and the top where the blank and vent should be.... when blasting the water through the inlet it came out of the outlet pretty quick, like it was just running along the bottom water way and not up, along the top and back down! it was black-sih for the first few second then charcoal and then clear pretty quick.

we also did the old bay rad before it, got some black water out of it but not masses...

Then we refilled the system with clean water, bleed all the rads, kicked the pump in for 10 mins on high to dilute any crub in the pipes we couldn't get out (with the hall rad locked off to stop any crud going in there)..after 10 mins, drained again, and it was pretty clear really...

then refilled with another shot of X800, the heating has been on for a few hours now, pump on speed 3 as it says and the hall rad is as before, only hot on the top and the first couple of water jackets.. I have been and balanced the system but its made no odds..the old bay rad which is before it red hot top to bottom all the way along, as are the others...

so what do people think? I have even tried hitting the rad at the bottom with a plastic hammer encase there is any crud stuck and the vibration will dis lodge it.. but it doesn't seem to have made any odds...

The rad is a single 1450mm, if that makes and odds, and I am sure it is the last on the loop..

any help of suggestions would be apprecaited, the hall isnt that cold... but it bugs me its not right as all the heat goes straight up the stairs, and I am a bit OCD about things being right..

Cheers

Karl

 

[AWheating]

system balanced correctly?

pipework sized correclty?

is it cold in the room?

 

[M7R]

system is balanced the best I can by touch,... but I forgot to say I have turned all the rads off before and its still pretty much the same.

pipe work is the standard 1/2 size

the hall is about 17-18deg, the thermostat is in there, but its a wireless one so can be moved, but the stat is demanding heat when I have been playing with it

 

[AWheating]

so if you turn the stat up to 30/max then does the rad get warmer?

 

[M7R]

the rad doesnt have a TRV stat, it has 2 normal values (wide open).

room stat set to 18 or 30 makes no odds, its demanding heat so the boiler is running. the boiler is set to 60deg temp too.

 

[AWheating]

id be tempted to change the rad and valves, wont cost much. You may also want to consider a power flush on the system.

 

[M7R]

Valves were new when the rad was installed, they seem to open and close fine... But I am thinking there could be a fault internally in the rad blocking flow along the bottom.... Ill see how the flush goes and may drop another on when we do the other 2, I have been tempted by a power flush but it seems quite expensive... Also when the 2 new rads are installed I will hopefully be adding a magnafilter at the same time

 

[stevebush]

does sound like hard sludge in radiator, power flush with a drill vibrator on problem rad would probably clear it but will be expensive, have you tried taking rad off and running garden hose though it, messy but its how we used to do it & does work,

 

[jase158]

you say that you have flushed with hose through vent and cap, this is not not right, take rad off, turn it upside down and flush through where the rad valves connect to rad.

Give the bottom a good hit with the bottom of a hammer/ rubber mallet.

leave flushing for 10-15 minutes, when it runs clear, turn it upside down/ hit it some more, until it is clean.

lift it up so the outlet is at bottom (on step or platform) and flush the rad.

Be careful not to scratch radiator.

This will remove all sludge from radiator.

 

[M7R]

I flushed it through all the inlets and outlets upside down, rights way round... Ill keep the x800 in for a week then take it off and whack it one next weekend, hopefully I can shift what ever is in there, it was running clear today, but I also can't be sure if its been faulty from day one...