Main fed or tank fed

Pinoy adventure

Hi

were getting a new ideal standard combi boiler,should the boiler be mains fed or from a tank in the attic ?

thanks

Sleeper12

Regulations and best practice says it should be fed from the attic tank. The cold supply coming from the tank & the water from the tank to the combi should have a pump. This gives you equal pressure at showers and mixer taps. Equal pressure is required for thermostatic cartridges to function correctly.

If you have a pumped electric shower then this needs a dedicated supply from the tank that doesn't go through the pump. If you have a power shower like a Triton as2000xt / novel, Mira event / vigour, Aqualisa Aquastream etc then plumber will need to fit pressure reducing valve in the inlets for these showers

Get each plumber you get a quote from to make a list of everything they plan to do. You will find the cheapest quote is for a combi boiler connected to the mains water supply and nothing else. These are cowboys. In their mind they are not responsible for anything except for the boiler. Connecting mains boiler to power shower means you can't adjust the temperature correctly. Not installing a pressure reduction valve will cause your power shower do blow gaskets and void the warranty. Cowboys won't accept responsibility for the damage they cause. "Nothing to do with me mate. I didn't go near your shower". We deal with the mess these leave behind on a weekly basis. Putting it right after the damage is done can go into the thousands.

Pinoy adventure

There is only electric showers in the house so no mixer valves.

so I’m thinking of tank too pump,pump too combi boiler and feed toilets/wash hand basin from combi both hot & cold.

8 rads directly from combi so no need for copper cylinder in hot press ?

would hot side from combi need a expansion vessel or is that in the combi ?

Sleeper12

Copper cylinder can go.

I don't do any work on boilers myself so not too familiar with the insides but pretty certain it has its own expansion vessel.

Pinoy adventure

Ok thanks