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Discuss Ahhh is there an M&E plumbing contractor in North East that can help me in the Plumbing Jobs | The Job-board area at PlumbersForums.net
Hi mate, no worries - I replied to your PM? Did you get it? Can you also let me know the following (forgive me for asking but I've been burned by one plumber so figure I should ask Qs up front):Hi mate
Sorry I didn't ring you back. I didn't save your number, so could you ring again?.
Pm sent too.
I think you should seek advice from a company, or consultant, who does a lot of this type of work. It definitely looks 'commercial' not 'domestic' to me and needs to be 'designed' not lashed up using rules of thumb.
The assumptions you put in about what performance is needed at periods of maximum demand are going to make a big difference to the cost and performance of the system. E.g. where did you get the '20 mins' average figure from? The average (domestic) shower apparently lasts 8 minutes:
People's showering habits revealed in survey - BBC News
and that average includes teenagers!
I imagine that, if one knows where to look, there are data available for shower usage patterns in hotels.
Hi @Chuck - forgot to stay thanks. You're spot on with that point about ave shower times. I ended up revising down from the crazy 20mins (based on how long my wife takes!) to a more realistic average of 10mins
Hi all,
So did some additional thinking based on messages from yesterday. Wanted to share and get thoughts based on people's input so far.
- Achieving that 25 litre per minute reheat capacity on two cylinders (12.5 litre per min * 2 cylinder) will require an upgrade of boiler from current proposed 50kw to 100kw
- But this would effectively double my monthly gas heating bill assuming I'm using boiler for same amount of time but its consuming 100kwh instead of 50kwh :O
Therefore, I did some thinking around how to lower flow rate demand through the pipes and from cylinders:
MID CASE DEMAND (MOST REALISTIC)
I'm taking a guess here but based on lower re-heat capacity of 12.5 litres per minute (6.25 litres per min x 2 cylinders) - what boiler size would I need? Could I get away with 65kw?
- 7 bathrooms (not 8) to be used during peak times for av. 10mins
- each shower will have flow rate of 9.5 litres per min instead of 11.5
- Litres per min used: 66.5 (9.5 x 7 showers) (total demand over 10mins = 665 litres)
- At 600 litres cylinder capacity, house will run out of hot water in 9 minutes
- However if boiler is able to re-heat two cylinders at 12.5 litres a minute (6.25 l x 2 cylinders), in that 9mins, an additional 113 litres of hot water would be available due to reheat capacity (9 mins * 12.5 litres per min reheat)
- This gives a total capacity of 713 litres of hot water (600 litre core capacity + 113 litres reheated over 9mins)
- NOTE 1: the 600 litres in 9 minutes indicates a flow rate of 66.5 litres per minute from the cylinder - Would this also require installation of a pump to support that kind of flow rate out?
- NOTE 2: At 66.5 litres per minute from cylinder + 12.5 litres per minute recharge capacity = 79 litres per minute flowing through the pipework
- NOTE 3: The above takes no account of radiators, toilets being flushed or sink basins being used. Should I factor more for this?
- NOTE 4: Assumes the 8th bedroom which is a staff room will not use the shower during peak periods
Hi
Your missing quite a lot
My spec was
2 rm 300 cylinders or preferably ACV same size.
2 vaillant system boilers giving a total of 60kw
Low loss header.
Suitable sized main heating pump
Mixing valve to give hot water priority
Vaillant sequence controller
Duty point pump set to give 120 lpm
This will need 42 mm primaries and connecting pipework
Motorised valves to all circuits
Think you may find your closer to £10,000 for materials
Regards
Paul
Chalk is on the right track N14 dump the worcester wave and you will need a bespoke control panel built to control your system time, tempreture control and weather comp will be built in this with a programable room thermostat in each room this may help you the last two projects i did we used Ideal Evomax worked very well . wishing you all the best kop
We are all different shaun work well for me in the past a M+E consultant is needed in my opion he needs someone to come back to as he has already been bitten once this should protect both installer and client with a satisfactory design and install. Cheers kop
hi @ShaunCorbs - is 26/60 the right kinda size? 42mm pipework will be flowing unto 120 litres per min in final state so want to ensure I'm not using the right size.
depends on size of property but he will know what size or im sure grunfos do a sizing app or calc
Might be missing something but what about the other 5 bathrooms and 4 bedrooms ?
Sounds cheap on both labour and materials
Boilers alone and bits would come to 3-4K
Unless you have all the bathroom stuff ?
thanks mateSounds ok if it's just for the heating works
thanks mate
Don't know if it's in the spec but you will require a secondary return circuit and pump (hot water)
Yeah that's part of the quote. Secondary return and the Magna3 pump.
Reply to Ahhh is there an M&E plumbing contractor in North East that can help me in the Plumbing Jobs | The Job-board area at PlumbersForums.net
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