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Discuss Ahhh is there an M&E plumbing contractor in North East that can help me in the Plumbing Forum area at UKPlumbersForums.co.uk.

  1. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    We're all here if you have any other questions / want to pass somthing by us
     
  2. n141311

    n141311 New Member

    Hi all
    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):

    - what's your trading name
    - are you gas safe registered for unvented system installs (I think this part F cert or something)
    - do you have a commercial ticket / able to install boilers at 65kw - 100kw (I don't want to go anywhere near 100kw due to monthly heating bills)
    - are you insured for your work
    - are you VAT registered (impacts whether I get hit with an extra 20%. ouch)

    Feel free to PM me on the above and let me know if you got my mobile number from the message I sent you. I'll text you if not.
     
  3. n141311

    n141311 New Member

    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)
    • 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
    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?

    RUNNING COSTS
    • KwH boiler: 65
    • Hrs used per day in winter: 6hrs
    • Total KwH per day: 390 (65 x 6 hrs)
    • Total KwH per month: 11,830
    • GBP per KwH: 0.06
    • GBP gas bill per month: 710
    • Winter demand assumption is that heating will run for 3hrs in the morning and 3hrs in the evening. Is this realistic based on modern u-value homes?
    • Finally, not sure if all of the above is based on faulty logic because of the way the unvented cylinders would work, ie. boiler usage will actually be a lot less than 6hrs as cylinders will keep water hot minimising need for boiler to be hammered during heating periods? Let me know your thoughts.
    Thanks to everyone who has helped out on this thread so far. I can't explain how much it has helped me get through this nightmare. I'm posting updates so a) others can learn and hopefully benefit from it b) to see this thing through to the end with hopefully a happy ending :)
     
  4. n141311

    n141311 New Member

    Hi @Chuck@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 :D
     
  5. Chuck

    Chuck Top Contributor!!

    You're welcome.

    I've only skim-read the rest of the thread as you seem to on the right track and it's looking like site-specific details. I will point out one incorrect assumption you seem to be making in your revised estimates, which is that a 100kW boiler will cost twice as much to run as a 50kW one. This is not going to be the case because if you want to heat a certain number of litres of water, e.g. 8 showers worth, the gas required will be the same in each case. The 100kW boiler will just be able to deliver it in half the time.
     
    • Like Like x 2
  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    post 2 should help you out with most of that
     
    • Like Like x 1
  7. n141311

    n141311 New Member

    Caught up with @Chalked@Chalked who gave the great idea about having a few smaller boilers in tandem. Plus M&E feedback that I need to have bigger cylinder capacity at c 840 litre minimum.

    Now looking at having:

    1x Bosch Greenstore TC300 indirect unvented cylinder
    1x Megaflo 570 litre indirect unvented cylinder.
    2 x 27.5 kW boilers in tandem

    Can anyone recommend a good boiler? I was looking at Vaillant ecoTEC Pro 28 but really haven't the foggiest what is best. Looking for something durable that won't break down and will last.
     
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    For the price I would go with 3 300L ones

    As you will be looking at aprox 2.5-3k for a commercial megaflow

    And what kw earring are you looking at total 65kw ?
     
  9. Chalked

    Chalked Plumber GSR

    Looking at this tomorrow, so will need to size it up first, before any real recommendation.
    Like Shaun mentions, commercial cylinders are more expensive than multiple domestic ones.
    I like to fit vaillants, so would normally reccomend them. Others are available, but I get a good service from the manufacturer.
    See you tomorrow.
     
    • Like Like x 1
  10. n141311

    n141311 New Member

    Hi All,


    @Chalked@Chalked came over today and was super helpful. Came up with a design along the lines of have a couple of boilers in tandem and arranging the pipework in 36mm branching off in the remaining part of the house, leaving open the option to add a water storage tank in the future. The property has two mains water supplies – one is apparently 4.0 Bar (measured by original plumber) but the one we measured only came out at 2.5 bar.


    Plan is to use the 2.5 Bar supply for toilets (already plumbed in that way by original plumber) and the other mains bar for everything else. If it turns out that demand is high and we suffer from poor pressure due to mains water, I’d then look to add a duty point tank in the future with piping already in place for a pump capable of 120 litres per minute flow rate. But I’m hoping all is good without having to go down that route :)


    Here’s what I’m looking to go with in interim, let me know thoughts:


    Proposed Equipment


    · Go with unvented indirect cylinder approach and Grohe showers at 9.5litres per min

    · 1 x RM Stelflow 400 Litre Indirect Unvented Stainless Steel Cylinder £885 inc VAT

    · 1 x RM Stelflow 300 Litre Indirect Unvented Stainless Steel Cylinder £616 inc VAT

    · 1 x Esi Dual Cylinder Thermostat to prevent legionalla – is this still needed for the RM cylinders?

    · 2 x Worcester Greenstar 32CDI Compact Combi ERP Boiler £1206 inc VAT

    · 2 x Worcester FW100 weather compensator £187 inc VAT

    · 1 x WORCESTER WAVE SMART HEATING CONTROL £211 inc VAT

    · Total equipment: £4,498 inc VAT


    Few questions:


    1. The cylinder pricing seems too good to be true – what am I missing here? I want to avoid buying duff equipment

    2. Are the selected boilers any good in terms of running efficiency and reliability / durability? Radiators will require about 38kW. Chaulked recommended getting a total of about 60kW so I figure two 38s should be more than enough.

    3. The weather compensator seems a bit crap. Is it worth the outlay in people’s opinion?

    4. @Chalked@Chalked - where plumbing should take 35mm from plant room for other side of house, should he branch off into 28 and then into 15 when he gets to shower / rads?


    Links:


    · RM Stelflow 400 Litre Indirect Unvented Stainless Steel Cylinder

    · RM Stelflow 300 Litre Indirect Unvented Stainless Steel Cylinder

    · Worcester Greenstar 32CDI Compact Combi ERP Boiler

    · Wave smart heating control - 7716192072

    · Worcester Greenstar FW100 Weather Compensator
     
  11. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    1, down to personal opinion and what your budget is my preference is gledhill

    StainlessLite Plus Indirect - Gledhill

    2, very good (my brand of choice) but thats a combi you have linked / talked about, you want a heat only boiler/regular

    something like this

    Worcester Greenstar 40CDI Classic Regular ErP Boiler

    Vitodens 200-W wall mounted gas condensing boiler - Viessmann UK

    ecoTEC plus - Vaillant

    3, wouldnt go with weather comp, just invest in a decent simple control system (chalked im sure will agree with this)
     
  12. Chalked

    Chalked Plumber GSR

    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
     
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  13. n141311

    n141311 New Member

    Hey thanks! What size should the main heating pump be in your opinion & any recommendations for a brand I should go for?

    Finally, if 42mm primaries go in, what would you recommend secondaries at - 22 or 15mm?
     
  14. king of pipes

    king of pipes Trusted Plumber GSR Top Contributor!!

    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
     

    Attached Files:

  15. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Wouldn't go ideal
     
  16. king of pipes

    king of pipes Trusted Plumber GSR Top Contributor!!

    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
     
    • Agree Agree x 1
  17. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Just had a bad kock with there customer services and warrenty, so wouldn't recommend them
     
    • Like Like x 1
  18. n141311

    n141311 New Member

    hey up all,

    thanks to Chalk - I managed to find a plumber who is going to follow his spec and we are finally back on track :) Wahey.

    The duty point tank has come out mega expensive and I'm going to see how demand is for showers and install one in future if necessary (plumber is going to pipe everything in so it's easy to add a duty point tank in future).

    He has recommended the following pump though: Magna3 26/60

    Anyone know if this is any good? I know that Chalk had said I'd need a "suitably sized mains heating pump" - is that what this is?

    Apologies in advance for the rookie Qs. (I don't want to **** off Chalk by asking him so many Qs so am posting to broader forum)
     
  19. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    you've had some good luck then :) if its sized right yes prefer dab myself but a pump is a pump

    and i feel your going to need a pump sorry to say
     
  20. n141311

    n141311 New Member

    hi @ShaunCorbs@ShaunCorbs - is 26/60 the right kinda size? 42mm pipework will have up to 120 litres per min flowing through them in final state so want to ensure I'm using the right size pump.
     
  21. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    depends on size of property but he will know what size or im sure grunfos do a sizing app or calc
     
  22. n141311

    n141311 New Member

    hey @ShaunCorbs@ShaunCorbs and @Chalked@Chalked

    I've had a plumber come back with a quote and wanted to get thoughts. Materials £7.5k for materials (excludes duty point) and £4.5k labour.

    Reckons it will take him 150 hrs between 2 men to do the following. Does that feel about right?

    Quote:

    - pressure test (hallways, 4 bedrooms, 3 ensuites)
    - Pipework for 1 bathroom inc. towel radiator, toilet, his/her dual basin, shower
    - move Primary 25mm mains water supply 2ft to duty point location (duty point will not yet be fitted but only piping done to enable one to go in)
    - move the Secondary mains water supply 1ft to plant room
    - hook up the speed fit underfloor heating kit to heating system (builder already installed it in kitchen)
    - install and commission the following equipment:

    2 x 300l RM indirect unvented cylinder
    2 x vaillant 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

    42 mm primaries and connecting pipework
    Motorised valves to all circuits
     
  23. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Might be missing something but what about the other 5 bathrooms and 4 bedrooms ?
     
  24. n141311

    n141311 New Member

    We've split it between Phase 1 and Phase 2.
    Quote covers Phase 1 (4 beds, 4 baths). Once that is done and system is in, phase 2 will involve doing the remaining pipework for the final set of 4 beds, 4 baths, 1 WC.
     
  25. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Sounds cheap on both labour and materials

    Boilers alone and bits would come to 3-4K

    Unless you have all the bathroom stuff ?
     
  26. n141311

    n141311 New Member

    Yeah it doesn't include fitting any of the showers or bathroom units. Literally just getting the stated equipment (boilers, cylinders) installed and commissioned.

    Fitting the rads, basins, toilets and showers / tiling etc will be extra.
     
  27. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Sounds ok if it's just for the heating works
     
    • Like Like x 1
  28. n141311

    n141311 New Member

    thanks mate :)
     
  29. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Don't know if it's in the spec but you will require a secondary return circuit and pump (hot water)
     
  30. n141311

    n141311 New Member

    Yeah that's part of the quote. Secondary return and the Magna3 pump.
     
  31. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Ok just make sure it's lagged/ insulated good

    Before you put the floors back
     
    • Like Like x 1
  32. oz-plumber

    oz-plumber Plumber

    We've done quite a few commercial type installations with Rinnai equipment.

    Why don't you get them to size the equipment for you.
    We've done them with banks of Rinnai's or Rinnai's bolted onto their cylinders.

    What you want is recovery rate so I would go for something like 1 cylinder with 2 Rinnai units connected to it. The recovery rate of something like that would almost be instant. The Rinnai's only heat the cylinder water via pump(s) operated by the tank stat.
    Never ever had a issue with anything they have sized or designed.

    Give them a try
     
  33. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    how you getting on op?
     
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