Water heaters advice needed...Please :)

[ziggy1979]

Hi Everyone!

We need some advice on powering 7-8 showers.

We have no idea what's a better option - multiple instant water heaters, storage heaters, unvented heaters,etc.

In an ideal world what we would like (in order of importance) is:

1. Efficiency (in both purchase/install costs and running costs)
2. Possibility of all showers running at the same time
3. Ideally a small footprint (which doesn't go in favour of storage heaters but we would allow for this if the tanks aren't too big, and the efficiencies compared to other options justify it (if there even are any!)). We had thought to allow 4-6m2 but the less the better!
4. Mains fed system (quicker install, etc).

We want to have the water to the showers set at a fixed temperature with push button operation (so that showers aren't left running). I think we were told average shower temperature should be approx 42-44C.

Thanks for all your help!!!

Zigs

 

[Agile]

You would get more help if you explained what this is for and how often the showers are to be used!

Eight showers will need a dynamic flow rate of about 80 litres per minute! Most London houses have about 10 li/min if they are lucky!

Upgrading the water supply alone could cost about £3000 ! As well as attracting a high standing charge !

If the showers are to be used for 12 min then that will need 1000 litres of hot water. So two 500 litre cylinders!

If you don't want to upgrade the mains supply then you will need a 1000 litre break tank and a pump capable of 80 li/min @ 1 Bar.

Still want to run eight showers? That would also need a boiler to reheat the cylinders depending on how soon you want to have more showers!

Tony

 

[ziggy1979]

Hi Agile

Thanks a lot for your reply!

The showers are for a gymnasium to be located on the first floor of commercial premises in London.

While not all the showers are likely to be used at the same time all the time it might be the case at certain times of the day, especially in the mornings. I expect there will however be overlap with people starting/ending showers at peak times.

Please let me know if there is any other info that would help in getting advice. We really want to know/understand a little more about it all to understand the best solution. In terms of number of showers we could definitely have 7 but I'm not sure we can go with less than that.

Thanks again!

Zigs

 

[SimonH2]

First of all you need to find out what your mains supply is capable of giving you - bearing in mind that it can vary significantly during the day. As a commercial premises, you may (or may not) have something a bit bigger than a domestic premises (depends what a previous owner was prepared to pay for !).

And as Agile says, you also need to think about where the heat is coming from - that could be a lot of water to heat, and some big boilers (needing a big gas pipe) to do it. You can of course trade off boiler size against storage - eg if you have large tanks, then a smaller boiler could "catch up" during lulls. At the other extreme, you'd need boiler capacity to match the showers - and that's a lot of boiler capacity.

And then you need to consider you're attitude to risk - with reasonably large storage tanks, you might be able to cope if one boiler (out of 2 or 3) broke down. But with small tanks, and/or a single boiler, then you wouldn't and might have unhappy customers.

And you have options regarding the showers - different heads can have greatly different flow rates.

So many options, but the first thing you need to know is what your supplies (water and gas) are capable of - everything else hinges on those.

 

[ziggy1979]

Hi Simon

Thanks for your reply.

We get the keys next week so we will need someone to come and check the water supply. Not sure if its possible to say but is there a standard or reasonable fee for this?

On the gas side, there is no gas supply. I've been reading up on Hamworthy boilers just now and they have one that runs on LPG so I'm not sure if that's an option. Alternatively, can electricity cope with this type of thing?

In terms of flow rates from shower heads, what's the lowest flow rate we could go for without having members annoyed by poor showers from day one? Or is this the least of our worries?

The complexity and likely (as well as overlooked) cost of this has sort of kicked me in the delicate area!

Thanks for your advice re risk. It's well noted!

Thanks again for all your help!

Zigs

 

[Porque223]

The demand factor for installations like this must be well known.

Once you know your spec limits you can run a cost analysis for candidate options that meet all or most of your spec's, upfront cost and likely maintenance costs.

 

[OwainDIYer]

Your, or the building's, insurance will probably prohibit the storage of LPG on the premises.

With no gas supply, and probably limited water supply, your only option is probably stored hot water heated by electricity, stored at high temp to prevent legionella and delivered through fixed thermostatic mixing valves to prevent scalding.

 

[Agile]

Your, or the building's, insurance will probably prohibit the storage of LPG on the premises.

Or even the Gas Regulations!

 

[Agile]

LPG is very expensive compared with NG.

A new supply will be needed and can cost £2000-£5000 if gas is available nearby!

A Gym is a large area so space for storage tanks should not be a problem perhaps a room 2m x 3m as a minimum.

There seem to be a lot of aspects that you have not costed/considered!

The shower flow I mentioned before is the minimum I think you can get away with. Most hotels have about 14 and I use them for at least 20 min although I expect some gym users have shorter 10 min showers.

Tony

 

[Porque223]

Here's some spec's for the disease mentioned by OwainDIYer -

"These species can be water-borne or present in soil, whereas L. pneumophila has only been found in aquatic systems, where it is symbiotically present in aquatic-borne amoebae.[2] It thrives in temperatures between 25 and 45 °C (77 and 113 °F), with an optimum temperature of 35 °C (95 °F).

 

[SimonH2]

We get the keys next week so we will need someone to come and check the water supply. Not sure if its possible to say but is there a standard or reasonable fee for this?

You can measure flow rate yoursefl - google "how to measure dynamic flow rate and pressure" or some variation on that.
It's not just the flow rate you can get with all taps wide open, it's what you can draw, while still retaining enough pressure for your needs.

Alternatively, can electricity cope with this type of thing?

Yes, if you have a large enough supply, and/or sufficient storage to ride through any peaks the supply can't cope with. As well as using storage to reduce peak demand on the lecky supply, you can also use it to take advantage of an off peak tariff. If you do go electric, then you'll need to sit down and work out the trade-offs between large storage (to use off peak) and the up front capital and space requirements, vs the higher ongoing costs for "instant" (or near instant) heating on a normal tariff. If you want to look ahead a bit more, I think that within perhaps 5 years, there will be "great incentives" to go onto variable tariffs (what smart meters are really for) which may have much higher rates at peak times.

The complexity and likely (as well as overlooked) cost of this has sort of kicked me in the delicate area!

Ouch, seems like someone didn't really do their homework. It's easy to do in all the excitement - "if I knew then what I know now" and all that.

 

[ziggy1979]

Hi Everyone

Thank you all again for your advice.

Agile you're right...we'd totally overlooked this and in all honesty (and in our ignorance) didn't think it would be such a big and complicated thing. We thought 7 showers to be reasonably little especially for a gym.

We've spoken to a couple of companies. General advice seems to be:

1. Invest in a gas supply. But they've told us we need a domestic gas supply and meter rather than a big commercial supply.
2. Consider 1 boiler and 3 x 210 litre cylinders with a 22 min reheat time, or
3. Storage heater with internally heated water circulating in a coil to heat mains water as it comes through, or
4. Condensing boiler with unvented kit. Runs at 85 kW and has a 435l storage and1380l/hr with a 19 minute reheat time.
5. We've also been advised to get push button taps so that water runs for 15-20 seconds at a time to ensure minimal wastage. I guess this might encourage Agile to spend less than 20 minutes in there pushing the button up to 80 times!

I'm really grateful for all your help! Any more thoughts or words of wisdom are much appreciated!

Zigs

 

[Porque223]

Now that you have several candidates, you can run cost calc's on these so that some stand out as clear winners and some as clear losers. Doing this upfront shows Due Diligence and Duty of Care, etc..

 

[ziggy1979]

Thanks Porque

We've also had a site visit this afternoon and it looks like we have the following:

1. 40-50mm water supply reduced (inside the building at point of entry on the ground floor) to a 22mm pipe. I'm guessing we can remove the reducer and run a larger pipe from here.

2. Gas main supply to the inside of the building (downstairs) BUT its been cut and capped with the meter sitting on the floor beside it (meter has a sticker saying Transco).

3. 100A 3 phase 660V(?)(this sounded strange to me) electrics.

Any advice/views on the above, especially on the gas being cut and the meter sitting on the floor are again happily received!

Thanks!!!

Z

 

[Porque223]

The last person who works on an inadequate and/or illegal installation owns it.