Existing 10mm pipes ok for new column radiator?

ChasingtheWelshdream

Hi all,

Tomorrow’s job is piping up a new radiator (finally getting heating in the kitchen, hooray!) The radiator is a small column rad, 4 columns with about 3000 btu. 900 x 300mm ish.

There used to be a radiator here, piped from above. This was removed and the pipes capped in the ceiling void. I plan to use these redundant feeds and bring the pipes back down the wall to the new rad.

The whole heating system is 10mm microbore which has generally behaved very well.

However, I have read that microbore can struggle with column radiators. (I have also read microbore is rubbish, but we haven’t had any issues so I am unsure how much is just personal preference.)

So my question is, will 10mm be able to power the column rad, or should I re-do in 15mm?

Working with the existing capped off 10mm would be much easier and quicker, but not if it ultimately doesn’t work.

If I did go for 15mm, I guess I would need to take right back to the 22mm - I couldn’t just add a 10-15mm coupler to the existing feeds?

As always, any and all thoughts and experiences are much appreciated.

(Edited to add, the total run for the 10mm would be approx 11meters, so a fair distance, I have no idea why the manifold was sited where it is. Although it must have worked for the previous rad I suppose. I could quite easily put in a new manifold much closer to the rad, but then I may as well just go for 15mm anyway.)

MoreProbs

The worst that could happen is that your system might need a slight rebalancing, but most likely not. This new column rad must be pretty close in output to the original rad that was there?

I wasn't aware that there could be issues supplying 'column' rads with microbore? Are we talking old-style cast-iron style rads? If so, would the supposed 'issue' be that these have a larger water volume content but smaller radiating surface, so might require a larger flow of hot water to maintain its output? Even if so, we are actually talking about a modest sized radiator here in any case, of around 900W output. I cannot see any issue doing this at all.

I fitted two larger 'vertical' column rads than these - 1850mm high x 450mm wide - either wide of a 6m-wide room, and ran it all in 10mm so I could sink the pipes easily into the insulation slab in the floor. They work with no issues. There is a light-but-audible hiss from the nearest rad, but this is due to that one's lockshield being tweaked down very far so it doesn't steal all the flow from the other rad. The sound isn't from the pipe, but from the rad, and I don't believe the cause is the use of m'bore - and it isn't that noticeable in any case, and certainly don't think it would be in a kitchen.

If you haven't got one already, I'd recommend fitting a magnetic filter in your system whilst it's drained down for this. And if the drained water is not clear, consider adding a long-term system cleaner to the fresh water, as well as the essential inhibitor.

ChasingtheWelshdream

Thank you.

Yes, I had just read (googled) that some radiators struggle with microbore, particularly large column rads. Which this isn’t. 

I have been pondering the system again and had completely forgotten I installed a 2 column rad with the 10mm (1000 x 800), and it is completely fine. 

I have been studying the pipes again as the ceiling is down in the room beneath the boiler so most are easy to see. I can’t fathom why some things were done, with miles of seemingly pointless 10mm when the manifold could have been sited much closer to at least 3 rads. I will be moving rads around room-by room, so at some point I will sort things out.

But in the meantime, I think I will just extend the existing feeds down with 10mm. If it doesn’t work satisfactorily, I can always change it. But it will be a much quicker job to try as it is.

And yes, I there is a magnaclean which I check a couple of times each year. The last time I drained the system everything was clear, which is why I don’t necessarily buy the ‘microbore is rubbish’ line I hear a lot.

rob7475

I have an 7000 BTU column radiator running off 10mm fine. It's the only radiator in the house running off 10mm and after a bit of balancing, it heats up as quickly as the rest of the radiators.

ChasingtheWelshdream

Thank you, much appreciated.

plumb1_2

Ya you’ll be ok with 10 mm