Circulation worries

[Daryl17]

Hi all, I have just purchased an old building which has a new combi boiler fitted with 22mm pipes across the 1st floor and then 15mm down to the rads on the ground floor, there are 10 in total on the ground floor. I wish to add 9 rads to the 1st floor !
I believe that the boiler is ok to heat the rads but Im worried about the circulation as I have read that 12 rads is the maximum.
A friend of mine has suggested fitting an additional pump to the 1st floor to increas the circulation to the new rads.

I was hoping that someone could help tell me and explain if this is possible and if the second pump would just be wired together with the first?

Any further suggestions would be appreciated
Thanks in advance

 

[doitmyself]

Do the following and post the results:

1. Work out the heating requirement of your house.
The easiest way is to use either Sedbuk Boiler Calculator or [DLMURL="http://www.energysavingtrust.org.uk/business/Business/Building-Professionals/Helpful-Tools/Whole-house-boiler-sizing-wizard"]EST online boiler calculator[/DLMURL]

2. Work out the heat output of existing radiators using the Stelrad Elite Catalogue

3. Post the make and exact model of your combi boiler

The amount of heat that a 22mm pipe can carry will depend on the temperature differential (flow and return) used. If it is 11C, it can carry about 15kW; at 20C it can carry about 27kW

I'm worried about the circulation as I have read that 12 rads is the maximum.

The number of rads is immaterial. It's the heat output which is important. You can't get more than 15kW out of a 15kW boiler. so there is no point having 20kW of rads.

A friend of mine has suggested fitting an additional pump to the 1st floor to increase the circulation to the new rads.

Not a good idea.

 

[stevetheplumber]

Hi all, I have just purchased an old building which has a new combi boiler fitted with 22mm pipes across the 1st floor and then 15mm down to the rads on the ground floor, there are 10 in total on the ground floor. I wish to add 9 rads to the 1st floor !
I believe that the boiler is ok to heat the rads but Im worried about the circulation as I have read that 12 rads is the maximum.
A friend of mine has suggested fitting an additional pump to the 1st floor to increas the circulation to the new rads.

I was hoping that someone could help tell me and explain if this is possible and if the second pump would just be wired together with the first?

Any further suggestions would be appreciated
Thanks in advance

you may well need to upsize pipework to 28mm for part of the circuit
you dont say what output your combis is
when you say downstairs id fed by 15mm do you mean a pair of 15s to each rad or the whole floor is suppplied by 15?

Hi all, I have just purchased an old building which has a new combi boiler fitted with 22mm pipes across the 1st floor and then 15mm down to the rads on the ground floor, there are 10 in total on the ground floor. I wish to add 9 rads to the 1st floor !
I believe that the boiler is ok to heat the rads but Im worried about the circulation as I have read that 12 rads is the maximum.
A friend of mine has suggested fitting an additional pump to the 1st floor to increas the circulation to the new rads.

I was hoping that someone could help tell me and explain if this is possible and if the second pump would just be wired together with the first?

Any further suggestions would be appreciated
Thanks in advance

you may well need to upsize pipework to 28mm for part of the circuit
you dont say what output your combis is
when you say downstairs id fed by 15mm do you mean a pair of 15s to each rad or the whole floor is suppplied by 15?

 

[migoplumber]

yes you can install a booster second pump in the circuit on 1st floor if you wish. yes you just wire the pumps in parallel. easy problem solver if circulation is suspect.

 

[Daryl17]

Hi All thank you all for the info above. The Boiler is a Worcester Greenstar R 30 HE Combi Condensing Gas Combination (Combi) boiler
High Efficiency: 90.6% Band: A
Boiler Maximum Heat Output in BTU/h: 100,683 (29.5 kW)
and is installed on the 1st floor, 22mm flow and return pipes run through floorboards to tops of walls then change to 15mm down the walls of the ground floor to the rads.
I have also used the Sedbuk calculator and using approx figures the result states Boiler output requires 50KW and if this is correct as DOITMYSELF suggests the boiler isnt up to the job.
I will price up the bigger boiler but could you also confirm the following:-
1) would I still need to fit booster pump on the 1st floor and ground floors to help with circulation?
2) the present boiler only has 22mm fittings for flow and return, Im guessing I can get a reducer to fit 28>22 and run the 28mm as up to and as close as i can get to all rads. Perhaps the larger output boiler will have 28mm fittings
3)I have calculated the excisting rads (Ground floor only) 10X11oowatts =11Kw and planned 1st floor rads at 9X1000watts =9Kw
Total 20KW. If this is correct then the 30HE boiler would be ok for the job, but if the sedbuk calculator is correct this would mean I would need at the very least to double the amount of rads I have in total to bring the hole house upto 21 degress?

Thanks again in advance
Rgds Daryl

 

[doitmyself]

I have also used the Sedbuk calculator and using approx figures the result states Boiler output requires 50KW and if this is correct as DOITMYSELF suggests the boiler isnt up to the job.

That seems very high. Is it a very big house with solid walls, cellar, leaky sash windows and no insulation?

Could you post the data you entered into the calculator? I will then check the result for you.

 

[Daryl17]

Thank you DOITMYSELF for the responce. Yes the house is very old and had been converted into a detatched social club, with a concert room and stage high cielings (3.3m) in all rooms and minimum insulation.
The windows once I replace them will be double glazed sash and i also intend to install suspended cielings in most of the rooms with 150mm insulation. The house is of solid brick construction without cavity walls.
Overal dimensions for the ground floor 12mX19m with 7 sash windows 2.1mX1.7m (to be double glazed)
1st floor 12mX13m 4 similar windows to the ground floor.
Hope this helps

 

[kirkgas]

Hi all, I have just purchased an old building which has a new combi boiler fitted with 22mm pipes across the 1st floor and then 15mm down to the rads on the ground floor, there are 10 in total on the ground floor. I wish to add 9 rads to the 1st floor !
I believe that the boiler is ok to heat the rads but Im worried about the circulation as I have read that 12 rads is the maximum.
A friend of mine has suggested fitting an additional pump to the 1st floor to increas the circulation to the new rads.

I was hoping that someone could help tell me and explain if this is possible and if the second pump would just be wired together with the first?

Any further suggestions would be appreciated
Thanks in advance

i assume your friend isn't a plumber

 

[doitmyself]

Yes the house is very old and had been converted into a detached social club, with a concert room and stage high ceilings (3.3m) in all rooms and minimum insulation.
Overall dimensions for the ground floor 12mX19m with 7 sash windows 2.1mX1.7m (to be double glazed)
1st floor 12mX13m 4 similar windows to the ground floor.

That's a large property! I take it you are converting it back to a dwelling house.

Both online calculators do say that they should only be used for boilers up to 25kW, so I think you have to treat the 50kW with some caution. It might be worthwhile getting advice from a installer who is familiar with larger properties. Multiple boilers might be a good idea.