Conflicting advice on flow and return for new install

[ArchieC]

I need some advice please.

I have had several quotes for a central heating and hot water installation for a large 3 storey house with 22 rads (inc towel rails) but the advice I am receiving is conflicting and just wanted a bit of insight please.

Chap number 1 suggests 22mm flow and return in the middle of the house (hallway) with the flow branching off to each floor from the single initial flow pipe at each floor. Then 15mm to radiators - some of the radiators are quite far away from the middle of the house so would mean the 15mm runs are quite long.

Chap number 2 suggest as number 1 but with 28mm.

Chap number 3 suggests as number 2 (28mm) but with the flow separating out of the boiler as early as possible and then separate 28mm to each floor.

Aside from the extra cost of options 2 and in particular option 3, are there any advantages/disadvantages?

 

[Scott_D]

22mm sounds too small to me

 

[Riley]

It's all about rapid and correct heat transfer. I'd say 22 is too small

 

[ShaunCorbs]

28mm min main runs

depending on how many rads on each floor 22-28mm

15mm to each rad

Low loss header by boiler

Do not install a combi boiler

 

[joni os]

28mm off boiler with 22mm tee off to each floor then 15mm tee off 22mm to supply each group of radiators with total output not exceeding 5Kw.

 

[hammers4spanner]

Plenty of 28mm
Plenty of 22mm
Plenty of 15mm
Prob do the job

 

[Riley]

Plenty of 28mm
Plenty of 22mm
Plenty of 15mm
Prob do the job

Quantity survey done!!

 

[ArchieC]

So is chap number 3's suggestion a bit overkill?

 

[ShaunCorbs]

So is chap number 3's suggestion a bit overkill?

nope nothing is overkill,

depends if you want each floor zoning

if you dont just do one 28mm main run and t off for each floor

 

[ArchieC]

Thanks. I would like 3 zones.

By way of update, chap number 1 and has suggested a Spirocross AX100 low loss header, whereas chap number 2 and 3 suggest this might be too small?

 

[ShaunCorbs]

Thanks. I would like 3 zones.

By way of update, chap number 1 and has suggested a Spirocross AX100 low loss header, whereas chap number 2 and 3 suggest this might be too small?

Depends on heating load think the ax100 can take upto 50kw

What size boiler / boilers are you going for / what's your heatloss calcs say

 

[Scott_D]

Might be best to get it designed properly
You can then get the drawings priced so you compare like for like and if it doesn't work you have someone to go back to

Unless you are looking for the cheapest option, then go with no.1

 

[SimonG]

Chap 3 for me. Broken into zones and pump per zone.

 

[ArchieC]

They've all told me their designs but I was just a bit concerned that some aspects vary wildly. Chap 1 is the cheapest.

They've offered me the option of a Worcester or Vaillant, l've chosen to go with the Vaillaint ecotec 637 which all 3 are happy to install.

Interestingly, only chap 1 (NRG Lex SCM) and 2 (Honeywell) mentioned a wiring centre, need to check with chap number 3.

 

[ShaunCorbs]

They've all told me their designs but I was just a bit concerned that some aspects vary wildly. Chap 1 is the cheapest.

They've offered me the option of a Worcester or Vaillant, l've chosen to go with the Vaillaint ecotec 637 which all 3 are happy to install.

Interestingly, only chap 1 (NRG Lex SCM) and 2 (Honeywell) mentioned a wiring centre, need to check with chap number 3.

Did they do a heat loss calc of your house ?? If not get them to do one

and bin chap 1