need advice on fitting combi boiler

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Hi Folks,

Single dad in Edinburgh trying to do as much as I can myself, I have to replace my existing system that has an old Baxi boiler with the separate hot water tank upstairs, taking up room. there is a large cold water tank to feed it in the attic, I guess it is a familiar old system.
I want to put in a good quality combi boiler, that can heat a bath of water easy. First, any make model to suggest? can anyone offer basic guidance on how much of the old system I need to keep, apart from the cold water mains of course.
I had thought to place it in the attic with a remote control panel but is it better to be in the kitchen where I can vent out easy, I could benefit from extra space but ease of use and maintenance is more important.
Basically I need some advice so I can do as much of this rip out and install as poss before having it finished or checked by a plumber.
Thanks for reading
 
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The the customer most important part of replacing any boiler is finding a good gas safe registered heating installer.

I can't stress enough you should find the installer before you start the work - agree with him what you will do and the new location of everything. Otherwise you could find yourself doing stuff that needs to be changed.

About what boiler - even on a budget do not go for cheapest. I recommend looking at what the manufacturer offers - good website is a good sign! Do they have their own team of engineers to do call outs? Is it easy to find a number for technical queries and when you phone it does any one answer.

What guarantee do the manufacturers offer? 2 years should be minimum but increasingly they are moving to 5 years parts and labour.

Our company would usually go for Worcester Bosch, or Remeha/ Baxi Potterton (all same group). But there are other good makes.

You must have good mains water pressure for a combi - 2 to 3 bar is best.
 
Combis are great for showers, not so hot (pun intended) for filling baths.
Some can take all weekend to fill a bath with reasonably hot water.

I've had 2. Both were the same when it came to filling a bath. One was a Glowworm, I can't remember what make the other was.
 
Thanks,

Will need plenty hot water for baths so maybe a combi boiler is useless for me, I was worried about that poor side of them..
 
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Just done a bit a research and basic maths:-

The typical capacity of a standard 1700x700 bath is between 175-210 litres to overflow

A reasonable combi with a flow rate of 10 l/min would fill (say) a 200 l bath in 20 mins. A very good one @ 15 l/min would fill it in 13.3 minutes.

More of a consideration is the dynamic flow rate from your mains water supply. 20 l/min @ 1bar being the recommended minimum for an unvented hot water installation. Even this would take 10 minutes.

However the above times are hot water only and to overflow. Most people only half fill the bath and use a mixture of both hot & cold.

So if we said half full, 50/50 hot and cold with a total flow rate of 20 l/min = 5 minutes; even with a reasonable combi. Not exactly a weekend.
 
Our company would usually go for Worcester Bosch, or Remeha/ Baxi Potterton (all same group). But there are other good makes.

You must have good mains water pressure for a combi - 2 to 3 bar is best.

Many would say there are BETTER boilers than those quoted!

Mains water pressure on its own is almost irrelevant. Its the dynamic flow rate thats important! Back to college?

The OP could learn to use showers, they can use less water, they are quicker and many say cleaner.

The traditional water volume for a bath is about 75 litres, thats for a practical bath depth and not a "filmstar" bath up to the overflow!

Tony
 
I have a 37cdi which gives a great shower, for as long as I want. However, it is slower than the old OV cylinder at filling my bath.

Still waiting ben....
 
I have a 37cdi which gives a great shower, for as long as I want. However, it is slower than the old OV cylinder at filling my bath.

Still waiting ben....


Maybe a combi's a bit slower but you aint gonna leave it filling the bath then go back and found its run out of hot water and cold's running in to the bath.................and you can fill a bath to the top with hot water froma combi
try doing that with a cylinder .......you cant.

But each job to its own and sometimes cylinders are the best option, just not always.

Bens on his hoss !
:LOL:
 
Why is that post wrong?

No need for the question , we all know that Charnwoods post was not 'wrong' , a simple question of someone getting out the wrong side of the bed this morning/afternoon. :mrgreen:..................but we all know Bengasser will come back with something. ;)

Would i ever install a combi in my own house? nooooooooooooooooooo....
 
I have a 37cdi which gives a great shower, for as long as I want. However, it is slower than the old OV cylinder at filling my bath.
Still waiting ben....
If you insist..... :rolleyes:

( Decent ) combi will fill a bath just as surely as a cylinder, just a bit slower. Bearing in mind that nobody in his right mind is standing next to the batch waiting til it's full whilst twiddling his thumbs, it makes no difference whether it takes 4 or 8 minutes.
What combi offers that ov cylinder doesn't is:
2nd, 3rd and 4th bath even if you forget turning the timer on.
Legionella-free water; contaminated cylinder water used to be #1 source of legionaires disease when we still all had open vents.
 
bengasman";p="2079729 said:
Legionella-free water; contaminated cylinder water used to be #1 source of legionaires disease when we still all had open vents.

Been in the trade for 35 years & NEVER come across this , most open vented cylinders were heated via gravity fed primaries where water was heated to a minimum of 70K with hot water being drawn off every day. ;)
 
Way I see it most houses , have legoinella bugs floating around some where ( maybe ?)
 

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