Boiler & radiator size query.

[Stivino]

About eight months ago I had central heating fitted in a house that's never had any heating in before.
It's a four bedroon semi on two floors with a concrete ground floor and wooden floorboards upstairs.
The boiler and radiators were supplied to the house the day before installation started and sat overnight in the spare bedroom where the computer is.
As the boiler was sitting next to me in it's box I noticed the make and model of the boiler. It was http://tinyurl.com/bsxryjy
AS I had noticed it said "Junior" on the box it got me thinking. So I looked at the makers website and it said "They’re suited to apartments and small to medium sized properties with 1 bathroom"
As I had intimated to the installer that I was going to be putting another toilet on the house and had asked him to leave provision for this, I thought I'd quiz his choice of boiler.
He assured me it was adequate but, I showed him the website and said I'd be happier if he fitted a larger boiler. So, he fitted the 30CDi combi.
Now, for the past few months when I've been putting the heating on the house is still very cold and the heating is hardly noticeable.
I wonder if it's possible that he's under estimated the whole job and I'd like some opinions on the choice of boiler, radiator sizing and positioning etc.
I'm in the process of fitting new carpets and decorating upstairs and would like to be sure that it's right before I put all the floor and carpets back upstairs.

EDIT; I've just noticed that where the asterixs are, it says kweery,

 

[PlumbGas]

30 cdi would/should be fine for a 4 bed, there are so many variables though it's difficult to say, has the system be balanced ?, whats the boiler stat set to ?, how big are the rads ?, how big are the rooms ?, how big are the windows ?, are they double glazed ?, how many outside walls, north or south facing, insulation in the walls, building material and the list goes on, call back the installer to discuss what your concerns are

 

[ALEC1]

and what about the pipe sizes?

 

[Agile]

Did he set the weather comnpensation curve correctly for your property?

 

[Whitespirit66]

Combi boilers are usually sized for their hot water performance, the CDi will be better than the junior in this respect. Both should have ample capacity to heat you house. Combis usually struggle when there are several hot taps, showers on at the same time.

Your boiler may have the required power for ch, but you need to find out if the the rads are up to heating the rooms they are in.

http://www.radcalcs.com/

What temp are you setting your room stat to, and does the house ever reach this temp?

 

[Stivino]

The radiators are all made by Purmo and the rads in the bedrooms all measure 600mm deep by 800mm wide.
One upstairs bedroom measures 2.5M wide X 4.3M long X 2.55M height. it has two outside walls, one facing North and one East. It has 2M² of window and the ceiling is insulated in the attic. And it's baltic in there.
The boiler is turned almost to full up and if I set the room stat to 20°C it won't reach it.

 

[PlumbGas]

The radiators are all made by Purmo and the rads in the bedrooms all measure 600mm deep by 800mm wide.
One upstairs bedroom measures 2.5M wide X 4.3M long X 2.55M height. it has two outside walls, one facing North and one East. It has 2M² of window and the ceiling is insulated in the attic. And it's baltic in there.[/quote

http://www.radcalcs.com/
Do the calcs yourself from this link

 

[Stivino]

Thanks, I've done that calc and the result seems to say that I need a 5409BTU radiator in that bedroom. When I look for one equal to that at this website http://tinyurl.com/bqglfzc it looks like I need the radiator to be twice the size.
Am I correct in thinking this?

 

[PlumbGas]

Thanks, I've done that calc and the result seems to say that I need a 5409BTU radiator in that bedroom. When I look for one equal to that at this website http://tinyurl.com/bqglfzc it looks like I need the radiator to be twice the size.
Am I correct in thinking this?

That would suggest the Rad you have is very small for the room yes, assuming you followed the Calc, it also depends on if the rad is a double panel, double convector or single panel, single convector etc, also what about all the other comments about, pipe size, stat temp, weather comp, etc, all these things also have a bearing

 

[Stivino]

I think I followed the calc correctly.
I don't know anything about weather comp but the rest I can answer, I think.
It's a single panel rad, they all are except for the one in the living room.
Purmo 600mm x 800mm K1 Single 794 watt - 2708 btu
The pipes under the floor all look like 10mm after the manifold.
I usually have the stat at 20 but it doesn't seem to matter what I set it at, it never feels warm in any room except the living room because there's a gas fire in there too.

 

[Agile]

Nowhere have you explained who installed this heating system and who chose the rad sizes.

The general requirement is for the system to attain 21 C when its -1 C outside.

If it does not the the rads are undersized and normally the installer will be legally liable to have to upsize them at his cost!

But that would involve taking him to court and if he lives in a council estate or gipsy camp he may have no assets to claim against!

Thats why chosing a suitable installer is very important ( unless you are a litigation barister! )

Tony

 

[Stivino]

Thanks for your input, tony.
The installer was a local heating engineer and it was he who chose the boiler and radiator sizes etc.
I've never been able to raise the temp to 21C.
And, although my partner is a lawyer, I'm not going to go down that route. If I need modifications done, I'd like to do it now, while I'm still doing renovations.
I'm just wondering if he's underestimated the whole system. Can the radiators really only be half the size they need to be? And, if I need to double the size of some/most of them, will the boiler be able to cope with all that?

 

[Whitespirit66]

Can the radiators really only be half the size they need to be?

And, if I need to double the size of some/most of them, will the boiler be able to cope with all that?

Yes and yes.

Don't worry about your boiler, 30kw is plenty for the ch. More than enough. Always better to slightly oversize rads - 20% over seems favourite. This helps your home heat up quicker, and modern condensing boilers run more efficiently like this.

 

[Stivino]

Thanks for your advice.
Would it be a good idea to replace some of the small radiators with one larger single radiator and use the old smaller one(s) to put two into another room. i.e. two in some rooms. Or, should I replace them all and throw the small ones away?

 

[JohnD]

Quite possibly, but we don't yet know what the size of your existing radiators is, or the size of the house.


Have you got cavity wall insulation and 250mm quilt in the loft? How are the windows and doors for draughts?

What heating controls have you got, and what hours does the CH run?

What's your average gas meter usage, in cubic metres per day?