How to extend heating system into loft conversion

[marlb]

Hi, I am about to extend the heating system up into the loft. I have a combi boiler which can handle the extra rads and the system is running through 10mm micro bore copper pipe. I was going to extend from the 22mm flow and return pipes with further 22mm pipe up to the third floor and then to the rads with 10mm micro bore. Is this the best option?

I have been told that I could go from the 22mm flow and return on the 2nd floor straight up to the third floor and to the rads with 15mm pipe. This would be easier and cheaper can anyone advise on the best option?

I have already calculated the rad sizes using an online calculator! Both will be about 2750 BTU.

 

[Agile]

As we usually find here, you have not told us your boiler model!

For such a small load you can easily use 15 mm tube.

In fact I would say that you could almost certainly do it with 10 mm tube but dont recommend it in case you find your heat loss is actually greater.

Tony

 

[marlb]

Thanks for the reply. It is an oil fired, Grant Vortex combi 26e. The pipes will run along a bedroom on the second floor about 2.8M and then up to the third floor, across the third floor bedroom about 3M and into the rad. The other rad is a further 3m.

 

[Agile]

I have already calculated the rad sizes using an online calculator! Both will be about 2750 BTU.

Just realised that can be wrong too!

"Both will be a total of 2750 BTU!

Or

"Both will be 2750 BTU EACH !"


Regardless, my advice will still be the same.

Tony

 

[Agile]

There is a slight anomaly in the boiler specifications.

The maximum cold system pressure is shown as 1.0 bar. Although the maximum is 2.5 bar.

To pump reliably to rads I usually recommend about 0.3 bar more than the static pressure. That ensures that any air collecting in the top rads will be easily ejected under some pressure.

It is not likely to cause any problems in practice but makes operating over three floors above the boiler level likely to be at the edge of the manufacturer's specifications.

I hope yours in not in a basement.

Tony