hi all. getting a new system boiler . need about 27 kw for ch & hw . was gonna get a veissmann vitogen 200 30 kw system boiler but i am also concidering the A series atag 32 kw system & the worcester bosh 30cdi system . both of these modulate down further than the viessmann (8.7) atag 6.1 . bosh 7.7 . Whats the backup etc like for the Atag in the midlands .
Atag , viessmann 200 or worcester bosh
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concidering considering bosh bosch
If you had stuck in at school you would have learned to spell. There is even an automatic spell check on this thing (though american spelling so as before) so no excuses really
i am also concidering the A series atag 32 kw system & the worcester bosh 30cdi system . both of these modulate down further than the viessmann (8.7) atag 6.1 . bosh 7.7 .
Why would you want/think the best, is the lowest modulating boiler? Do you think you will burn less gas if it modulates lower?
Don't expect a same day call!
Btw don't take this personal. It is late, i have been reading some amount of pysh and i am not in a very tolerant mood.
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i did a very comprehensive heat load calc via stelrad stars prog , it came out at needing a 27 kw boiler at 65 mwt
27kW is a lot for a system boiler. You must have either a very large house or one with very little insulation!
May I suggest you do a whole house calculation using Sedbuk Boiler Calculator or EST online boiler calculator
To prevent incorrect answers, please note that Length and Width are internal dimensions and Height is room height (floor to ceiling). External walls are those open to the elements, i.e not a party wall.
If you need 25 kW of heating then the annual gas bill will probably be well over £2000 depending on how many hours of heating you use.
Can you give a description of the size? E.g. six bedroom detached with solid walls and only 100 mm loft insulation for example.
Tony
its an old 4 bed plus attic room detached with around 50% cavity ( with insulation ) & 50% solid walls . i have spent the winter insulating the loft & the attic walls etc with 30cm of insulation . its got old upvc dbl glazed windows ( 50 sq meters ). house has total floor area of 210 sq metres . its at the top of a hill and very exposed . i did the whole house method first & it came to 18.15 kw heat loss . the stars prog came out at 21kw heatloss . i set the mwt to 65 as advised and stars prog said i needed 27kw with the hot water with the bigger rad sizes on 65 mwt. one thing i wasn,t sure about was the ceiling temp in the program for the bedrooms . it automatically defaulted to -3 . so i assume thats the worst case loft temp .
i used minus 3 as the design temp . not minus 1 .
As far as I am aware its still the standard way to calculate boiler sizes using a -1°C in England as advised by EST etc.
I would still expect the correct boiler size should be closer to 20 kW.
As a matter of interest what addition, if any, have you made in each case in respect of water heating?
Tony
I would still expect the correct boiler size should be closer to 20 kW.
As a matter of interest what addition, if any, have you made in each case in respect of water heating?
Tony
Tony , why cant you accept that the guy has worked it out correctly? He has used a decent calculator and if he has oversized it by 4/5/6/ KW wahts the drama? It will still modulate down to under 10
OP the viessmann 100 26KW system boiler is really good , so another one for you to look at!
OP the viessmann 100 26KW system boiler is really good , so another one for you to look at!
i changed the settings to -1 and it came down to 25kw with the hw calculated in , I could then get away with a 26kw system boiler with lower modulation would this be better or am i opening up a can of worms with this argument . obviously i will go with my installers reccomendations , but i know he hasn,t calculated the house heat loss to this amount of detail as he didn,t have all the details i used with the stars prog. i also don,t want to be cold if we have another winter like this one .
I am a keen exponent of boilers which modulate down to be able to continue to run most of the time without having to resort to cycling as thats more efficient and better for the boiler.
But rather than oversizing the boiler and trying to find one that modulates more then 3:1 its better in my view to correctly size the boiler in the first place.
Tony
But rather than oversizing the boiler and trying to find one that modulates more then 3:1 its better in my view to correctly size the boiler in the first place.
Tony
I Agree if we are talking 15kw to a 30kw but 20 to 25? come on Tony, why don't you hold your hands up and say ' ok i agree, that boiler will work fine on your system'?
You know you are wrong but its killing you a mere householder can work this out.....
You know you are wrong but its killing you a mere householder can work this out.....
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