Three very different systems dilemma-help?

[indus]

Hi there

I've brought this subject up from time to time over the last 18 months, so apologies for bringing it up again. I'm having major home refurb and extension work done and plan to have a new hot water and ch system fitted.

When I first brought this up things were at the planning stage of the build. Now the build is well under way and I really need to make my mind up and I'd really appreciate some final help.

My main concern is not the heating side of things but hot water, ie running a number of showers at the same time.

1) The house will be approx 3500 sqft over three floors, but the third floor is only about 350 sqft

2) There are five shower rooms

3) I'm pretty sure my supply pipe is 22mm, or at least that is the size pipe that appears from underneath the floor and leads to the stop cock.

4) There is a prv just after the stop cock set to 3 bar. I have inserted a pressure meter into the prv and I can measure up to 5 bar if I adjust the prv to its maximum

The pressure drops from 3 to a measured 2 bar when the taps are opened. However even when the taps are open I can increase the measured pressure up to 4 bar by opening up the prv.

My flow rate at 3 bar is 18l/min and this increases to about 26l/min at 5 bar.


In terms of hot water my requirements are to be able to run two showers comfortably at the same time (assume 15l/min each) and be able to open a sink tap. It's essential I can do this without any problem.

I've been 'offered' three different systems by three different plumbers to provide this (btw they have all said it would be a good idea to upgrade the supply pipe on my property to 32mm)

1) One or two system boilers + 300l unvented cylinder + break tank with booster pumps

2) One or two system boilers + 300l unvented cylinder + accumulator

3) One combi boiler to supply hot water to the kitchen and ch to ground floor and then system boiler + 300 litre unvented cylinder to supply hw and ch to the upper floors. This guy doesn't see the need for accumulators or break tanks/booster pumps but wants not only the supply pipe on my property boundary upgraded but also the mains feed upgraded on the road (by Thames Water)

phew!

I'd appreciate your thoughts

Many thanks

 

[Norcon]

Just fit a tank in the loft and gravity feed the system. You have the height with three floors.
Cheapest option out there and effective.
Job done.

(Now 30 pages will ensue with the op still none the wiser)

 

[mogget]

I can't believe I'm saying this But I agree with Norcon.

 

[dreadnoughtheating]

Norcon is correct that 30 pages of contrariness will ensue.

IMHO I suggest a 24kw Heatline Combi, B&Q on a wednesday and take your/someone else's parents for 10%off.

Or, better yet, go to CIPHE.org find a Registered Plumber from the Register to get a proper installer to discuss your project over a nice pot of tea and biccies. Keep him/her onside and job's a good'un.

Unless you are running a guesthouse/brothel it is unlikely that all hot-water draw-off points will need full-flow at the same time.

PS, if its in Norwich, call me.

DH. MCIPHE, RP.

 

[Dan Robinson]

Option 1.

There. A definitive answer.

Now I need to go and rinse myself in detol to try and shift the dirty feeling I have having just agreed with and thanked Nobcorn.


I feel ill.

 

[Norcon]

 

[indus]

Just fit a tank in the loft and gravity feed the system. You have the height with three floors.
Cheapest option out there and effective.
Job done.

(Now 30 pages will ensue with the op still none the wiser)

Hi Norcon

So, none of the three options offered to me?

Are you basically proposing the 'older' established system people had in the Uk prior to the popularity of combis and uvented cylinders?

Thanks for your help

 

[indus]

Option 1.

There. A definitive answer.

Now I need to go and rinse myself in detol to try and shift the dirty feeling I have having just agreed with and thanked Nobcorn.


I feel ill.

Hi Dan

I'm confused by your post. You say your preference is option 1 (which in my post refers to break tank and booster pumps) but then you also say you agree with Norcon who proposes a gravity fed system.

Thanks for your help

 

[indus]

Norcon is correct that 30 pages of contrariness will ensue.

IMHO I suggest a 24kw Heatline Combi, B&Q on a wednesday and take your/someone else's parents for 10%off.

Or, better yet, go to CIPHE.org find a Registered Plumber from the Register to get a proper installer to discuss your project over a nice pot of tea and biccies. Keep him/her onside and job's a good'un.

Unless you are running a guesthouse/brothel it is unlikely that all hot-water draw-off points will need full-flow at the same time.

PS, if its in Norwich, call me.

DH. MCIPHE, RP.

Hello.

Are you confident that a 24kw combi boiler can

1) Heat a 3500 sqft house with about 30 rads

2) At peak hours allow two simultaneous 15l/min showers to run effectively, as well as the odd sink tap being opened or bog being flushed?

Thanks

 

[swbjackson]

I could heat a 3500 sq ft house with a 12kw boiler if the house were well enough insulated.

Choice of system will also be dependent on the layout of the property. If all outlets are close together a single cylinder will be the way to go. If they are spread around you will want to look at secondary hot water circulation. If all bathrooms are close together but the kitchen and utility are remote a combi to feed the kitchen and utility with a cylinder for the bathrooms will be best.

as for flow rates, if you are sticking with unvented then the best option is to upgrade the incoming main but you need to check with the water undertaking that their main is capable of supplying the flow rates you require. There's no point in spending money on this if it won't improve the flow rate.

 

[indus]

Thanks swb.

And bumped hoping for some further opinions