15mm rising main to 4 apartments?

[dan_the_plumber]

Hi
I’m currently working on a 3 story house that’s being converted into 4 flats. I installing 40kw boiler, 15 rads, 4 Heating zones plus a hot water zone. Etc etc
Each flat has a kitchen sink, toilet, basin and electric shower.
Problem is, I’ve got a 15mm rising main. ‭Im hoping it’ll just be adequate.
However as back up I’ve thought about installing a booster set.
As a back up to the back up I’ve thought about installing a break cistern then a booster set.
I wondered if you had some experience and thoughts on this?
I’m sort of dreading telling the client that he needs a 25mm rising main, especially when the main also supplies 2-3 buildings. Thanks...Dan

 

[Last Plumber]

Hi
I’m currently working on a 3 story house that’s being converted into 4 flats. I installing 40kw boiler, 15 rads, 4 Heating zones plus a hot water zone. Etc etc
Each flat has a kitchen sink, toilet, basin and electric shower.
Problem is, I’ve got a 15mm rising main. ‭Im hoping it’ll just be adequate.
However as back up I’ve thought about installing a booster set.
As a back up to the back up I’ve thought about installing a break cistern then a booster set.
I wondered if you had some experience and thoughts on this?
I’m sort of dreading telling the client that he needs a 25mm rising main, especially when the main also supplies 2-3 buildings. Thanks...Dan

I think you've hit the nail on the head with the tank and pump set.

How high is the Building and what is the Static pressure at ground level?

 

[ShaunCorbs]

Won't work on just mains if your right at the top be around a bar loss

 

[Scott_D]

15mm for 4 flats and 2-3 other buildings?

 

[dan_the_plumber]

I think you've hit the nail on the head with the tank and pump set.

How high is the Building and what is the Static pressure at ground level?

Thanks s lot well I’ve got 2.5 bar at ground, then top outlet is about 7 M up. So I recon 0.7 Bar loss. Minus equivalent pipe length, minus fittings.

Thing is there’s really no chance of having mains pipe re-run in 25mm. So you recon a break cistern and booster set is way to go then?

 

[ShaunCorbs]

Thanks s lot well I’ve got 2.5 bar at ground, then top outlet is about 7 M up. So I recon 0.7 Bar loss. Minus equivalent pipe length, minus fittings.

Thing is there’s really no chance of having mains pipe re-run in 25mm. So you recon a break cistern and booster set is way to go then?

Can you get 22mm pipe upto the flat ?

 

[Scott_D]

Whats supplying the hot water?
Is there a plant room where the boiler etc are going?

 

[dan_the_plumber]

Whats supplying the hot water?
Is there a plant room where the boiler etc are going?

Yeah we’re doing a plant room, 40kw heat only boiler and Unvented cylinder

 

[ShaunCorbs]

Yeah we’re doing a plant room, 40kw heat only boiler and Unvented cylinder

Where's that going ?

 

[dan_the_plumber]

Can you get 22mm pipe upto the flat ?

No I think it’s pretty unlikely that’ll be happening. The pipe actually runs under the next door property.

 

[dan_the_plumber]

Where's that going ?

Downstairs at the back of property. Incidentally, that’s where the rising main also comes in.

 

[ShaunCorbs]

Does the 15mm main do all property's or just that one flat ?

 

[Last Plumber]

Thanks s lot well I’ve got 2.5 bar at ground, then top outlet is about 7 M up. So I recon 0.7 Bar loss. Minus equivalent pipe length, minus fittings.

Thing is there’s really no chance of having mains pipe re-run in 25mm. So you recon a break cistern and booster set is way to go then?

I do think you are best with that set up but you will need to increase the size of the riser anyway in my opinion.
Personally, I would use 22 mm Copper, it needs calculating though.
The 15mm would be too restricted and noisy. (if that is what you are thinking)

 

[dan_the_plumber]

I do think you are best with that set up but you will need to increase the size of the riser anyway in my opinion.
Personally, I would use 22 mm Copper, it needs calculating though.
The 15mm would be too restricted and noisy. (if that is what you are thinking)

Thanks for advise. Yeah I was thinking of running all cold pipe work from outlet of booster set pump in 22mm. Then reducing down to 15mm say 2M before appliances.

Does that sound right to you? Thanks

 

[ShaunCorbs]

Thanks for advise. Yeah I was thinking of running all cold pipe work from outlet of booster set pump in 22mm. Then reducing down to 15mm say 2M before appliances.

Does that sound right to you? Thanks

Thought you said you couldn't get 22mm upto the flat ?

 

[king of pipes]

15mm will definately not do three apartments bud you can only get out what you put in 15mm wont even do the unvented cylinder you need a re think . kop

 

[dan_the_plumber]

Thought you said you couldn't get 22mm upto the flat ?

I thought you meant from the external stop tap into the building

 

[ShaunCorbs]

I thought you meant from the external stop tap into the building

no from the basement to the new flat?

 

[dan_the_plumber]

15mm will definately not do three apartments bud you can only get out what you put in 15mm wont even do the unvented cylinder you need a re think . kop

No. But I’m thinking of break cistern then booster set. 22mm jp through building then reducing down a meter or two before appliances. What do you think?

 

[ShaunCorbs]

yea you will be ok if you only have 15mm into the break tank just need to size it so it can cope with peak demand and then 28mm into the pump from the tank and then 22mm to the flat

will the pump supply the whole building?

 

[king of pipes]

You will need to boost it somehow bud your probably on the right track i would be covering my arse and telling the client your conserns about it being under sized put it in writing just in case of problems down the line. Cheers kop

 

[dan_the_plumber]

yea you will be ok if you only have 15mm into the break tank just need to size it so it can cope with peak demand and then 28mm into the pump from the tank and then 22mm to the flat

will the pump supply the whole building?

Well I suppose the pump will do all of the DHW (through unvented cylinder) Then I suppose it’s only really got to do cold water for upstairs flats.

Only other thing I’m wondering...Presumably the booster pump will also need a small accumulator. This, just to start the pump running when a tap upstairs is opened?

 

[dan_the_plumber]

How about one of these? Maybe then I wouldn't need a break cistern? Stuart Turner Flomate Mains Boost Extra 100 Low Water Pressure Pump 46635

 

[ShaunCorbs]

so yes you need to boost the whole place unless you want to replace the mains

no that wont do all of them

your best option is to get it specd properly

Pump World | Leading UK Distributor of Booster Pumps, Shower Pumps and Central Heating Pumps

speak to them you will need a big tank tho and a decent pump wont be shy off 3-5 k ish

 

[king of pipes]

TWS contact them bud heres one thats been in 6years 20mm supply in and does 2 properties . kop