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pipe sizes for complete heating/DHW system

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WHPES As i have said before the plumbers i have called in are real numptys!... and so i have to gain the knowledge and have some sort of idea where to go with this install. it seems all the good and "Knowlegable" plumbers are up north!...lol
 
vern i had always said i would go for the Megaflo 300l cylinder but gray0689 has suggested the ACV cylinder (tank in tank system) with unbelievable reheat times (not sure wot the after sale support will be like?), so am seriously considering this cylinder aswell.
Thanks for the "only use copper" pipe tip as apposed to plastic.

Am i right to believe that the secondary return that you and others have mentioned is there to eliminate cold water stagnent in the pipework when DHW is not being used for a while, and this cold water should be removed periodacally through the day to prime the DHW system with "instant" DHW at the outlets when the outlets (taps/showers) are used? and is 15mm copper pipework sufficient for this purpose?

Had a look at the megaflo commercial!... too much of a big beast to house in my installation!

you are right i have a standard gas meter (which will be moved to the outside of the house; currently under the stairs). There will be no gas fires but there will 2 Baumatic gas Hobs in addition to the 2 WB 24Ri boilers (Ovens will be electric). So hopefully the plumber will size the copper pipework up accordingly (22mm or 28mm)! so hopefully will not run into gas pressure inlet problems.

I have also looked at the WB low loss header(LLH) and seems like a "Toy" comapred to other headers i have seen on the internet!... i wanted to know how can you suggest using this LLH without working out the pipework sizes or flow/return calculations? I mean will this toy of a unit suffice for my domestic install (you mentioned "pumps Pipeworks, expansion vessel etc sized to suit site and system condition)?
In my underfloor heating there will be 3 manifolds (1 downstairs/1 upstairs/1 for the loft conversion) so will we have enough ports on this LLH to supply these demands?
 
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vern spoke to WB this afternoon and was sent a PDF of their recommended system install plan using their LLH. i have attached this PDF. On page 11 of this PDF it shows a full system diagram of how to hookup this LLH.
From what you described earlier about distribution to the underfloor heating manifolds on the secondary flow and return; as i mentioned earlier i have 3 heating manifolds and all the ports on the LLH on the secondary side would be used on the 2 branches for the first 2 manifolds (ground floor and first floor), so how would i connect the 3rd (last) manifold (the loft rooms) using this WB low loss header?
Also since each underfloor heating manifold has a circulating heat pump on its own corresponding manifold can i omit the heating pump in this WB plan just before their Radiators are, i.e where the corresponding new underfloor heating manifolds will be situated? oh no just realised you can't attach the PDF as it is too big a file 🙁 i hope you know what i mean though 🙂
 
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pappasmurf said:
vern spoke to WB this afternoon and was sent a PDF of their recommended system install plan using their LLH. i have attached this PDF. On page 11 of this PDF it shows a full system diagram of how to hookup this LLH.
From what you described earlier about distribution to the underfloor heating manifolds on the secondary flow and return; as i mentioned earlier i have 3 heating manifolds and all the ports on the LLH on the secondary side would be used on the 2 branches for the first 2 manifolds (ground floor and first floor), so how would i connect the 3rd (last) manifold (the loft rooms) using this WB low loss header?
Also since each underfloor heating manifold has a circulating heat pump on its own corresponding manifold can i omit the heating pump in this WB plan just before their Radiators are, i.e where the corresponding new underfloor heating manifolds will be situated? oh no just realised you can't attach the PDF as it is too big a file 🙁 i hope you know what i mean though 🙂
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I will keep it brief as you really need someone on site!

Option 1.......If you use WB LLH you can common the upstairs and loft F&R's just run the circs to the upstairs UFH manifold and tee off to the loft UFH manifold, 28mm should do it, BUT i dont know the load or length of runs.
No you need a pump from the secondary's to the UFH manifolds the manifold pumps only circ through UFH pipe and mixing valve due to resistance, you also need a pump for each boiler on the primary's making 5 pumps (1 for each boiler =2,.......1 for each manifold=2 as up and loft are common'ed up..... 1 x DHW coil on megaflo........ + 1 bronze for DHW secondary re circs making 9 as you have 3 already on the UFH manifolds built in!!!

Option 2.......Use a broag LLH header which has 2 x 1" primary's for 2 boilers and 1 x "2" secondary's come off in 54mm or 42mm copper with reducing tees as needed for 3 x UFH manifolds and 1 dhw ..Totals pumps 10 as above + 1 pump for loft maifold as it would be not common'ed up to upstairs!

Option 3 ......Junk the 24 Ri ,bash in a 40 CDi (actually 41KW) no LLH Commercial spec grunfos pump for primary's say 42mm copper so 11/2" flanged, 4 zone valves (DHW,1 for each UFH Manifold) with autobypass honeywell DU146........5 pumps = 1 x main 1 x bronze secondary 3 already fitted on UFH manifolds, ensure megflo has a balancing valve fiited on return from coil, to obtain 20 deg diff, as 1/1/2" pump will send it through the coil too quickly on DHW mode only, Autobypass will sort the rest, and UFH manfiolds will look after themselves due to mixing valve etc...........
Aww Cr@p book me a hotel!!!!
 
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You don't always need a LLH
For your set up I'd be looking at weather compensation unit controlling mixing valve and 1 large pump a grundfos magna modulating pump
numynujy.jpg
u4yza4yz.jpg

Disregard the oil boilers
But similar to what you want 3 floors all underfloor with a few rads in a circuit and towel rails in a circuit
And a 500ltr buffer tank
 
vern what have you been smokin!...lol...lol.... man looks like you've had your 3 weetabix today...lol...well done 🙂
i was gonna post on here just now that i think i have also sussed it out aswell; i went for the option 1 aswell, only i went one better in that i thought we could just tee off again from the second floor manifold to the loft manifold without using even the second pump or mzv. checked with wavin today and was advised that with the heating calculations that they had done we should only need 8.5Litres/min (Total) from the downstairs heating pump to supply "All" 3 manifolds and that a standard grundfos pump should be fine. i don't need another motorized zone valve anywhere else on this heating circuit as the manifolds and controls will cater for these anyway 🙂
i can't ditch the 24Ri option as i have just bought this and a second back up boiler is really useful as my neighbours have found out; the hard way!!!....
I have redrawn the WB low loss header circuit to fit my spec and wouldn't mind sending it to you for approval if could have a look for me 🙂
 
gray0689 these pictures look very commercial!...lol... your sending me at a different tangent now 🙁 weather compensation unit/ grundfos magna modulating pump!... i was thinking of using the new grudfos alpha 2 which i think should be ok, pls advise 🙂
 
Here a picture of a broag LLH (very compact black box) it is rated @ 80 - 120 KW, here it is with 2 x WB 30CDI system boilerswith vertical flues, feeding the heat, along side a 300L megaflo

Megaflo2.jpg

Not our best....... but gives you a visual...... we only had 3 days as we had the nursing home shut down, and had to join on to what was there pipe and system wise, and they would not allow us to move the washer or dryer you see in the pics making it very tight!! in this time we had to move some rads fit a new remote repressurisation unit and strip out a packaged burner ACV combi and flue, which was where the Megaflow is now sat

Megflo 1.jpg
 
I don't know the size if your house that one was 6500square foot so yes it was verging on light commercial
Alpha 2 is a good pump
But I'm sure 1 will not be enough
Will there be any radiators in house or towel rails?
 
Nice work too Vern. Lots of plumbing smut on here tonight for us trully sad gits.
 
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vern that is a very impress install
Grays0689 yes there will be 4 towel rails in all the shower rooms. why did u say that it wont be enough 🙁((
 
pappasmurf said:
only i went one better in that i thought we could just tee off again from the second floor manifold to the loft manifold without using even the second pump or mzv.

🙂
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if you read option 1 lol i used the term common'ed up same as above
 
Pappa Smurf, you need to hire someone like the two gents who have posted photos to do this. It can't be done by your average jobbing plumber. Doesn't matter that what you want isn't a nuclear power station. It is still very far removed from bread and butter work for most guys.

If your pockets are deep enough, then get one of these blokes down to do it. The problem is, no one is going to want to spend hours speccing and designing this, only for you to give the job to some one else.

I've done a fair few big systems, but it's not my average day at the office. You need to speak to some one who is doing this every single day.
 
vern said:
Here a picture of a broag LLH (very compact black box) it is rated @ 80 - 120 KW, here it is with 2 x WB 30CDI system boilerswith vertical flues, feeding the heat, along side a 300L megaflo

View attachment 8502

Not our best....... but gives you a visual...... we only had 3 days as we had the nursing home shut down, and had to join on to what was there pipe and system wise, and they would not allow us to move the washer or dryer you see in the pics making it very tight!! in this time we had to move some rads fit a new remote repressurisation unit and strip out a packaged burner ACV combi and flue, which was where the Megaflow is now sat

View attachment 8504
Click to expand...

Looks good for the room you had mate
Nice work
 
If you go with weather compensation with mixing valve and one pump you can still have a towel rain circuit no problem
 
Gray0689 noooooooooooooooo more to think about! .......bo ho bo ho bo ho 🙁
 
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