Micro bore

27 Jan 2004
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United Kingdom
Apart from the usual possible problems with micro bore sludge build up etc, Can anyone advise me of any other problems I may come across when fitting a sealed system with 24 rads all in micro bore hep2o.


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Tip -use a good leak sealer when filling system -
also try to stick to a low pressure.
Thanks for all your lovely info :LOL:
Customer wants sealed system, customer wants plastic micro bore

Anything technical to add.

Breezer yes I have lol

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Customer wants head looking at. If you think it's not a good idea (and only an idiot would) DON'T do it. When all the problems come along YOU could be held responsible and it could cost you dear.
For this I would sit down with scaled plan of the property and calculate pipe runs from first principles. Microbore may well be easier in 10mm plastic (or copper if that is the second choice), but when the rads will not heat when the system has been set up, you end up being in a corner with regards to getting paid for the job.

If the client is asking for microbore and you are suggesting small bore, get it on paper. For me copper is always the first choice. It looks better and stays in shape. But then I do very little installation work.
Nothing wrong with Hep20, or microbore, use the barrier pipe, Hep20 doesn't come any smaller than 10mm anyway, just make sure you use the proper cutter, make sure your pipes are large enough to take the amount of btu you are trying to get through them, I run large pipes up to a convenient point then reduce down to microbore about last three metres, only use 10mm pipe for rads less than 10,000btu, any bigger use 15mm, you wont get any sludge problems with a sealed system with a modern boiler, especially if you fit it as per flushing and inhibitor specification.
You can always use copper where pipe visible and chage to Hep20 wher hidden
Thanks for your help

Customer wants all pipe to be hidden, pipe runs per floor are no more than 10 mts per rad per floor.

Idea was to have a bank of manifolds on each floor connected to the three port via 22mm pipe work. The only single rad over 10,000 btu is on the ground floor I can run that pipe in unipipe through the Jabolite.
Guys - can I pitch in on this please. I am not a heating engineer which is why I have been looking at Marley Equator pipe to install central heating. My house has a solid ground floor and based on info from Marley it seems to me I could do what you guys are discussing here which is install a bank of manifolds at a central point in the upstairs floor run flow and return to boiler in 22mm and use 10mm (or even 15mm) pipe runs down the corner of the rooms below and out to the upstairs rads The rooms are quite small so max pipe run is only about 6m.
Can anyone see any problems with that please?
I would do vertical drops to downstairs rads up to 10,000btu in 10mm copper in plastic trunking, run along horizontal clipped to skirting board, then connect with Hep20 under the upstairs floor, upstairs rads I would come straight out of the floor clipped against the skirting offset out straight into the rad valve with the Hep20, just be careful when cutting carpets with stanley knife.

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