Radiator--cold at bottom and hot at top???

Betsysquared · 12-01-2012 09:45PM #1

Hi,

Anyone any ideas about this?

Thanks

portach king · 12-01-2012 09:51PM

Sounds like it needs to be bled.

portach king · 12-01-2012 09:52PM

Sounds like it needs to be bled.

racso1975 · 12-01-2012 09:54PM

Whats the best way to do this

DoneDL · 12-01-2012 09:55PM

It could be several things, most likely a room stat turning the boiler off if it`s set too low.

ollaetta · 12-01-2012 09:56PM

portach king wrote: »

Sounds like it needs to be bled.

Would that not be for the other way round with air keeping the hot water from reaching the top of the rad?

micropig · 12-01-2012 09:57PM

portach king wrote: »

Sounds like it needs to be bled.

+1 usually use a key to open the valve at the top side of the radiator. let the air out until water starts to come out (may be warm/hot if radiator on)

you can get the key at any hardware or the newer ones take a flat head screwdriver.

Betsysquared · 12-01-2012 10:02PM

DoneDL wrote: »

It could be several things, most likely a room stat turning the boiler off if it`s set too low.

Thanks for reply, but all other radiators are fine..would that still be the case then??
also I thought you bled a radiator if its cold at the top and warm at the bottom?

DoneDL · 12-01-2012 10:11PM

You most probably need to tweek the balancing of the system, there are other threads on this.

also I thought you bled a radiator if its cold at the top and warm at the bottom? Today 21:57 yes.

sullzz · 12-01-2012 10:12PM

Betsysquared wrote: »

Thanks for reply, but all other radiators are fine..would that still be the case then??
also I thought you bled a radiator if its cold at the top and warm at the bottom?

Your correct , it doesnt need to be bled , the problem is that the water is not circulating through the rad , probably because of either an airlock on the pipework , a stuck thermostatic rad valve , or the rad blocked with sludge , if you have a trv fitted to this rad take the head off it , sometimes the head sticks in the closed position and forces the valve closed , also try turning off all the other rads to try and force the circulation through this rad , when it heats leave all of the other rads off for an hour then open as normal .
You might need to balance your system .

heated · 13-01-2012 09:59AM

This problem usually indicates an accumulation of sludge in the bottom of the radiator. If you do as last poster suggested, it may free up that rad, but the sludge will still be in your system and may end up somewhere causing even more problems such as your boiler. Ideally you should get the system power flushed and then treated with rust inhibitor and consider fitting a "magnaclean" filter also.

Betsysquared · 13-01-2012 04:17PM

heated wrote: »

This problem usually indicates an accumulation of sludge in the bottom of the radiator. If you do as last poster suggested, it may free up that rad, but the sludge will still be in your system and may end up somewhere causing even more problems such as your boiler. Ideally you should get the system power flushed and then treated with rust inhibitor and consider fitting a "magnaclean" filter also.

Is this a big job?
Is it expensive?

heated · 13-01-2012 04:56PM

Could cost €500 - €700 to have system properly flushed and treated with rust inhibitor.

You could try to remove just that rad and clean it through with a hose outside, but it is likely that there is more sludge throughout the system. You would still need to add rust inhibitor which is not expensive.

DoneDL · 13-01-2012 09:02PM

heated wrote: »

Could cost €500 - €700 to have system properly flushed and treated with rust inhibitor.

You could try to remove just that rad and clean it through with a hose outside, but it is likely that there is more sludge throughout the system. You would still need to add rust inhibitor which is not expensive.

If all the other rads are fine why would the problem be sludge.

Marcanthony · 13-01-2012 09:24PM

DoneDL wrote: »

If all the other rads are fine why would the problem be sludge.

Hi DD. Why would it not.

rugbyman · 13-01-2012 09:39PM

I had a problem with sludge abouteighteen months ago. I do not recall how it showed up, prob rads not warming up.Got a guy with a super de luxe machine to sort all out, sucks out water and sludge and replaces it. it was far too expensive, 600 euro,.

at the end of the day one rad was not right , it was upstairs . the fitter, nice guy, said it would be cheaper to replace that rad than re do all again..

we did this , problem solved..
however ,now back to square one. the same rad is hot at bottom, will not bleed ,either air or water, needsreplacing, or taking outside and cleaning.
new rad is 75 euro so will prob go that route.

this rad is upstairs and furthest from the boiler, can anyone suggest why the silt clogs there?

rugbyman

Paul.C · 13-01-2012 10:09PM

Hi there, Im having the same problem and so far i have removed and washed out the rad(no sludge), removed thermostat and checked pin was ok(it was), turned of all rads but this one to hopefully blast airlock out to no avail.

I was gonna start my own thread for this but its very similar to this one so here are my individual details. First off Im a Carpenter but im very handy with plumbing. Problem is im not great when it comes to central heating.

Im going to balance the system next monday and see if that sorts it.

Now the other contributing factors are.

The boiler was serviced buy a RGI company last July. Ever since then(not to sure which month) I have had to kepp topping it up to 1.5 bars via the cylinder filling loop every month. Last week an olive on the gate valve on the return on the cylinder failed and cause a bit of a leak(enough to leave a damp circle on ceiling below about 2ft in diameter)

Anyway I presume this is why I had to keep topping up a it was more than likely leaking slowly.

Problem now is the boiler needs to be emptied via the release gate valve in the hotpress every 3 days or so as it seems to be building in pressure up to 3.5 bar:eek: Thats not very good. Anyway Gas man is coming on wednesday to sort out that part hopefully. I have done necessary check ie. checked filling loop is closed and thats as far as im going to go with boiler for safety reasons.

So my 3 main questions are

1. What else can i do to get heat in this cold rad(all others are perfect)this one has hot flow and cold return. And part of the top half is warm although I think this is conduction. My other guess would be a partial blockage in or after the return valve.

2.Why is the pressure rising in the boiler.

3.Am I missing anything???

Sorry OP if I have hijacked your thread but im sure this is common and posting here will no doubt be helpfull for all parties..;)

Cheers

Marcanthony · 13-01-2012 10:45PM

rugbyman wrote: »

I had a problem with sludge abouteighteen months ago. I do not recall how it showed up, prob rads not warming up.Got a guy with a super de luxe machine to sort all out, sucks out water and sludge and replaces it. it was far too expensive, 600 euro,.

at the end of the day one rad was not right , it was upstairs . the fitter, nice guy, said it would be cheaper to replace that rad than re do all again..

we did this , problem solved..
however ,now back to square one. the same rad is hot at bottom, will not bleed ,either air or water, needsreplacing, or taking outside and cleaning.
new rad is 75 euro so will prob go that route.

this rad is upstairs and furthest from the boiler, can anyone suggest why the silt clogs there?

rugbyman

you have a problem with water pressure. If its a pressurised system you need to top up water supply.If its open vented / semi sealed system. supply valve is turned off and needs to be opened.Rad is only hot at bottom for the amount of water in the rad is only at the bottom. .

Marcanthony · 13-01-2012 10:52PM

Paul.C wrote: »

So my 3 main questions are

1. What else can i do to get heat in this cold rad(all others are perfect)this one has hot flow and cold return. And part of the top half is warm although I think this is conduction. My other guess would be a partial blockage in or after the return valve.

2.Why is the pressure rising in the boiler.

3.Am I missing anything???

Sorry OP if I have hijacked your thread but im sure this is common and posting here will no doubt be helpfull for all parties..;)

Cheers

1. Could be a combination of things.dead leg ect. Turn off all rads other than the faulty one and balancing valve on cylinder and if the rad is flowing and returning thru the rad and pipe work.This will help identify your uniqur situation.
2. filler valve is probably passing.Disconnect filling loop to identify
3. ????????????????

Paul.C · 13-01-2012 11:02PM

rugbyman wrote: »

I had a problem with sludge abouteighteen months ago. I do not recall how it showed up, prob rads not warming up.Got a guy with a super de luxe machine to sort all out, sucks out water and sludge and replaces it. it was far too expensive, 600 euro,.

at the end of the day one rad was not right , it was upstairs . the fitter, nice guy, said it would be cheaper to replace that rad than re do all again..

we did this , problem solved..
however ,now back to square one. the same rad is hot at bottom, will not bleed ,either air or water, needsreplacing, or taking outside and cleaning.
new rad is 75 euro so will prob go that route.

this rad is upstairs and furthest from the boiler, can anyone suggest why the silt clogs there?

rugbyman

From my experience, balancing the system should sort this out. The further away the heater the more need for pressure. The closer the heater the less need. Adjust the non adjustable side of the heaters until you get an even flow to each heater. Takes a while to do but usually sorts this out.

Also if I had paid a bloke 600euro to attach a pump to the system and stand there for few hours then I would be expecting every rad working after.

His overheads are chemicals for pumping into the system and labour to complete the process. 600euro was too much. He should have fixed the problem as part of the job. Not fobbed you off

Marcanthony · 13-01-2012 11:11PM

Paul.C wrote: »

From my experience, balancing the system should sort this out.

id say thats what his problem is. But if he just allows heat pump to that rad . It will confirm.

rugbyman · 29-01-2012 09:57AM

Thank you both for your replies, marcanthony, with that name, I suppose you learned all you know in the steam houses of ancient Rome, with brutus and Caesar.

called a genius plumber in the end, fixed it in two shakes of a lambs tail.

my system every few months refuses to stay going. this tells us that the pressure has fallen too low. opening a tap ,fitted in the system for a few seconds sorts that out. however I let the pressure rise to 2 bars or over. this was too high, the genius lowered it ,using a screw driver. bled the rad and bob s your uncle.(this rad would not bleed ,air nor water, for me)
I was not there, nor did I get talking to him yet ,so as to add to my own sparse info chest

regards,Rugbyman

Radiator--cold at bottom and hot at top???

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