New Boiler

[JtB]

Our Ideal (Minimiser) boiler finally packed up on 28th Dec and British Gas can no longer repair it due to parts obsolescence. Today we are having a new Viessmann condensing boiler fitted which has a stainless steel heat exchanger as required due to having water softener.

 

[sight-pin]

If you can afford it, get a bigger HW cylinder fitted. Ours was a piddling 80 litres (the house was built for a family of 6!) so we increased it to 160 litres, the issue being that a pump does empty the cylinder quite fast and three long showers will use up the stored water. A

Nice idea, however if the mains supply to the tank is lacking (or the tank size is insufficient) it can drain the tank dry and cause air locks when it's trying to refill.

 

[postman]

Worcester or Vailiant.Our new one is the Vailiant.Top quality.

 

[Globalti]

Nice idea, however if the mains supply to the tank is lacking (or the tank size is insufficient) it can drain the tank dry and cause air locks when it's trying to refill.

Your HW cylinder should be supplied from a header tank in the attic and the pipework should be 22mm, which can easily cope with the demand from the smallest pump. Fresh water enters from the bottom and the hot supply is usually taken from the top (or the side near the top) of the cylinder and the only possibility is that the pump may suck air down the expansion pipe. However there is a special outlet with a dip tube to reduce the risk of this happening.

Our own HW supply to the taps is very sluggish for reasons I've never been able to ascertain, probably lack of head, but the shower pump works just fine.

 

[sight-pin]

Your HW cylinder should be supplied from a header tank in the attic and the pipework should be 22mm, which can easily cope with the demand from the smallest pump. Fresh water enters from the bottom and the hot supply is usually taken from the top (or the side near the top) of the cylinder and the only possibility is that the pump may suck air down the expansion pipe. However there is a special outlet with a dip tube to reduce the risk of this happening.

Our own HW supply to the taps is very sluggish, for reasons I've never been able to ascertain, probably lack of head, but the shower pump works just fine.

No, i mean the mains water tank, not draining the cylinder...... the 'header tank' is the small one that supplies the top up for just the heating.
What i was trying to say is that if the cold mains supply to the main water tank is slow or insufficient the tank can drain dry.

 

[Globalti]

You must have very poor mains pressure! How good is the pressure at the kitchen tap?

 

[sight-pin]

No i'm not talking about me lol. i was referring to your suggestion to the OP about pumping the DHW from the cylinder.