central heating design

[gregd72002]

Hello,

I am renovating my 3 bedroom house and currently dealing with central heating. I got a plumbing 'expert' who designed a central heating for the house:

It is all on hep2o with 22mm manifolds. From there 10mm pipes goes to every room. It looks like this:



As you can imagine this is sub optimal with the long runs. The big radiator in living space takes long time to heat up and never reaches the target temperature (but it is not too bad).

So I'm thinking to redesign this with minimum disruption (as most of the house renovation is finished).

I hope to run 15mm pipes from the manifolds to 3 corners of the house (red line on the diagram) and from there tee off with 10mm (blue line) and 15mm (red line) to each of the radiators. This way the 10mm runs will be relatively short.



Will this work? Will this improve the circulation?

 

[Nostrum]

Is the existing system balanced?

 

[Old Account]

Hello and welcome ,

First thing why would you run all in 10mm pipe why not leaving it in 15 mm ?
The long distance I'd run in 22mm and reduce it down to 15 mm when it connects into the rads so you won't have any issues to get what you pay for.


Secondly did you balance ? Is the system new or old ? Has the plumber installed a new boiler ? If yes did he flush the system ? Or do you have a complete new pipe work and boiler ?

 

[gregd72002]

Hi,

It is a completely new system with new pipes and new combi boiler. We tried to balance it but the living room rad was always around 10 deg less than others.

The system is all on 10mm pipes hence the idea to upgrade some of them to 15mm and cut down the runs for 10mm pipes.

 

[Old Account]

I would upgrade all of them just to avoid having issues in the future. I would not plumb it in 10mm in the first place.

 

[gregd72002]

Agreed, I would not run it in 10mm knowing the issues.

We have pretty much finished the renovation just to realise that the heating does not work well.

So I do not want to open floors/walls/ceilings to replace every single pipe. The re-design I put forward can be done without much mess in the house.

Can I tee a 15mm pipe to feed 2 radiators - one being 5.5m long of 15mm pipe and the other being 4m long of 10mm pipe?

Will this work, will I manage to balance these radiators?

 

[ShaunCorbs]

Agreed, I would not run it in 10mm knowing the issues.

We have pretty much finished the renovation just to realise that the heating does not work well.

So I do not want to open floors/walls/ceilings to replace every single pipe. The re-design I put forward can be done without much mess in the house.

Can I tee a 15mm pipe to feed 2 radiators - one being 5.5m long of 15mm pipe and the other being 4m long of 10mm pipe?

Will this work, will I manage to balance these radiators?

if it doesnt work get the person who installed it back simple

 

[Old Account]

All will work but the question is for how long 4 m in 10mm seems quite long run if you asking me. You can upgrade and T in but also pay attention on fittings I am not a lover of push fits if you have got hep2o

 

[AWheating]

If you read the hep2o guide it should give you info on the max lengths and carrying capacity of its pipe work.

For my rule of thumb on 10mm plastic you want a rad no greater than 1.5kw, a total pipe length in 10mm of no more than 8m (flow plus return) coming off your 22mm main circuit. Not scientific I grant you.

 

[ShaunCorbs]

If you read the hep2o guide it should give you info on the max lengths and carrying capacity of its pipe work.

For my rule of thumb on 10mm plastic you want a rad no greater than 1.5kw, a total pipe length in 10mm of no more than 8m (flow plus return) coming off your 22mm main circuit. Not scientific I grant you.

+1 and thats why your living rad isnt heating up at 2.2kw you would need to up it to 15mm get the installer back who did it

 

[Nostrum]

Have you calculated the flow rates and pipe sizing?

 

[Old Account]

+1 and thats why your living rad isnt heating up at 2.2kw you would need to up it to 15mm get the installer back who did it

That's what I am saying Shaun, why would you do it in the first place with 10mm if you know that 10mm will clock up anyway

 

[ShaunCorbs]

That's what I am saying Shaun, why would you do it in the first place with 10mm if you know that 10mm will clock up anyway

people use it because its easy to use and easy/quick to lay hate the stuff never use it and defo never install it

 

[Old Account]

people use it because its easy to use and easy/quick to lay hate the stuff never use it and defo never install it

I can't understand it but they are the specialists and they should look after their customers. It does my headache if I know I do a bad job just earn money. The end of the day you will loose the customers coz now he has to come back even though he won't charge it just looks bad in my opinion.

Same as those push fits nice and easy and fast to fit but not for long term.
I'd rather take a day longer but all is fine ...

For an emergency or temporary fix that's great but not long term

 

[gregd72002]

Have you calculated the flow rates and pipe sizing?

No, have not done it. Not quite sure how to do it?

 

[ShaunCorbs]

No, have not done it. Not quite sure how to do it?

go back to the expert and tell him hes designs wrong

 

[gregd72002]

He is no an expert but an 'expert'... cowboy if you wish... after he left (2 weeks late), things were missing from my house. I do not want to see him anywhere close to my house!

 

[ShaunCorbs]

He is no an expert but an 'expert'... cowboy if you wish... after he left (2 weeks late), things were missing from my house. I do not want to see him anywhere close to my house!

right contact trading stands and find another heating eng as more things may be wrong with the boiler etc

 

[gregd72002]

I do not have cash for this anymore! I've got a friendly gas safe engineer that is happy to come over and do final checks but not to redesign the entire heating system.

I have to move in in the next month as my current accommodation is being sold.

Will my design work?

 

[ShaunCorbs]

I do not have cash for this anymore! I've got a friendly gas safe engineer that is happy to come over and do final checks but not to redesign the entire heating system.

I have to move in in the next month as my current accommodation is being sold.

Will my design work?

in short no as 10mm will only cope with 1.5kw (rad size) which is just over 5000btu

 

[gregd72002]

Thanks ShaunCorbs, what about the improved design I'm trying to put forward.

Most of the 10mm runs are changed for 15mm
The 10mm runs are kept to bear minimum



Will the kitchen and bedroom above work well with the 15mm reduced to 10mm on the last meter?

 

[ShaunCorbs]

Thanks ShaunCorbs, what about the improved design I'm trying to put forward.

Most of the 10mm runs are changed for 15mm
The 10mm runs are kept to bear minimum

View attachment 22833

Will the kitchen and bedroom above work well with the 15mm reduced to 10mm on the last meter?

red 15mm? if so your overloading that as well normally max is 4kw just over 13000 btu

 

[gregd72002]

red 15mm? if so your overloading that as well normally max is 4kw just over 13000 btu

yep, red is 15mm. Are you thinking about the living room + bedroom? This sums up to 13306btu, or 3.9kw so should be ok.

what about the reduction from 15mm to 10mm above kitchen? does this make sense or should i run 10mm all the way (1+2.5m)?

 

[ShaunCorbs]

yep, red is 15mm. Are you thinking about the living room + bedroom? This sums up to 13306btu, or 3.9kw so should be ok.

what about the reduction from 15mm to 10mm above kitchen? does this make sense or should i run 10mm all the way (1+2.5m)?

left(2) and right(3) bottom over the length is pushing it pas the max tbh

put it this way i would do most/ as far as i could in 22mm

 

[doitmyself]

Where did you get the flow rate of 18.6 litres/min from?

The rads add up to 39101 BTU, which is 11.46 kW. With a 20C differential the flow rate is 11.46/(4.18 x 20) = 0.137 litres/sec or 8.22 litres/min.

I am assuming that the rad outputs shown are actual values, i.e they take into account the flow and return temps, and not those quoted in the manufacturer's literature.

Are the pipe lengths shown the total, i.e flow plus return, or do you have to double the number to give the total?