Water and Heating Design Options

[GeorgeWBush]

Hi,

New to the forum so hello to everyone .

I have 3 bedroom detached house, 1 combined Bathroom and w.c., 7 rads, currently with a Ravensheat Combi, about 10 years old. Will not be keeping this as it has cost us a small fortune to keep it going - not complaining, we never serviced it so were asking for trouble!

I'm looking to do an extension which will take us to 4 bedrooms, a w.c./shower room down stairs and a bathroom shower and w.c upstairs. The downstairs extension will probably have underfloor heating - maybe replace existing rads as well with ufh... upstairs probably keep rads.

Measured water pressure at the outside water tap at just over 2.5 bar. Flow rate is appx 15 lt/minute.

I would like to be in situation where we can have the bath flowing and have both showers on and have good pressure and regular flow/temperature for each source.

Is this possible or am i dreaming?

We have a garage appx 15' from the house. Have a loft we could use, but ideally would like to keep option of converting to a room later on.

I've tried to read up on this but I think I've overloaded my brain and to be honest am confused about the various options...

Hope you guys can give me some options...

Thanks in advance.

 

[Norcon]

Is this possible or am i dreaming?

At 2.5 bar @15L/min yer dreamin.

Did one recently of an unvented with 2 rain heads and two shower roses running concurrently and all was fine.
His incomer was 6 bar though distributed in 28mm > 22mm> 15mm.

 

[picasso]

have you got room in your garage for a break tank and pump? if so you could go for an unvented cylinder,although even then I dont think you could have your bath and both showers running at the same time.

 

[GeorgeWBush]

Norcon, thanks for clarifying.

Picasso, yes, have room in the garage (once I have get rid of several years worth of junk that's in there).

Is a break tank a cold water storage tank?

If the water is pumped to the house do you know (roughly of course) what flow rates I could get?

 

[picasso]

yes the break tank is a cold water storage tank, the flow rates depend on how much you want to spend, more £££s more pressure and flow.

 

[GeorgeWBush]

Thanks again for the help

OK, so basically a large water tank in the garage and a pump to push into the house. The more powerful the pump, the better the flow rate.

What happens if there is a power cut? Would i basically be stuffed ending up with no water?

What are the options on heating the water? Could i get a powerful boiler that would heat the water instantaneously or what I have to go with storing and heating slowly (slowly to me means anything more than a few minutes)?

 

[picasso]

when I install break tanks I always put in a bypass, if there is a power cut just open the bypass and you have what ever the mains can deliver,(which will be better than nothing) my personal prefernce is unvented cylinders, with high recovery coils a 250ltr cylinder can be reheated very quickly, there are 50kw combis on the market if you want instant hot water but the will never compete with unvented cylinders.

 

[GeorgeWBush]

Does an unvented cyclinder heat the water all by itself, or would I need a boiler as well?

Are there any alternatives to an unvented cyclinder?

Could 2 combis be an option...?

 

[picasso]

there are lots of options open to you,

unvented cylinder with system boiler

50kw combi

system boiler for ch with rinnai water heaters

2 combis

thermal stores (my least favourite)

and probably lots of others (that I cant think of at the moment)

I normally install unvented cylinders with system boilers because the customers are happy with the performance IF the mains is up to it, just my personal preference.

 

[GeorgeWBush]

Thanks for your time. I'll look into these further...

 

[Biggles..]

Have a look at Grundfos Homebooster-self contained 200litr break tank with 5 bar pump.In built software makes them run like an accumulator rather than a constant pressure pump.

Also as your having mixed temperature circuite(ufh and rads) i'd seriously consider a thermal store-check out DPS but they dont come cheap.

Second advantage is the plate heat for the DHW can be sized more accurately for your outlets than an unvented.

Personnaly like the twinflow but BSS cant shift them,2 main reasons at present,cost and uncertainty in the market about the product,which is a bit of a shame.

 

[GeorgeWBush]

Have a look at Grundfos Homebooster-self contained 210litr break tank with 5 bar pump.In built software makes them run like an accumulator rather than a constant pressure pump.

First thing that comes to mind is looks pricy for a pump and a tank! Ideally would like 2 pump set up incase one fails. Probably a bigger tank as well.

Also as your having mixed temperature circuite(ufh and rads) i'd seriously consider a thermal store-check out DPS but they dont come cheap.

Do you know roughly how much £ ? Would this need a boiler as well?

Personnaly like the twinflow but BSS cant shift them,2 main reasons at present,cost and uncertainty in the market about the product,which is a bit of a shame.

Is this the Rinnai Twin Flow? Says in the literature that this can provide 20l/min raised 33C, is this enough for a bath + 2 showers? When you say uncertainty, is this because it is new?

 

[Agile]

If you really must be able to run all three at the same time you need about 30 li/min DYNAMIC flow rate. Thats difficult to achieve and expensive.


You have two options to increase flow rate:-

Upgrade mains supply, about £1000-£2000

Install pump and break tank £1500-£3500

Whatever else you have you will need a cylinder ( normally unvented ) and a boiler. About £1700-£2400 and about £1800 for boiler.

If you must guard against an electrical outage then a standby generator would be the cheapest option at about £2800+

As you are realising, your pipe dreams are possible but expensive.

A much better solution would be to settle for what most people have which is a system which can deliver enough for one hot water outlet at a time.

Being logical just why do you want the extreme luxury of being able to use all three at the same time? Why not dicipline your family to stagger their useage times by 15 minutes?

Tony

 

[Biggles..]

Homebooster is £720+vat add on storage tanks available

DPS store average about £2000+vat but you won't need the blending pumps with the underfloor manifolds.

Flow rates of 30-50litres easily achieveable if pipesized correctly.

 

[GeorgeWBush]

Being logical just why do you want the extreme luxury of being able to use all three at the same time? Why not dicipline your family to stagger their useage times by 15 minutes?

I didn't see it as an extreme luxury, BUT am now realising it is...