boiler output size (b.t.u.)

[clarky]

I have recently converted my attic into a bedroom,and now want to install central heating up there,to do this i need to replace my conventional boiler for a combi,but i'm not sure as to what size output of boiler yo get, that will run 10 radiaters over three levels, without putting to much "strain on the boiler.
if anyone could help or offer advice it would be most appreciated.
clarky

 

[breezer]

dont. get a corgi registered person in.

You are not allowed to touch gas, and as for the plumbing, (you doing it) would you finish a job some one else started, then put your name to it?

Quite often this question is asked and most answers are the same as above.

How ever I have an idea, why not find some one to do it for you FIRST, and ask what they will let you do (if any thing) they may let you buy the materials and do the donkey work. As i said at the end of the day they have to put their name to what YOU have done

you may also want to read this from this forum, particularly last few posts

 

[clarky]

you mis-understand i dont want to do the work myself, i only want to know what output size of boiler, because i will be purchasing the bolier
clarky

 

[breezer]

fair point, but also you should still find a corgi person first, you may get brand x only to find no one will install it because they are "alkward" the boiler not the corgi person

 

[oilman]

You don't NEED to fit a combi. If you can't get the feed and expansion tank up high enough, you only need to convert it to a sealed system, and you can probbly keep the same boiler. It is unlikely to "strain it", industrial boilers are not much different, but they are sized so that one half of a two stage burner is on almost all of the time to balance the normal continuous heating load. You may need to look at the pump as well.

 

[ollski]

I may be wrong but i would guess that if you are feeding 10 rads you probably have a fairly big house and probably a family using more than one bathroom. If this is the way it is then a combi will be no use to you as it won,t be able to feed the hot water you'll need. A combi is basically an overgrown electric shower in that it heats the water directly as you know and if you start running lots of hot water draw offs there will be no hot water pressure to go round, especially if you are running washing machines / dishwashers a lot

 

[Goofyish]

I wouldn't have thought the hot water load would be that great - most dishwashers are cold fill only, and if you do most of your clothes washing at 40 deg.C then your washing machine will only use the cold fill too.

So only hot water use would be baths, power shower (if not go an electric), and the odd bit of non-disher washer washing up.

Isn't it a case of adding the btu value of each radiator in the house to get the required boiler size?

 

[clarky]

cheers everbody for the help and advice, i've now all the info i need,
once again thanks.
clarky

 

[masona]

Isn't it a case of adding the btu value of each radiator in the house to get the required boiler size?

That what I thought,I've spoken to my plumber mate of mine and he now putting in a lower btu output boiler as he find it more economical than a bigger btu boiler as the boiler come on more regular in short time rather than the boiler is on longer time.

hmmmm ! this should be interesting to see what the others plumber's guru think

 

[ollski]

I wouldn't have thought the hot water load would be that great - most dishwashers are cold fill only, and if you do most of your clothes washing at 40 deg.C then your washing machine will only use the cold fill too.

So only hot water use would be baths, power shower (if not go an electric), and the odd bit of non-disher washer washing up.

Isn't it a case of adding the btu value of each radiator in the house to get the required boiler size?

But is it worth compromising all these things just so you can get a combi put in?...the main reason combis took off was because they are so easy to install not because they have any operational benefits for customers (unless of course space is really tight). I mean a house with 2 bathrooms and say 3 or 4 teenage kids in the middle of winter will constantly freezing due to the heating shutting off whenever the hot water is used. small houses with low hot water demand fine, otherwise forget combis that's all i mean.

btu wise yes that's about all there is to it.....maybe leave a little in reserve for future expansion.

 

[masona]

Have to agreed with ollski regarding combi boiler,a plumber friend of mine always put in combi if he can as it's easier for him to install & regardless what the water pressure is which combi relied on,let alone what the owner want,sad isn't it.......Read this from my previous post..

If you look on this forum 90% boiler problems are combi.They were ordinary design for tower block flats with no loft space for water tank & space saving for cylinder,then started to installed them in bungalow and then onto family 3-4 bedroom property.My potterson floorstanding boiler is still going strong after 23 years compare with combi lasting according to this forum 7-8 years.My parent have a valliant boiler which take 15 minutes to fill up the bath because of low water pressure and has broken down 4 times in 3 years.If you listen to everybody opinions you wouldn't buy nothing ! Don't let me put you off buying a combi as they are getting better all the time,I probably will buy a combi next time but personally I don't think the combi manufacter have got it quite right yet but they are economical and some happy combi owners out there.This is personally my own opinion.

 

[corgiman]

ahh nuts to that pop a fully modulating 30 to 80 boiler in

Only joking

get some in who knows there way around a MEARS calculator and she be right