Combi Boiler Install Flow Rates/Pressures

[cr0ft]

Hi all,

Again, after some advice from someone with more experience than I. I'm considering a 39KW combi boiler install at a customer's property. I measured static mains pressure at 3.25 bars this afternoon. This dropped to 3 bars when I opened a tap in their loft conversion which is also mains fed.

The flow rate from the kitchen tap is 15l/min but this is coming in through a flexi-hose underneath which is obviously reducing the bore below the 15mm on the incoming mains.

The boiler I am thinking of is the Broag Remaha Avanta Plus 39KW which has a hot water flow rate of 16l/min. I think these flow rates and pressures are more than adequate to run this boiler. Does anyone disasgree or have any further advice to share?

I've installed a few of these boilers but tbh this is the first time I've done more than a visual examination of flow rates and pressures.

 

[cr0ft]

bump..

 

[Centralheatking]

Here we go again - big combi with high capacity hot water flow rates - IF THE MAINS SUPPLY IS UP TO IT - and at all times of the year. When its cold the temp lift is going to reduce the flow rate and in the summer because everyone without a meter is watering their garden all day and night pressure will drop - esp on a loft conversion. Combis are only for flats and small houses as a space saving alternative to conventional systems.

If a domestic dwelling has more than 3/4 people in it with more than 1 ensuite just forget it and
install a proper system.

week after week this forum has all sorts of people posting about concerns and problems like this.

centralheatking