central heating dilemma

[john1]

hello everyone new to forum and have query regarding my central heating setup.
basically one vaillant turbomax 242 in kitchen.
22mm c.h pipes up to bathroom above and a few feet along.
10mm copper pipes directly joined to this for all rads in house.
10mm pipe to towel rad then progresses 12 feet along landing and down to ground floor 600x1400 one panel single convector rad.then another 12 feet and branches to right to bedroom similar rad.next a few feet and down to ground floor similar rad. a few more feet and at top floor rad.
so only 4 rads and towel rad all fed off same 10mm pipe.
is this ok? towel rad gets hot and first rad on circuit but others poor especially last rad which takes forever and only gets luke warm.system has been powerflushed(not helped much!) and b.g says needs repiping.
willing to get new rads and repiping but only if this would help flow and everything gets toasty hot.
have taken trvs off rads and boiler control on top whack but no difference.
sorry for all the info but hope somebody can give me their professional thoughts on this.

 

[newbie1]

no reason microbore shouldnt get hot..who did the powerflush and using what equip
my son flushed a microbore system and it got toasty hot faster straight away cant see repiping would be needed unless the orig piping has been incorrectly run

 

[Plucky]

System is underpiped, repiping in 22mm with 15mm drops would help greatly.

 

[john1]

powerflushed by birmingham company dont know about equipment but was attached to boiler pump throughout process. rads seemed to get hot with additional pressure whilst being flushed and got some crap out. just thought it maybe something to do with all rads being teed off same 10mm pipe wouldnt 15mm run of main 22mm pipe b better?had quote from c.h engineer who talked of manifolds and seperate pipes to each rad whilst informing me my gas supply pipe which is 22mm reducing to 15mm a couple of metres before the boiler may be the problem. quoted £2200 including new rads? still baffled any other ideas. cheers

 

[Flanners]

The engineer is exactly right.
10mm Flow and return to each intervidual radiator from a 22mm circuit (manifold)

price sounds ok aswell.

 

[john1]

thanks for that so 2 options 22mm to 15mm for rads or 22mm to manifold with 10mm pipes. mmm. but which is better than the other or are both reliable and likely to get reqd flow etc.
thinking of time and materials, on "balance" (get it?) suppose both would cost roughly same.
anyone used any of above regularly when plumbing with consistent results?

 

[timlaz]

hi there,

yeh pipe work is way under sized. you'll need run at least 15mm, and preferable 22mm to first couple of rads (flow and return, not to actually rads) then 15mm thereafter.

tim

 

[Plouasne]

hi there,

yeh pipe work is way under sized. you'll need run at least 15mm, and preferable 22mm to first couple of rads (flow and return, not to actually rads) then 15mm thereafter.

tim

Surly this depends on the radiator size, and the circulator head available ??

This is what get me, on this forum, the amount of bland statements "you need this" with out any qualification to the statement

 

[stevetheplumber]

Surly this depends on the radiator size, and the circulator head available ??

This is what get me, on this forum, the amount of bland statements "you need this" with out any qualification to the statement

its not rocket science plousane were looking at a domestic premesise with a 24kw combi available pump head is fixed by the manufacturers rads are not going to be huge so we can use our experience to make sweeping statements theres always loads of ways to skin a cat but the end results will be the same
personally id rerun the rads in ten mm back to the 22mm f and r you can actually run 2 small rads of one pair of 10mm pipes as ive done it when an extra small rad was wanted in a previously unheated toilet babc to back with a towel rail

 

[david williams]

skin your cat as you like(do you have a foul traders licence if you intend to ) but you can not push the energy needed for the rads fitted through such a small pipe

 

[john1]

thanks gents got more ideas from this site in a few hours than any book & other sites. seems everyone has their own preference as with most things in life- i say tomato you say tomato!
will extrapolate, conjugate, disect and disemmenate and when ive finished looking in the dictionary to c what that means probably get last word on subject from registered gas man whos servicing our fire tomorrow.
if anyone has any last comments on subject feel free.

 

[smoggs03]

as a rule of thumb i wouldn't feed more than 2 rads of 15mm pipe on a new install. 22mm circulating pipes(or larger when req). i never have bother balancing. so put that up against what you have.

 

[P4ULT]

also 10mm is likely to give you more problems than 15mm in future.

 

[stevetheplumber]

what is the general hatred of microbore on here ? i go to a house where i fitted copper microbore nearly 30 years ago and still working fine sealed sytem always fernoxed
the original boiler was a flexiflame(great boiler no electrics could be fitted in bath room ) which lasted nearly twenty years now running a vailant 242 combi

skin your cat as you like(do you have a foul traders licence if you intend to ) but you can not push the energy needed for the rads fitted through such a small pipe

that realy does depend on the size of the rads

 

[smoggs03]

i hate microbore because i always see it tee'd feeding a few rads.. etc.. i work for a big company who employ sales advisors who advise a new boiler!! so there you are @ 4:30 all ready to go but alas rad not hot....... that and blockages ..... worked alright before....

 

[John Flower]

Micro bore is fine on sealed systems which have been cleaned and dosed with the correct inhibitor. To do the job properly you need to size the pipework to suit the size of the rad. Too many times have i been to jobs where there has been multiple rads on 15mm or 10mm and the system takes ages to warm ect. If you are replacing rads or fitting a new system then it pays to design the flow rates /pipe /rad sizes correctly as it cuts out any call backs at a later date. Typically the client will always say that the system worked fine before you came. So it pays to check over the system to note any design faults and point these out before you start.

 

[Plucky]

Ive fitted several systems using 10mm plastic, each rad with its own flow and return to a manifold. System works extremely well. All balancing is done on manifold.

Microbore is crap when idiots install more than one rad of a 10mm run.

 

[jpm]

only feed 1 rad off 10mm pipe,end of!Microbore is great to work with and it looks tidy too,now nearly the same price per metre as 15mm BTW!!!But you can only feed one rad per run,water takes the easiest route ALWAYS and will not flow through a rad when there is an easier option.

 

[migoplumber]

not gonna bother working out the energy you can push through a 10mm pipe, however as steve says 10mm will run most domestic rads quite happily and without a problem, also running 10mm from a manifold to individual rads is a very good system design and easy to maintain, flush, and balance!

 

[Plouasne]

10 mm microbore will be sufficient to supply a 3.5 kW rad with a head loss of 0.247 mt / mt run, its all listed nice and easy in the link

http://www.ukcopperboard.co.uk/literature/pdfs/pub-150-copper-tubes-in-domestic-heating-systems.pdf

 

[migoplumber]

good link plousanne, many thanks.