System Boiler Advice required, please help!

[Sohail]

Hi All. I am refurbishing a house i recently bought. It would have 4 shower rooms and 6 vanity units in the bed rooms plus kitchen tap and a tap in utility room plus if i conver the loft into living space it need to be future proof to add one more shower room. Total radiators would be 16-17 in total. I have been advised various systems but of all Worcester Bosch 35CDI plus 300 litre HeatraeSadie Eco Plus Megaflo seems most appropriate.

Questions:
Do you think its appropriate in term of efficiency and value for money
Do i need external expansion vessel
Do i need accumulator . If yes which one (brand and capacity) would you recommend?
Whats size plumbing pipes i need to the tank 22mm/28mm?
Water pressure at mains is 1.1bar. Would that be sufficient. If not how can it be improved to be fit for the purpose in this installation? Water pump before water tank possiblilty. Which make / spec would be better?
What do i need to ensure that builder/plumber carry other than corgi registration to ensure long warranty period?
Anything else to bear in mind?

Thanks very much in advance

Rgds.
Sohail

 

[ShaunCorbs]

tbh before you go that far job like that will cost the best part of 20k could be more to do decently and be able to work do you have this ?

 

[Sohail]

tbh before you go that far job like that will cost the best part of 20k could be more to do decently and be able to work do you have this ?

Yes the work has already started for the refurbishment and this installation would have to be done. I can choose to keep the cost down by changing the brands but the work need to be carried out otherwise no water in the bath rooms. I must correct there are three bath room as fourth one will have electric shower.

 

[Scott_D]

You need someone gas safe registered for the boiler and G3 for the unvented cylinder

 

[ShaunCorbs]

ok lets break it down

yes you want an unvented cylinder if you going over really 2 bathrooms so youve made the right choice

yes you will require an expansion vessel for your heating as if you go with a system boiler this will be too small but if you go with a heat only boiler you will need one around 20l min

this comes in with your water pressure tbh this is very low for three bathrooms (looking a min of around 12lpm per bathroom so 36lmp required min and around 4 bar + dynamic), so your only option is a break tank and pump have a look at dab easy sys or scubatank

28mm water mains dont go smaller

make sure the heating system and water is designed by the heating engy and plumber also get them to put a guarantee on the flow rates (as you want to be able to use more than one outlet at a time)

gas safe registered
G3 Registered (unvented)

dont let them put a combi in also you need to make sure the plumber / heating engy knows what hes doing else if it goes wrong you will only be able to use around one bathroom at a time etc

 

[Sohail]

ok lets break it down

yes you want an unvented cylinder if you going over really 2 bathrooms so youve made the right choice

yes you will require an expansion vessel for your heating as if you go with a system boiler this will be too small but if you go with a heat only boiler you will need one around 20l min

this comes in with your water pressure tbh this is very low for three bathrooms (looking a min of around 12lpm per bathroom so 36lmp required min and around 4 bar + dynamic), so your only option is a break tank and pump have a look at dab easy sys or scubatank

28mm water mains dont go smaller

make sure the heating system and water is designed by the heating engy and plumber also get them to put a guarantee on the flow rates (as you want to be able to use more than one outlet at a time)

gas safe registered
G3 Registered (unvented)

dont let them put a combi in also you need to make sure the plumber / heating engy knows what hes doing else if it goes wrong you will only be able to use around one bathroom at a time etc

Thanks mate. Thats very helpful. I am olanning to keep this boiler system and the mega flo tank in utility room as no other space. Where would the water tank Dabs/scubatank) go? Can accumulator help for the water flow rate?

 

[ShaunCorbs]

Thanks mate. Thats very helpful. I am olanning to keep this boiler system and the mega flo tank in utility room as no other space. Where would the water tank Dabs/scubatank) go? Can accumulator help for the water flow rate?

Depends on space needs to go where the water main comes in really but if there’s space could go with boiler and unvented etc

No accumulators won’t boost the pressure only flow

 

[Sohail]

Depends on space needs to go where the water main comes in really but if there’s space could go with boiler and unvented etc

No accumulators won’t boost the pressure only flow

So i suppose i need both pressure and flow. Does the water tank increase both the pressure and flow?

 

[ShaunCorbs]

So i suppose i need both pressure and flow. Does the water tank increase both the pressure and flow?

Yes

Yes you can set what you want and it will pump that out

 

[Sohail]

Yes

Yes you can set what you want and it will pump that out

DAB E.SYBOX MINI 3 seems like a reasonable option. Do i need the systern or would the booster pump be sifficient?

 

[ShaunCorbs]

DAB E.SYBOX MINI 3 seems like a reasonable option. Do i need the systern or would the booster pump be sifficient?

Need to have the tank / cistern as you can’t pump from the water main

 

[Sohail]

Thanks Shaun. Really appreciate it.
[automerge]1567548494[/automerge]

Thanks Shaun. Really appreciate it.

Need to have the tank / cistern as you can’t pump from the water main

Sorry just one more question for my understanding: once the cistern runs out of the water how it filled to sustaik that high flow rate and pessure?

 

[ShaunCorbs]

From the mains water

So mains water in eg 1.1 bar desired pressure and flow out

 

[Sohail]

From the mains water

So mains water in eg 1.1 bar desired pressure and flow out

Sorry for my lack of understanding. The mains flow is 1 bar which is around 12 liter per minute. If all the showers running and assuming water in cistern runs out then the flow rate of 12 liter would be divided among all shower rooms right? Nothing there to stop cistern running out. The only option i see is water tank of 300 liter plus water cistern of 500liter should not really run out even when gour bath rooms are in use at the same time for 10 min but they might if all showers are used for long time at the same time. So in my head this cannot be sustainable for ever right?
[automerge]1567549337[/automerge]

Sorry for my lack of understanding. The mains flow is 1 bar which is around 12 liter per minute. If all the showers running and assuming water in cistern runs out then the flow rate of 12 liter would be divided among all shower rooms right? Nothing there to stop cistern running out. The only option i see is water tank of 300 liter plus water cistern of 500liter should not really run out even when gour bath rooms are in use at the same time for 10 min but they might if all showers are used for long time at the same time. So in my head this cannot be sustainable for ever right?

I.e. the flow rate?

 

[ShaunCorbs]

Sorry for my lack of understanding. The mains flow is 1 bar which is around 12 liter per minute. If all the showers running and assuming water in cistern runs out then the flow rate of 12 liter would be divided among all shower rooms right? Nothing there to stop cistern running out. The only option i see is water tank of 300 liter plus water cistern of 500liter should not really run out even when gour bath rooms are in use at the same time for 10 min but they might if all showers are used for long time at the same time. So in my head this cannot be sustainable for ever right?
[automerge]1567549337[/automerge]

I.e. the flow rate?

Yes you would sized the cistern to match eg 600l etc