Accumulator Specification Help

[rossyl]

Hi All

Due to out incoming water supply, we were advised to have an accumulator
Our engineer reviewed and specified and was to install a 330litre Salamander Accuboost Pumped Accumulator. These are now completely out of stock.

Instead we are being supplied with

A Global Water Challenger 300 Litre vessel

And

A Stuart Turner Mainsboost VariQ 47322


Im concerned whether this new specification will work as well?
Anyone have any experience of this and its performance?
Is there a better solution?

It is being connected to
- Megaflo 300litre Unvented Cylinder
- Vaillant Ecotec System Boiler.

Many thanks

 

[Madrab]

Who specc'd you an accumulator on an unvented system?

Without knowing the mains figures it is hard to confirm outputs but even @ max output the 300L salamander system would only provide 30L/Min for 9min, then it will revert to pumped mains @ 12L/Min @ around 1.5 bar which to be honest isn't any use for a 300L unvented. I assume you have that size of cylinder as you have a lot of HW outlets to supply?

 

[rossyl]

Hi

It's 4 baths and a toilet.

Is there a better solution? Grateful for thoughts.

Thanks.

 

[Madrab]

What's the situation with your incoming water supply? You could spend as much on building in a convoluted solution where a new mains supply pipe may sort it out in one go.

 

[Madrab]

Don't get me wrong, the ST Variboost is an excellent choice to be honest, it can deliver excellent pressure and flow but it really comes down to how well the mains can replenish the storage system.
The variboost is designed to boost cold stored water (not the mains) but if your mains supply is really bad, there is always the possibility that if the mains can't replace it quickly enough, then the pump will run through that stored water in no time at all, at a peak of 4.5 bar @ 97L/Min, if there is ever the possibility or running 4 bathrooms or multiple hot and cold high flow outlets at the same time.

It would need very careful design of lower flow outlets/water saving aerators etc, to ensure that the demand couldn't outstrip the capacity.

 

[rossyl]

Hi, the mains from the road into the house was upgraded to 25mm.

With regard to pressure and flow, not sure what else we can really do to improve it.

 

[Madrab]

Do you know what the mains pressure and flow is? North London, in fact anywhere in London, I believe is notoriously bad for mains pressure/flow.

There may be other pro's on here that are more familiar with solutions that work in these locations in London.

All I can be sure of is that running a whole house from an 300L accumulator with a 300L unvented cylinder could be problematic. Again though that all depends on how it may be used.

 

[muggles]

Speak to Greatwater, they'll be able to advise on the best specification for you

Great Water

Water systems. Water softeners, water filters and mains pressure boosting systems

greatwater.co.uk

 

[Johntheo5]

Who specc'd you an accumulator on an unvented system?

Without knowing the mains figures it is hard to confirm outputs but even @ max output the 300L salamander system would only provide 30L/Min for 9min, then it will revert to pumped mains @ 12L/Min @ around 1.5 bar which to be honest isn't any use for a 300L unvented. I assume you have that size of cylinder as you have a lot of HW outlets to supply?

A accumulator assuming 3bar system pressure requirement and with a charging pressure of 4.5bar will give 27.3% effective capacity of a storage tank with a pumped system supply. A 300L accumulator will only provide 82L. If 2bar is a acceptable system pressure then the accumulator will provide 45.3%, 136L from a 300L accumulator with the same charging pressure of 4.5bar.
If the mains can't be upgraded then difficult IMO to see how a accumulator can provide the answer.

 

[rossyl]

Mains pressure is 2.5bar static middle of day, and 2bar with one tap on.

However, this drops to just over 1bar static in the morning at peak times.

Flow I am unsure of, but given the 25mm SUPPLY I didn't think it much of an issue.

 

[Johntheo5]

Can you measure that one tap flowrate under those conditions.

 

[Madrab]

Mains pressure is 2.5bar static middle of day, and 2bar with one tap on.

However, this drops to just over 1bar static in the morning at peak times.

Flow I am unsure of, but given the 25mm SUPPLY I didn't think it much of an issue.

The only reason I would ever spec an accumulator would be if the mains is below 12L/Min peak @ a dynamic pressure of 1bar or lower. Then that needs to be matched to the design requirements of what is required and it certainly wouldn't be feeding a 300L unvented and all the cold outlets too. A mains wholesome CWSC of say around 100Gal, with an on demand pumped system would be an option but a 300L accumulator would not be the first choice here I don't think.

If you are getting a dynamic mains of 2 bar with a flow rate of at least 15L/Min then there wouldn't be any reason to have an accumulator. Static figures are not important here.

Peak time pressure/flow drop would need to be managed by in house usage but even @ 1 bar it wouldn't be the end of the world. Dynamic Pressure and flow rates need to be well understood when in house usage is at its peak. A simulation of the number of outlets that could be used at one given time would be needed and then readings taken at that point. That way peak requirements are known, that coupled with what the mains can deliver at certain times of the day will give a very specific starting point as far as what solution will fit the requirements.

Just flinging in an accumulator to match a 300L unvented cylinder is not the way to go IMO.

updated for shacking spilling

 

[Johntheo5]

Maybe something along these lines.

DAB ESYBOX and ESYTANK Cold Water Booster & Storage Tank

The DAB E.sybox and E.sytank is our best selling all in one booster set and water storage tank for domestic and residential applications. The ESYTANK is a potable (drinking) water storage tank designed specifically for simple integration with the ESYBOX electronic water booster system. The...

www.completepumpsupplies.co.uk

 

[rossyl]

At non-peak times, when static is 2.5bar, a d dynamic is 2bar.

Flow is approx 19ltr per minute.

 

[Johntheo5]

Thats not bad for a 0.5bar pressure loss, theoretically, if you opt for a storage tank on the ground floor then assuming a dynamic 0.5 bar while refilling off peak time you might get a refilling rate of ~ 30/35LPM and at peak times ~ 15/19LPM.