Another boiler question

heating-eng

ziggyman99 wrote: »

So a 15kW boiler is OK on 40m of 15mm pipe is it? ALL installations must be correctly sized for a working pressure of 19mb or higher. A blanket statement such as yours is completely incorrect and would be frowned upon by any Gas Safe inspector.

I'm new to gas which is why I probably do things correctly.

im not new to gas and been doing gas for 20 years and i didnt say 40m of gas would be ok please learn to read what people post before you comment

heating-eng

heating-eng wrote: »

it is always best to fit trv,s but you do not have to do it and there is nothing that says you do.

If the inlet to the boiler is 15mm then normally 15mm pipe will be ok as long as its not to far...your installer can check this to make sure..but you can normally run quite a bit of 15mm pipe on a 15kw boiler.
you are quoting a 831 combi this is totally different.

please read what i have put then go away and read up on a 15KW boiler and see if i have said something thats incorrect...

find out what normally means
And also ..as long as its not to far..
and also ...your installer can check this...

When you have been working on gas as long as me then come back and tell me i am wrong..

Gloomendoom

I'm no expert, but I always thought that it was the pressure drop at the boiler inlet that determined the supply pipe bore requirements.

I must admit that I am baffled as to why modern condensing boilers are so needy when it comes to the gas. My 30+ year old, and probably very inefficient, 35kw Potterton seems to function perfectly well on a long run of 15mm pipe.

gas4you

The inlet pressure of gas that is needed to make a particular boiler operate can be nothing like the regulations dictating the pressure drop allowed between the gas meter and each appliance.

Many years ago pipe sizing was not carried out as it is today. As long as a boiler worked it was deemed ok.

DVardysShadow

carly wrote: »

thanks very much, that is reassuring. We've never bothered with a TRV in the lounge because it's too flipping cold, faces north and the room is always the coldest in the house but it wouldnt be a big job to fit one

But then you would have TRVs on all rads. Not recommended unless there is a bypass in the system. I would put a thermostat in the room without TRVs - which is best if it is the coldest room, so your lounge would do - but if you upsize the rads there, then somewhere like a hall is good for a room stat - but best with an undersized rad.

Canucklehead

Gloomendoom;31319647]I'm no expert, but I always thought that it was the pressure drop at the boiler inlet that determined the supply pipe bore requirements.

That's part of the equation.

I must admit that I am baffled as to why modern condensing boilers are so needy when it comes to the gas.

A new boiler is no more needy than an old one.
Any boiler new, old ,condensing or not will not work to it's optimum if the gas supply is not as per the boiler specification.

My 30+ year old, and probably very inefficient, 35kw Potterton seems to function perfectly well on a long run of 15mm pipe.

Test and measurement will be a much more accurate method rather than 'seems to function perfectly well';).

GSR.

storm_6000

Yes its always best to fit TRV's they allow more control over your heating system. I'm afraid i don't know about boilers

ziggyman99

heating-eng wrote: »

can you explain where it is divided ???
the post asks about a 15KW boiler from what i have read i might be wrong..

but 15kw only needs 15mm gas.. i used to train BG engineers on pipe sizing for many years so i no all about pipe sizing ..Thanks

I don't care if you have been in the industry 20 years, your wrong. You cannot make sweeping statements such as "but 15kw only needs 15mm gas".
Apologies for raking up an old thread but just read it.

ziggyman99

heating-eng wrote: »

please read what i have put then go away and read up on a 15KW boiler and see if i have said something thats incorrect...

find out what normally means
And also ..as long as its not to far..
and also ...your installer can check this...

When you have been working on gas as long as me then come back and tell me i am wrong..

I'm telling you your wrong. I don't need to wait 20 years. "Normally", "as long as its not too far". I haven't read anything about using wishy washy methods to pipe size in any of my training books.

heating-eng

I will try and explain .
Normally if you need a 15kw the house is quite small and normally you wouldnt need a bigger gas pipe.
I have never needed a pipe bigger than 15mm in all the years of fitting boilers and also when doing training.
It could be possible that a bigger pipe would be needed but that is why we would pipe size each job to find out.
Hope this helps