High or Low pressure mixer taps?

redser7

Hi,

We're in the market for a new kitchen mixer tap. There's a far bigger choice with high pressure taps. We have a tank in the attic so I assumed we'd be restricted to low pressure taps. But! We also have a Worchester gas condensing system boiler. So does this give us the necessary minimum 1 bar pressure in the hot tap to allow us to buy a high pressure tap?
Sorry, not great with heating systems!!

Cheers

tDw6u1bj

redser7 wrote: »

Hi,

We're in the market for a new kitchen mixer tap. There's a far bigger choice with high pressure taps. We have a tank in the attic so I assumed we'd be restricted to low pressure taps. But! We also have a Worchester gas condensing system boiler. So does this give us the necessary minimum 1 bar pressure in the hot tap to allow us to buy a high pressure tap?
Sorry, not great with heating systems!!

Cheers

You need low pressure taps unless your system is pumped or is mains pressurised (the correct way of doing it which happens to be illegal).

You said you've a tank in the attic and haven't mentioned a pump so we can assume neither of the above apply.

redser7

Thanks for the reply!!
No, we don't have a pump installed. But we recently upgraded our old regular boiler (Ideal Classic) to this system boiler ...
https://www.worcester-bosch.ie/products/boilers/directory/greenstar-i-system-9kw-to-24kw

When it's on and heating the house and water the pressure gauge shows about 1.5 - 2 bar. So I was hoping this boiler was putting the whole system under pressure and would do the job to allow us to get a high pressure tap. I know the cold will be fine and we only use hot water from the tap when we have it from heating the house. Am I missing something?

Thanks a lot

tDw6u1bj

The combi boiler itself won't pressurise anything, it just heats water.

You've maybe been a bit mislead re the boiler because of how it would be set up elsewhere.

Configuration of a system in any other country:
Cold: Mains supply >> tap
Hot : Mains supply >> combi-boiler >> tap
^all supply is in an unbroken supply from mains and thus stays at mains pressure (say, 3-4 bar)


Configuration in Ireland:
Cold: Mains supply >> attic storage tank >> tap
Kitchen cold: Mains supply >> tap
Hot : Mains supply >> attic storage tank >> combi-boiler >> tap.
^ kitchen cold supply is at mains, all other supply has pressure coming purely from the head to the attic tank (0 to 0.4 bar)

Now, it does sometimes happen that a plumber will ignore the rules and configure it [Hot : Mains supply >> combi-boiler >> tap], as they work better this way. If this is the case you'll notice much higher hot pressure than cold pressure in sinks that aren't your kitchen (toilet or whatever).

Another thing to keep in mind is that a lot of places in ireland have bad poor mains water pressure, barely hovering above 1 bar (a lot of places in dublin are bad for this). These taps are designed to work in places where mains pressure is min. 3.5bar, and normally close to 5. The specs on the taps give a minimum of 1 bar but they're usually pretty awful anywhere below 2 and aren't "good" until 3 or so.

redser7 wrote: »

When it's on and heating the house and water the pressure gauge shows about 1.5 - 2 bar.

This is probably the pressure gauge for the heating system - it's a closed loop of water that recirculates from your boiler, around all your radiators and back again, and again. It's filled and pressurised from the mains (before being sealed off from it when it's full and hits the right pressure, 1.5-2 is a normal pressure for this system). BTW, that doesn't mean your mains is at 1.5, that just means they stopped filling the system when it got to that pressure.


TL:DR, get a low pressure tap.

redser7

Great post! Thanks a lot. I've got it now.