What boiler for 25 radiators in an office on a single floor?

[bashmaystor]

Hi fellas

I am going to price up a job, which involves installing 25 double panel single convector radiators (1000/600) in an office, that is on a single floor. My concern is: will the pump on a 35kw Ideal Logic+ be strong enough to circulate the water around the whole system effectively?
The boiler in question has 119000btu's and 25 rads combined require exactly that amount from a boiler, so that aspect is fine.
Pipe sizing wise I will go 22mm copper all around the system and only tail out to the rads in 15mm.
Let me know about your experience with installing a large amount of radiators and wether the pump on the combi copes with it ok?

P.O.I.
I have been in another office, where they had 24 large rads and a 28kw combi boiler, which didn't circulate well even when the system was power flushed and balanced.. And half of the office remained cold. So I ended up installing another circulator pump on the far end of the system, which improved the flow significantly and got all the rads hot. (not piping hot due to the small KW rating of the boiler )

Cheers
Veniamin

 

[Chalked]

22mm is too small for output and distance.
Run it into a low loss header, then get a properly siized pump on the heating side. You will also need an extra expansion vessel to accomadate the volume.

 

[AWheating]

heat only, expansion vessel kit, 28mm magnaclean, light commercial pump.

work out the index circuit and size pump correctly.

is it one room/ open office? no zones needed?

 

[Dotty]

I said I'd reopen and move your other thread for you, didn't I, Ven.

I'll go do that now.

 

[joni os]

28mm flow & return at boiler. I believe your intended boiler will not give BTus required when in heat mode.

 

[stevetheplumber]

another thing to remember is exspansion if the pipe runs are long youll need exspansion joints in the runs ive seen two rads come of the wall on a run of steel pipe with copper it will just buckle and burst

 

[stevetheplumber]

the combi only goes to 25kw in heating mode use a heat only boiler and minimum of 28mm pipe depending on the layout if its all on one run then you will need some 35 to get away from the boiler personally i would keep it simple for offices header tank above boiler then you will not get call backs for low pressure
im always looking for work and local to you so if you need a hand

 

[Mike Jackson]

Intergas 36/40 gives 40Kw to heating and has an uprated pump.

 

[IDCHAPPY]

Vogue 32kw system, has a 7m head pump.

 

[bashmaystor]

Thank you all for your replies.
I will run most of the pipework in 28mm, like all of you suggested.
Run it into a low loss header first. Pun an additional expansion vessel and a light commercial pump like the Grundfos UPS2 25-80. But for the boiler, Im thinking it will have to be a Intergas 36/40 combi, because they will need hot water in the kitchen and in the toilets. Will the external light commercial pump and the pump that's in the boiler be compatible working together? Or does the Intergas 36/40 has a big enough pump and doesn't need an external one?
Much appreciate all your advice
Cheers

 

[bashmaystor]

Its going to be as one whole zone. And TRV's on each rad.

 

[IDCHAPPY]

Vogue 40kw combi will do 34kw for heat and 16l/m hot water (not that they'll need it for a kitchen sink but) also comes with a 10 year warranty .

 

[Mike Jackson]

The pump in the 36/40 is Wilo 25/7 pump that has a 7m head and will flow up to 5 cubic metres per hour. This is not much less than the 25-80 and with the free flowing heat exchanger in the intergas may well be sufficient. i'd givr them a call and check before pricing for a low loss header and second pump.