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When I trained as a Quantity Surveyor in Glasgow more than 50 years ago I was told that a radiator should not be level but should rise ever so slightly towards the air bleed valve end. This seemed to make sense to me at the time, and indeed still does. However, mentioning this to someone recently was met with disbelief and ridicule! So much so that I trawled the internet to justify the theory and was amazed to find no mention of such a thing anywhere. Every piece of advice was that a radiator should be level.

Is anyone able to confirm this theory and restore the credibility of an old man? Additionally, an explanation of the change in thinking would be of great interest to me.

Thank you in anticipation, and keep up the good work!

I am an electrician, many times I have been called to central heating systems only to find the fault was not electric, however where possible I would try to get the system running.

One of the regular faults was lock shield valve not set, or if set blocked with rubbish, the TRV works best on the incoming as it has more time to react to the temperature change, so lock shield would be on return, so lifting the return side slightly would mean sediment would remain in the radiator rather than block the lock shield, and bleed would need to be on lock shield side, however today with no header tank and sealed system with inhibitor added 10 years latter water is still clear.

So today no reason for tilt, but maybe there was 20 years ago?

Thanks for your interesting reply ericmark. The reason for the slight tilt, as I understood it all these years ago was that it forced any air to gather at the top corner, beside the air bleed valve. If it gathered at the other side, (if IT was higher), then the only thing opening the bleed valve would expel would be water. It seems that this logic has been lost over the years?

If you have a small amount of air in the radiator as long as tubes are covered not really a problem, maybe slight change in design to lower top of tubes so water does not need to be as high?

But thinking back to early systems they were often single pipe, so any air would stop them working.

Looking at my 'Beginners guide to central heating ' published in the Do it yourself magazine by George Steele it says a radiator should have a slight rise toward the air vent. There you have it by someone who guided thousands to installing their own heating systems. How we lived in the 1960 s compared to the snowflake generation now? I installed my own gas boiler in fact , a Baxi Majorca.

Hey, thanks for that aethelwulf. I was beginning to think I must have been dreaming at that lecture! I have carried that info with me all these years and when I mentioned it to someone the immediately checked it out on Google to see if I spoke with forked tongue. And guess what? Apparently, until now aethelwulf, it seemed that I was. Thank you so much for taking the trouble to authenticate my words and vindicate me. So all you young and budding plumbers out there take note. Only a couple of degrees OFF the level gets all the air out!