Need design advice - double combi + tanks

[Davejo]

Need some recommendations for a large new build. (400m2)

3 showers, 5 handbasins, 2 baths, 5 WC's, 4 sinks, 2 dishwashers, 2 washing machines.

32mm incoming main at just over 3 bar.
mains gas.


The spec is:
Limitless hot water
full pressure for 3 simultaneous showers (15 lpm each) with zero pressure drop if basins/sink/washing machine etc used.
heating at same time as above

What setup could achieve this best ?

thanks

 

[Brambles]

If it is a new build, I would look at ground or air source heat pumps with either solar thermal or voltaic feeding a suitably sized thermal store.

With respect to hot water - if that is genuinely the specification you need to achieve - it needs to be properly designed. In my experience - to offer a performance guarantee, it will probably need to be driven by a pumped accumulator.

With systems of this scale ask your designer/ installer for references, visit at least one and ask the owner what they think of it.

Hope this helps

 

[Davejo]

thanks for the reply, we have discounted ASHP as they would result in hot water running out due to their slow heating.

 

[Brambles]

That is why the design is important. 3 years ago we retrofitted a 10 bedroomed boutique hotel in Woodstock - with ASHP, thermal solar (to maximise RHI) and 34KW if solar voltaic. Other than an open log fire there are no other heat sources - it is never had a problem even at minus 6 C.

The ASHP - high heat technology available now, would give the system even greater security of supply, at a lower capital cost

 

[Davejo]

i was referring to hot water, a heat pump couldn't replenish the hot water fast enough with all showers running for say 20 mins each.

 

[ShaunCorbs]

Break tank and pump
Accumulator for the toilets

Two Rinnai’s in parallel

heating what’s the load eg kw also ufh etc

 

[Davejo]

Break tank and pump
Accumulator for the toilets

Two Rinnai’s in parallel

heating what’s the load eg kw also ufh etc

thanks, could you explain it a little how it would work ?

 

[Davejo]

UFH 8 zones down 9 zones up

 

[ShaunCorbs]

thanks, could you explain it a little how it would work ?

break tank and pump would do the baths, showers / high demand items

the 400l accumulator would do the toilets, sinks etc low demand items

the Rinnai’s would be fed from the break tank and pump, also secondary return loop so instant / near instant hot water is accessible

What is the kw rating off the ufh

 

[Davejo]

sounds a great solution, will find out the kwh of the ufh but a normal combi copes with it no problem apparently.

recommend a firm to design and fit the system in Worcestershire ?

 

[ShaunCorbs]

sounds a great solution, will find out the kwh of the ufh but a normal combi copes with it no problem apparently.

recommend a firm to design and fit the system in Worcestershire ?

Would go air source if you can but over spec it and run a buffer

tbh your best bet is a commercial plumbing and heating

most domestics don’t go that advanced

it won’t be cheap but it will work to your spec

 

[oz-plumber]

2 x HD 200 Rinnnai units and a 315 litre cylinder will give you near 2000 litres of hot water per hour.
All you need to worry about is the mains pressure to achieve what you want.

Expensive system - but performs and achieves.
Contact Rinnai to help design a system to your requirements.
They are helpful and back up their design with a guarantee

 

[oz-plumber]

Miss read post - thought you said 8 showers.
1 Rinnai & 250 ltr or 315 ltr tank would be suitable.

In all honesty, you shouldn't be asking advice on a public forum with the specs you have.
If you have doubts about you ability to design a system to the specs required, get some professional help.

I'm not doubting you can do the work, but designing the system may be beyond you.

I only work for a couple of builders now and on the larger projects, I get them to get a design by a Consultant.
Takes a lot of stress off the job as you only have to follow plans provided.

 

[Davejo]

Miss read post - thought you said 8 showers.
1 Rinnai & 250 ltr or 315 ltr tank would be suitable.

In all honesty, you shouldn't be asking advice on a public forum with the specs you have.
If you have doubts about you ability to design a system to the specs required, get some professional help.

I'm not doubting you can do the work, but designing the system may be beyond you.

I only work for a couple of builders now and on the larger projects, I get them to get a design by a Consultant.
Takes a lot of stress off the job as you only have to follow plans provided.

thanks , im not a plumber! Just want to make sure im speccing the right thing. Could you dm me the consultant you use, no problem paying for a spec!

thanks

 

[oz-plumber]

No.
You want to provide plumbing specifications for a house with 3 showers and you come to an open plumbing forum.
Any domestic plumber should be able to quote on the specifications you require.
If you can't find a domestic plumber that can size and install a system you require - keep looking.
It's not that hard!

 

[SimonG]

Best bet is direct to a manufacturer or a consulting design firm.

You want peace of mind that once installed it meets your requirements.

Out of interest what's the flow out the main litres/minute

 

[Davejo]

Best bet is direct to a manufacturer or a consulting design firm.

You want peace of mind that once installed it meets your requirements.

Out of interest what's the flow out the main litres/minute

thanks, I'll be putting the main in so I could goto 63mm.

thanks for the advise for manufacturer, any particular good ones to speak to ?