100KW gas boiler for domestic install!

[lame plumber]

5 beds = lots of people potential a combi would not be my choice and remember a domestic installer only goes to 70kw max so are you thinking you reallyneed a commercial size boiler!! get more quotes and give your plans to a merchant and they will estimate rad sizing and boiler size you need to check against your installers quote.

 

[Roger Welton]

Ding, even if a combi was OK to do the hot water flow requirements first thing in the morning when 5 bedrooms worth of people are washing, and getting ready it won't have much time to be heating the house.

 

[Dannypipe]

I suggest you do some rough heat loss size calcs yourself.

I frankly can't be bothered to go through the list you gave us and do it (long day) but why don't you take advantage of online boiler calulators and check his calculations.

100KW is a lot. You would almost certainly cascade two boilers, with a low loss header, and several zones off the LLH.

But if it's 100KW it's not domestic. We can work up to 70KW.

I've put some big systems in. Biggest has been oil installation with two cascaded/sequenced 50KW boilers. The house was MASSIVE.

Like a mansion massive.

 

[Howsie]

Sounds wrong to me. How did you find this installer? Get a couple of quotes if I were you.

 

[R1CKY]

No way in hell do you need a 100KW boiler! Hard to say without seeing the property and I haven't looked at the measurments, but I'd guess a 30KW system boiler with an Unvented Cylinder would be sufficient!

 

[infromthecold]

I suggest you do some rough heat loss size calcs yourself.

Thanks for replying. I've used many of the online calculators, even used formulas in excel and can only ever come up with around 25-26KW for central heating requirement.
Seems that the replies you guys have been giving me point toward what the installer says is not correct.

Cheers

 

[Dannypipe]

Right.

In which case, you already know what to do, get another installer in and don't use that guy!!

100KW boiler when you need a 30KW at most....actually funny. Imagine if he fitted it!!!

Anyway, good luck with and welcome to the forum. Come back for any other help we can give.

 

[infromthecold]

Trouble is he has started the job. Hanged the rads and laid pipe. Now is saying the boiler needs to be bigger than originally thought following a discussion with Worcester.

Looks like I have an argument about to start :disappointed:

 

[snowhead]

Trouble is he has started the job. Hanged the rads and laid pipe. Now is saying the boiler needs to be bigger than originally thought following a discussion with Worcester.

Looks like I have an argument about to start :disappointed:

Ring Worcester yourself.

 

[Dannypipe]

Oh.

He's had to have a chat with Worcester to size up the boiler. Alarm bells are ringing!

Well good luck in your negotiations. You have every right to ask why he didn't size it correctly in the first instance.

What size was the old boiler? That may have given him a rough clue! Not that most experienced guys use the old boiler as a benchmark for the new boiler. Instead they prefer to do their own calcs. But it is a start point.