can you link 2 boilers dhw outlets together?

[Gillygong]

Is it possible to link the domestic hot water outlet from a combination boiler to the dhw outlet of another combination boiler?
Both boilers are connected to same mains water, both water and gas supplies to building have been upgraded.

4 storey house, 6 showers, multi let property.
Storage cylinder not an option.

Running 2 showers and heating 17 rads, 2x bathroom sink dhw from glowworm 35cxi .

Running 2 showers and dhw to all other outlets from Second boiler. (Not purchased yet) is there a boiler that will just heat water for showers from mains pressure? Without central heating? Or just get combined and loop ch? Mmmmmmm. Got me thinking....can you use the 22mm ch outlet to produce dhw?? some clever bugger will Know of a way to do it!

 

[Gillygong]

Srry, the other 2 showers will be electrically heated.

 

[holty]

Rinnai

 

[Gillygong]

Rinnai

???

 

[Dan Robinson]

Rinnai water heaters.

 

[Agile]

Surely you should be asking your gas registered installer these questions and let him explain what can and cannot be done?

Tony

 

[muggles]

As above, you need a gas-fired water heater rather than a boiler. Either Rinnai or Andrews

 

[St0rmer66]

Surprised nobody has mentioned a gash yet!

 

[Dan Robinson]

 

[Gillygong]

Surely you should be asking your gas registered installer these questions and let him explain what can and cannot be done?

Tony

Because he wants to install an unvented storage system, I don't agree it is the right choice as even with a 300Ltr tank on 6 showers, hot still runs out. Tenants don't mind running showers 10 mins before the get in it! Then standing in it for half hour!

Why would this forum excist if we should only take the advice of our gas engineers? Mine didn't mention the Rinnai boiler, I have just looked at them, perfect! Thanks Dan!

 

[Agile]

But don't you realise that to run 6 showers you need a mains dynamic flow rate of 60 litres per minute? Do you really have that?

But you installer should know about the Rinnais and all the possible alternatives.

Tony

 

[algas]

You could fit timed shower valves, would save lots of water!

 

[ScottishGasMan]

Because he wants to install an unvented storage system, I don't agree it is the right choice as even with a 300Ltr tank on 6 showers, hot still runs out

True, But hes a lot closer to the mark than you are.

1. You cant run DHW through the boilers CH pipes, it just doesnt work like that.
2. As said you need a LOT of water to run 6 showers at once (not even looking at hot water yet)
3. Storage cylinder even at 300litres, kept at a high temp, in the region of 70 to 75 degrees then can be mixed down to useable temperature with cold giving a higher effective capacity.
4. Combis are no good at water demand. Even if its a big one, it will stop heating the radiators completely while hot water is being drawn, so 6 showers and however many basin taps being run on and off will effectively render the combi usless as a central heating source in the winter

Lot more reasons why its a stupid idea, but we can start with that.

 

[ScottishGasMan]

PS: to answer the origional question, yes, you can link two boiler DHW outputs together, not advisable but it is possible, they would need to be the same boiler make and model, positioned next to each other and piped spesifically to ensure an even flow rate through them, Even at max capacity you ronly looking at 25 litres per minute at a 40*c rise, which in winter will leave very little in the way of hot water to mix down.

Its not a case of being imaginative, its physics. You need to know flow rates/working presures/pipe sizes/actual usage etc before you even try to set up a system like that