Heating pump size.

I'm after an idiots guide to heating pump sizing. What do the numbers mean? How do I know what size pump I need for my system?
Thanks

 

I'm a bit pushed for time this morning DP. But I'll call in later & give you the full SP.

It'll interesting to see what the course Cowboys & so called experts here come up with in the interim.......😃😃

 

Port size- deci meters head- length

Ie 15-50/130

As for what you need, how longs a piece of string.

 

Do you plumbers just guess then? Or is there a way to calculate it?

 

Course it's calculated.

Are you heating, cooling or chilled, what's your system filled with, what's your output, what's your delta t,what's your flow rate, what's you pipe sizes, system layout, what's your appliance KPa, what's your valves KPa, what's your index circuit KPa???????????????

A plumber may guess but he'd be excused for not understanding heating!

Nearly as open ended question as asking a forum "how much will it cost??"

 

For the majority of DOMESTIC systems either a 5 or 6 metre pump will suffice, unless the boiler manufacturer requires larger. 3 speeds on pumps allow matching to almost any domestic system. There are calculations for sizing involving pipe length, resistance, heat load etc, but I would suggest that most would find it too complicated to do and rely on experience. The availability of generally only 5 and 6 metre pumps would suggest that its really not difficult to size a pump. Now I'll wait for Sir Dick to come back and give us all the benefit of his wit.

 

LeeC has pretty much covered it with his input for domestic heating systems. Hopefully I can explain in simple terms what it all means;
For starters, it's a circulation pump, not a pump as such.
They are generally sized by 'head' 5M or 6M for domestic system as said. This means it'll lift the fluid 5 or 6M.
Think about a Fair Ground Big Wheel, the wheel is powered to take you to the top & gravity gets you back down again, that's what the head is, the top of the wheel.
Then there's the index radiator(furthest from the boiler) on standard two pipe domestic heating system, the circulation pump is sized to carry the whole heat load & if it can do the index radiator it'll do the remaining radiators.
Again on domestic systems the Delta T(temperature difference between the Flow & Return pipes) must be maintained throughout the whole system. This is critical for getting the correct radiator/emitter output & ensuring condensing boilers condence as much as possible.

Most commercial systems are adjusted on Delta P(pressure difference between The Flow & Return) & a commission engineer will rely on that more than Delta T.

A correctly sized circulation pump is acertaned when pipe sizing a system - both are not dark arts & easily done.
HTH

 

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