Microbore or 15mm pipes & which boiler? *Now with added queries!*

plumb1 wrote: »

So if you installed a rad with a 9500 btu output? You would use 8mm?
A pipe can only carry a certain amount of heat.

No,

8mm is fine to about 5500 btu, above that, then go to 15mm. We don't know the size of the rads involved in each room! Maybe I should have asked for more info.......;)

Good morning: A new client had a problem with his central heating in his newly renovated and extended property. Unfortunately, the microbore, an ancient HW cylinder and the Potterton Suprim:eek: hadn't been replaced ( also the builders had gone bankrupt and returned overseas). A rash of problems developed...the owner called a well-known/London based company and almost £2000/two months later still no improvement. The OH took a look as a favour and discovered the boiler did not have adequate ventilation, the pump was piped incorrectly, the unidirectional TRVs were on the wrong end, several rads were stone-cold/underperforming/leaking, the rads in the extension were undersized by half and the system kept losing pressure.

The property now has a new boiler (Viessmann) with a Boiler Buddy, the system has been flushed (took most of the day), the old rads have new TRVs and the system no longer loses pressure. The microbore and the old radiators will remain until spring and the undersized new rads will be replaced. The clients regret not replacing the microbore etal at the time of renovations and will have the remaining issues addressed at great expense and disruption.

In other words....another example of central heating being the poor relation during renovations and an expensive hangover afterwards. A RGI recommended to you by a source you trust would be best placed to advise you after completion of a site survey.

HTH

Canucklehead