Microbore pipes OK for Gas central heating system

[Briony]

Hello,
My daughter is having an oil boiler replace by gas, as mains gas is at the bottom of her drive. Various plumbers have told her that she should also replace all her radiators and micro bore piping (circa 1980s) for the most efficient system. Are they correct? Would keeping the existing microbore and radiators be more cost effective (even allowing for loss of efficiency)?
Thanks for any advice,
Briony

 

[kay-jay]

Its hard to say without seeing the property. Microbore is acceptable to use on heating systems however it is the length of each leg of pipe that is crucial because there is a limit to how fast a given volume of hot water can pass through a given pipe diameter and length. Larger bore pipes off ere greater flow and less resistance but heating targets can be achieved with microbes pipe as long as each leg isn't too long.
Refer to the UK copper board who offer guidance on their website then go looking for your tape measure

 

[tamz]

There is nothing actually wrong in having a microbore system provided it was installed within its limitations. It was however sometimes used beyond its capacity so if there are any large or long radiators you may find they do not (and never have) give out the correct amount of heat and are cooler in the middle due to lack of water flow.
It could be argued that microbore is a more efficient system as there is much less water content to heat.
Replacing the radiators depends on what condition the existing ones are in.
If all the radiators heat well i'd probably advise to leave them as they are but repipe any big radiators in 15mm. If the existing radiators have both pipes going in the same side of the radiator they should be swapped to valves each end but it depends on what you are happy with and are willing to pay.

 

[plumber0808]

If various plumbers are recommending to replace the whole lot I would take the advise and get the quotes.
Microbore is a perfectly acceptable way of piping a system but over time can become restricted due to its size from any sludge build up.

if the system is 30 years old is it worth replacing. The plumbers who have seen the system think so.

 

[racine]

The house we're in had gas CH installed when we bought it, with microbore piping. Over the years the radiator in the bathroom stopped working completely, almost certainly due to the pipework being blocked. Fortunately this rad is on the wall next to the airing cupboard, so it was possible to disconnect and seal the microbore pipes, and reconnect this rad with proper bore piping. This last winter the rad in the downstairs cloakroom finally went stone cold after years of being tepid. To repipe this would be major work, involving removing tiles, digging into walls and getting under floorboards; at present I have no idea how we'll deal with this. Worse, the rad in the dining room is cooler than a couple of years ago, so that's another item on the Worry List".! Based on this I would never contemplate buying another house with microbore piping under any circumstances, but of course you must make your own decision.

 

[stevetheplumber]

your system can be cleaned racine i doubt its had inhibitor in the system if your having these problem

 

[pierrot]

If its in 8mm I would bite the bullet and replace it, if its 10mm Id get a really good powerflush done.
:book: