Heating Calculation help

merlynthewizard

Can any explain this equation

shane0007

merlynthewizard wrote: »

Can any explain this equation

Where have you picked it from?

merlynthewizard

a design heating requirement question. A building has a design requirement of 35kw at a design temp difference of 22 degrees c..the building has a seasonal efficiency of 85%
My correction factors for the building and the 8hrs a day, 5 days a week the heating is running is Week length .75, hrs per day for 8hrs is factor 1 and the intermittent slow system for a light weight building is .7

degree days per annum is 2296

How i slot all that together to get an answer i do not know.

gifted

Ok, If a plumber is meant to know that then I am soooo out of touch with my trade...:eek:

shane0007

merlynthewizard wrote: »

a design heating requirement question. A building has a design requirement of 35kw at a design temp difference of 22 degrees c..the building has a seasonal efficiency of 85%
My correction factors for the building and the 8hrs a day, 5 days a week the heating is running is Week length .75, hrs per day for 8hrs is factor 1 and the intermittent slow system for a light weight building is .7

degree days per annum is 2296

How i slot all that together to get an answer i do not know.

I have never come across that calculation. I would more so go on material & construction component U values to determine exact heat losses. I have very detailed forms to enable accurate individual room losses to the point of room temperatures between external walls but also internal walls where the room beside it would be warmer than outside.
Delta T of 22C would not be accurate as it would depend on the room. Generally, design delta T would be outside -3C, kitchens, living rooms, etc would be 20C to DT would be 23C but bathrooms would be 22C so DT would be 25C. Bedrooms 18C so DT would be 21C.
Seasonal efficiency of home would be very useful to know, but not one I have used before.
Increase room design temps by 2C for elderly.
Pipe work losses should also be taken into account, usually 10% of system is best practice.

I would definitely like to know more on your calculation, if you have something to share that would be great.

Dtp79

gifted wrote: »

Ok, If a plumber is meant to know that then I am soooo out of touch with my trade...:eek:

Looks like quite a basic formula

merlynthewizard

Best i can work out is to do 35/22-1*2296*24(0.75*1*0.7/85)

shane0007

merlynthewizard wrote: »

Best i can work out is to do 35/22-1*2296*24(0.75*1*0.7/85)

But what is the 15.5?
Also why are you using the T0 as 1. I would have assumed the T's are design temp & outside or something to that affect.

merlynthewizard

shane0007 wrote: »

But what is the 15.5?
Also why are you using the T0 as 1. I would have assumed the T's are design temp & outside or something to that affect.

inside and outside temp? 22 inside..guessed 1 for outside. maybe try 2296*15.5 in the middle

shane0007

merlynthewizard wrote: »

inside and outside temp? 22 inside..guessed 1 for outside. maybe try 2296*15.5 in the middle

General areas inside would be 20.
Outside generally designed to be -3.

Still not sure what the 15.5 could be.

Where did you pull the equation from?

gifted

Dtp79 wrote: »

Looks like quite a basic formula

I was out sick that day in college :pac:

shane0007

gifted wrote: »

I was out sick that day in college :pac:

I agree. It's not a standard calculation for sure.
I have yet to see seasonal efficiency for a building. I can certainly see the benefits of having this & would love to have a means of calculating this accurately.

gifted

I'm digging through my old folder I had when i was an apprentice and no sign of it, even gone through notes I had for doing city and guilds and no joy so he's made that up...thats it...he made up that formula..:D

Outkast_IRE

It looks like something you would get in one of the CIBSE books (Chartered institute of Building Services Engineers), they are very good books but must be looked at in their entirety.

A lot of these formulas would require you to account for worst case scenario outside temps which people generally use -10 for in this country. Most of the cibse formulas are intended for use in large commercial, industrial buildings.

They do have simple formulas for heat loss etc.

Dtp79

gifted wrote: »

I was out sick that day in college :pac:

I was out sick alot of days in collage!!

gifted

I miss college..:P

Dtp79

gifted wrote: »

I miss college..:P

Who wouldn't miss getting paid 400+ a week to go to college. I loved athlone!

gifted

Went to RTC, now CIT, parents house only across the road from it, back then the company paid us while we were out there, brilliant getting cheque in the post every thursday morning..not so brilliant when i was docked a whole week for missing time :pac:

Dtp79

gifted wrote: »

Went to RTC, now CIT, parents house only across the road from it, back then the company paid us while we were out there, brilliant getting cheque in the post every thursday morning..not so brilliant when i was docked a whole week for missing time :pac:

I'd say in phase 4 I was hungover more often than not

gifted

I was on block release when Kentz went bust and the class was packed with Kentz apprentices, so packed that they had to split the class when the practical exam was on. I done the exam on the first day and the other half done it the next day so of course a few of us headed up to the outpost for a few...a few hours later I ended up in the workshop warped out of my skull trying to give a fellow I knew money, jesus the instructor ****ed me out of it..but he never reported me

Dtp79

gifted wrote: »

I was on block release when Kentz went bust and the class was packed with Kentz apprentices, so packed that they had to split the class when the practical exam was on. I done the exam on the first day and the other half done it the next day so of course a few of us headed up to the outpost for a few...a few hours later I ended up in the workshop warped out of my skull trying to give a fellow I knew money, jesus the instructor ****ed me out of it..but he never reported me

De good auld days

sullzz

Dtp79 wrote: »

I was out sick alot of days in collage!!

Is that why you can't spell " college ":D

Dtp79

sullzz wrote: »

Is that why you can't spell " college ":D

Ha probabely !

sullzz

Dtp79 wrote: »

Ha probabely !

Your ok , I did phase 4 in athlone , the plumbing lecturers weren't too good at teaching English

Dtp79

sullzz wrote: »

Your ok , I did phase 4 in athlone , the plumbing lecturers weren't too good at teaching English

Jaysus who knows... We could have been in the same class!!

sullzz

Dtp79 wrote: »

Jaysus who knows... We could have been in the same class!!

Coulda been , think I was there about 2003

Dtp79

sullzz wrote: »

Coulda been , think I was there about 2003

Me too I think

scudo2

shane0007 wrote: »

I agree. It's not a standard calculation for sure.
I have yet to see seasonal efficiency for a building. I can certainly see the benefits of having this & would love to have a means of calculating this accurately.

Big boiler for big building.
Small boiler for small building.
Big radiator for big room.
Small radiator for small room.

Only jokeing. I'm totally impressed. Like some of the others I was outside having a fag when this equation was explained and so I had to buy the three rotary disc caculator.

Ps only jokeing ok. You know that you know your stuff.
But can you bend a pipe?

shane0007

scudo2 wrote: »

Big boiler for big building.
Small boiler for small building.
Big radiator for big room.
Small radiator for small room.

Only jokeing. I'm totally impressed. Like some of the others I was outside having a fag when this equation was explained and so I had to buy the three rotary disc caculator.

Ps only jokeing ok. You know that you know your stuff.
But can you bend a pipe?

Yes, I can.

Also it's called a Mear's calculator, that three wheel rotary thingy....

scudo2

gifted wrote: »

I was on block release when Kentz went bust and the class was packed with Kentz apprentices, so packed that they had to split the class when the practical exam was on. I done the exam on the first day and the other half done it the next day so of course a few of us headed up to the outpost for a few...a few hours later I ended up in the workshop warped out of my skull trying to give a fellow I knew money, jesus the instructor ****ed me out of it..but he never reported me

Remember Jimmy the witch, plumbing store keeper in CIT ?
PS. I'm talking 27 years ago. I spent more time in SR. HENRYS with him than in class.

esox28

Athlone 2003...Charlie 's for a pint of soup.....im mean a pint with your soup I think, there was no talk of resession in them day's.

What was the lecturers name, the Dublin guy had a beard he was head buck cat when I was there, he was always looking for a lift home to Dublin on a Friday evening. Good guy though and great times.

gifted

scudo2 wrote: »

Remember Jimmy the witch, plumbing store keeper in CIT ?
PS. I'm talking 27 years ago. I spent more time in SR. HENRYS with him than in class.

Was he a biker dude with a ZZ top beard? Richard Crowley ( RIP) was the instructor I had ..sound man he was.

Dtp79

esox28 wrote: »

Athlone 2003...Charlie 's for a pint of soup.....im mean a pint with your soup I think, there was no talk of resession in them day's.

What was the lecturers name, the Dublin guy had a beard he was head buck cat when I was there, he was always looking for a lift home to Dublin on a Friday evening. Good guy though and great times.

Pat I think

sullzz

Dtp79 wrote: »

Pat I think

Ther e was another lecturer from Roscommon , Robert I think his name was , he used to try and get lads to do nixers with him in the evenings , he couldn't say cylinder correctly it used to bug the hell out of me ..... Clinder. :mad:

Dtp79

sullzz wrote: »

Ther e was another lecturer from Roscommon , Robert I think his name was , he used to try and get lads to do nixers with him in the evenings , he couldn't say cylinder correctly it used to bug the hell out of me ..... Clinder. :mad:

Ye that's him

sullzz

Dtp79 wrote: »

Ye that's him

He's the only instructor i can remember from there , I don't know if its because its 10 years ago or the fact that the amount of beer consumed killed my brain cells ..... I wonder are any of the houses in willow park still standing.

Dtp79

sullzz wrote: »

He's the only instructor i can remember from there , I don't know if its because its 10 years ago or the fact that the amount of beer consumed killed my brain cells ..... I wonder are any of the houses in willow park still standing.

Drove by there a few months back. Very dreary looking place now

scudo2

gifted wrote: »

Was he a biker dude with a ZZ top beard? Richard Crowley ( RIP) was the instructor I had ..sound man he was.

Jimmy was the biker dude. (RIP also I afraid) a good friend also.

esox28

Yea pat that's right, used to let us were our hoodie up in class, something about if we were insulated our necks and kept warm we would learn more. Loved telling the story bout his roof snow not melting before all his naighbours cause it was so well insulated.

Rob...the badger formally known as, sound guy seen him other day at the tullamore show.

esox28

I'm I the only one here who got lost trying to get outa willow park the morning after the night before.

Dtp79

esox28 wrote: »

I'm I the only one here who got lost trying to get outa willow park the morning after the night before.

By god yer not

sullzz

esox28 wrote: »

I'm I the only one here who got lost trying to get outa willow park the morning after the night before.

Haha , I got lost going into the estate after a night out , had to park my car further down the road from the house earlier in the day as road was full of cars, came home from the session , couldn't remember where the house was , staggered up and down the road pressing the central locking button on the car keys trying to follow the flashing indicators , best nights sleep down there and it was in the car

braka

merlynthewizard wrote: »

Can any explain this equation

Not an expert in any of this building energy calculations....but Equations interest me for Mathematical reasons.
Have a look at :

http://www.cedengineering.com/upload/Heat%20Loss%20Calculations%20and%20Principles.pdf

also DD appear to be Degree Days.... see Met Eireann website

http://www.met.ie/climate/degree-day.asp

and also:

http://www.guntermannengineering.com/images/A%20Simplified%20Degree%20Day%20Method%20for%20Commercial%20and%20Industrial%20Buildings/scan.pdf

Hope these help.

shane0007

braka wrote: »

Not an expert in any of this building energy calculations....but Equations interest me for Mathematical reasons.
Have a look at :

http://www.cedengineering.com/upload/Heat%20Loss%20Calculations%20and%20Principles.pdf

also DD appear to be Degree Days.... see Met Eireann website

http://www.met.ie/climate/degree-day.asp

and also:

http://www.guntermannengineering.com/images/A%20Simplified%20Degree%20Day%20Method%20for%20Commercial%20and%20Industrial%20Buildings/scan.pdf

Hope these help.

Excellent, well done. That's a good explanation of DD @ average of 15.5C.

shane0007

OK, so what I make from it is:
E heating = Overall kw demand required
Q heating = Overall collective heat loss of the building, as a U value
T Ai = Inside air design air temperature (commercial given as 18C)
T Ao = Outside air temperature (given as average outside temp, lowest + highest / 2)
DD = 18C
Correction Factors = 1 for full use or percentage of 1 for partial use
N seasonal = Seasonal efficiency of the building (a separate calculation)

Well done Braka