Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous showers

[woking]

Hi Guys,

I am hoping to get some advice from you to know what to ask my heat engineer to design / install.
The aim is to have enough hot water to run two showers simultaneously without use of unvented cylinder. I am planning to move boilers to the low pitch loft (second floor) and could not fit decent vertical unvented there. There is also a bit of work be needed to reinforce the loft to accommodate large cylinder. I have Greenstar 24 System boiler that I could re-use as a system boiler and install high performance hot water only boiler or possibly replace it by two 42CDi.

Here are options I am considering please let me know if there are any other high flow water only boilers I should consider:
1. Greenstar 24 System + Greenspring CWi47
2. Greenstar 24 System + Rinnai Infinity 26i
3. Greenstar 42 + Greenstar 42
4. Greenstar 42CDi + Greenspring CWi47

Have any of you installed / had any feedback from people using first two boilers or similar setup to option 3?
I am planning to upgrade gas supply pipe and getting U16 meter and also replacing current water mains (30 meters run from outside stopcock to the house) with 2 X 32MDPE water mains with the view to achieve decent water flow / pressure and be able to use one of the above setups.
I recently got waterboard to replace my old and rusty water meter and measure flow/ pressure. They said at the meter (about 30 meters from the property) I have 40L/ flow and 2.75bar.

Any thoughts or advice would be much appreciated and I hope not to cause too much controversy :smile:

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Hi Guys,

Got a bit of update and more questions

After speaking with South east water and checking my water bill it appears that I have 15mm water meter.
They could potential upgrade it to 20mm or 40mm but at a cost to me and slight increase in standing charge. It increases a lot if meter is 50mm.

I've bough myself mains water pressure gauge and didn't like what I've seen. My static pressure at garden tap is 2bar.
With mains fed kitchen tap fully on it drops to 1.4 bar.

My ideal scenario was to have boiler and mains fed hot water from gas fired hot water only heater located in the loft of a two store house.

- I guess I have to forget about it and consider going unvented route?

- If I go ahead with mains water pipes / meter upgrade and have good flow lets say 40l/min. Would I be able to use just some kind of pump to increase my water pressure? Or would this always require break tank?

- Would I get any increase in water flow by increasing mains water pipe to 32mm between the house and the water meter if meter remains the same 15mm?

I was really hoping to save some space and not have any tanks with water in the house...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

can i ask why you would want to run two showers at the same time ???

and dont forget you will need a commercial gas safe company and not a normal heating company

as the meter is a commercial one and you would prob need a 35 or 42mm gas main depending on length which is classed as commercial

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Well we get clashes in the morning when two people need to use showers.
I had a chat with one gas safe engineer and he seemed to be happy to reconnect new meter to existing gas in the house... I guess I could pay National grid to get it reconnected if I need to.

I think my main problem would be low mains pressure and flow. I only get 12L at 1.4 bar pressure on the ground floor... While I could hopefully increase my flow I guess there is nothing I can do to increase my mains pressure. And all Water company will say is we only have to provide you with 1 bar and 9L/min...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Well we get clashes in the morning when two people need to use showers.
I had a chat with one gas safe engineer and he seemed to be happy to reconnect new meter to existing gas in the house... I guess I could pay National grid to get it reconnected if I need to.

I think my main problem would be low mains pressure and flow. I only get 12L at 1.4 bar pressure on the ground floor... While I could hopefully increase my flow I guess there is nothing I can do to increase my mains pressure. And all Water company will say is we only have to provide you with 1 bar and 9L/min...

ask them to up the main to at-least 32mm that will give you more than enough supply (and not just 32mm from your meter to your house from the main main )

and i would check that the gas safe company you use is register for commercial (easy to check http://www.User PlumbersForums.net ... content, don't link to it.co.uk/Default.aspx non domestic and pipework and commissioning)

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks Shaun,

That's what I was going to ask them for and also increase my water meter.

Is there away to find out what flow can 32mm pipe provide at 2 bar that I have? Do you think I can have decent shower with say 26l/min for two showers in the 1st floor floor via HW only boiler if I put it on the ground floor?

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks Shaun,

That's what I was going to ask them for and also increase my water meter.

Is there away to find out what flow can 32mm pipe provide at 2 bar that I have? Do you think I can have decent shower with say 26l/min for two showers in the 1st floor floor via HW only boiler if I put it on the ground floor?

well put it this way a stnd combi runs at about 13-16lpm when using hot water so your calcs arnt too far off with 26lpm and if you want the best flow possible slightly oversize your pipework eg instead of using 15mm you would use 22 etc

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I had idea of placing water only heater to the loft but with my mains water pressure I guess this is out of the questions as pressure would drop too much. I just wondering id water heater on the ground floor would work efficiently if my dynamic pressure will be 1.4 bar on the ground floor. ans also would I ave enough flow / pressure to my showers on the 1st floor? Manual for Worchester 42CDI states that maximum flow is achieved at 2 bar minimum... I guess same rule would apply to water only heater? good question is whether they are talking dynamic or static pressure...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I had idea of placing water only heater to the loft but with my mains water pressure I guess this is out of the questions as pressure would drop too much. I just wondering id water heater on the ground floor would work efficiently if my dynamic pressure will be 1.4 bar on the ground floor. ans also would I ave enough flow / pressure to my showers on the 1st floor? Manual for Worchester 42CDI states that maximum flow is achieved at 2 bar minimum... I guess same rule would apply to water only heater? good question is whether they are talking dynamic or static pressure...

cant the water board up the pressure from 1.4 to 3.0???????? if they have said no have you asked them why

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I have not though about asking them. I assumed they would just not do it as they only have to provide 1 bar. 1.4 bar is what I get if fully open one of the taps when taking measurement. When everything is off it is 2 bar...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I have not though about asking them. I assumed they would just not do it as they only have to provide 1 bar. 1.4 bar is what I get if fully open one of the taps when taking measurement. When everything is off it is 2 bar...

especially when your talking about upping your water main they might be able to open a valve and up it to 3 bar anw way worth a phone call/ meeting and tell them what you are planning to do

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks for the tip Shaun. I will meet with them on Monday and panning to have very good chat with their engineer to explore my options. Do you know hat can I mention they could do to increase the pressure? What valve do they need to pen to increase it?

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks for the tip Shaun. I will meet with them on Monday and panning to have very good chat with their engineer to explore my options. Do you know hat can I mention they could do to increase the pressure? What valve do they need to pen to increase it?

thats down to the water supply there might be nothing they can do for the pressure but you never know, and it never harms to ask : keep us updated tho sounds like a good project but i bet it wont be a cheap one

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks Shaun, I'll post any updates I have and hopefully it will help someone else.
Oh well we are talking few grands just to get water and gas mains up to the job...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Thanks Shaun, I'll post any updates I have and hopefully it will help someone else.
Oh well we are talking few grands just to get water and gas mains up to the job...

your more than welcome

 

[oz-plumber]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I have not though about asking them. I assumed they would just not do it as they only have to provide 1 bar. 1.4 bar is what I get if fully open one of the taps when taking measurement. When everything is off it is 2 bar...

Gee you guys have low water pressure.
Our mains are generally 1000 kPa ( 10 bar ) and higher at different locations.
We have regs now that we have to provide a 500 kPa ( 5 bar ) pressure reducing valve at the meter.

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Lucky you Oz plumber,

I must be living in a wrong area. Do you think Rinnai HW heater would work well if placed on the ground floor to feed two showers at the same time on the first floor if I manage to get proper water flow?

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Also did you have any feedback from people you fit them for? Are they happy with the flow and can use two showers at the same time?

 

[stevetheplumber]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

lots of expensive cures whats wrong with tanks cylinder and a pump

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

Nothing wrong. Just trying to address root cause. Tank and cilinder take quite a bit of useful space...

 

[Rickster123]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

If you go for the combi I think you will regret it in the long run. Cut down on the towels and sheets and go with a cylinder.

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

My main concern with the cylinder is situation where it runs out of water and we left with no hot water for a bit which I feel could happen even with the biggest 300l unvented. With our current usage we get one shower from 115 L conventional tank. Second person is out of water 5 minutes after the shower. The shower we have now is run from gravity system and really slow. I just feel that with good flow that unvented system can provide there definitely cannot be 3 bath / showers in the row which happens sometimes and is someone takes shower for a bit too long it might not even last two... Washing up contributes to hot water usage as well...

So what would be benefits of the Unvented opposed to system boiler and water only heater in a long run?

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I think if we address flow rate issue with water board now and not have to go with break tank and pump we would save in a longer run as a break tank and pump will fail at some point and upgraded water mains is more or less permanent...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

you mean a combi vs a unvented cylinder ???????

a system boiler still requires a cylinder

 

[woking]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I thought that Worchester 24I system boiler we have now is not using our current tank for heating. I am still in two minds whether to replace it with 42CDI comby boiler + HW only boiler or reuse 24I. I don't quate like controls I could use for it (only thous with 3 time periods seem to be compatible) We are using Honeywell CT6400c with it now...

 

[ShaunCorbs]

Re: Greenspring CWi47 VS Rinnai 26i VS 2X Greenstar 42CDi for two simultaneous shower

I thought that Worchester 24I system boiler we have now is not using our current tank for heating. I am still in two minds whether to replace it with 42CDI comby boiler + HW only boiler or reuse 24I. I don't quate like controls I could use for it (only thous with 3 time periods seem to be compatible) We are using Honeywell CT6400c with it now...

best thing to do is have a word like you are with the water board and go from there/ make a verdict what to do