rads Ok upstairs, freezing downstairs.

[jb1468]

As it says in the title, all the rads upstairs are perfect and all the ones downstairs are ice cold!

New problem just happened last 2 days and before I call a plumber in I wanted to check if it could be something simple? What are the likely causes of such a problem

Thanks

 

[Cookingongas]

Turn all the rads off that are hot make sure the valves are open on the cold rads. Call for heating only and shut all bypasses, if trvs check the pins aren't stuck

 

[jb1468]

Turn all the rads off that are hot make sure the valves are open on the cold rads. Call for heating only and shut all bypasses, if trvs check the pins aren't stuck

will do ta

 

[Space cat]

If the problem arose suddenly, maybe the pump has failed. Gravity circulation could heat the upstairs rads (depending on pipe layout) but the downstairs ones would get nothing.

 

[jb1468]

It was in a friends house which i went to this evening. I turned all the valves of on the rads that were working and turned the boiler on and the heat went ok to the downstairs, but once i turned on the upstairs again (i turned the lockshield valves on but even not as much as they were before) the heat eventually left the downstairs again

Does this mean the pump is more likely to be at fault. Up to 48 hours ago there was no problem with them all heating, now for whatever reason any one of them will heat when the rest are isolated but there does not seem enough power/pressure to get them all heating at the same time

so is it the pump that's failed

 

[Space cat]

Gravity circulation will only send hot water to radiators that are higher than the boiler so, unless the boiler is in a basement, the pump must be doing something to get heat to the downstairs rads.

Pumps usually just stop working altogether so I would look elsewhere first. How does the hot water work. Is there a three port valve - or other motorized valves - in the system or is it a combi boiler with direct hot water?

 

[jb1468]

Gravity circulation will only send hot water to radiators that are higher than the boiler so, unless the boiler is in a basement, the pump must be doing something to get heat to the downstairs rads.

Pumps usually just stop working altogether so I would look elsewhere first. How does the hot water work. Is there a three port valve - or other motorized valves - in the system or is it a combi boiler with direct hot water?

its a combi boiler (gas). When I isolated the working rads and turnt the boiler on i called only for heat. the hot water is rarely called for along with the heat

 

[JohnD]

It was in a friends house which i went to this evening. I turned all the valves of on the rads that were working and turned the boiler on and the heat went ok to the downstairs, but once i turned on the upstairs again (i turned the lockshield valves on but even not as much as they were before) the heat eventually left the downstairs again

Then you have a balancing problem. Turn all the lockshields on the hot radiators off and let them cool down, then, with the pump running and turn ONE of the upstairs lockshields on by half a turn. Put your hand on the pipes of the rad and see if they start to warm up after a minute. If not, open it ONE QUARTER TURN MORE ONLY and see if one of the pipes warms up. Repeat if necessary but do not turn it more than a quarter turn each time. As soon as one of the pipes starts to warm up, even a little, do not turn it more, go to the next rad..

As soon as the pipe starts to warm up, go and open the next lockshield by a similar amount. A lockshield has very little movement between "closed" and "open".

After half an hour go and feel all the upstairs and downstairs rads. They should all be heating up. Feel the flow and return pipes on all rads. The flow pipe should be "too hot to hold" and the return pipe should be "too hot to hold for long." If any of the Return pipes is hotter than the others, turn that lockshield down by a quarter turn and wait ten minutes to see if it has cooled down to match the others. If not, close it another quarter turn. If you still have some rads that are cold, turn down the lockshields on all the hot rads by a quarter turn. Repeat as necessary.

You do not mention TRVs but perhaps they are fitted and are faulty, or perhaps in this cold weather the upstairs ones are staying open for longer.

 

[jb1468]

It was in a friends house which i went to this evening. I turned all the valves of on the rads that were working and turned the boiler on and the heat went ok to the downstairs, but once i turned on the upstairs again (i turned the lockshield valves on but even not as much as they were before) the heat eventually left the downstairs again

Then you have a balancing problem. Turn all the lockshields on the hot radiators off and let them cool down, then, with the pump running and turn ONE of the upstairs lockshields on by half a turn. Put your hand on the pipes of the rad and see if they start to warm up after a minute. If not, open it ONE QUARTER TURN MORE ONLY and see if one of the pipes warms up. Repeat if necessary but do not turn it more than a quarter turn each time. As soon as one of the pipes starts to warm up, even a little, do not turn it more, go to the next rad..

As soon as the pipe starts to warm up, go and open the next lockshield by a similar amount. A lockshield has very little movement between "closed" and "open".

After half an hour go and feel all the upstairs and downstairs rads. They should all be heating up. Feel the flow and return pipes on all rads. The flow pipe should be "too hot to hold" and the return pipe should be "too hot to hold for long." If any of the Return pipes is hotter than the others, turn that lockshield down by a quarter turn and wait ten minutes to see if it has cooled down to match the others. If not, close it another quarter turn. If you still have some rads that are cold, turn down the lockshields on all the hot rads by a quarter turn. Repeat as necessary.

You do not mention TRVs but perhaps they are fitted and are faulty, or perhaps in this cold weather the upstairs ones are staying open for longer.

Thanks, John. I will try and balance them as you have instructed.......what confuses me is why did they work OK for the last few years? No one has touched the lockshield valves during that time - only me last night when the downstairs rads failed. The fact that they all worked OK till 48 hours ago indicates to me (lay person) that the balancing really could not have that much out.....but nonetheless I will try it all again.

P.S. need reassurance on some of the rads lockshields. I am used to ones that have a pull of cap and a little narrow valve that turns. On two of them there is a screw removed cap and the valve is square rather than narrow - I assume these should turn just as the narrow ones with the pull caps? Silly question but confirmation just reassures me. Never been that comfortable working with plumbing.

P.S. yes all bar one hall which is working have TRV's

 

[JohnD]

yes you just turn the spindle. If using an adjustable spanner (not a mole, please) make sure it is a very good fit or the brass spindle will get scabby. Or you can buy a replacement universal radiator valve knob which comes with fittings to suit most common spindles.

the TRV heads might have failed and stayed fully open upstairs.

If there's an HW cylinder it might be stealing some of the flow

If it's an old open vented system it might be getting sludged up and clogging circulation.

 

[jb1468]

If it's an old open vented system it might be getting sludged up and clogging circulation.

I suspect this might be the problem as the tops of all rads are hot and the bottoms not so much....indicating as i understand what I've read elsewhere, sludge build up

Nevertheless will try rebalancing as you have instructed. I appreciate your assistance - thanks

 

[jb1468]

JohnD,

Just to let you know I followed your instructions and all seems to be well again. A big thank you from my friend who has heat again!!

Just for my own information/knowledge if you have time to answer a few questions i would be grateful.

Of the 8 radiators, 6 are now only open a half turn and the other 2 three quarters of a turn and it seems to be perfect. Why would the original installer have them all open between 6-7 full turns? Thats quite a margin or is adjustments required over time.

If the flow pipe heats up first and return second (which I assume) why on some of the rads did the TRV heat up first and on others the lockshield valve. Is it simply that the flow in can be the TRV or lockshield side?

The flow in pipe is as you said too hot to hold on 7 of the 8 and on the 8th just a little cooler. However on the return I would say they are ranging from luke warm to hot, but never too hot to hold. You could hold all of them all night. It does not seem to matter too much as the rads are all perfect temperature as I would expect. This is after several hours of constant heating because of this I did not make any other fine adjustments through fear of loosing heat in any of them. Friend is delighted as got perfect heat back in all rads so best left alone I thought. Do I really need to be aiming for all return pipes to be too hot to hold for too long?

Sorry if too many questions there.....just keen to understand better.

Once again thanks for the very simple process of how to gain a better balance and it resulted in a fix. Big thanks!!

 

[Agile]

JohnD,

Of the 8 radiators, 6 are now only open a half turn and the other 2 three quarters of a turn and it seems to be perfect. Why would the original installer have them all open between 6-7 full turns? Thats quite a margin or is adjustments required over time.

Once again thanks for the very simple process of how to gain a better balance and it resulted in a fix.

Big thanks!!

Most installers are lazy and dont bother to do balancing if all rads are warm. It takes 1-2 hours to do it properly.

Many dont even know how it should be done anyway!

Many think that you DONT need to balance if there are TRVs ( Wrong of course! )

Its all a result of lazy and unconcerned installers whose only interest is getting as many boilers fitted as they can in a week. The days of conscientious people who will spend extra time to do work properly are in most cases gone.