Central heating question. Should i use a Manifold???

MARTY_macfly

Hi all i am looking for some info and some help on plumbing and heating.

Ok ill try explain it best i can. We have started work on a single storey extension to the rear of our existing 2 storey house and we are also renovating the rest of the house, insulating, updating the heating system, new floors etc etc. I am doing alot of the work my self as i am very "handy with my hands" altho my backround is an Architectural Technologist.

The house is currnetly heated by oil and this is to be changed over to an A rated gas condensing boiler. I have come to a halt as i am finding it hard to get a plumber at the right price and that i can trust to do the job the way i want, plus i am also lost on what is the best way to do this.
My idea is to have the existing H/W clylinder replaced with a 200/250 ltr dual coil vented cylinder ( allowing for the addiation of solar later next year which i am qualfied to install). I was wondering as i still need the heating system working while i am living here working on the house can i all the pex first fixing for the new rads be done back to a central location so that they can be feed from a manifold? I take it that the new flow and return from the new gas boiler will go to the manifold then this manifold will have its independant flow and returns to all my radiators? If this could be done it would give me the option of just adding adiational rads later on without much hassel as i can simply plumb them to the new manifold? Have i lost the plot or can this be done. It makes sense to me.

Also we will have a wood burn (room heat only) this is to be located in the (living room / kitchen / dining room) open plan of about 36sqm. If there are trvs on the 3 rads in these open plan rooms will the rad shut off when my burner is lighting as i am a little be confussed on trvs? The burner is bout 7kw by the way.

I would appreciate a plumbers view on this please, tho all comments are welcome. Thanks again for you time, this is my first thread!

Chear Marty.

brianc27

what sort of controller you using with that, a lot of people seem to be going back to vinyl, maybe give that a shot

MARTY_macfly

How do ya mean controller.

Scubadevils

Moved from DJing and electronic music - this seems a better home for a thread about erm, plumbing.

MARTY_macfly

ffs. Great help this thread was so!

jjd

I used manifolds for my oil central heating with no problems
3 bed bungalow so all the plumbing was done in the attic stud partition walls so i drilled in from above and fed the pex down through the walls to the rads

ran all the pex back to central location a & bought 4X 4port ( Chadwicks did not have any 8 port) manifolds that you could screw together to make 2X 8port manifolds 1 for flow & 1 for return connected 7 rads blanking plug on the last port of 1 manifold & length of pex with an auto air valve on the other

put 6 thermostatic rad valves & locksheild valves on main rads & on the bathroom put 2 locksheild valves to allow the water to flow if all the thermostatic valves closed
bit of a pig to bleed as the flow & return pipes 3/4" are above the rads in the attic with 1/2" pex down to the rads
closed loop with a 12ltr expansion tank on the return circuit
works a treat as the rads heat up in about 10 mins the thermostatic valves stop the flow of hot water into the rad when it gets up to temprature forcing the hot water on to the next rad & so on
only thing i would have done differently in hindsight
should have put gate valves on the flow & return in the attic (Forgot)so that i could partialy drain the system if needed
& should have put a drain tap somewhere in the circuit instead of having to use the drain in the external boiler housing

MARTY_macfly

Finally a reply. Thanks JJD so i havent lost the plot. To me it make total sense and i dont know why every plumbing is not done this way


Sounds like you know your stuff alright are you a plumber by trade and are you looking for work???
At the mo the back to 2 bed rooms and the open plan living, dining kitchen are ready to be first fixed basically the back the whole back of the house. The New cylinder will go in the old hot press on the first floor. I am not ready to removed the old cylinder and disconnect the old heating just yet so my idea was to use the hot press as my central location for my manifold. First fix the the new 1/2" pex for these five new rads back to this location so i can slab and floor these new rooms. When i say first fix i mean i will just run enough pex from the rad position to the manifold position. And then add rads as i go. I will have 12 rads in total. Sounds alot but 4 of these will be tiny rads of only about 400/500 watts.

I have been looking at manifolds online and there are some pretty tastey ones out there. Will the rads with trvs shut down in the room with the wood burner. Thats what i am hoping will happen when i light the wood burner that the 3 rads in the room will shut off as there will be enough heat coming from the fire??

heinbloed

The OP asks:

Will the rads with trvs shut down in the room with the wood burner. Thats what i am hoping will happen when i light the wood burner that the 3 rads in the room will shut off as there will be enough heat coming from the fire??

Yes. That's exactly the job which a TRV is supposed to do.
Once it senses the set temperature it closes, stops the flow.

MARTY_macfly

heinbloed thanks for your reply.

Thats what i was hoping for it to do. Will i need to sets of manifolds to do two different zones?

Have you or any one else heard of a weather compensated heating control instead of a room stat??? I heard that this is much more efficent that a room sta as it keeps a steady flow of a lower temp thru the rads rather than the boiler burning high till it reach the room stat, knockin off and then kicking back in.

What is your view on the idea of have about manifolds?????

All comments still welcome and again thanks for your time people.

heinbloed

Better contact a competent person to design the heating system.


Weather compensation influences the output ("flow"-)temperature of the boiler. Not the room temperature.
To regulate the room temperature thermostats are necessary.
These could be so-called room thermostats (fixed to the walls) or radiator thermostats (fixed to the radiators).

jjd

MARTY_macfly wrote: »

are you a plumber by trade and are you looking for work???
??

No not a plumber just thought i could save a few bob by doing a lot of the work myself
I did work for a precision engineering company for 20 years though
there are some nice manifolds on line with taps for each outlet would be handy if you wanted to change a rad later like i did i underestimated a rad in the front bedroom i had put in a 600 mm X 600 single rad room is only 10 x10
but exposed corner of the house although the rad was roasting it just could not heat the room
changed it for a Double 600 X 600 and worked a charm
If you get rads bigger than you need you can turn down the valve to reduce the heat but if your rads are too small you will be sitting in the cold
i got the control gear programmer / timer and room stat on fleabay (Sunvic)
did not put any seprate zones as there are only 7 rads in a small bungalow
but i am planning to change the Hot water cylinder to a coil type and use the last outlet on the manifolds to heat the hot water will probably put in a electronic valve for that
i used compression fittings with the black inserts on the pex with no problems at all
also make sure to insulate all the pipework i even insutlated the pex inside the stud partition

Outkast_IRE

hey marty i have worked with weather compesnstaion devices on heating systems but to be honest they are overkill for the average domestic situation , money would be better spent elsewhere on the system , no problem with doing a manifold system i would stick to a sealed system for the heating when using manifolds though , there tends to be less hassle with air locks etc after refilling.

Also a lot of the manifolds you are looking at online may also be overkill, if your installing trvs on each radiator then a pretty standard manifold will do ya.

Main things to remember would be if its a sealed system install a safety valve and expansion vessel if they arent incorporated into boiler .
I would also install a manual bypass, they are incorporated into some boilers but i still prefer a manual one.
Also incorporate good automatic air vents near the manifolds and cylinder coil .

MARTY_macfly

thanks jjd. Again fair play to you u know you stuff.
Im kinda afraid to tackle the first fix as im worried when someone comes to do the rest of the plumbing i.e install the new cylinder, boiler etc that they will tell me what ive done is wrong. First fix is pretty handy tho.

MARTY_macfly

Hey outkast.

Nice one for the reply. Its good to get some feed back.
The heating will be a presurised closed circut but the cylinder will be vented.
It will also have two coils one for the solar which hopefully i will install myself. Ive done the fetac solar course a couple of months ago.

On the weather com, i had read up about them and heard that they are very efficent. Is it really over kill for a domestic situation. From what ive heard fairly hight tech and much more advanced than room tem stats. Im not mad about room stats because i heard the boiler will burn lets say 70degress till the room reachs say 20 degress and then shut the boiler off, but the room temp will actaully climb to say 22 then the room temp will have to fall to around 18 before the wall stat kick back in the boiler repeating the cylce. With the comp it will burn at a lower temp keeping a steady flow thru the rads therefore costing less in gas and being more efficent. Is this right or wrong or have a got it totally mixed up..

Are you a plumber by the way?

They do to different jobs.
A room stat tells the boiler what temperature the room/house is at.
A outdoor sensor tells the boiler if it can reduce the heat output to achieve the room temperature given by the room stat, without one the boiler dosen't know when the room is sufficiently warm.

It would be the boiler you choose that should determine the wiring requirements as not all boilers use a room stat to determine room temperature, but most do, when it comes to the wiring keep it simple, simple is good:D

what you would have to be careful of is the temperature you heat the cylinder to, if you get it wrong with weather compensation then you risk legionaries.

As for your description of how a roomstat works, I have never come across temperature swings like that.

MARTY_macfly

Hi garry. Thanks for you reply.
Is that not how a room stat works? If the boiler burns to supply the temp for the room stat and the temp has to climb to reach its desired temp of the room stat i.e 20c then when the boiler reaches that temp it will knock off at eactly 20 degress, will the room temp not actually still rise to about 22 then before falling again. then as the temp drops to the level when the room stat is to kick back in it will keep falling down to around 17/18 before the boiler can get the heat to the rads to get the temp back to 20c. Make sense? Or have i lot the plot???

So does a boiler have a weather com already in it that will take the outdoor temp? I am going to use a 24kw bosch condensiong gas boiler (size giving by heat merchants, and another plumber i spoke to) althought i worked more acurate calcs and it would seem i only need 15kws to heat all rads and h/w so i might get the 18kw bosch instead. Why would they over size so much?

MARTY_macfly

Thanks for your help lads, keep the info coming if ya can :-)

MARTY_macfly

MARTY_macfly wrote: »

Hi garry. Thanks for you reply.
Is that not how a room stat works? If the boiler burns to supply the temp for the room stat and the temp has to climb to reach its desired temp of the room stat i.e 20c then when the boiler reaches that temp it will knock off at eactly 20 degress, will the room temp not actually still rise to about 22 then before falling again. then as the temp drops to the level when the room stat is to kick back in it will keep falling down to around 17/18 before the boiler can get the heat to the rads to get the temp back to 20c. Make sense? Or have i lot the plot???

Anything is possible, but I find that room stats do a job and I have yet to have a complaint of temperature swings like you describe, the sighting of the stat and the type is more important, how would you tell the boiler what temperature your house is at without one, all your doing with a outdoor sensor is turning down the heat output on a warm day, a lot of people turn down the boiler stat manually on a warm day.

I think a heating system is better with a room stat than not, outdoor sensors are ok but you risk under heating your hot water cylinder on warm days, if you keep a installation simple (unless your on top of your game) that's a good thing, I have seen more installations shagged because they were over cooked than installation with room stat issues

MARTY_macfly wrote: »

So does a boiler have a weather com already in it that will take the outdoor
temp?

Some have a position on the PCB to bring one to and some don't, read the manual;).

MARTY_macfly wrote: »

I am going to use a 24kw bosch condensiong gas boiler (size giving by heat merchants, and another plumber i spoke to) althought i worked more acurate calcs and it would seem i only need 15kws to heat all rads and h/w so i might get the 18kw bosch instead. Why would they over size so much?

They are not fitting the boiler, why would they be worried if it's right or wrong?
On commissioning, the boiler output should be adjusted to meet the heating load, so I would find out your heating requirements, you could try getting a BER done, wouldn't hurt.

Carlow52

gary71 wrote: »

As for your description of how a roomstat works, I have never come across temperature swings like that.

There are some CCS one out there that have big gaps in the on off.

Not in regular quality stuff

Carlow52

Carlow52 wrote: »

There are some CCS one out there that have big gaps in the on off.

Not in regular quality stuff

Agreed, it's maybe that householders have adapted to the installation room stat, is the reason I don't get complaints, if a room stat is fitted properly on a system with no circulation issues then it should do the job, it's when they are fitted above tv's, rads & toasters:pac: that they bececome a pain.

Outkast_IRE

MARTY_macfly wrote: »

Hi garry. Thanks for you reply.
Is that not how a room stat works? If the boiler burns to supply the temp for the room stat and the temp has to climb to reach its desired temp of the room stat i.e 20c then when the boiler reaches that temp it will knock off at eactly 20 degress, will the room temp not actually still rise to about 22 then before falling again. then as the temp drops to the level when the room stat is to kick back in it will keep falling down to around 17/18 before the boiler can get the heat to the rads to get the temp back to 20c. Make sense? Or have i lot the plot???

So does a boiler have a weather com already in it that will take the outdoor temp? I am going to use a 24kw bosch condensiong gas boiler (size giving by heat merchants, and another plumber i spoke to) althought i worked more acurate calcs and it would seem i only need 15kws to heat all rads and h/w so i might get the 18kw bosch instead. Why would they over size so much?

They all oversize to cover themselves nothing is worse than an undersized boiler, if they told you a size and it was under they would leave themselves open to possible legal action.

Im just thinking in terms of costs vs benefits.
You have the idea of weather compensation right, it does adjust temp of the water in the heating circuit .
But to me i would see a similar efficency gain by installing high quality digital thermostats in the right postions , and being smart about the postions of thermostats and any motorized valves they control.

Also as i said if it was me personally and i had the space i would be seriously considering , installing a buffer tank and linking both solar and gas boiler to it, you will not get better efficency than a boiler linked to a high quality buffer tank . they are said to improve efficency up to 20% in some systems

MARTY_macfly

how would you tell the boiler what temperature your house is at without one, all your doing with a outdoor sensor is turning down the heat output on a warm day

ok i get ya, so without the room stat the boiler will keep burning until the clock tells it to knock off. So all the weather comp will adjust them temp of the boiler while its burning. I thought they where a little more high tech than that. Will the both work together???


I think a heating system is better with a room stat than not, outdoor sensors are ok but you risk under heating your hot water cylinder on warm days, if you keep a installation simple (unless your on top of your game) that's a good thing, I have seen more installations shagged because they were over cooked than installation with room stat issues.

Once the water is heated above 60 once a week there will be no risk this will kill any legonella. Plus the water will never really be stagnated as it will be constantly in use.
Im prob just being too particular with it am i??? Am i trying to do too much???? Only i I just want the boiler to run as efficently as possible and if it mean complicating it well i dont mind. Its just tryin to get the right person to do the job!



Some have a position on the PCB to bring one to and some don't, read the manual;).

True will have to do my home work if i opt for one.

They are not fitting the boiler, why would they be worried if it's right or wrong? On commissioning, the boiler output should be adjusted to meet the heating load, so I would find out your heating requirements, you could try getting a BER done, wouldn't hurt.[/QUOTE]

Yeah i know they are not fitting the boiler. But they were all talk about giving the room sizings etc so they could work out the total heat loss for each room. The sizes of the rads they cam back with were in my opinion huge. I am insulating the house and have brought down the uvalue of the walls from 1.48 to .27. They just use basic formula for working out the heat loss so i used "stelrads" heat loss caculator and rad size programe. I used all acurate figure with insulation, uvaule of windows sqms of glass, exposed walls etc and rads came back half the size of the ones sized by other people. Which also means less out lay on money. The half of the house that has been insulate (that has no rads) is very + 4kws to my hot water and cam up with a figure of 14kw. Seems low for a 4bed semi-d. Tho the rooms would not be huge as the house is 33 years old. Its prob about 1300sqft or maybe more. ( id have to check my drawings) We are getting a ber done after as per grant rules so we can get back the 700 grant.

Are you a plumber? Are you looking for work???????

Outkast_IRE

Also i believe that the weather compensation valve should just be a mixing valve linking the flow and return to adjust the temp to the rad circuit , the idea would be to split off the flow and return for the coil before the weather compensation mixing valve comes into play.
This way the boiler is always working to a constant temp but you are reducing it via a mixing valve before the rad circuit .

MARTY_macfly

Outkast_IRE wrote: »

They all oversize to cover themselves nothing is worse than an undersized boiler, if they told you a size and it was under they would leave themselves open to possible legal action.

Yeah i under stand that but why have calculations if they over size by so much. Its crazy really. I said it to a couple of guys on was on a solar course and they said, " ya always over size in case ya need new rads" There will be not more new rads going into this house. haha no room, no money!

Im just thinking in terms of costs vs benefits.
You have the idea of weather compensation right, it does adjust temp of the water in the heating circuit .
But to me i would see a similar efficency gain by installing high quality digital thermostats in the right postions , and being smart about the postions of thermostats and any motorized valves they control.

That might be something to think of alright. Thanks for that.

Also as i said if it was me personally and i had the space i would be seriously considering , installing a buffer tank and linking both solar and gas boiler to it, you will not get better efficency than a boiler linked to a high quality buffer tank . they are said to improve efficency up to 20% in some systems

I am changing the h/w cylinder to a 200/250 ltrs dual coil cylinder (open vented) to take solar at a later date hopefully next year as i dont the budget will stretch to it this year. We dont really have the money for the buffer tank but thanks for the advice.


also are you a plumber?

MARTY_macfly

sorry lads think i made a balls of "quotinG" ya this is my first time using this.

Outkast_IRE

MARTY_macfly wrote: »

Outkast_IRE wrote: »

They all oversize to cover themselves nothing is worse than an undersized boiler, if they told you a size and it was under they would leave themselves open to possible legal action.

Yeah i under stand that but why have calculations if they over size by so much. Its crazy really. I said it to a couple of guys on was on a solar course and they said, " ya always over size in case ya need new rads" There will be not more new rads going into this house. haha no room, no money!

Im just thinking in terms of costs vs benefits.
You have the idea of weather compensation right, it does adjust temp of the water in the heating circuit .
But to me i would see a similar efficency gain by installing high quality digital thermostats in the right postions , and being smart about the postions of thermostats and any motorized valves they control.

That might be something to think of alright. Thanks for that.

Also as i said if it was me personally and i had the space i would be seriously considering , installing a buffer tank and linking both solar and gas boiler to it, you will not get better efficency than a boiler linked to a high quality buffer tank . they are said to improve efficency up to 20% in some systems

I am changing the h/w cylinder to a 200/250 ltrs dual coil cylinder (open vented) to take solar at a later date hopefully next year as i dont the budget will stretch to it this year. We dont really have the money for the buffer tank but thanks for the advice.


also are you a plumber?

ya i am a plumber and have worked on many one off new builds so have a good idea of the best options in such cases.

MARTY_macfly

MARTY_macfly wrote: »

I thought they where a little more high tech than that. Will the both work together???

It can be as simple or as funky as you want it to be, you can get a boiler, wire in to it a outdoor sensor, roomstat and cylinder stat(via motorised valves), then when the heating is on you get the impact of the outdoor sensor, as soon as the cylinder calls the boiler disregards the sensor signal until the cylinder achieves temperature, also you can put the boiler I'm thinking of in to auto mode where it monitors the time taken for the heating to achieve temperature then automatically adjusts the boiler output to match the heating load and best position for efficiency.

MARTY_macfly wrote: »

Once the water is heated above 60 once a week there will be no risk this will kill any legonella. Plus the water will never really be stagnated as it will be constantly in use.

Why take the risk? If the sensor is stopping the circuit from reaching 60c then there is a risk, I don't think any cost savings with a outdoor sensor are worth it if you leave even a minimal risk, just my opinion.

MARTY_macfly wrote: »

Im prob just being too particular with it am i??? Am i trying to do too much???? Only i I just want the boiler to run as efficently as possible and if it mean complicating it well i dont mind. Its just tryin to get the right person to do the job!

Nothing wrong with complicated if it's done right, the problems come when you try to put all the pieces together, if it's kept simple there's little to mess up, if it is outside the norm then that's where it can go wrong, if you can try and find a boiler with a decent installation manual and fit as per the instructions that might help.

MARTY_macfly wrote: »

Are you a plumber? Are you looking for work???????

No I'm a gasman, I'm to lazy to install boilers I'm much better at walking around after the fact and having a good bitch:D

MARTY_macfly

Outkast_IRE wrote: »

MARTY_macfly wrote: »

ya i am a plumber and have worked on many one off new builds so have a good idea of the best options in such cases.

Thanks Outkast for your help.
Are you based in dublin? Would you be interested talking about doing some work for me?

MARTY_macfly

gary71 wrote: »

It can be as simple or as funky as you want it to be, you can get a boiler, wire in to it a outdoor sensor, roomstat and cylinder stat(via motorised valves), then when the heating is on you get the impact of the outdoor sensor, as soon as the cylinder calls the boiler disregards the sensor signal until the cylinder achieves temperature, also you can put the boiler I'm thinking of in to auto mode where it monitors the time taken for the heating to achieve temperature then automatically adjusts the boiler output to match the heating load and best position for efficiency.

Anything i do is never simple lol. Thanks for you advice on this



Nothing wrong with complicated if it's done right, the problems come when you try to put all the pieces together, if it's kept simple there's little to mess up, if it is outside the norm then that's where it can go wrong, if you can try and find a boiler with a decent installation manual and fit as per the instructions that might help.

No I'm a gasman, I'm to lazy to install boilers I'm much better at walking around after the fact and having a good bitch:D

I wouldnt be installing the boiler or anything myself id get a plumber in to do that for me. Im just trying to suss out the best way to tell him to do it. If i leave it up to someone else they may just do an easy quck job. Plus i one of those people that likes to know how things are being done!

Being an Architectural Technologist and the lack of construction work my days of walking around and having a good bitch at others people works is sadly over :-(. Tho i do like a good bitch haha.

Thanks again. Feel free if ya think of anything else

Outkast_IRE

MARTY_macfly wrote: »

Outkast_IRE wrote: »

Thanks Outkast for your help.
Are you based in dublin? Would you be interested talking about doing some work for me?

Done in cork so almost as far from dublin as you can get really, but im working full time at the moment anyway . Best of luck finding someone good to help ya out anyway.

MARTY_macfly

Outkast_IRE wrote: »

MARTY_macfly wrote: »

Done in cork so almost as far from dublin as you can get really, but im working full time at the moment anyway . Best of luck finding someone good to help ya out anyway.

Ah b#ll%x. Couldnt be any further is right. Yeah i dont want to end up with someone will do a sloppy job so to speak.

Thanks again ,feel free if ya think of anything else.

M