pipe sizes for complete heating/DHW system

[Gray0689]

If your in London there is a couple of boys on this site who could possibly help you out
But you do relies you will have to have a large budget
Ps you will also need a secondary return on hot water

 

[AWheating]

AWheating your suggestion on my neighbours installation is much appreciated. but lets come back to my spec 🙁
That link you've sent is a company based in Leicester!.... surely there must be a company in London (The centre of the universe)?

was it not you who asked about the issues with the pictured install? so why sad face?

as regards the company i linked they dont need to visit your house (although probably best) to do you a design if you have full set of building layouts they can use them to create the design. If you want to find one in london use google as i did to find the link i gave, try abit harder! as its the cenre of the universe there should be loads or phone british gas.

 

[WHPES]

Look for plumbers who have been established ages and have a good reputation locally.

 

[vern]

I love jobs like this done a fair few, but your too far!

If you go for the 300 l megaflo, get the titanium option kit, it basically another 3 kw immersion heater and stat, that goes in the standard cylinders blank, it will come with 1 x 3 kw immersion as standard, meaning you have hot water back up if a pump or boiler goes down, an electrician can wire via 2x2.5 mm cables back to your consumer unit depending on length of run etc...

As others have said use the secondary return tapping, pipe in 15 mm Do not use any plastic if you intend to run the loop 24 hrs a day or it will leak within 2 years, use copper, if the loop is timed you can use plastic, but do a proper job and use copper.

28 mm cold feed off 32 mm PE should be fine, as the PRV and outlets are only 22mm compression anyhow, BUT if you have a lot of occupants or intend to use multiple showers or outlets go for the megaflo commercial it has a 6 bar PRV as standard and much bigger inlets and outlets, I need to visit site to spec accurately!

i will post up how to do the boilers in a bit.

 

[vern]

Regards boilers.....
i assume you have a domestic gas meter a U6' which can pass 6 m3 per hour, 2 x 24 RI's on full chat will use around 5.2 m3 per hour depending on return temps, if you have a range cooker and gas fires this needs to be taken into consideration as you may run into gas pressure inlet problems (a good installer will know this)

Connect 2 x 24RI's via the Bosch low loss header, it has 2 inlets sets for 2 boilers, and 3 x outlet flow and returns, use one set of outlets for the hot water cylinder, 2nd for the UF heating manifolds downstairs, 3rd for UF heating manifolds upstairs.
do not Connect the boilers separately as you have no back up of a tandem system, also do not tandem them up in reverse return as you loose the efficiency and balance of a low loss header!

Pumps, pipework, expansion vessel etc etc sized to suit site and system conditions.

 

[pappasmurf]

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

 

[pappasmurf]

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?

 

[pappasmurf]

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 🙂

 

[Howsie]

Post up on the plumber wanted section. This isn't a complicated set up at all.

 

[vern]

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 🙂

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!!!!

 

[Gray0689]

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

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

 

[pappasmurf]

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 🙂

 

[pappasmurf]

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 🙂

 

[vern]

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



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

 

[Dannypipe]

I always love pics of Gray's (Alex) work.

Just art. Always brilliant work.

 

[Gray0689]

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?

 

[Gray0689]

I always love pics of Gray's (Alex) work.

Just art. Always brilliant work.

Thanks Danny but I'm sure your work every bit as good and better

 

[Dannypipe]

Nice work too Vern. Lots of plumbing smut on here tonight for us trully sad gits.

 

[Dannypipe]

Thanks Danny but I'm sure your work every bit as good and better

No mate, it's not! LOL.

 

[pappasmurf]

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 🙁((