recommendation And advice are welcome.

[Last Plumber]

It is a 938 mate so with no taps on the stores still empty.

What do you mean?
I meant that if you turned the water off to the Boiler and water still runs from a hot tap, it must be getting in elsewhere. If that is happening, when you run a hot tap with the Boiler working, it will mix and cool the DHW. It can also out balance the hot totally and allow only cold to run, depending on the system. There will always be slightly more resistance through the Boiler than direct.

If we are talking at cross purposes, let me know?

 

[Harvest Fields]

I miss understood. When the boiler cold is isolated the 2 x storage vessels empty then the water stops is what I meant. Sorry.

 

[Last Plumber]

I miss understood. When the boiler cold is isolated the 2 x storage vessels empty then the water stops is what I meant. Sorry.

Oh I see. If the flow stops then no you're right, it won't be a passing valve lol.

 

[Scott_D]

The cylinder won’t run empty. As explained earlier it’s capable of making as much as a conventional cylinder.

Do you mean with a blending valve it’s the equivalent of a conventional tank?
It won’t run empty but once the 20 litres is used it just works as an 838 then reheats the cylinder when it gets chance

 

[sammathias]

Don’t fit the 938 mate. I’m having a mare with one and the hot water at the minute. Boiler and unvented for me

Don't talk dirty about our beloved vaillants.

What's wrong with it?

 

[Harvest Fields]

Don't talk dirty about our beloved vaillants.

What's wrong with it?

It’s all detailed in the previous posts mate. I would never bad mouth Vaillant’s. They are all I fit normally.

 

[Old Account]

Do you mean with a blending valve it’s the equivalent of a conventional tank?
It won’t run empty but once the 20 litres is used it just works as an 838 then reheats the cylinder when it gets chance

That’s correct I may misunderstood you scott. Yes it would be equivalent to a conventional tank of 70l

 

[Harvest Fields]

That’s correct I may misunderstood you scott. Yes it would be equivalent to a conventional tank of 70l

Am I missing something here?

 

[Last Plumber]

Am I missing something here?

Lol.

 

[Harvest Fields]

The store on a 938 is 15ltrs. How will that be like a 70ltr tank?