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

[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