15mm mains, any point in 22mm in house?

[samtheman1k]

Our house has a 15mm mains water into the house. We are about to buy an indirect thermal store that will provide mains pressure hot water to the taps/shower/bath (there will be no cistern in the loft).

The connections on the store are 22mm, so is there any point in using 22mm pipes anywhere? Will it provide less resistance around the house & thus faster flow rates? Will it provide faster flow rates of hot water? Or is it all restricted by the 15mm mains?

 

[petetheleak]

Best 2 fit 22mm pipe won't do any harm , you maybe at a later date decide to fit a larger mains supply.

 

[chrishutt]

You can see how much of a pressure drop your internal pipework is causing by attaching a pressure gauge to a point near where the water enters and a point near where it will be used (e.g. bathroom) and comparing the dynamic pressures for a particular flow rate.

For example if you set up a flow of 20 litres/min and the dynamic pressure where the water enters the house is 2.0 bar but only 1.5 bar at the point of use then you are loosing 0.5 bar pressure as a result of the internal pipework. Upgrading to 22mm will reduce that pressure loss to virtually zero.

If you also check the static pressure (no flow) you will see what the mains pressure is and the sort of pressure you might get if you upgraded the supply all the way back to the mains.

There will be a limit to the rate at which the thermal store will deliver mains pressure hot water so there's no point in exceeding this.

 

[samtheman1k]

Thanks for the informative responses. The 15mm mains goes into the floor in the kitchen, so doubt that's ever going to be upgraded! I was going to use 22mm just out of cause, but with it being double the price of 15mm, I only wanted to use it if there was any benefit, of which there seems to be, so I shall!