Discussion in 'Plumbers' Talk' started by richkeys, Aug 9, 2017.
Can a radiator return pipe be higher than the rad when it joins the ring back to the boiler?
Depends on layout of system and whether it's pressurised or gravity fed. Why do you ask?
Its gravity. Have put a new rad on the system and it isnt getting very hot - the return pipe isnt getting hot at all!
Probs air Locked! Have you bled it with the pump off? If that don't fix it turn of some of the other rads ,that will allow more umph to move the airlock. You have turned on rad valves on both ends!
Yes valves on at both ends and bleeding it produces water - not tried with pump off. Will try what you suggest tomorrow - as have now lost the will to live!! Thanks for the advice.
Welcome to the world of plumbing!!!!
Post a pic of new radiator!
Don't you just luv it when u don't find out what happened!!!!!
Well what happened is that as it wasnt raining for a couple of days I have been re-roofing a large out building. However rain is forecast for tomorrow so I will get back to a rad. I tried everything you said but no joy. One thing I hadnt mentioned is that pipework i did that links to the flow and return goes for about 1m in plastic pipe then back to 15mm copper. I am now working on the theory that the bore of the plastic pipe(and especially the inserts) are causing a drop in flow to this rad. So I am going to remove the plastic pipe and replace with copper. Will keep you posted on progress.
Won't make any odds! Post a pic it may be obvious to US!.
Yes Im not sure about the plastic pipes - used them before with no issues (but that was a pressurized system). Here's a couple of pictures. The top pipe is the return. The flow and return pipes go up to the bathroom rad (only) and that gets very hot.
looks like you have taken your pipework from the branch pipes going to and from the rad in the bathroom ,rather from the main flow and return pipework ,which would most likely be 22 mm not 15 mm. However it is not impossible for it to work the way you have done it. you will need to balance the two rads ,if not the whole system . just to ensure the trv on your new rad is not a problem ,remove the top ( the white plastic sensor ) part ,and make sure the pin in the centre of the valve ( the part still on the pipework ) is moving up and down freely ,and is in the UP position ( fully open ). make sure the lockshield valve is also fully open ,by removing the white cap and turning the spindle fully anticlockwise. turn off every other radiator trv ( or wheel head if no trv ). close the lockshield valve fully on the bathroom rad ( so both valves closed on bathroom rad ). turn on heating and be prepared to bleed any air from your new rad as it collects then report back .this should concentrate the circulation thru your new rad / cylinder coil and any by pass pipework and boiler of course .shifting any trapped air to where you can bleed it off. let us know how it goes, we can then advise further.
Thanks for your reply. Have tried all you suggested. The rad only gets hot at the top. The flow pipe is lovely and hot and the return pipe cold. Bleeding only produces water. How about turning up the pump speed?
Is it a new radiator? Cold at the bottom suggests it may be full of crud.
Yes new Acova rad.
Mis-read your previous post- I thought you said the return pipe was also hot.
It sounds as if there is a problem with the return. There is presumably still a little flow with the hot water entering the radiator rising and heating the top.
What happened when you shut off all other rads? Did it make any difference?
Did the new rad come with plastic plugs.
Did you remove BOTH of them?
richkeys ,if you followed EXACTLY the procedure I layed out in my previous post , And it made NO difference AT ALL ,then you may have a physical obstruction in the rad / lockshield valve / pipe or unions. before attaching new rad ,did you flush pipework thoroughly via both trv and lockshield valves ,to clear out residues of swarf /solder / flux ,system gunge etc ? I suggest you remove rad ,check for blockage in rad ,connect hose from lockshield to drainage ,open lockshield valve and observe outflow. do same on trv. reconnect rad and refill / bleed air . try system again with all other rads off.
Ok thanks will try this ....and report success (or not!)
Have removed rad and flushed it. There is flow from supply(TRV) and return(lockshield). Have now put it all back together and it is still much the same. Would turning pump up to higher speed help?
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