Radiator Cooler at Bottom

Sep 06, 2009 7 Replies
M

I=92ve just drained & refilled my CH system (first time I=92ve done it myself) & it went fine. The water that came out was surprisingly clear, with no signs of black sludge. (It was last drained 2 yrs ago & Fernox was added.)


1 small thing I=92ve noticed is that 1 downstairs rad has more of a difference between top & bottom than other rads (eg when I measured it the radiator was about 44 deg C at the top & about 38 at the bottom). I think the rad was also a couple of degrees cooler than some of the others. The radiator bleeds fine.

From a google it looks like sludge might be the cause ... except the water that came out was pretty clear. Not sure if I just need to give it a bit longer, or if it=92s maybe something to do with the rad valves needing to be adjusted?



Michael


Vote
Twitter Facebook LinkedIn
F

What's the radiator temperature at the pipe exit? Is that at 38 deg C?

Vote
Twitter Facebook LinkedIn
N

44 vs 38 is fine. Fwiw its probably the one getting the least water flow per rad volume.

NT

Vote
Twitter Facebook LinkedIn
A

If the return pipe is hotter than the cold part of the radiator, then it's sludge. If the return pipe is same temperature as the cold part of the radiator, then it's due to low flow through the radiator. Is your system properly balanced?

Vote
Twitter Facebook LinkedIn
M

No it hasn't been balanced for at least the last 4 years. I'll check the return pipe temp this evening.

Michael

Vote
Twitter Facebook LinkedIn
M

Right I=92ve measured it again (deg C):

Bottom of radiator In: 54 Middle: 36 Return: 38

Top of radiator In: 50 Return: 48

So it=92s fairly constant across the top, but differs markedly across the bottom. For info it=92s an oldish radiator and it=92s long =85 probabl= y about 10 feet long. I=92ve a feeling it=92s one of the last in the circuit and it definitely hasn=92t been balanced for some time.

Not sure if this indicates sludge as the water that came out when I drained it was very clean =85 unless the sludge somehow gathered there & didn=92t travel round to the drain point?

Michael

Vote
Twitter Facebook LinkedIn
F

The exit temperature is pretty much the lowest temperature of the radiator, that suggest the flow is quite low rather than a problem with the radiator itself. It may well be caused by either being the furthest leg of the system, or perhaps may benefit from from some improved system balancing.

Vote
Twitter Facebook LinkedIn
D

What's the flow temperature set to at the boiler?

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required