heating problem

[D_Hailsham]

Apart from having radiators which are possibly too small, you also have a boiler which is massively oversized. This is the fault of the installer, who has only taken the hot water requirement when sizing a combi boiler.

The 824 has a heat output between 6.7 and 19kW and your rads only total 3.8KW. This means that the lowest output of the boiler is nearly twice that of the rads. No wonder there is little difference between flow and return temperatures. It would be worth adjusting d.0 down to about 8kW.

What temperature drop are you trying to get across the boiler and rads when you balance?

 

[Tezzuk1]

thanks

i have reset d.0 to 10 , using the code in d40 and d41 before any ajustment i had 75/74 ive balanced rads only by feel and got a better flow of 75/71 this is best i got ,

system seams to stay on a bit longer now , rads all seam to warm up at almost same time and get hot but flat still never over 16c in this warm weather , i was aiming for a 10c drop at boiler controls , was told this reading can be lower than the actual flow and return temps due to bypass

I belive its rads but as ive said , i make my needs to be 7,000-8,000 in livingroom, the installer thinks 5100 btu he got using MEAR is over sized

But all info contradicts that room temp , trv have to be wide open , flow and return temp

Thanks


Tezz

 

[D_Hailsham]

I was aiming for a 10c drop at boiler controls

The boiler is designed to have a 20C drop between flow and return!

I would still reduce d.0 to 8kW.

What is the d.19 setting? It should be on 2.


On a general note, your system is so badly designed that it could be classed as "not fit for purpose", so it might be a good idea to get in touch with your local Trading Standards department and ask for their advice.

 

[simond]

How can the boiler be sized smaller? There isn't a combi smaller than a 24kw.

Frankly i think you are barking up the wrong tree.

Get the bypass screwed down. Buy some rads the correct size for the rooms, I think this is being over- thought.

 

[D_Hailsham]

How can the boiler be sized smaller? There isn't a combi smaller than a 24kw.

But there are boilers which can modulate below 6.7kW for CH. The OP only has about 4kW of rads (though that may be too little), so he does not need a boiler with a minimum CH output greater than his requirement.

The new Baxi Platinum 2 Combi 28 GA would have been a better choice as it modulates down to 2.4kW.

 

[Tezzuk1]

How can the boiler be sized smaller? There isn't a combi smaller than a 24kw.

Frankly i think you are barking up the wrong tree.

Get the bypass screwed down. Buy some rads the correct size for the rooms, I think this is being over- thought.

as i understand it and this all new to me you can range set these boilers , i belive should be done at install along with balancing rads

but i agree with you on rads , problem is im not customer council is and im expressly forbiden to change anything , i think its a simple fix but as stated i recon rads about 2,000 btu under installers say according to mears the 5,000 they fitted is over

 

[Tezzuk1]

I was aiming for a 10c drop at boiler controls

The boiler is designed to have a 20C drop between flow and return!

I would still reduce d.0 to 8kW.

What is the d.19 setting? It should be on 2.


On a general note, your system is so badly designed that it could be classed as "not fit for purpose", so it might be a good idea to get in touch with your local Trading Standards department and ask for their advice.

D 19 is on 2 and no way i got a 20c drop

 

[Tezzuk1]

ok a simple answer to this would i think would remove all dout what rad do i need

Flat is on Ground floor , Living room 15x11x8 , solid concrete floor not insulated on dirt ,solid concrete ceiling also uninsulated, 1external 11x8 wall with full size DG door and 1.6mx1.8 DGm window pre 2002 so im gussing not the best this wall is 4inch brick with studded out dry lining on inside if i remmber there is a thin layer of insulation , party wall 15x8 is i belive 4inch block with dry ling each side , other 2 walls are just internal 4 inch stud work , i worked on -3 out side and 21c inside

using 3 different calculators i came up with 7,000 to 8,000 , (im told stars best matches mears)
http://www.starsapp.co.uk/
http://www.radcalcs.com/
and the basic lxwxhx5 plus 15% for my poor construction

they have installed a 5100 btu , they said worked out using MEAR end of discussion im wrong, but rooms still cold

so either they are correct or me or we both wrong or we need to look elsewhere

thanks for all your time

 

[vicvapour]

been trying to balance rads ect got flow and returns a bit better on d40 d41could not work out why bathroom rad pipes both hot as in no change even on ajusting locksheild , have now they fitted TRV on return pipe , as i only have 5KW rads turned boiler down to 10KW will see how that gose

One thing i have noticed with this boiler is that even when tuned of over night it uses about 40-50p of gas , im guessing in built frost stat

Hi there, yes this boiler has an integral frost thermostat which is designed to protect the boiler, so periodically it will fire up through the night if the temperature drops to around 3 degrees or below.

 

[Tezzuk1]

thanks that explains gas usage and yes most nites is under 3 in this flat some times cold enough to freeze condensation on inside of double glazing

Thanks

Im guessing working out the rad i need and if my calcs are correct or not is a more complex question than i understood it to be

thanks to all who have posted so far

Tezz

 

[vicvapour]

thanks that explains gas usage and yes most nites is under 3 in this flat some times cold enough to freeze condensation on inside of double glazing

Thanks

Im guessing working out the rad i need and if my calcs are correct or not is a more complex question than i understood it to be

thanks to all who have posted so far

Tezz

No problem, remember also if it is that cold, it might be worth considering Self Regulating Heating Tape installed on the condesate pipe too, if insulation on the pipe is not adequte enough, last thing you want that frozen on a cold winters morning.

 

[D_Hailsham]

as i understand it and this all new to me you can range set these boilers , i believe should be done at install along with balancing rads

That's what d.0 is doing - setting the maximum output. You now have it on 10kW so the boiler will vary its output between 6.7 and 10kW, but that's still more than your existing rads can use.

I'm not customer, council is, and I'm expressly forbidden to change anything.

Who sized the rads and the boiler - a council employee or the installer?

Whoever it was, you need to complain loudly to the Council that the installation has not been properly sized.

Use the Whole House Boiler Size Calculator to find out the heating requirement of your flat. (Set the Domestic Hot Water Allowance to 0kW as you have a combi.)

 

[Tezzuk1]

Oh ive been complaining all right getting no where fast , council say call main contractor as they design it from floor plans, main contractor says call council as they supplied floor plans , i say rads too small main contractor say MEAR says there not , so its like a merry go round , but i would not mind betting im being bullshitted as i seam to rember rad sizes being writen down on a note pad on inspection before install ,but they wont supply me calculations they have for my flat on how they worked it out , then add into the mix the main contractor subbed it out and blokes had 1 day to complete works , which explains why boiler not commisioned properly and i have 1 TRV on return flow and rest on Flow

Bear in mind this is a brand new install and every room was supposed to be min of 21c thats about only fact they all agree on

the one problem i have is even tho iv found 3 ways to calculate rad and all facts point to im correct im not an heating engineer, main contractor says he used MEAR industry standard , council seam to accept this

I just need to know if the experianced heating engineers hear think my calcs are close or way off based on information iv given , that way i can then print of my 3 ways as i will have confidence they are correct give them to council and ask main contractor do same

On plus side HW is great , whole flat now of mains and me bath shower taps like a power shower

i used whole house calc and it came out at 8.3 inc HW

 

[D_Hailsham]

Oh ive been complaining all right getting no where fast

You have my sympathy.

main contractor says he used MEAR industry standard , council seem to accept this,

And the slide rule and log tables were the "standard" for mathematical calculations in the 19th Century.

The Stelrad calculator is reliable. I don't know about the other two - particularly the one which just multiplies the room volume by a number. This was the method used in the 1950's and 1960's before proper heat loss calculations were the norm.

Ask the Council to provide you with the heat loss calculations as you want to get them checked by an independent consultant!

I used whole house calc and it came out at 8.3 inc HW

So that's 6.3kW for heating.

If this is a brand new building, it has to meet the the requirements of the Building Regulations, which give minimum standards for heat loss etc. Did you assume the best standards (cavity filled walls etc) when using the boiler calculator?

Do any other residents have any problems with their heating? If so, you should get together and make a joint complaint to the council. Involve your local councillors if necessary.

 

[Tezzuk1]

No not a new build , old building new heating install from scratch so no reason for any mistakes

Yes i made it 6.3 , which take of kitchen as they say they dont have to heat that , 2 very large walk in cupboards all seam to suggest the amount i make rooms under is about what house calcs show as well