H
happyflyer
Tamz,
Was that a good guess Tamz, your formula was near enough.
Was that a good guess Tamz, your formula was near enough.
Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
View the thread, titled "Calculate size of low Loss Header" which is posted in UK Plumbers Forums on UK Plumbers Forums.
If you have the Domestic Heating Design Guide it is section 13.8 (well it is in my old one)
flow rate = H / (TD x SH) = kg/s where
H = heat output in watts (50kW = 50,000 watts)
TD = temperature difference between flow & return in deg C (either 11 old or 20 new systems/boilers)
SH = specific heat of water in J/kg (which is 4186)
So flow rate = 50000 / (20 x 4186) = 50000 / 83720 = 0.5972 kg/s round it up to 0.6 kg/s
Using Tables 13.1a & b look down the column's of figures until you see >0.6 above the 0.5 m/s Velocity line that works it way across the table/page, in this case it appears in the first column on table 13.1b which is 42mm pipe size but it is only just, it might be better to use the next size up i.e 54mm in which case the velocity would drop to around 0.3 m/s.
So rule of thumb boilers up to 50kW can be connected to a 54mm copper or larger L.L.Header if using a delta T of 20deg C.
The pipe work connections should be arranged so that all the flows are at one end & all the return are at the other with a reasonable section of clear pipe between (say 150mm or 5 x inlet pipe dia minimum)
The F&R to boiler/s (or any draw off circuit) could be sized in the same way as above but normal velocity for domestic systems is </=1.0 m/s. Or use the quick pipe sizer 13.2 (28mm can carry upto 40,000 to little & 35mm upto 62,000) so 35mm it is.
Better to arrange header so it is in the vertical (air & dirt separation) & make sure it has an AAV on top end & drain off on bottom.
Anyone got any thing to add (have I got it right ?)
flow rate = H / (TD x SH) = kg/s where
H = heat output in watts (50kW = 50,000 watts)
TD = temperature difference between flow & return in deg C (either 11 old or 20 new systems/boilers)
SH = specific heat of water in J/kg (which is 4186)
So flow rate = 50000 / (20 x 4186) = 50000 / 83720 = 0.5972 kg/s round it up to 0.6 kg/s
Using Tables 13.1a & b look down the column's of figures until you see >0.6 above the 0.5 m/s Velocity line that works it way across the table/page, in this case it appears in the first column on table 13.1b which is 42mm pipe size but it is only just, it might be better to use the next size up i.e 54mm in which case the velocity would drop to around 0.3 m/s.
So rule of thumb boilers up to 50kW can be connected to a 54mm copper or larger L.L.Header if using a delta T of 20deg C.
The pipe work connections should be arranged so that all the flows are at one end & all the return are at the other with a reasonable section of clear pipe between (say 150mm or 5 x inlet pipe dia minimum)
The F&R to boiler/s (or any draw off circuit) could be sized in the same way as above but normal velocity for domestic systems is </=1.0 m/s. Or use the quick pipe sizer 13.2 (28mm can carry upto 40,000 to little & 35mm upto 62,000) so 35mm it is.
Better to arrange header so it is in the vertical (air & dirt separation) & make sure it has an AAV on top end & drain off on bottom.
Anyone got any thing to add (have I got it right ?)
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tamz
Never guess anything :wink:
Doesn't mean it or I am right does it, looking for your input. Which might be useful to us all.
Your just the bl**dy same as the rest of my students, attention span of a goldfish. LOL
E
Ermintrude
Bit of 100mm box section plate top and bottom 😉 any one ?
I was a student of yours, mature one at that!
H
happyflyer
Yep Ermi, I go with that, which is the easiest to get your hands on these days 100 mm box or 100 mm ms tube???
T
tamz
Depends who you know
H
happyflyer
Picture paints a thousand words....
T
tamz
Thats not really a header. Its more like a spirocross air and dirt seperator.
You can make your own up just the same.
Design it at around 2 litres/kw with a flow rate of 0.1m/s or less. That allows for the muck to settle and stratification to take place.
You can make a better one yourself anyway. Its easy if you know how.
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In which case you were much much better than the normal ones which sit in front of me !
I say that especially cos your only round the corner from me. 😳
How big are you kozak & do you have an brothers ?
I usually make my own. As a rule of thumb I usually make the header 2-3 sizes bigger than the biggest primary pipework size and this always works for me. For example on a 45kw loads I used 35mm primarys, and then made one with 54mm tube. Flow and returns have to be a minimum of 800 apart.
This is a rule of thumb method iv used and obviously not the technical way of doing it, but they always work well for me. Always better going on the larger size.
This is a rule of thumb method iv used and obviously not the technical way of doing it, but they always work well for me. Always better going on the larger size.
H
happyflyer
Tamz,
If I turn that drawing on its side will you be happy will it look like a LLH then, bloody Scots, :90: never happy "Independence Day" hey Tamz, :furious3:what will your currency be then "Groats"
T
tamz
Que sera sera :wink:
S
S.SAADABADI
We need to build Low Loss Header for chiller-fancoil piping system, however we do not have enough information. I have some questions about designing L.L.P?
- Are the secondary connection and primary connections are exactly opposite?
- Some manufacturers add a baffle plate inside the LLP, does it recommend?
- We design the diameter of LLP, with 2 ft/s velocity, is it correct?
- Is it correct to suppose the distance between the inlet and outlet connections equal to 4*diameter of connection?
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Ermintrude
What's consultant spesified? Never go opposite unless baffled
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Ermintrude
Don't make it too big you want turbulent not laminar flows across the ports. So it mixes
What's the heat load ?
What's the heat load ?
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Chiller system?
you're playing by a different set of rules to us then if i remember rightly.
get it designed imho
you're playing by a different set of rules to us then if i remember rightly.
get it designed imho
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happyflyer
Are we on chilled water here or heating, LL headers are not rocket science they can't be it's plumbing :smilewinkgrin:
D
Dotty
The chap's from Iran and doesn't strike me as a spammer so there could be some translation losses guys.
Even so, can't imagine them needing heating much!
H
happyflyer
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Ermintrude
You do at night!
H
happyflyer
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Ermintrude
Oooh beach holiday in Iran? You better pilot than a navigator me hopes!
H
happyflyer
Emi, I will weld up the LL header, fly it down there and you fit it, we will need about 10 refuel stops from your hoose in a single engine Piper
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Ermintrude
I'm making sarnies hope u like tea! Loaded up batton berg and space invaders.
H
happyflyer
Take mi 30 mins to make up the header, take us 4 weeks to fly it down there, if we get stopped in customs anywhere with the header
you can do the explaining what is for in broad jordie, they won't have a clue. Wi I mun
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Ermintrude
Eeee that's a reet canny idea pet. Be doon tannas bank in about an hour.
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