100KW gas boiler for domestic install!

[infromthecold]

Hi All

New member and first post.

I'm not in the trade so hoping folks on here with all the knowledge can assist.

Got 5 bed detached Victorian house that has no central heating so in process of getting boiler and rads spec'd.

Have been told that will need a 100kw boiler and that this boiler will need a a larger gas supply pipe even though there is 22mm already.
Was hoping for a combi as there is only one bathroom with shower over bath.
Room sizes (in metres) are listed below, All double glazed with solid walls but I calculate heat requirement at 25KW so where the 100KW comes from I have no idea hence this post. All the on-line calculators I have used are all coming in around 25 - 26 KW for heating.

Hope someone can help or offer advice. I would think 100KW is large enough for a school or factory or a 5 bed with 14/15 rads.

Cheers

Room H, W, D
Living Room 3.1, 5.49, 4.88
Sitting Room 3.1, 4.22, 3.91
Dining Room 3.1, 3.23, 3.12
Kitchen 3.1, 5.18, 4.47
Bed 1 3.1, 4.42, 3.2
Bed 2 3.1, 4.42, 2.29
Bed 3 3.1, 7.21, 3.56
Bed 4 3.1, 3.86, 3.23
Bed 5 3.1, 4.27, 4.11
Bath 3.1, 4.42, 3

 

[vern]

Assuming U6 meter STOP YOUR GAS METER WILL ONLY PASS 62 kw absolute max, fires, cookers etc will take this away from the boiler available kw rating too, not even worked it out but would be very surprised if a 30 or 40 kw boiler did not suit you.

 

[Reltub]

Get a 40kw combi

 

[REDSAW]

what has the heating installer quoted for the requirement?

 

[Billy Bob Bob]

wheres that piccie of a 100 kw combi on the wall in a 3 bed house LOL

 

[Billy Bob Bob]

SURE ITS NOT A 100,000 BTU boiler you have been told to get?

 

[Rickster123]

Vaillant ecotec plus 837. May well require a 28mm gas run depending on distance.

You sure you want a combi tho??

 

[vern]

SURE ITS NOT A 100,000 BTU boiler you have been told to get?

Yep more like it Mark good thinking, maybe the installer still works in "old money"

 

[infromthecold]

thanks for all replies so far.
I asked if it was BTU but was told no it is 100KW!

Was hoping combi would suit but not against system boiler with unvented cylinder.

Main objectives are not to get fleeced, not to have supply pipe changed or have something that takes have the gas piped into town

 

[Rickster123]

System boiler and unvented. Every day! You won't regret it.

 

[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.

 

[Dannypipe]

By old boiler I mean the original one, on the old system.

 

[Dannypipe]

Sorry, just re-read your first post. It didn't have any heating right?

 

[Dotty]

Double check his gsr card. As stated previously if he only has domestic he cannot fit a 100kw boiler.

 

[infromthecold]

Sorry, just re-read your first post. It didn't have any heating right?

boiler had been previously removed and have no knowledge of what it was, All I have to go on is standard meter with 22mm pipe so that must have been enough for previous install. This is a house I have just bought and am trying to get so can move in.

 

[R1CKY]

What van does he have? I bet its a Berlingo with a 6.2 V12!

 

[snowhead]

Replacement Boiler Size Calculator

Using the above you don't need room sizes, just outside wall sizes.

If you oversize it, use all the worst window and insulation choices, pick Scotland as location, it comes in at 40kw.

To get 100kw you need a 20mtr square, 4mtr ceiling, 2 storey metal single glazed, flat roof building in Scotland with 15kw allowance for water.

 

[Dannypipe]

OK, this might not be helpful, but here's some laymans terms

Victorian, converted train station. New boiler (30KW)




Very large (modern) country house. 70KW (Two, sequenced, low loss header and zoned).


Tudor house, large - 45/50 KW (single boiler, zoned)

Internal, of tudor house, showing the manifold and zones.

1970's (ultra modern for the time) house. Two cascaded boilers, on a low loss header. With an additional boiler for the pool. Can't remember sizes, but no where near 100KW. Think about 50KW in total, but split over two boilers and sequenced to reduce wear and tear.

I know these are just photos but it shows you what 100KW's is in laymans terms.

 

[infromthecold]

thanks very much for that. certainly puts it into perspective. very impressive installs!

 

[Dannypipe]

No problem. I haven't shown the installs, really. But I think it puts 100KW into perspective, so you can weigh it up against your own property and see if your installer is talking any sense.

Remember Worcester will be quite happy to sell you a bigger boiler. It's the installers job to specify it, not theres.

 

[lame plumber]

how did you get all that lot in your van! tidy work old son pat on back time

 

[Dannypipe]

LOL! Thanks. Now you see why I need a bigger van.

It's not just my work. The guys I work with are brilliant, and know their stuff inside out.

 

[Deleted member 32524]

LOL 100kw!!

 

[Rob Sale]

he must mean 100'000 btu's

 

[stevetheplumber]

OK, this might not be helpful, but here's some laymans terms

Victorian, converted train station. New boiler (30KW)

View attachment 10687

View attachment 10688
Very large (modern) country house. 70KW (Two, sequenced, low loss header and zoned).

View attachment 10689
Tudor house, large - 45/50 KW (single boiler, zoned)

View attachment 10690Internal, of tudor house, showing the manifold and zones.
View attachment 10691
1970's (ultra modern for the time) house. Two cascaded boilers, on a low loss header. With an additional boiler for the pool. Can't remember sizes, but no where near 100KW. Think about 50KW in total, but split over two boilers and sequenced to reduce wear and tear.

I know these are just photos but it shows you what 100KW's is in laymans terms.

not bad for a monday what you got on tommorrow ?

 

[Dannypipe]

Got a bog to unblock Steve....and no gloves.