large soildfuel boiler pipe sizing

[dancn]

Someone who's installed a large solidfuel boiler may help with my pipe sizing query.
Sorry about the imperial sizes...
I'm laying pipes before screed to my gnd floor utiltity room.
Next to where DHW cylinder is I'm going out through at bottom of the wall with flow/return pipes to a garage to a 50Kw solid fuel boiler.
The type of boiler I'm planning using has a G2" internal thread to boiler flow/return.
I will have an oil boiler as back up, and I'm planning taking both boiler lines into house and connecting with a neutraliser (sytemlink)
Now the sytemlink link spec says the heat capacity of their 1,1/4" ports neutraliser is 56kw.
So why the big difference, is the boiler manufacturer just fitting oversized ports that can be reduced down , This G2 size is used down to 32kw models. 10kw-30kw use 1,1/2" ports.
So if the systemlink spec is right I only need 1,1/4" pipe (or less) from garage to boiler.
pipe run is less than 6metres. Sytemlink then has a pump for each zone to distribute, no MVs.
Or am I'm missing something, with internal external thread thing ..

 

[tamz]

"large solidfuel boiler"
How large is large?

 

[dancn]

sorry boiler is 50KW

 

[tamz]

Should be ok to bush down to 1 1/4" but best speaking to the boiler manu.

 

[ecowarm]

You should be looking at a very large accumulator tank >2500l and a loading valve like The Laddomat 21-60 is ideally suited for boilers up to 60kW output and promotes safe, efficient loading of the system water.

 

[jonmanty]

Dancn

The main point is that pipe size is not necessarily related to the connection size ports on the equipment.

Main factors are the temperature difference between flow and return pipework at which the system operates and the maximum (velocity) speed at which the circulating fluid is going to travel.

With a standard temperature drop of 10 degrees centigrade, underfloor systems will be different to this and a maximum recommended velocity of 1m/s for larger pipework, it is possible to go up to 1.5m/s on heating circuits but is not particularly recommended on larger pipework due to possible excessive noise.

35 mm copper tube can deliver - 25kW
42mm copper tube can deliver - 38kW
54mm copper tube can deliver - 63kW

The reason why some tapping sizes vary is that they work on the principle that there will be an isolated and localised increase in velocity at the point of connection, an example is a larger gas condensing boiler with say 32kW output but with 28mm connections. The installation instructions don't normally provide the exact pipe size but invariably indicate that the pipe size immediately connecting to the appliance should be larger than the boiler connections.

In your case if the heat load from the boiler is 50kW then the pipe size should be 54mm, bushed down at any point of connection to the neutraliser.

Also agree with the feedback re- the buffer tank alternative suggested as well.

Jon

 

[dancn]

thanks for the replies folks,
the increase in velocity at the connection point makes sense, and explains the 56kw capacicty of the neutraliser with 1,1/4 port.
The buffer and mixing laddomat are on the list aswell.

Forgeting the oil boiler input for a moment. would a modualting pump be a good idea as the primary pump. Given that the neutraliser outputs with their own pumps, will vary with opening/closing zones, and trvs open/closing within these zones.

 

[ecowarm]

The primary pump is the labdomat

 

[dancn]

Nice one, all in one unit,