Enough Hot Water??

[bobby62]

Hello,

I am currently involved in the renovation of an old small sports club, and this has meant the renewal of the exisitng plumbing and heating system.

The club consists of 7 showers (they all used to be electric). We have got a price off a local plumber to install a new hot water system. We want to install some solar panels on the south roof to feed twin coil cylinders with the boiler. The quote from the plumber has allowed for 2 x 300litre Heatrae Sadia cylinders, 600litre total. Firstly in your opinion do you think there will be enough hot water (there will be 15-20 people wanting a shower, on a weekend say after a football match, and they will be a standard shower fitting). I don't want to accept the cost or look for other proices if I am unsure whether they will do the job.

Secondly, as a cylinder goes are the Heatrea Sadia twin coil a good bit of kit or have you any other preferred choices?

Many thanks

 

[Agile]

Working backwards, 600 li gives just 30 li each if you ignore reheating during showering which will be very limited.

As the water is stored at 60° but used at only 40° then that would give just a four minute shower at 10 li/min.

That a pretty short shower! But it might be adequate?

With 7 showers from unvented cylinders that will need a mains water dynamic flow rate of 70 li/min. Thats about five times what an average house usually gets!

A school gym I visited recently in Paddington had two 500 li unventeds and a boiler capacity of 240 kW!

Its a very expensive installation for such intense use just a couple of times a week. Far cheaper to install with electric showers! But that still needs an 300 Amp supply capacity which would need a three phase supply.

As the use will only be very occasional the cost of the solar option will be VERY expensive indeed for very limited payback. A domestic solar system saves about £100-£150 p.a. but thats with seven day a week water use!

Tony

 

[bobby62]

Working backwards, 600 li gives just 30 li each if you ignore reheating during showering which will be very limited.

As the water is stored at 60° but used at only 40° then that would give just a four minute shower at 10 li/min.

That a pretty short shower! But it might be adequate?

With 7 showers from unvented cylinders that will need a mains water dynamic flow rate of 70 li/min. Thats about five times what an average house usually gets!

A school gym I visited recently in Paddington had two 500 li unventeds and a boiler capacity of 240 kW!

Its a very expensive installation for such intense use just a couple of times a week. Far cheaper to install with electric showers! But that still needs an 300 Amp supply capacity which would need a three phase supply.

As the use will only be very occasional the cost of the solar option will be VERY expensive indeed for very limited payback. A domestic solar system saves about £100-£150 p.a. but thats with seven day a week water use!

Tony

Thanks Tony,

I agree with what you are saying. I think a quick 4 min shower after a football match is all they will take (its not far off that now, as a lot like to shower when they get home), however that said, I do need to assume worst case. The solar panels will be free, we have managed to get a grant for these, so anything helps when we have a tight budget.

There will be 50kW of power going into the cylinders aswell as the solar coil. Do you think this should be increased to improve the reheat time?

One other option is to install showers with 8 l/m heads and with push button type timer?

 

[stevebamford]

solar panels

Do most of the matches get played in the winter ? In Bradford ?

 

[bobby62]

solar panels

Do most of the matches get played in the winter ? In Bradford ?

I see where you are coming from (and we did have this discussion!) but like I said they are free so why not?

 

[bobby62]

With 7 showers from unvented cylinders that will need a mains water dynamic flow rate of 70 li/min. Thats about five times what an average house usually gets!

There are 7 electric showers currently running ok off this water main supply

 

[Agile]

You need to measure the flow rate as that will determine the mains supply and what you can get away with.

I assume the 50 kW is a gas boiler?

That will have negligible effect on reheat so I would suggest its downsized to a 24 kW boiler as that will give Ch and heat the water in a couply of hours anyway.

These kind of things are usually totally wrongly sized because "plumbers" are often very thick.

We find it most often in hairdressers!

Tony

 

[bobby62]

You need to measure the flow rate as that will determine the mains supply and what you can get away with.

I assume the 50 kW is a gas boiler?

That will have negligible effect on reheat so I would suggest its downsized to a 24 kW boiler as that will give Ch and heat the water in a couply of hours anyway.

These kind of things are usually totally wrongly sized because "plumbers" are often very thick.

We find it most often in hairdressers!

Tony

Thanks Tony, yes this is a 50kW condensing gas boiler. He did say it would be slightly bigger than normal to provide better 'HW recovery'.

With regard to the flow rate, if it is slightly lower than what is ideally required will it just be a case of the showers just 'dipping' in performance slightly should they all be on at once?

 

[stevebamford]

solar panels

Do most of the matches get played in the winter ? In Bradford ?

I see where you are coming from (and we did have this discussion!) but like I said they are free so why not?

Not being funny but it doesn't seem as if you'll get much benefit from this (and how did you manage to get a grant for it ??)

 

[bobby62]

solar panels

Do most of the matches get played in the winter ? In Bradford ?

I see where you are coming from (and we did have this discussion!) but like I said they are free so why not?

Not being funny but it doesn't seem as if you'll get much benefit from this (and how did you manage to get a grant for it ??)

Its nce and sunny at the moment!! We got the grant through phase 2 of the Low Carbons Building Programme, they seem to be pushing it now and don't mind funding things for non-profit organisations

 

[stevebamford]

hmmmm do you think i count as a 'non-profit organisation' ???

 

[spacethegas]

more of our tax money being thrown down the drain.