Ahhh is there an M&E plumbing contractor in North East that can help me

[n141311]

hi all,

I know this is a long shot but I'm wondering if there are any M&E contractors who specialise in plumbing that can help me. I think my plumber has messed up the plumbing for my property by using the wrong pipe size

BACKGROUND & DESIGN CHALLENGE

I've got an 8 bedroom, 8 bath property that I'm refurbishing and want to have piping hot, high pressure showers in the ensuites with a system that can accommodate all showers being used at same time during peak periods. As the property will be used as a boutique luxury hotel - these design requirements are a must.

The property is split into three sections with the boiler being located in the centre - with 4 bedrooms on one section of the house, and another 4 bedrooms on the other section of the house.

I had Bosch do me a system design to meet this design challenge and they proposed an unvented system comprising:

• 2 x Greenstore cylinders 300l
• Worcester GB162 50kw boiler
• Salamander home boost pump
• 28mm piping branching into 22mm
• No point double coiling

The inputs they were given along with layout designs were:

• -!Current standing pressure is 4.2 bar
• - Over 22 litres per minute flow rate on cold
• - At 4bar pressure, shower will deliver 17 litres of water per minute
• - 8 thermostatic showers to be installed at the property and used during peak periods
• - 8 size heated towel rails (to come on at same time as radiators) - 1,119 BTU per radiator
• - 15 radiators - average 3,500 BTU per radiator
• Property is split into two sections with the boiler being located in the centre: section 1 will have 4 bathrooms section 2 will have 4 bathrooms

• - During peak times (mornings) 8 showers will be used simultaneously!
• - Heating will be on 8hrs a day, 7 days a week during the winter
• - Heating will be on 3hrs a day, 7 days a week during the summer

WHAT HAPPENED NEXT

I had work start on section A of the building comprising 4 bedrooms and bathrooms. The plumber re-did all of the pipework for radiators, hot and cold feeds for showers and basins....except he decided to use 22mm pipework branching off into 15mm instead of follow Bosch' guidelines.

I am now worried about the impact this deviation will have - will it still be able to meet the design challenge or does it make no difference?

I did some back of the envelope calcs and wondered if someone can:

a) help me validate if my back of the envelope calcs / assumptions / conclusions are correct? I am not an engineer or plumber.

b) suggest if there's a possible fix to still ensure I can meet the design challenge for the rooms that have already been piped up (luckily they are positioned close-ish to the boiler)

I have a CAD version of the property layout as well las technical docs for all of the proposed equipment to go in.

MY BACK OF THE ENVELOPE CALCS & ASSUMPTIONS

Grohe Grohtherm Cube Perfect Shower Set - 34506000

• Assuming 11.5 litres per minute flow rate per shower
• Ave shower time will be 20mins
• Assuming 8 showers during peak times, that’s 92 litres per minute required

• 22mm pipe has flow rate of 0.6 litres per second // 36 litres per minute
• 28mm pipe has flow rate of 1.1 litres per second // 66 litres per minute

Assuming there will be a feed for section A of the property covering 4 bathrooms and another feed for section B covering bathrooms, this means max flow rate required will be 11.5 litres per minute * 4 showers = 46litres per minute needed from each main feed

Conclusion 1. 28mm piping should be used to meet the 46 litres per minute (22mm would be restrictive at max flow of 36)

However, there is also the issue of ensuring the cylinders themselves can supply enough water given peak time demand and then push it through at appropriate flow rate to avoid loss of pressure. To aid this, the spec indicated 2 x greenstore unvented cylinders at 300l each.

• Greenstore SC300 can re-heat 300l of water in 24 mins = 12.5 litres a minute
• At 2 cylinders in tandem, this means a re-heat capacity of 25 litres per minute

• Going back to design challenge of 8 showers on at same time during peak periods:
• 600 litre total capacity would be used up in 6.5mins (600 litres / 92 litres per min)
• But in those 6.5 mins, the cylinders would reheat 163 litres of water (25 litres per min reheat capacity * 6.5 mins) = 1.7 mins
• Total shower time at max demand: 8.2 minutes (6.5 mins from 600 litre capacity + 1.7 mins from reheat capacity)

Conclusion 2. while this doesn't quite meet the 20 mins at 100% utilisation, I think Bosch' proposed 2 cylinders is quite balanced because not everyone will shower for 20mins and it's unlikely that all 8 showers will be used at exactly the same time for exactly the same duration. If one or two people did find cold showers, total reheat time is quite healthy at 25l per minute - essentially covering 2 showers at 11.5 litres per minute flow rate.

CAVEATS & IMPORTANT NOTES

I know I've totally neglected pipe runs and the number of bends. I have layout drawings and a CAD version of layout that I can share if necessary.[/LIST]

 

[n141311]

would think if you wanted the re heat times as you stated with heating on the same time 100 kw is what you want, if your happy with a slightly longer re heat time (approx 20 mins more 80kw sounds about right)

rinnais are very good and can handle the load but its more cost (alot more) esp if you have already bought the cylinders but agree with his pressure/flow thoughts as hes on site

dont agree it will limit hot water temp, under sizing will only limit flow rate and esp if you havent got a secondary return it will add to the water draw off before it hot

you have two options (one you might not like)

one try and get as close as you can and re pipe in correct size (and hope its enough)

two re pipe the lot and either put the costs onto the inexperienced plumber for any damage to the walls / finish

best option is normally the worst sorry to say

sorry i couldn't be of more assistance

Hi Shaun,

Cylinders and boilers haven't been purchased yet.

What are the pros / cons of the Remmai solution vs unvented cylinders in your opinion? I'm concerned about the 3 things: instant hot water, delivered high pressure, in a cost efficient manner so I don't get killed by running costs

Appreciate your experience mate.

 

[ShaunCorbs]

Right ok (thought they had been )

Both if installed correctly will give instant hot water

Your water main governs both so no difference there

You need a high pressure water source either mains fed or tank and booster set (I would recommend the second if you have the space)

Usage should be about the same

One downside to the Rinnai's is more to go wrong than an unvented cylinder

Other than that there about the same

 

[n141311]

Right ok (thought they had been )

Both if installed correctly will give instant hot water

Your water main governs both so no difference there

You need a high pressure water source either mains fed or tank and booster set (I would recommend the second if you have the space)

Usage should be about the same

One downside to the Rinnai's is more to go wrong than an unvented cylinder

Other than that there about the same

Gotcha. Ok so my thinking is if I have a breakdown, I really don't want to stuck trying to find a plumber that can sort it. appreciate your other points - didn't realise it was virtually identical in all other aspects.

Got another thought: if we upgrade where we can & pray...there is still the rest of the house yet to be piped up. If we do that properly, will those other rooms at least get high pressure water without any issues? Or are we now f* through the whole house because part of the piping is in wrong size?

 

[ShaunCorbs]

The only part that will be effected is the bits he's done / you can't get at

If the other parts / the rest is done right / to what somone works out they should be fine

(Hope that makes sense)

 

[n141311]

The only part that will be effected is the bits he's done / you can't get at

If the other parts / the rest is done right / to what somone works out they should be fine

(Hope that makes sense)

Thanks mate. That message made my night. Have been crapping myself thinking the whole house might be compromised. Thankfully the guy only did 4 rooms.

 

[ShaunCorbs]

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

 

[n141311]

Hi all

Hi mate
Sorry I didn't ring you back. I didn't save your number, so could you ring again?.
Pm sent too.

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.

 

[n141311]

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

 

[n141311]

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

 

[Chuck]

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

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.

 

[ShaunCorbs]

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?

post 2 should help you out with most of that

 

[n141311]

Caught up with @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.

 

[ShaunCorbs]

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 ?

 

[Chalked]

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.

 

[n141311]

Hi All,


@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 - 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

 

[ShaunCorbs]

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)

 

[Chalked]

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

 

[n141311]

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

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?

 

[king of pipes]

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

 

[ShaunCorbs]

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

Wouldn't go ideal

 

[king of pipes]

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

 

[ShaunCorbs]

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

Just had a bad kock with there customer services and warrenty, so wouldn't recommend them

 

[n141311]

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 Sod off Chalk by asking him so many Qs so am posting to broader forum)

 

[ShaunCorbs]

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

 

[n141311]

hi @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.

 

[ShaunCorbs]

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

 

[n141311]

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

hey @ShaunCorbs and @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

 

[ShaunCorbs]

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

 

[n141311]

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

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.

 

[ShaunCorbs]

Sounds cheap on both labour and materials

Boilers alone and bits would come to 3-4K

Unless you have all the bathroom stuff ?